Natural-Language
stringlengths 13
387
| Bash-Command
stringlengths 1
532
| Linux-Utilities
stringlengths 5
54
| Base-Finetune
stringlengths 108
1.01k
| TLDR-Finetune
stringlengths 313
7.3k
| Manual-Page-Finetune
stringlengths 861
969k
|
---|---|---|---|---|---|
Create a compressed archive of "/home" and split the contents into files with at most 4000 MiB each and use prefix "/media/DRIVENAME/BACKUPNAME.tgz" | tar --one-file-system -czv /home | split -b 4000m - /media/DRIVENAME/BACKUPNAME.tgz | ['tar', 'split'] | Output a Bash command to accomplish the following task. Task: Create a compressed archive of "/home" and split the contents into files with at most 4000 MiB each and use prefix "/media/DRIVENAME/BACKUPNAME.tgz" Bash Command:<START>tar --one-file-system -czv /home | split -b 4000m - /media/DRIVENAME/BACKUPNAME.tgz<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # tar\n\n> Archiving utility.\n> Often combined with a compression method, such as `gzip` or `bzip2`.\n> More information: <https://www.gnu.org/software/tar>.\n\n- [c]reate an archive and write it to a [f]ile:\n\n`tar cf {{path/to/target.tar}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive and write it to a [f]ile:\n\n`tar czf {{path/to/target.tar.gz}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive from a directory using relative paths:\n\n`tar czf {{path/to/target.tar.gz}} --directory={{path/to/directory}} .`\n\n- E[x]tract a (compressed) archive [f]ile into the current directory [v]erbosely:\n\n`tar xvf {{path/to/source.tar[.gz|.bz2|.xz]}}`\n\n- E[x]tract a (compressed) archive [f]ile into the target directory:\n\n`tar xf {{path/to/source.tar[.gz|.bz2|.xz]}} --directory={{path/to/directory}}`\n\n- [c]reate a compressed archive and write it to a [f]ile, using the file extension to [a]utomatically determine the compression program:\n\n`tar caf {{path/to/target.tar.xz}} {{path/to/file1 path/to/file2 ...}}`\n\n- Lis[t] the contents of a tar [f]ile [v]erbosely:\n\n`tar tvf {{path/to/source.tar}}`\n\n- E[x]tract files matching a pattern from an archive [f]ile:\n\n`tar xf {{path/to/source.tar}} --wildcards "{{*.html}}"`\n # split\n\n> Split a file into pieces.\n> More information: <https://www.gnu.org/software/coreutils/split>.\n\n- Split a file, each split having 10 lines (except the last split):\n\n`split -l {{10}} {{path/to/file}}`\n\n- Split a file into 5 files. File is split such that each split has same size (except the last split):\n\n`split -n {{5}} {{path/to/file}}`\n\n- Split a file with 512 bytes in each split (except the last split; use 512k for kilobytes and 512m for megabytes):\n\n`split -b {{512}} {{path/to/file}}`\n\n- Split a file with at most 512 bytes in each split without breaking lines:\n\n`split -C {{512}} {{path/to/file}}`\n Task: Create a compressed archive of "/home" and split the contents into files with at most 4000 MiB each and use prefix "/media/DRIVENAME/BACKUPNAME.tgz" Bash Command:<START>tar --one-file-system -czv /home | split -b 4000m - /media/DRIVENAME/BACKUPNAME.tgz<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: tar(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training tar(1) Linux manual page NAME | SYNOPSIS | NOTE | DESCRIPTION | OPTIONS | RETURN VALUE | SEE ALSO | BUG REPORTS | COPYRIGHT | COLOPHON TAR(1) GNU TAR Manual TAR(1) NAME top tar - an archiving utility SYNOPSIS top Traditional usage tar {A|c|d|r|t|u|x}[GnSkUWOmpsMBiajJzZhPlRvwo] [ARG...] UNIX-style usage tar -A [OPTIONS] -f ARCHIVE ARCHIVE... tar -c [-f ARCHIVE] [OPTIONS] [FILE...] tar -d [-f ARCHIVE] [OPTIONS] [FILE...] tar -r [-f ARCHIVE] [OPTIONS] [FILE...] tar -t [-f ARCHIVE] [OPTIONS] [MEMBER...] tar -u [-f ARCHIVE] [OPTIONS] [FILE...] tar -x [-f ARCHIVE] [OPTIONS] [MEMBER...] GNU-style usage tar {--catenate|--concatenate} [OPTIONS] --file ARCHIVE ARCHIVE... tar --create [--file ARCHIVE] [OPTIONS] [FILE...] tar {--diff|--compare} [--file ARCHIVE] [OPTIONS] [FILE...] tar --delete [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --append [--file ARCHIVE] [OPTIONS] [FILE...] tar --list [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --test-label [--file ARCHIVE] [OPTIONS] [LABEL...] tar --update [--file ARCHIVE] [OPTIONS] [FILE...] tar {--extract|--get} [--file ARCHIVE] [OPTIONS] [MEMBER...] NOTE top This manpage is a short description of GNU tar. For a detailed discussion, including examples and usage recommendations, refer to the GNU Tar Manual available in texinfo format. If the info reader and the tar documentation are properly installed on your system, the command info tar should give you access to the complete manual. You can also view the manual using the info mode in emacs(1), or find it in various formats online at https://www.gnu.org/software/tar/manual If any discrepancies occur between this manpage and the GNU Tar Manual, the later shall be considered the authoritative source. DESCRIPTION top GNU tar is an archiving program designed to store multiple files in a single file (an archive), and to manipulate such archives. The archive can be either a regular file or a device (e.g. a tape drive, hence the name of the program, which stands for tape archiver), which can be located either on the local or on a remote machine. Option styles Options to GNU tar can be given in three different styles. In traditional style, the first argument is a cluster of option letters and all subsequent arguments supply arguments to those options that require them. The arguments are read in the same order as the option letters. Any command line words that remain after all options have been processed are treated as non-option arguments: file or archive member names. For example, the c option requires creating the archive, the v option requests the verbose operation, and the f option takes an argument that sets the name of the archive to operate upon. The following command, written in the traditional style, instructs tar to store all files from the directory /etc into the archive file etc.tar, verbosely listing the files being archived: tar cfv etc.tar /etc In UNIX or short-option style, each option letter is prefixed with a single dash, as in other command line utilities. If an option takes an argument, the argument follows it, either as a separate command line word, or immediately following the option. However, if the option takes an optional argument, the argument must follow the option letter without any intervening whitespace, as in -g/tmp/snar.db. Any number of options not taking arguments can be clustered together after a single dash, e.g. -vkp. An option that takes an argument (whether mandatory or optional) can appear at the end of such a cluster, e.g. -vkpf a.tar. The example command above written in the short-option style could look like: tar -cvf etc.tar /etc or tar -c -v -f etc.tar /etc In GNU or long-option style, each option begins with two dashes and has a meaningful name, consisting of lower-case letters and dashes. When used, the long option can be abbreviated to its initial letters, provided that this does not create ambiguity. Arguments to long options are supplied either as a separate command line word, immediately following the option, or separated from the option by an equals sign with no intervening whitespace. Optional arguments must always use the latter method. Here are several ways of writing the example command in this style: tar --create --file etc.tar --verbose /etc or (abbreviating some options): tar --cre --file=etc.tar --verb /etc The options in all three styles can be intermixed, although doing so with old options is not encouraged. Operation mode The options listed in the table below tell GNU tar what operation it is to perform. Exactly one of them must be given. The meaning of non-option arguments depends on the operation mode requested. -A, --catenate, --concatenate Append archives to the end of another archive. The arguments are treated as the names of archives to append. All archives must be of the same format as the archive they are appended to, otherwise the resulting archive might be unusable with non-GNU implementations of tar. Notice also that when more than one archive is given, the members from archives other than the first one will be accessible in the resulting archive only when using the -i (--ignore-zeros) option. Compressed archives cannot be concatenated. -c, --create Create a new archive. Arguments supply the names of the files to be archived. Directories are archived recursively, unless the --no-recursion option is given. -d, --diff, --compare Find differences between archive and file system. The arguments are optional and specify archive members to compare. If not given, the current working directory is assumed. --delete Delete from the archive. The arguments supply names of the archive members to be removed. At least one argument must be given. This option does not operate on compressed archives. There is no short option equivalent. -r, --append Append files to the end of an archive. Arguments have the same meaning as for -c (--create). -t, --list List the contents of an archive. Arguments are optional. When given, they specify the names of the members to list. --test-label Test the archive volume label and exit. When used without arguments, it prints the volume label (if any) and exits with status 0. When one or more command line arguments are given. tar compares the volume label with each argument. It exits with code 0 if a match is found, and with code 1 otherwise. No output is displayed, unless used together with the -v (--verbose) option. There is no short option equivalent for this option. -u, --update Append files which are newer than the corresponding copy in the archive. Arguments have the same meaning as with the -c and -r options. Notice, that newer files don't replace their old archive copies, but instead are appended to the end of archive. The resulting archive can thus contain several members of the same name, corresponding to various versions of the same file. -x, --extract, --get Extract files from an archive. Arguments are optional. When given, they specify names of the archive members to be extracted. --show-defaults Show built-in defaults for various tar options and exit. -?, --help Display a short option summary and exit. --usage Display a list of available options and exit. --version Print program version and copyright information and exit. OPTIONS top Operation modifiers --check-device Check device numbers when creating incremental archives (default). -g, --listed-incremental=FILE Handle new GNU-format incremental backups. FILE is the name of a snapshot file, where tar stores additional information which is used to decide which files changed since the previous incremental dump and, consequently, must be dumped again. If FILE does not exist when creating an archive, it will be created and all files will be added to the resulting archive (the level 0 dump). To create incremental archives of non-zero level N, you need a copy of the snapshot file created for level N-1, and use it as FILE. When listing or extracting, the actual content of FILE is not inspected, it is needed only due to syntactical requirements. It is therefore common practice to use /dev/null in its place. --hole-detection=METHOD Use METHOD to detect holes in sparse files. This option implies --sparse. Valid values for METHOD are seek and raw. Default is seek with fallback to raw when not applicable. -G, --incremental Handle old GNU-format incremental backups. --ignore-failed-read Do not exit with nonzero on unreadable files. --level=NUMBER Set dump level for a created listed-incremental archive. Currently only --level=0 is meaningful: it instructs tar to truncate the snapshot file before dumping, thereby forcing a level 0 dump. -n, --seek Assume the archive is seekable. Normally tar determines automatically whether the archive can be seeked or not. This option is intended for use in cases when such recognition fails. It takes effect only if the archive is open for reading (e.g. with --list or --extract options). --no-check-device Do not check device numbers when creating incremental archives. --no-seek Assume the archive is not seekable. --occurrence[=N] Process only the Nth occurrence of each file in the archive. This option is valid only when used with one of the following subcommands: --delete, --diff, --extract or --list and when a list of files is given either on the command line or via the -T option. The default N is 1. --restrict Disable the use of some potentially harmful options. --sparse-version=MAJOR[.MINOR] Set which version of the sparse format to use. This option implies --sparse. Valid argument values are 0.0, 0.1, and 1.0. For a detailed discussion of sparse formats, refer to the GNU Tar Manual, appendix D, "Sparse Formats". Using the info reader, it can be accessed running the following command: info tar 'Sparse Formats'. -S, --sparse Handle sparse files efficiently. Some files in the file system may have segments which were actually never written (quite often these are database files created by such systems as DBM). When given this option, tar attempts to determine if the file is sparse prior to archiving it, and if so, to reduce the resulting archive size by not dumping empty parts of the file. Overwrite control These options control tar actions when extracting a file over an existing copy on disk. -k, --keep-old-files Don't replace existing files when extracting. --keep-newer-files Don't replace existing files that are newer than their archive copies. --keep-directory-symlink Don't replace existing symlinks to directories when extracting. --no-overwrite-dir Preserve metadata of existing directories. --one-top-level[=DIR] Extract all files into DIR, or, if used without argument, into a subdirectory named by the base name of the archive (minus standard compression suffixes recognizable by --auto-compress). --overwrite Overwrite existing files when extracting. --overwrite-dir Overwrite metadata of existing directories when extracting (default). --recursive-unlink Recursively remove all files in the directory prior to extracting it. --remove-files Remove files from disk after adding them to the archive. --skip-old-files Don't replace existing files when extracting, silently skip over them. -U, --unlink-first Remove each file prior to extracting over it. -W, --verify Verify the archive after writing it. Output stream selection --ignore-command-error Ignore subprocess exit codes. --no-ignore-command-error Treat non-zero exit codes of children as error (default). -O, --to-stdout Extract files to standard output. --to-command=COMMAND Pipe extracted files to COMMAND. The argument is the pathname of an external program, optionally with command line arguments. The program will be invoked and the contents of the file being extracted supplied to it on its standard input. Additional data will be supplied via the following environment variables: TAR_FILETYPE Type of the file. It is a single letter with the following meaning: f Regular file d Directory l Symbolic link h Hard link b Block device c Character device Currently only regular files are supported. TAR_MODE File mode, an octal number. TAR_FILENAME The name of the file. TAR_REALNAME Name of the file as stored in the archive. TAR_UNAME Name of the file owner. TAR_GNAME Name of the file owner group. TAR_ATIME Time of last access. It is a decimal number, representing seconds since the Epoch. If the archive provides times with nanosecond precision, the nanoseconds are appended to the timestamp after a decimal point. TAR_MTIME Time of last modification. TAR_CTIME Time of last status change. TAR_SIZE Size of the file. TAR_UID UID of the file owner. TAR_GID GID of the file owner. Additionally, the following variables contain information about tar operation mode and the archive being processed: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. Handling of file attributes --atime-preserve[=METHOD] Preserve access times on dumped files, either by restoring the times after reading (METHOD=replace, this is the default) or by not setting the times in the first place (METHOD=system). --delay-directory-restore Delay setting modification times and permissions of extracted directories until the end of extraction. Use this option when extracting from an archive which has unusual member ordering. --group=NAME[:GID] Force NAME as group for added files. If GID is not supplied, NAME can be either a user name or numeric GID. In this case the missing part (GID or name) will be inferred from the current host's group database. When used with --group-map=FILE, affects only those files whose owner group is not listed in FILE. --group-map=FILE Read group translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single group. It must consist of two fields, delimited by any amount of whitespace: OLDGRP NEWGRP[:NEWGID] OLDGRP is either a valid group name or a GID prefixed with +. Unless NEWGID is supplied, NEWGRP must also be either a valid group name or a +GID. Otherwise, both NEWGRP and NEWGID need not be listed in the system group database. As a result, each input file with owner group OLDGRP will be stored in archive with owner group NEWGRP and GID NEWGID. --mode=CHANGES Force symbolic mode CHANGES for added files. --mtime=DATE-OR-FILE Set mtime for added files. DATE-OR-FILE is either a date/time in almost arbitrary format, or the name of an existing file. In the latter case the mtime of that file will be used. -m, --touch Don't extract file modified time. --no-delay-directory-restore Cancel the effect of the prior --delay-directory-restore option. --no-same-owner Extract files as yourself (default for ordinary users). --no-same-permissions Apply the user's umask when extracting permissions from the archive (default for ordinary users). --numeric-owner Always use numbers for user/group names. --owner=NAME[:UID] Force NAME as owner for added files. If UID is not supplied, NAME can be either a user name or numeric UID. In this case the missing part (UID or name) will be inferred from the current host's user database. When used with --owner-map=FILE, affects only those files whose owner is not listed in FILE. --owner-map=FILE Read owner translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single UID. It must consist of two fields, delimited by any amount of whitespace: OLDUSR NEWUSR[:NEWUID] OLDUSR is either a valid user name or a UID prefixed with +. Unless NEWUID is supplied, NEWUSR must also be either a valid user name or a +UID. Otherwise, both NEWUSR and NEWUID need not be listed in the system user database. As a result, each input file owned by OLDUSR will be stored in archive with owner name NEWUSR and UID NEWUID. -p, --preserve-permissions, --same-permissions Set permissions of extracted files to those recorded in the archive (default for superuser). --same-owner Try extracting files with the same ownership as exists in the archive (default for superuser). -s, --preserve-order, --same-order Tell tar that the list of file names to process is sorted in the same order as the files in the archive. --sort=ORDER When creating an archive, sort directory entries according to ORDER, which is one of none, name, or inode. The default is --sort=none, which stores archive members in the same order as returned by the operating system. Using --sort=name ensures the member ordering in the created archive is uniform and reproducible. Using --sort=inode reduces the number of disk seeks made when creating the archive and thus can considerably speed up archivation. This sorting order is supported only if the underlying system provides the necessary information. Extended file attributes --acls Enable POSIX ACLs support. --no-acls Disable POSIX ACLs support. --selinux Enable SELinux context support. --no-selinux Disable SELinux context support. --xattrs Enable extended attributes support. --no-xattrs Disable extended attributes support. --xattrs-exclude=PATTERN Specify the exclude pattern for xattr keys. PATTERN is a globbing pattern, e.g. --xattrs-exclude='user.*' to include only attributes from the user namespace. --xattrs-include=PATTERN Specify the include pattern for xattr keys. PATTERN is a globbing pattern. Device selection and switching -f, --file=ARCHIVE Use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable `TAPE'. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default. The default value can be inspected either using the --show-defaults option, or at the end of the tar --help output. An archive name that has a colon in it specifies a file or device on a remote machine. The part before the colon is taken as the machine name or IP address, and the part after it as the file or device pathname, e.g.: --file=remotehost:/dev/sr0 An optional username can be prefixed to the hostname, placing a @ sign between them. By default, the remote host is accessed via the rsh(1) command. Nowadays it is common to use ssh(1) instead. You can do so by giving the following command line option: --rsh-command=/usr/bin/ssh The remote machine should have the rmt(8) command installed. If its pathname does not match tar's default, you can inform tar about the correct pathname using the --rmt-command option. --force-local Archive file is local even if it has a colon. -F, --info-script=COMMAND, --new-volume-script=COMMAND Run COMMAND at the end of each tape (implies -M). The command can include arguments. When started, it will inherit tar's environment plus the following variables: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. TAR_FD File descriptor which can be used to communicate the new volume name to tar. If the info script fails, tar exits; otherwise, it begins writing the next volume. -L, --tape-length=N Change tape after writing Nx1024 bytes. If N is followed by a size suffix (see the subsection Size suffixes below), the suffix specifies the multiplicative factor to be used instead of 1024. This option implies -M. -M, --multi-volume Create/list/extract multi-volume archive. --rmt-command=COMMAND Use COMMAND instead of rmt when accessing remote archives. See the description of the -f option, above. --rsh-command=COMMAND Use COMMAND instead of rsh when accessing remote archives. See the description of the -f option, above. --volno-file=FILE When this option is used in conjunction with --multi-volume, tar will keep track of which volume of a multi-volume archive it is working in FILE. Device blocking -b, --blocking-factor=BLOCKS Set record size to BLOCKSx512 bytes. -B, --read-full-records When listing or extracting, accept incomplete input records after end-of-file marker. -i, --ignore-zeros Ignore zeroed blocks in archive. Normally two consecutive 512-blocks filled with zeroes mean EOF and tar stops reading after encountering them. This option instructs it to read further and is useful when reading archives created with the -A option. --record-size=NUMBER Set record size. NUMBER is the number of bytes per record. It must be multiple of 512. It can can be suffixed with a size suffix, e.g. --record-size=10K, for 10 Kilobytes. See the subsection Size suffixes, for a list of valid suffixes. Archive format selection -H, --format=FORMAT Create archive of the given format. Valid formats are: gnu GNU tar 1.13.x format oldgnu GNU format as per tar <= 1.12. pax, posix POSIX 1003.1-2001 (pax) format. ustar POSIX 1003.1-1988 (ustar) format. v7 Old V7 tar format. --old-archive, --portability Same as --format=v7. --pax-option=keyword[[:]=value][,keyword[[:]=value]]... Control pax keywords when creating PAX archives (-H pax). This option is equivalent to the -o option of the pax(1) utility. --posix Same as --format=posix. -V, --label=TEXT Create archive with volume name TEXT. If listing or extracting, use TEXT as a globbing pattern for volume name. Compression options -a, --auto-compress Use archive suffix to determine the compression program. -I, --use-compress-program=COMMAND Filter data through COMMAND. It must accept the -d option, for decompression. The argument can contain command line options. -j, --bzip2 Filter the archive through bzip2(1). -J, --xz Filter the archive through xz(1). --lzip Filter the archive through lzip(1). --lzma Filter the archive through lzma(1). --lzop Filter the archive through lzop(1). --no-auto-compress Do not use archive suffix to determine the compression program. -z, --gzip, --gunzip, --ungzip Filter the archive through gzip(1). -Z, --compress, --uncompress Filter the archive through compress(1). --zstd Filter the archive through zstd(1). Local file selection --add-file=FILE Add FILE to the archive (useful if its name starts with a dash). --backup[=CONTROL] Backup before removal. The CONTROL argument, if supplied, controls the backup policy. Its valid values are: none, off Never make backups. t, numbered Make numbered backups. nil, existing Make numbered backups if numbered backups exist, simple backups otherwise. never, simple Always make simple backups If CONTROL is not given, the value is taken from the VERSION_CONTROL environment variable. If it is not set, existing is assumed. -C, --directory=DIR Change to DIR before performing any operations. This option is order-sensitive, i.e. it affects all options that follow. --exclude=PATTERN Exclude files matching PATTERN, a glob(3)-style wildcard pattern. --exclude-backups Exclude backup and lock files. --exclude-caches Exclude contents of directories containing file CACHEDIR.TAG, except for the tag file itself. --exclude-caches-all Exclude directories containing file CACHEDIR.TAG and the file itself. --exclude-caches-under Exclude everything under directories containing CACHEDIR.TAG --exclude-ignore=FILE Before dumping a directory, see if it contains FILE. If so, read exclusion patterns from this file. The patterns affect only the directory itself. --exclude-ignore-recursive=FILE Same as --exclude-ignore, except that patterns from FILE affect both the directory and all its subdirectories. --exclude-tag=FILE Exclude contents of directories containing FILE, except for FILE itself. --exclude-tag-all=FILE Exclude directories containing FILE. --exclude-tag-under=FILE Exclude everything under directories containing FILE. --exclude-vcs Exclude version control system directories. --exclude-vcs-ignores Exclude files that match patterns read from VCS-specific ignore files. Supported files are: .cvsignore, .gitignore, .bzrignore, and .hgignore. -h, --dereference Follow symlinks; archive and dump the files they point to. --hard-dereference Follow hard links; archive and dump the files they refer to. -K, --starting-file=MEMBER Begin at the given member in the archive. --newer-mtime=DATE Work on files whose data changed after the DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --no-null Disable the effect of the previous --null option. --no-recursion Avoid descending automatically in directories. --no-unquote Do not unquote input file or member names. --no-verbatim-files-from Treat each line read from a file list as if it were supplied in the command line. I.e., leading and trailing whitespace is removed and, if the resulting string begins with a dash, it is treated as tar command line option. This is the default behavior. The --no-verbatim-files-from option is provided as a way to restore it after --verbatim-files-from option. This option is positional: it affects all --files-from options that occur after it in, until --verbatim-files-from option or end of line, whichever occurs first. It is implied by the --no-null option. --null Instruct subsequent -T options to read null-terminated names verbatim (disables special handling of names that start with a dash). See also --verbatim-files-from. -N, --newer=DATE, --after-date=DATE Only store files newer than DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --one-file-system Stay in local file system when creating archive. -P, --absolute-names Don't strip leading slashes from file names when creating archives. --recursion Recurse into directories (default). --suffix=STRING Backup before removal, override usual suffix. Default suffix is ~, unless overridden by environment variable SIMPLE_BACKUP_SUFFIX. -T, --files-from=FILE Get names to extract or create from FILE. Unless specified otherwise, the FILE must contain a list of names separated by ASCII LF (i.e. one name per line). The names read are handled the same way as command line arguments. They undergo quote removal and word splitting, and any string that starts with a - is handled as tar command line option. If this behavior is undesirable, it can be turned off using the --verbatim-files-from option. The --null option instructs tar that the names in FILE are separated by ASCII NUL character, instead of LF. It is useful if the list is generated by find(1) -print0 predicate. --unquote Unquote file or member names (default). --verbatim-files-from Treat each line obtained from a file list as a file name, even if it starts with a dash. File lists are supplied with the --files-from (-T) option. The default behavior is to handle names supplied in file lists as if they were typed in the command line, i.e. any names starting with a dash are treated as tar options. The --verbatim-files-from option disables this behavior. This option affects all --files-from options that occur after it in the command line. Its effect is reverted by the --no-verbatim-files-from option. This option is implied by the --null option. See also --add-file. -X, --exclude-from=FILE Exclude files matching patterns listed in FILE. File name transformations --strip-components=NUMBER Strip NUMBER leading components from file names on extraction. --transform=EXPRESSION, --xform=EXPRESSION Use sed replace EXPRESSION to transform file names. File name matching options These options affect both exclude and include patterns. --anchored Patterns match file name start. --ignore-case Ignore case. --no-anchored Patterns match after any / (default for exclusion). --no-ignore-case Case sensitive matching (default). --no-wildcards Verbatim string matching. --no-wildcards-match-slash Wildcards do not match /. --wildcards Use wildcards (default for exclusion). --wildcards-match-slash Wildcards match / (default for exclusion). Informative output --checkpoint[=N] Display progress messages every Nth record (default 10). --checkpoint-action=ACTION Run ACTION on each checkpoint. --clamp-mtime Only set time when the file is more recent than what was given with --mtime. --full-time Print file time to its full resolution. --index-file=FILE Send verbose output to FILE. -l, --check-links Print a message if not all links are dumped. --no-quote-chars=STRING Disable quoting for characters from STRING. --quote-chars=STRING Additionally quote characters from STRING. --quoting-style=STYLE Set quoting style for file and member names. Valid values for STYLE are literal, shell, shell-always, c, c-maybe, escape, locale, clocale. -R, --block-number Show block number within archive with each message. --show-omitted-dirs When listing or extracting, list each directory that does not match search criteria. --show-transformed-names, --show-stored-names Show file or archive names after transformation by --strip and --transform options. --totals[=SIGNAL] Print total bytes after processing the archive. If SIGNAL is given, print total bytes when this signal is delivered. Allowed signals are: SIGHUP, SIGQUIT, SIGINT, SIGUSR1, and SIGUSR2. The SIG prefix can be omitted. --utc Print file modification times in UTC. -v, --verbose Verbosely list files processed. Each instance of this option on the command line increases the verbosity level by one. The maximum verbosity level is 3. For a detailed discussion of how various verbosity levels affect tar's output, please refer to GNU Tar Manual, subsection 2.5.2 "The '--verbose' Option". --warning=KEYWORD Enable or disable warning messages identified by KEYWORD. The messages are suppressed if KEYWORD is prefixed with no- and enabled otherwise. Multiple --warning options accumulate. Keywords controlling general tar operation: all Enable all warning messages. This is the default. none Disable all warning messages. filename-with-nuls "%s: file name read contains nul character" alone-zero-block "A lone zero block at %s" Keywords applicable for tar --create: cachedir "%s: contains a cache directory tag %s; %s" file-shrank "%s: File shrank by %s bytes; padding with zeros" xdev "%s: file is on a different filesystem; not dumped" file-ignored "%s: Unknown file type; file ignored" "%s: socket ignored" "%s: door ignored" file-unchanged "%s: file is unchanged; not dumped" ignore-archive "%s: archive cannot contain itself; not dumped" file-removed "%s: File removed before we read it" file-changed "%s: file changed as we read it" failed-read Suppresses warnings about unreadable files or directories. This keyword applies only if used together with the --ignore-failed-read option. Keywords applicable for tar --extract: existing-file "%s: skipping existing file" timestamp "%s: implausibly old time stamp %s" "%s: time stamp %s is %s s in the future" contiguous-cast "Extracting contiguous files as regular files" symlink-cast "Attempting extraction of symbolic links as hard links" unknown-cast "%s: Unknown file type '%c', extracted as normal file" ignore-newer "Current %s is newer or same age" unknown-keyword "Ignoring unknown extended header keyword '%s'" decompress-program Controls verbose description of failures occurring when trying to run alternative decompressor programs. This warning is disabled by default (unless --verbose is used). A common example of what you can get when using this warning is: $ tar --warning=decompress-program -x -f archive.Z tar (child): cannot run compress: No such file or directory tar (child): trying gzip This means that tar first tried to decompress archive.Z using compress, and, when that failed, switched to gzip. record-size "Record size = %lu blocks" Keywords controlling incremental extraction: rename-directory "%s: Directory has been renamed from %s" "%s: Directory has been renamed" new-directory "%s: Directory is new" xdev "%s: directory is on a different device: not purging" bad-dumpdir "Malformed dumpdir: 'X' never used" -w, --interactive, --confirmation Ask for confirmation for every action. Compatibility options -o When creating, same as --old-archive. When extracting, same as --no-same-owner. Size suffixes Suffix Units Byte Equivalent b Blocks SIZE x 512 B Kilobytes SIZE x 1024 c Bytes SIZE G Gigabytes SIZE x 1024^3 K Kilobytes SIZE x 1024 k Kilobytes SIZE x 1024 M Megabytes SIZE x 1024^2 P Petabytes SIZE x 1024^5 T Terabytes SIZE x 1024^4 w Words SIZE x 2 RETURN VALUE top Tar's exit code indicates whether it was able to successfully perform the requested operation, and if not, what kind of error occurred. 0 Successful termination. 1 Some files differ. If tar was invoked with the --compare (--diff, -d) command line option, this means that some files in the archive differ from their disk counterparts. If tar was given one of the --create, --append or --update options, this exit code means that some files were changed while being archived and so the resulting archive does not contain the exact copy of the file set. 2 Fatal error. This means that some fatal, unrecoverable error occurred. If a subprocess that had been invoked by tar exited with a nonzero exit code, tar itself exits with that code as well. This can happen, for example, if a compression option (e.g. -z) was used and the external compressor program failed. Another example is rmt failure during backup to a remote device. SEE ALSO top bzip2(1), compress(1), gzip(1), lzma(1), lzop(1), rmt(8), symlink(7), xz(1), zstd(1). Complete tar manual: run info tar or use emacs(1) info mode to read it. Online copies of GNU tar documentation in various formats can be found at: https://www.gnu.org/software/tar/manual BUG REPORTS top Report bugs to <bug-tar@gnu.org>. COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. COLOPHON top This page is part of the tar (an archiver program) project. Information about the project can be found at http://savannah.gnu.org/projects/tar/. If you have a bug report for this manual page, see http://savannah.gnu.org/bugs/?group=tar. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/tar.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-09-12.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org TAR July 11, 2022 TAR(1) Pages that refer to this page: attr(1), dpkg-deb(1), dpkg-source(1), machinectl(1), rsync(1), st(4), suffixes(7), symlink(7), cupsd-helper(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. split(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training split(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON SPLIT(1) User Commands SPLIT(1) NAME top split - split a file into pieces SYNOPSIS top split [OPTION]... [FILE [PREFIX]] DESCRIPTION top Output pieces of FILE to PREFIXaa, PREFIXab, ...; default size is 1000 lines, and default PREFIX is 'x'. With no FILE, or when FILE is -, read standard input. Mandatory arguments to long options are mandatory for short options too. -a, --suffix-length=N generate suffixes of length N (default 2) --additional-suffix=SUFFIX append an additional SUFFIX to file names -b, --bytes=SIZE put SIZE bytes per output file -C, --line-bytes=SIZE put at most SIZE bytes of records per output file -d use numeric suffixes starting at 0, not alphabetic --numeric-suffixes[=FROM] same as -d, but allow setting the start value -x use hex suffixes starting at 0, not alphabetic --hex-suffixes[=FROM] same as -x, but allow setting the start value -e, --elide-empty-files do not generate empty output files with '-n' --filter=COMMAND write to shell COMMAND; file name is $FILE -l, --lines=NUMBER put NUMBER lines/records per output file -n, --number=CHUNKS generate CHUNKS output files; see explanation below -t, --separator=SEP use SEP instead of newline as the record separator; '\0' (zero) specifies the NUL character -u, --unbuffered immediately copy input to output with '-n r/...' --verbose print a diagnostic just before each output file is opened --help display this help and exit --version output version information and exit The SIZE argument is an integer and optional unit (example: 10K is 10*1024). Units are K,M,G,T,P,E,Z,Y,R,Q (powers of 1024) or KB,MB,... (powers of 1000). Binary prefixes can be used, too: KiB=K, MiB=M, and so on. CHUNKS may be: N split into N files based on size of input K/N output Kth of N to stdout l/N split into N files without splitting lines/records l/K/N output Kth of N to stdout without splitting lines/records r/N like 'l' but use round robin distribution r/K/N likewise but only output Kth of N to stdout AUTHOR top Written by Torbjorn Granlund and Richard M. Stallman. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/split> or available locally via: info '(coreutils) split invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 SPLIT(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a compressed archive of "/home" and split the contents into files with at most 4000 MiB each and use prefix "/media/DRIVENAME/BACKUPNAME.tgz" Bash Command:<START>tar --one-file-system -czv /home | split -b 4000m - /media/DRIVENAME/BACKUPNAME.tgz<END> |
Create a copy of index.html in all directories in current directory whose name contains Va, pausing for confirmation before overwriting any existing files - names may not contain spaces. | find . -mindepth 1 -maxdepth 1 -type d| grep \/a |xargs -n 1 cp -i index.html | ['find', 'xargs', 'grep', 'cp'] | Output a Bash command to accomplish the following task. Task: Create a copy of index.html in all directories in current directory whose name contains Va, pausing for confirmation before overwriting any existing files - names may not contain spaces. Bash Command:<START>find . -mindepth 1 -maxdepth 1 -type d| grep \/a |xargs -n 1 cp -i index.html<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # xargs\n\n> Execute a command with piped arguments coming from another command, a file, etc.\n> The input is treated as a single block of text and split into separate pieces on spaces, tabs, newlines and end-of-file.\n> More information: <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/xargs.html>.\n\n- Run a command using the input data as arguments:\n\n`{{arguments_source}} | xargs {{command}}`\n\n- Run multiple chained commands on the input data:\n\n`{{arguments_source}} | xargs sh -c "{{command1}} && {{command2}} | {{command3}}"`\n\n- Delete all files with a `.backup` extension (`-print0` uses a null character to split file names, and `-0` uses it as delimiter):\n\n`find . -name {{'*.backup'}} -print0 | xargs -0 rm -v`\n\n- Execute the command once for each input line, replacing any occurrences of the placeholder (here marked as `_`) with the input line:\n\n`{{arguments_source}} | xargs -I _ {{command}} _ {{optional_extra_arguments}}`\n\n- Parallel runs of up to `max-procs` processes at a time; the default is 1. If `max-procs` is 0, xargs will run as many processes as possible at a time:\n\n`{{arguments_source}} | xargs -P {{max-procs}} {{command}}`\n # grep\n\n> Find patterns in files using regular expressions.\n> More information: <https://www.gnu.org/software/grep/manual/grep.html>.\n\n- Search for a pattern within a file:\n\n`grep "{{search_pattern}}" {{path/to/file}}`\n\n- Search for an exact string (disables regular expressions):\n\n`grep --fixed-strings "{{exact_string}}" {{path/to/file}}`\n\n- Search for a pattern in all files recursively in a directory, showing line numbers of matches, ignoring binary files:\n\n`grep --recursive --line-number --binary-files={{without-match}} "{{search_pattern}}" {{path/to/directory}}`\n\n- Use extended regular expressions (supports `?`, `+`, `{}`, `()` and `|`), in case-insensitive mode:\n\n`grep --extended-regexp --ignore-case "{{search_pattern}}" {{path/to/file}}`\n\n- Print 3 lines of context around, before, or after each match:\n\n`grep --{{context|before-context|after-context}}={{3}} "{{search_pattern}}" {{path/to/file}}`\n\n- Print file name and line number for each match with color output:\n\n`grep --with-filename --line-number --color=always "{{search_pattern}}" {{path/to/file}}`\n\n- Search for lines matching a pattern, printing only the matched text:\n\n`grep --only-matching "{{search_pattern}}" {{path/to/file}}`\n\n- Search `stdin` for lines that do not match a pattern:\n\n`cat {{path/to/file}} | grep --invert-match "{{search_pattern}}"`\n # cp\n\n> Copy files and directories.\n> More information: <https://www.gnu.org/software/coreutils/cp>.\n\n- Copy a file to another location:\n\n`cp {{path/to/source_file.ext}} {{path/to/target_file.ext}}`\n\n- Copy a file into another directory, keeping the filename:\n\n`cp {{path/to/source_file.ext}} {{path/to/target_parent_directory}}`\n\n- Recursively copy a directory's contents to another location (if the destination exists, the directory is copied inside it):\n\n`cp -r {{path/to/source_directory}} {{path/to/target_directory}}`\n\n- Copy a directory recursively, in verbose mode (shows files as they are copied):\n\n`cp -vr {{path/to/source_directory}} {{path/to/target_directory}}`\n\n- Copy multiple files at once to a directory:\n\n`cp -t {{path/to/destination_directory}} {{path/to/file1 path/to/file2 ...}}`\n\n- Copy all files with a specific extension to another location, in interactive mode (prompts user before overwriting):\n\n`cp -i {{*.ext}} {{path/to/target_directory}}`\n\n- Follow symbolic links before copying:\n\n`cp -L {{link}} {{path/to/target_directory}}`\n\n- Use the full path of source files, creating any missing intermediate directories when copying:\n\n`cp --parents {{source/path/to/file}} {{path/to/target_file}}`\n Task: Create a copy of index.html in all directories in current directory whose name contains Va, pausing for confirmation before overwriting any existing files - names may not contain spaces. Bash Command:<START>find . -mindepth 1 -maxdepth 1 -type d| grep \/a |xargs -n 1 cp -i index.html<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. xargs(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training xargs(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | EXIT STATUS | STANDARDS CONFORMANCE | HISTORY | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON XARGS(1) General Commands Manual XARGS(1) NAME top xargs - build and execute command lines from standard input SYNOPSIS top xargs [options] [command [initial-arguments]] DESCRIPTION top This manual page documents the GNU version of xargs. xargs reads items from the standard input, delimited by blanks (which can be protected with double or single quotes or a backslash) or newlines, and executes the command (default is echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored. The command line for command is built up until it reaches a system-defined limit (unless the -n and -L options are used). The specified command will be invoked as many times as necessary to use up the list of input items. In general, there will be many fewer invocations of command than there were items in the input. This will normally have significant performance benefits. Some commands can usefully be executed in parallel too; see the -P option. Because Unix filenames can contain blanks and newlines, this default behaviour is often problematic; filenames containing blanks and/or newlines are incorrectly processed by xargs. In these situations it is better to use the -0 option, which prevents such problems. When using this option you will need to ensure that the program which produces the input for xargs also uses a null character as a separator. If that program is GNU find for example, the -print0 option does this for you. If any invocation of the command exits with a status of 255, xargs will stop immediately without reading any further input. An error message is issued on stderr when this happens. OPTIONS top -0, --null Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally). Disables the end-of-file string, which is treated like any other argument. Useful when input items might contain white space, quote marks, or backslashes. The GNU find -print0 option produces input suitable for this mode. -a file, --arg-file=file Read items from file instead of standard input. If you use this option, stdin remains unchanged when commands are run. Otherwise, stdin is redirected from /dev/null. --delimiter=delim, -d delim Input items are terminated by the specified character. The specified delimiter may be a single character, a C- style character escape such as \n, or an octal or hexadecimal escape code. Octal and hexadecimal escape codes are understood as for the printf command. Multibyte characters are not supported. When processing the input, quotes and backslash are not special; every character in the input is taken literally. The -d option disables any end-of-file string, which is treated like any other argument. You can use this option when the input consists of simply newline-separated items, although it is almost always better to design your program to use --null where this is possible. -E eof-str Set the end-of-file string to eof-str. If the end-of-file string occurs as a line of input, the rest of the input is ignored. If neither -E nor -e is used, no end-of-file string is used. -e[eof-str], --eof[=eof-str] This option is a synonym for the -E option. Use -E instead, because it is POSIX compliant while this option is not. If eof-str is omitted, there is no end-of-file string. If neither -E nor -e is used, no end-of-file string is used. -I replace-str Replace occurrences of replace-str in the initial- arguments with names read from standard input. Also, unquoted blanks do not terminate input items; instead the separator is the newline character. Implies -x and -L 1. -i[replace-str], --replace[=replace-str] This option is a synonym for -Ireplace-str if replace-str is specified. If the replace-str argument is missing, the effect is the same as -I{}. The -i option is deprecated; use -I instead. -L max-lines Use at most max-lines nonblank input lines per command line. Trailing blanks cause an input line to be logically continued on the next input line. Implies -x. -l[max-lines], --max-lines[=max-lines] Synonym for the -L option. Unlike -L, the max-lines argument is optional. If max-lines is not specified, it defaults to one. The -l option is deprecated since the POSIX standard specifies -L instead. -n max-args, --max-args=max-args Use at most max-args arguments per command line. Fewer than max-args arguments will be used if the size (see the -s option) is exceeded, unless the -x option is given, in which case xargs will exit. -P max-procs, --max-procs=max-procs Run up to max-procs processes at a time; the default is 1. If max-procs is 0, xargs will run as many processes as possible at a time. Use the -n option or the -L option with -P; otherwise chances are that only one exec will be done. While xargs is running, you can send its process a SIGUSR1 signal to increase the number of commands to run simultaneously, or a SIGUSR2 to decrease the number. You cannot increase it above an implementation-defined limit (which is shown with --show-limits). You cannot decrease it below 1. xargs never terminates its commands; when asked to decrease, it merely waits for more than one existing command to terminate before starting another. Please note that it is up to the called processes to properly manage parallel access to shared resources. For example, if more than one of them tries to print to stdout, the output will be produced in an indeterminate order (and very likely mixed up) unless the processes collaborate in some way to prevent this. Using some kind of locking scheme is one way to prevent such problems. In general, using a locking scheme will help ensure correct output but reduce performance. If you don't want to tolerate the performance difference, simply arrange for each process to produce a separate output file (or otherwise use separate resources). -o, --open-tty Reopen stdin as /dev/tty in the child process before executing the command. This is useful if you want xargs to run an interactive application. -p, --interactive Prompt the user about whether to run each command line and read a line from the terminal. Only run the command line if the response starts with `y' or `Y'. Implies -t. --process-slot-var=name Set the environment variable name to a unique value in each running child process. Values are reused once child processes exit. This can be used in a rudimentary load distribution scheme, for example. -r, --no-run-if-empty If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there is no input. This option is a GNU extension. -s max-chars, --max-chars=max-chars Use at most max-chars characters per command line, including the command and initial-arguments and the terminating nulls at the ends of the argument strings. The largest allowed value is system-dependent, and is calculated as the argument length limit for exec, less the size of your environment, less 2048 bytes of headroom. If this value is more than 128 KiB, 128 KiB is used as the default value; otherwise, the default value is the maximum. 1 KiB is 1024 bytes. xargs automatically adapts to tighter constraints. --show-limits Display the limits on the command-line length which are imposed by the operating system, xargs' choice of buffer size and the -s option. Pipe the input from /dev/null (and perhaps specify --no-run-if-empty) if you don't want xargs to do anything. -t, --verbose Print the command line on the standard error output before executing it. -x, --exit Exit if the size (see the -s option) is exceeded. -- Delimit the option list. Later arguments, if any, are treated as operands even if they begin with -. For example, xargs -- --help runs the command --help (found in PATH) instead of printing the usage text, and xargs -- --mycommand runs the command --mycommand instead of rejecting this as unrecognized option. --help Print a summary of the options to xargs and exit. --version Print the version number of xargs and exit. The options --max-lines (-L, -l), --replace (-I, -i) and --max- args (-n) are mutually exclusive. If some of them are specified at the same time, then xargs will generally use the option specified last on the command line, i.e., it will reset the value of the offending option (given before) to its default value. Additionally, xargs will issue a warning diagnostic on stderr. The exception to this rule is that the special max-args value 1 ('-n1') is ignored after the --replace option and its aliases -I and -i, because it would not actually conflict. EXAMPLES top find /tmp -name core -type f -print | xargs /bin/rm -f Find files named core in or below the directory /tmp and delete them. Note that this will work incorrectly if there are any filenames containing newlines or spaces. find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing spaces or newlines are correctly handled. find /tmp -depth -name core -type f -delete Find files named core in or below the directory /tmp and delete them, but more efficiently than in the previous example (because we avoid the need to use fork(2) and exec(2) to launch rm and we don't need the extra xargs process). cut -d: -f1 < /etc/passwd | sort | xargs echo Generates a compact listing of all the users on the system. EXIT STATUS top xargs exits with the following status: 0 if it succeeds 123 if any invocation of the command exited with status 1125 124 if the command exited with status 255 125 if the command is killed by a signal 126 if the command cannot be run 127 if the command is not found 1 if some other error occurred. Exit codes greater than 128 are used by the shell to indicate that a program died due to a fatal signal. STANDARDS CONFORMANCE top As of GNU xargs version 4.2.9, the default behaviour of xargs is not to have a logical end-of-file marker. POSIX (IEEE Std 1003.1, 2004 Edition) allows this. The -l and -i options appear in the 1997 version of the POSIX standard, but do not appear in the 2004 version of the standard. Therefore you should use -L and -I instead, respectively. The -o option is an extension to the POSIX standard for better compatibility with BSD. The POSIX standard allows implementations to have a limit on the size of arguments to the exec functions. This limit could be as low as 4096 bytes including the size of the environment. For scripts to be portable, they must not rely on a larger value. However, I know of no implementation whose actual limit is that small. The --show-limits option can be used to discover the actual limits in force on the current system. HISTORY top The xargs program was invented by Herb Gellis at Bell Labs. See the Texinfo manual for findutils, Finding Files, for more information. BUGS top It is not possible for xargs to be used securely, since there will always be a time gap between the production of the list of input files and their use in the commands that xargs issues. If other users have access to the system, they can manipulate the filesystem during this time window to force the action of the commands xargs runs to apply to files that you didn't intend. For a more detailed discussion of this and related problems, please refer to the ``Security Considerations'' chapter in the findutils Texinfo documentation. The -execdir option of find can often be used as a more secure alternative. When you use the -I option, each line read from the input is buffered internally. This means that there is an upper limit on the length of input line that xargs will accept when used with the -I option. To work around this limitation, you can use the -s option to increase the amount of buffer space that xargs uses, and you can also use an extra invocation of xargs to ensure that very long lines do not occur. For example: somecommand | xargs -s 50000 echo | xargs -I '{}' -s 100000 rm '{}' Here, the first invocation of xargs has no input line length limit because it doesn't use the -i option. The second invocation of xargs does have such a limit, but we have ensured that it never encounters a line which is longer than it can handle. This is not an ideal solution. Instead, the -i option should not impose a line length limit, which is why this discussion appears in the BUGS section. The problem doesn't occur with the output of find(1) because it emits just one filename per line. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 19902023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top find(1), kill(1), locate(1), updatedb(1), fork(2), execvp(3), locatedb(5), signal(7) Full documentation <https://www.gnu.org/software/findutils/xargs> or available locally via: info xargs COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org XARGS(1) Pages that refer to this page: dpkg-name(1), find(1), grep(1), locate(1), updatedb(1), lsof(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. grep(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training grep(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | REGULAR EXPRESSIONS | EXIT STATUS | ENVIRONMENT | NOTES | COPYRIGHT | BUGS | EXAMPLE | SEE ALSO | COLOPHON GREP(1) User Commands GREP(1) NAME top grep - print lines that match patterns SYNOPSIS top grep [OPTION...] PATTERNS [FILE...] grep [OPTION...] -e PATTERNS ... [FILE...] grep [OPTION...] -f PATTERN_FILE ... [FILE...] DESCRIPTION top grep searches for PATTERNS in each FILE. PATTERNS is one or more patterns separated by newline characters, and grep prints each line that matches a pattern. Typically PATTERNS should be quoted when grep is used in a shell command. A FILE of - stands for standard input. If no FILE is given, recursive searches examine the working directory, and nonrecursive searches read standard input. OPTIONS top Generic Program Information --help Output a usage message and exit. -V, --version Output the version number of grep and exit. Pattern Syntax -E, --extended-regexp Interpret PATTERNS as extended regular expressions (EREs, see below). -F, --fixed-strings Interpret PATTERNS as fixed strings, not regular expressions. -G, --basic-regexp Interpret PATTERNS as basic regular expressions (BREs, see below). This is the default. -P, --perl-regexp Interpret PATTERNS as Perl-compatible regular expressions (PCREs). This option is experimental when combined with the -z (--null-data) option, and grep -P may warn of unimplemented features. Matching Control -e PATTERNS, --regexp=PATTERNS Use PATTERNS as the patterns. If this option is used multiple times or is combined with the -f (--file) option, search for all patterns given. This option can be used to protect a pattern beginning with -. -f FILE, --file=FILE Obtain patterns from FILE, one per line. If this option is used multiple times or is combined with the -e (--regexp) option, search for all patterns given. The empty file contains zero patterns, and therefore matches nothing. If FILE is - , read patterns from standard input. -i, --ignore-case Ignore case distinctions in patterns and input data, so that characters that differ only in case match each other. --no-ignore-case Do not ignore case distinctions in patterns and input data. This is the default. This option is useful for passing to shell scripts that already use -i, to cancel its effects because the two options override each other. -v, --invert-match Invert the sense of matching, to select non-matching lines. -w, --word-regexp Select only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word-constituent characters are letters, digits, and the underscore. This option has no effect if -x is also specified. -x, --line-regexp Select only those matches that exactly match the whole line. For a regular expression pattern, this is like parenthesizing the pattern and then surrounding it with ^ and $. General Output Control -c, --count Suppress normal output; instead print a count of matching lines for each input file. With the -v, --invert-match option (see above), count non-matching lines. --color[=WHEN], --colour[=WHEN] Surround the matched (non-empty) strings, matching lines, context lines, file names, line numbers, byte offsets, and separators (for fields and groups of context lines) with escape sequences to display them in color on the terminal. The colors are defined by the environment variable GREP_COLORS. WHEN is never, always, or auto. -L, --files-without-match Suppress normal output; instead print the name of each input file from which no output would normally have been printed. -l, --files-with-matches Suppress normal output; instead print the name of each input file from which output would normally have been printed. Scanning each input file stops upon first match. -m NUM, --max-count=NUM Stop reading a file after NUM matching lines. If NUM is zero, grep stops right away without reading input. A NUM of -1 is treated as infinity and grep does not stop; this is the default. If the input is standard input from a regular file, and NUM matching lines are output, grep ensures that the standard input is positioned to just after the last matching line before exiting, regardless of the presence of trailing context lines. This enables a calling process to resume a search. When grep stops after NUM matching lines, it outputs any trailing context lines. When the -c or --count option is also used, grep does not output a count greater than NUM. When the -v or --invert-match option is also used, grep stops after outputting NUM non-matching lines. -o, --only-matching Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line. -q, --quiet, --silent Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected. Also see the -s or --no-messages option. -s, --no-messages Suppress error messages about nonexistent or unreadable files. Output Line Prefix Control -b, --byte-offset Print the 0-based byte offset within the input file before each line of output. If -o (--only-matching) is specified, print the offset of the matching part itself. -H, --with-filename Print the file name for each match. This is the default when there is more than one file to search. This is a GNU extension. -h, --no-filename Suppress the prefixing of file names on output. This is the default when there is only one file (or only standard input) to search. --label=LABEL Display input actually coming from standard input as input coming from file LABEL. This can be useful for commands that transform a file's contents before searching, e.g., gzip -cd foo.gz | grep --label=foo -H 'some pattern'. See also the -H option. -n, --line-number Prefix each line of output with the 1-based line number within its input file. -T, --initial-tab Make sure that the first character of actual line content lies on a tab stop, so that the alignment of tabs looks normal. This is useful with options that prefix their output to the actual content: -H,-n, and -b. In order to improve the probability that lines from a single file will all start at the same column, this also causes the line number and byte offset (if present) to be printed in a minimum size field width. -Z, --null Output a zero byte (the ASCII NUL character) instead of the character that normally follows a file name. For example, grep -lZ outputs a zero byte after each file name instead of the usual newline. This option makes the output unambiguous, even in the presence of file names containing unusual characters like newlines. This option can be used with commands like find -print0, perl -0, sort -z, and xargs -0 to process arbitrary file names, even those that contain newline characters. Context Line Control -A NUM, --after-context=NUM Print NUM lines of trailing context after matching lines. Places a line containing a group separator (--) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given. -B NUM, --before-context=NUM Print NUM lines of leading context before matching lines. Places a line containing a group separator (--) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given. -C NUM, -NUM, --context=NUM Print NUM lines of output context. Places a line containing a group separator (--) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given. --group-separator=SEP When -A, -B, or -C are in use, print SEP instead of -- between groups of lines. --no-group-separator When -A, -B, or -C are in use, do not print a separator between groups of lines. File and Directory Selection -a, --text Process a binary file as if it were text; this is equivalent to the --binary-files=text option. --binary-files=TYPE If a file's data or metadata indicate that the file contains binary data, assume that the file is of type TYPE. Non-text bytes indicate binary data; these are either output bytes that are improperly encoded for the current locale, or null input bytes when the -z option is not given. By default, TYPE is binary, and grep suppresses output after null input binary data is discovered, and suppresses output lines that contain improperly encoded data. When some output is suppressed, grep follows any output with a message to standard error saying that a binary file matches. If TYPE is without-match, when grep discovers null input binary data it assumes that the rest of the file does not match; this is equivalent to the -I option. If TYPE is text, grep processes a binary file as if it were text; this is equivalent to the -a option. When type is binary, grep may treat non-text bytes as line terminators even without the -z option. This means choosing binary versus text can affect whether a pattern matches a file. For example, when type is binary the pattern q$ might match q immediately followed by a null byte, even though this is not matched when type is text. Conversely, when type is binary the pattern . (period) might not match a null byte. Warning: The -a option might output binary garbage, which can have nasty side effects if the output is a terminal and if the terminal driver interprets some of it as commands. On the other hand, when reading files whose text encodings are unknown, it can be helpful to use -a or to set LC_ALL='C' in the environment, in order to find more matches even if the matches are unsafe for direct display. -D ACTION, --devices=ACTION If an input file is a device, FIFO or socket, use ACTION to process it. By default, ACTION is read, which means that devices are read just as if they were ordinary files. If ACTION is skip, devices are silently skipped. -d ACTION, --directories=ACTION If an input file is a directory, use ACTION to process it. By default, ACTION is read, i.e., read directories just as if they were ordinary files. If ACTION is skip, silently skip directories. If ACTION is recurse, read all files under each directory, recursively, following symbolic links only if they are on the command line. This is equivalent to the -r option. --exclude=GLOB Skip any command-line file with a name suffix that matches the pattern GLOB, using wildcard matching; a name suffix is either the whole name, or a trailing part that starts with a non-slash character immediately after a slash (/) in the name. When searching recursively, skip any subfile whose base name matches GLOB; the base name is the part after the last slash. A pattern can use *, ?, and [...] as wildcards, and \ to quote a wildcard or backslash character literally. --exclude-from=FILE Skip files whose base name matches any of the file-name globs read from FILE (using wildcard matching as described under --exclude). --exclude-dir=GLOB Skip any command-line directory with a name suffix that matches the pattern GLOB. When searching recursively, skip any subdirectory whose base name matches GLOB. Ignore any redundant trailing slashes in GLOB. -I Process a binary file as if it did not contain matching data; this is equivalent to the --binary-files=without-match option. --include=GLOB Search only files whose base name matches GLOB (using wildcard matching as described under --exclude). If contradictory --include and --exclude options are given, the last matching one wins. If no --include or --exclude options match, a file is included unless the first such option is --include. -r, --recursive Read all files under each directory, recursively, following symbolic links only if they are on the command line. Note that if no file operand is given, grep searches the working directory. This is equivalent to the -d recurse option. -R, --dereference-recursive Read all files under each directory, recursively. Follow all symbolic links, unlike -r. Other Options --line-buffered Use line buffering on output. This can cause a performance penalty. -U, --binary Treat the file(s) as binary. By default, under MS-DOS and MS-Windows, grep guesses whether a file is text or binary as described for the --binary-files option. If grep decides the file is a text file, it strips the CR characters from the original file contents (to make regular expressions with ^ and $ work correctly). Specifying -U overrules this guesswork, causing all files to be read and passed to the matching mechanism verbatim; if the file is a text file with CR/LF pairs at the end of each line, this will cause some regular expressions to fail. This option has no effect on platforms other than MS-DOS and MS-Windows. -z, --null-data Treat input and output data as sequences of lines, each terminated by a zero byte (the ASCII NUL character) instead of a newline. Like the -Z or --null option, this option can be used with commands like sort -z to process arbitrary file names. REGULAR EXPRESSIONS top A regular expression is a pattern that describes a set of strings. Regular expressions are constructed analogously to arithmetic expressions, by using various operators to combine smaller expressions. grep understands three different versions of regular expression syntax: basic (BRE), extended (ERE) and perl (PCRE). In GNU grep, basic and extended regular expressions are merely different notations for the same pattern-matching functionality. In other implementations, basic regular expressions are ordinarily less powerful than extended, though occasionally it is the other way around. The following description applies to extended regular expressions; differences for basic regular expressions are summarized afterwards. Perl-compatible regular expressions have different functionality, and are documented in pcre2syntax(3) and pcre2pattern(3), but work only if PCRE support is enabled. The fundamental building blocks are the regular expressions that match a single character. Most characters, including all letters and digits, are regular expressions that match themselves. Any meta-character with special meaning may be quoted by preceding it with a backslash. The period . matches any single character. It is unspecified whether it matches an encoding error. Character Classes and Bracket Expressions A bracket expression is a list of characters enclosed by [ and ]. It matches any single character in that list. If the first character of the list is the caret ^ then it matches any character not in the list; it is unspecified whether it matches an encoding error. For example, the regular expression [0123456789] matches any single digit. Within a bracket expression, a range expression consists of two characters separated by a hyphen. It matches any single character that sorts between the two characters, inclusive, using the locale's collating sequence and character set. For example, in the default C locale, [a-d] is equivalent to [abcd]. Many locales sort characters in dictionary order, and in these locales [a-d] is typically not equivalent to [abcd]; it might be equivalent to [aBbCcDd], for example. To obtain the traditional interpretation of bracket expressions, you can use the C locale by setting the LC_ALL environment variable to the value C. Finally, certain named classes of characters are predefined within bracket expressions, as follows. Their names are self explanatory, and they are [:alnum:], [:alpha:], [:blank:], [:cntrl:], [:digit:], [:graph:], [:lower:], [:print:], [:punct:], [:space:], [:upper:], and [:xdigit:]. For example, [[:alnum:]] means the character class of numbers and letters in the current locale. In the C locale and ASCII character set encoding, this is the same as [0-9A-Za-z]. (Note that the brackets in these class names are part of the symbolic names, and must be included in addition to the brackets delimiting the bracket expression.) Most meta-characters lose their special meaning inside bracket expressions. To include a literal ] place it first in the list. Similarly, to include a literal ^ place it anywhere but first. Finally, to include a literal - place it last. Anchoring The caret ^ and the dollar sign $ are meta-characters that respectively match the empty string at the beginning and end of a line. The Backslash Character and Special Expressions The symbols \< and \> respectively match the empty string at the beginning and end of a word. The symbol \b matches the empty string at the edge of a word, and \B matches the empty string provided it's not at the edge of a word. The symbol \w is a synonym for [_[:alnum:]] and \W is a synonym for [^_[:alnum:]]. Repetition A regular expression may be followed by one of several repetition operators: ? The preceding item is optional and matched at most once. * The preceding item will be matched zero or more times. + The preceding item will be matched one or more times. {n} The preceding item is matched exactly n times. {n,} The preceding item is matched n or more times. {,m} The preceding item is matched at most m times. This is a GNU extension. {n,m} The preceding item is matched at least n times, but not more than m times. Concatenation Two regular expressions may be concatenated; the resulting regular expression matches any string formed by concatenating two substrings that respectively match the concatenated expressions. Alternation Two regular expressions may be joined by the infix operator |; the resulting regular expression matches any string matching either alternate expression. Precedence Repetition takes precedence over concatenation, which in turn takes precedence over alternation. A whole expression may be enclosed in parentheses to override these precedence rules and form a subexpression. Back-references and Subexpressions The back-reference \n, where n is a single digit, matches the substring previously matched by the nth parenthesized subexpression of the regular expression. Basic vs Extended Regular Expressions In basic regular expressions the meta-characters ?, +, {, |, (, and ) lose their special meaning; instead use the backslashed versions \?, \+, \{, \|, \(, and \). EXIT STATUS top Normally the exit status is 0 if a line is selected, 1 if no lines were selected, and 2 if an error occurred. However, if the -q or --quiet or --silent is used and a line is selected, the exit status is 0 even if an error occurred. ENVIRONMENT top The behavior of grep is affected by the following environment variables. The locale for category LC_foo is specified by examining the three environment variables LC_ALL, LC_foo, LANG, in that order. The first of these variables that is set specifies the locale. For example, if LC_ALL is not set, but LC_MESSAGES is set to pt_BR, then the Brazilian Portuguese locale is used for the LC_MESSAGES category. The C locale is used if none of these environment variables are set, if the locale catalog is not installed, or if grep was not compiled with national language support (NLS). The shell command locale -a lists locales that are currently available. GREP_COLORS Controls how the --color option highlights output. Its value is a colon-separated list of capabilities that defaults to ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36 with the rv and ne boolean capabilities omitted (i.e., false). Supported capabilities are as follows. sl= SGR substring for whole selected lines (i.e., matching lines when the -v command-line option is omitted, or non-matching lines when -v is specified). If however the boolean rv capability and the -v command-line option are both specified, it applies to context matching lines instead. The default is empty (i.e., the terminal's default color pair). cx= SGR substring for whole context lines (i.e., non- matching lines when the -v command-line option is omitted, or matching lines when -v is specified). If however the boolean rv capability and the -v command-line option are both specified, it applies to selected non-matching lines instead. The default is empty (i.e., the terminal's default color pair). rv Boolean value that reverses (swaps) the meanings of the sl= and cx= capabilities when the -v command- line option is specified. The default is false (i.e., the capability is omitted). mt=01;31 SGR substring for matching non-empty text in any matching line (i.e., a selected line when the -v command-line option is omitted, or a context line when -v is specified). Setting this is equivalent to setting both ms= and mc= at once to the same value. The default is a bold red text foreground over the current line background. ms=01;31 SGR substring for matching non-empty text in a selected line. (This is only used when the -v command-line option is omitted.) The effect of the sl= (or cx= if rv) capability remains active when this kicks in. The default is a bold red text foreground over the current line background. mc=01;31 SGR substring for matching non-empty text in a context line. (This is only used when the -v command-line option is specified.) The effect of the cx= (or sl= if rv) capability remains active when this kicks in. The default is a bold red text foreground over the current line background. fn=35 SGR substring for file names prefixing any content line. The default is a magenta text foreground over the terminal's default background. ln=32 SGR substring for line numbers prefixing any content line. The default is a green text foreground over the terminal's default background. bn=32 SGR substring for byte offsets prefixing any content line. The default is a green text foreground over the terminal's default background. se=36 SGR substring for separators that are inserted between selected line fields (:), between context line fields, (-), and between groups of adjacent lines when nonzero context is specified (--). The default is a cyan text foreground over the terminal's default background. ne Boolean value that prevents clearing to the end of line using Erase in Line (EL) to Right (\33[K) each time a colorized item ends. This is needed on terminals on which EL is not supported. It is otherwise useful on terminals for which the back_color_erase (bce) boolean terminfo capability does not apply, when the chosen highlight colors do not affect the background, or when EL is too slow or causes too much flicker. The default is false (i.e., the capability is omitted). Note that boolean capabilities have no =... part. They are omitted (i.e., false) by default and become true when specified. See the Select Graphic Rendition (SGR) section in the documentation of the text terminal that is used for permitted values and their meaning as character attributes. These substring values are integers in decimal representation and can be concatenated with semicolons. grep takes care of assembling the result into a complete SGR sequence (\33[...m). Common values to concatenate include 1 for bold, 4 for underline, 5 for blink, 7 for inverse, 39 for default foreground color, 30 to 37 for foreground colors, 90 to 97 for 16-color mode foreground colors, 38;5;0 to 38;5;255 for 88-color and 256-color modes foreground colors, 49 for default background color, 40 to 47 for background colors, 100 to 107 for 16-color mode background colors, and 48;5;0 to 48;5;255 for 88-color and 256-color modes background colors. LC_ALL, LC_COLLATE, LANG These variables specify the locale for the LC_COLLATE category, which determines the collating sequence used to interpret range expressions like [a-z]. LC_ALL, LC_CTYPE, LANG These variables specify the locale for the LC_CTYPE category, which determines the type of characters, e.g., which characters are whitespace. This category also determines the character encoding, that is, whether text is encoded in UTF-8, ASCII, or some other encoding. In the C or POSIX locale, all characters are encoded as a single byte and every byte is a valid character. LC_ALL, LC_MESSAGES, LANG These variables specify the locale for the LC_MESSAGES category, which determines the language that grep uses for messages. The default C locale uses American English messages. POSIXLY_CORRECT If set, grep behaves as POSIX requires; otherwise, grep behaves more like other GNU programs. POSIX requires that options that follow file names must be treated as file names; by default, such options are permuted to the front of the operand list and are treated as options. Also, POSIX requires that unrecognized options be diagnosed as illegal, but since they are not really against the law the default is to diagnose them as invalid. NOTES top This man page is maintained only fitfully; the full documentation is often more up-to-date. COPYRIGHT top Copyright 1998-2000, 2002, 2005-2023 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. BUGS top Reporting Bugs Email bug reports to the bug-reporting address bug- grep@gnu.org. An email archive https://lists.gnu.org/mailman/listinfo/bug-grep and a bug tracker https://debbugs.gnu.org/cgi/pkgreport.cgi?package=grep are available. Known Bugs Large repetition counts in the {n,m} construct may cause grep to use lots of memory. In addition, certain other obscure regular expressions require exponential time and space, and may cause grep to run out of memory. Back-references are very slow, and may require exponential time. EXAMPLE top The following example outputs the location and contents of any line containing f and ending in .c, within all files in the current directory whose names contain g and end in .h. The -n option outputs line numbers, the -- argument treats expansions of *g*.h starting with - as file names not options, and the empty file /dev/null causes file names to be output even if only one file name happens to be of the form *g*.h. $ grep -n -- 'f.*\.c$' *g*.h /dev/null argmatch.h:1:/* definitions and prototypes for argmatch.c The only line that matches is line 1 of argmatch.h. Note that the regular expression syntax used in the pattern differs from the globbing syntax that the shell uses to match file names. SEE ALSO top Regular Manual Pages awk(1), cmp(1), diff(1), find(1), perl(1), sed(1), sort(1), xargs(1), read(2), pcre2(3), pcre2syntax(3), pcre2pattern(3), terminfo(5), glob(7), regex(7) Full Documentation A complete manual https://www.gnu.org/software/grep/manual/ is available. If the info and grep programs are properly installed at your site, the command info grep should give you access to the complete manual. COLOPHON top This page is part of the GNU grep (regular expression file search tool) project. Information about the project can be found at https://www.gnu.org/software/grep/. If you have a bug report for this manual page, send it to bug-grep@gnu.org. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/grep.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-09-14.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU grep 3.11.21-102b-dirty 2019-12-29 GREP(1) Pages that refer to this page: look(1), pmrep(1), sed(1), regex(3), regex(7), bridge(8), ip(8), tc(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. cp(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training cp(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON CP(1) User Commands CP(1) NAME top cp - copy files and directories SYNOPSIS top cp [OPTION]... [-T] SOURCE DEST cp [OPTION]... SOURCE... DIRECTORY cp [OPTION]... -t DIRECTORY SOURCE... DESCRIPTION top Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY. Mandatory arguments to long options are mandatory for short options too. -a, --archive same as -dR --preserve=all --attributes-only don't copy the file data, just the attributes --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument --copy-contents copy contents of special files when recursive -d same as --no-dereference --preserve=links --debug explain how a file is copied. Implies -v -f, --force if an existing destination file cannot be opened, remove it and try again (this option is ignored when the -n option is also used) -i, --interactive prompt before overwrite (overrides a previous -n option) -H follow command-line symbolic links in SOURCE -l, --link hard link files instead of copying -L, --dereference always follow symbolic links in SOURCE -n, --no-clobber do not overwrite an existing file (overrides a -u or previous -i option). See also --update -P, --no-dereference never follow symbolic links in SOURCE -p same as --preserve=mode,ownership,timestamps --preserve[=ATTR_LIST] preserve the specified attributes --no-preserve=ATTR_LIST don't preserve the specified attributes --parents use full source file name under DIRECTORY -R, -r, --recursive copy directories recursively --reflink[=WHEN] control clone/CoW copies. See below --remove-destination remove each existing destination file before attempting to open it (contrast with --force) --sparse=WHEN control creation of sparse files. See below --strip-trailing-slashes remove any trailing slashes from each SOURCE argument -s, --symbolic-link make symbolic links instead of copying -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY copy all SOURCE arguments into DIRECTORY -T, --no-target-directory treat DEST as a normal file --update[=UPDATE] control which existing files are updated; UPDATE={all,none,older(default)}. See below -u equivalent to --update[=older] -v, --verbose explain what is being done -x, --one-file-system stay on this file system -Z set SELinux security context of destination file to default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit ATTR_LIST is a comma-separated list of attributes. Attributes are 'mode' for permissions (including any ACL and xattr permissions), 'ownership' for user and group, 'timestamps' for file timestamps, 'links' for hard links, 'context' for security context, 'xattr' for extended attributes, and 'all' for all attributes. By default, sparse SOURCE files are detected by a crude heuristic and the corresponding DEST file is made sparse as well. That is the behavior selected by --sparse=auto. Specify --sparse=always to create a sparse DEST file whenever the SOURCE file contains a long enough sequence of zero bytes. Use --sparse=never to inhibit creation of sparse files. UPDATE controls which existing files in the destination are replaced. 'all' is the default operation when an --update option is not specified, and results in all existing files in the destination being replaced. 'none' is similar to the --no-clobber option, in that no files in the destination are replaced, but also skipped files do not induce a failure. 'older' is the default operation when --update is specified, and results in files being replaced if they're older than the corresponding source file. When --reflink[=always] is specified, perform a lightweight copy, where the data blocks are copied only when modified. If this is not possible the copy fails, or if --reflink=auto is specified, fall back to a standard copy. Use --reflink=never to ensure a standard copy is performed. The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups As a special case, cp makes a backup of SOURCE when the force and backup options are given and SOURCE and DEST are the same name for an existing, regular file. AUTHOR top Written by Torbjorn Granlund, David MacKenzie, and Jim Meyering. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top install(1) Full documentation <https://www.gnu.org/software/coreutils/cp> or available locally via: info '(coreutils) cp invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 CP(1) Pages that refer to this page: install(1), pmlogmv(1), rsync(1), cpuset(7), symlink(7), e2image(8), readprofile(8), swapon(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a copy of index.html in all directories in current directory whose name contains Va, pausing for confirmation before overwriting any existing files - names may not contain spaces. Bash Command:<START>find . -mindepth 1 -maxdepth 1 -type d| grep \/a |xargs -n 1 cp -i index.html<END> |
Create a copy of index.html in all directories in current directory, pausing for confirmation before overwriting any existing files - names may not contain spaces - names may not contain spaces. | find . -mindepth 1 -maxdepth 1 -type d| xargs -n 1 cp -i index.html | ['find', 'xargs', 'cp'] | Output a Bash command to accomplish the following task. Task: Create a copy of index.html in all directories in current directory, pausing for confirmation before overwriting any existing files - names may not contain spaces - names may not contain spaces. Bash Command:<START>find . -mindepth 1 -maxdepth 1 -type d| xargs -n 1 cp -i index.html<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # xargs\n\n> Execute a command with piped arguments coming from another command, a file, etc.\n> The input is treated as a single block of text and split into separate pieces on spaces, tabs, newlines and end-of-file.\n> More information: <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/xargs.html>.\n\n- Run a command using the input data as arguments:\n\n`{{arguments_source}} | xargs {{command}}`\n\n- Run multiple chained commands on the input data:\n\n`{{arguments_source}} | xargs sh -c "{{command1}} && {{command2}} | {{command3}}"`\n\n- Delete all files with a `.backup` extension (`-print0` uses a null character to split file names, and `-0` uses it as delimiter):\n\n`find . -name {{'*.backup'}} -print0 | xargs -0 rm -v`\n\n- Execute the command once for each input line, replacing any occurrences of the placeholder (here marked as `_`) with the input line:\n\n`{{arguments_source}} | xargs -I _ {{command}} _ {{optional_extra_arguments}}`\n\n- Parallel runs of up to `max-procs` processes at a time; the default is 1. If `max-procs` is 0, xargs will run as many processes as possible at a time:\n\n`{{arguments_source}} | xargs -P {{max-procs}} {{command}}`\n # cp\n\n> Copy files and directories.\n> More information: <https://www.gnu.org/software/coreutils/cp>.\n\n- Copy a file to another location:\n\n`cp {{path/to/source_file.ext}} {{path/to/target_file.ext}}`\n\n- Copy a file into another directory, keeping the filename:\n\n`cp {{path/to/source_file.ext}} {{path/to/target_parent_directory}}`\n\n- Recursively copy a directory's contents to another location (if the destination exists, the directory is copied inside it):\n\n`cp -r {{path/to/source_directory}} {{path/to/target_directory}}`\n\n- Copy a directory recursively, in verbose mode (shows files as they are copied):\n\n`cp -vr {{path/to/source_directory}} {{path/to/target_directory}}`\n\n- Copy multiple files at once to a directory:\n\n`cp -t {{path/to/destination_directory}} {{path/to/file1 path/to/file2 ...}}`\n\n- Copy all files with a specific extension to another location, in interactive mode (prompts user before overwriting):\n\n`cp -i {{*.ext}} {{path/to/target_directory}}`\n\n- Follow symbolic links before copying:\n\n`cp -L {{link}} {{path/to/target_directory}}`\n\n- Use the full path of source files, creating any missing intermediate directories when copying:\n\n`cp --parents {{source/path/to/file}} {{path/to/target_file}}`\n Task: Create a copy of index.html in all directories in current directory, pausing for confirmation before overwriting any existing files - names may not contain spaces - names may not contain spaces. Bash Command:<START>find . -mindepth 1 -maxdepth 1 -type d| xargs -n 1 cp -i index.html<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. xargs(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training xargs(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | EXIT STATUS | STANDARDS CONFORMANCE | HISTORY | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON XARGS(1) General Commands Manual XARGS(1) NAME top xargs - build and execute command lines from standard input SYNOPSIS top xargs [options] [command [initial-arguments]] DESCRIPTION top This manual page documents the GNU version of xargs. xargs reads items from the standard input, delimited by blanks (which can be protected with double or single quotes or a backslash) or newlines, and executes the command (default is echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored. The command line for command is built up until it reaches a system-defined limit (unless the -n and -L options are used). The specified command will be invoked as many times as necessary to use up the list of input items. In general, there will be many fewer invocations of command than there were items in the input. This will normally have significant performance benefits. Some commands can usefully be executed in parallel too; see the -P option. Because Unix filenames can contain blanks and newlines, this default behaviour is often problematic; filenames containing blanks and/or newlines are incorrectly processed by xargs. In these situations it is better to use the -0 option, which prevents such problems. When using this option you will need to ensure that the program which produces the input for xargs also uses a null character as a separator. If that program is GNU find for example, the -print0 option does this for you. If any invocation of the command exits with a status of 255, xargs will stop immediately without reading any further input. An error message is issued on stderr when this happens. OPTIONS top -0, --null Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally). Disables the end-of-file string, which is treated like any other argument. Useful when input items might contain white space, quote marks, or backslashes. The GNU find -print0 option produces input suitable for this mode. -a file, --arg-file=file Read items from file instead of standard input. If you use this option, stdin remains unchanged when commands are run. Otherwise, stdin is redirected from /dev/null. --delimiter=delim, -d delim Input items are terminated by the specified character. The specified delimiter may be a single character, a C- style character escape such as \n, or an octal or hexadecimal escape code. Octal and hexadecimal escape codes are understood as for the printf command. Multibyte characters are not supported. When processing the input, quotes and backslash are not special; every character in the input is taken literally. The -d option disables any end-of-file string, which is treated like any other argument. You can use this option when the input consists of simply newline-separated items, although it is almost always better to design your program to use --null where this is possible. -E eof-str Set the end-of-file string to eof-str. If the end-of-file string occurs as a line of input, the rest of the input is ignored. If neither -E nor -e is used, no end-of-file string is used. -e[eof-str], --eof[=eof-str] This option is a synonym for the -E option. Use -E instead, because it is POSIX compliant while this option is not. If eof-str is omitted, there is no end-of-file string. If neither -E nor -e is used, no end-of-file string is used. -I replace-str Replace occurrences of replace-str in the initial- arguments with names read from standard input. Also, unquoted blanks do not terminate input items; instead the separator is the newline character. Implies -x and -L 1. -i[replace-str], --replace[=replace-str] This option is a synonym for -Ireplace-str if replace-str is specified. If the replace-str argument is missing, the effect is the same as -I{}. The -i option is deprecated; use -I instead. -L max-lines Use at most max-lines nonblank input lines per command line. Trailing blanks cause an input line to be logically continued on the next input line. Implies -x. -l[max-lines], --max-lines[=max-lines] Synonym for the -L option. Unlike -L, the max-lines argument is optional. If max-lines is not specified, it defaults to one. The -l option is deprecated since the POSIX standard specifies -L instead. -n max-args, --max-args=max-args Use at most max-args arguments per command line. Fewer than max-args arguments will be used if the size (see the -s option) is exceeded, unless the -x option is given, in which case xargs will exit. -P max-procs, --max-procs=max-procs Run up to max-procs processes at a time; the default is 1. If max-procs is 0, xargs will run as many processes as possible at a time. Use the -n option or the -L option with -P; otherwise chances are that only one exec will be done. While xargs is running, you can send its process a SIGUSR1 signal to increase the number of commands to run simultaneously, or a SIGUSR2 to decrease the number. You cannot increase it above an implementation-defined limit (which is shown with --show-limits). You cannot decrease it below 1. xargs never terminates its commands; when asked to decrease, it merely waits for more than one existing command to terminate before starting another. Please note that it is up to the called processes to properly manage parallel access to shared resources. For example, if more than one of them tries to print to stdout, the output will be produced in an indeterminate order (and very likely mixed up) unless the processes collaborate in some way to prevent this. Using some kind of locking scheme is one way to prevent such problems. In general, using a locking scheme will help ensure correct output but reduce performance. If you don't want to tolerate the performance difference, simply arrange for each process to produce a separate output file (or otherwise use separate resources). -o, --open-tty Reopen stdin as /dev/tty in the child process before executing the command. This is useful if you want xargs to run an interactive application. -p, --interactive Prompt the user about whether to run each command line and read a line from the terminal. Only run the command line if the response starts with `y' or `Y'. Implies -t. --process-slot-var=name Set the environment variable name to a unique value in each running child process. Values are reused once child processes exit. This can be used in a rudimentary load distribution scheme, for example. -r, --no-run-if-empty If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there is no input. This option is a GNU extension. -s max-chars, --max-chars=max-chars Use at most max-chars characters per command line, including the command and initial-arguments and the terminating nulls at the ends of the argument strings. The largest allowed value is system-dependent, and is calculated as the argument length limit for exec, less the size of your environment, less 2048 bytes of headroom. If this value is more than 128 KiB, 128 KiB is used as the default value; otherwise, the default value is the maximum. 1 KiB is 1024 bytes. xargs automatically adapts to tighter constraints. --show-limits Display the limits on the command-line length which are imposed by the operating system, xargs' choice of buffer size and the -s option. Pipe the input from /dev/null (and perhaps specify --no-run-if-empty) if you don't want xargs to do anything. -t, --verbose Print the command line on the standard error output before executing it. -x, --exit Exit if the size (see the -s option) is exceeded. -- Delimit the option list. Later arguments, if any, are treated as operands even if they begin with -. For example, xargs -- --help runs the command --help (found in PATH) instead of printing the usage text, and xargs -- --mycommand runs the command --mycommand instead of rejecting this as unrecognized option. --help Print a summary of the options to xargs and exit. --version Print the version number of xargs and exit. The options --max-lines (-L, -l), --replace (-I, -i) and --max- args (-n) are mutually exclusive. If some of them are specified at the same time, then xargs will generally use the option specified last on the command line, i.e., it will reset the value of the offending option (given before) to its default value. Additionally, xargs will issue a warning diagnostic on stderr. The exception to this rule is that the special max-args value 1 ('-n1') is ignored after the --replace option and its aliases -I and -i, because it would not actually conflict. EXAMPLES top find /tmp -name core -type f -print | xargs /bin/rm -f Find files named core in or below the directory /tmp and delete them. Note that this will work incorrectly if there are any filenames containing newlines or spaces. find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing spaces or newlines are correctly handled. find /tmp -depth -name core -type f -delete Find files named core in or below the directory /tmp and delete them, but more efficiently than in the previous example (because we avoid the need to use fork(2) and exec(2) to launch rm and we don't need the extra xargs process). cut -d: -f1 < /etc/passwd | sort | xargs echo Generates a compact listing of all the users on the system. EXIT STATUS top xargs exits with the following status: 0 if it succeeds 123 if any invocation of the command exited with status 1125 124 if the command exited with status 255 125 if the command is killed by a signal 126 if the command cannot be run 127 if the command is not found 1 if some other error occurred. Exit codes greater than 128 are used by the shell to indicate that a program died due to a fatal signal. STANDARDS CONFORMANCE top As of GNU xargs version 4.2.9, the default behaviour of xargs is not to have a logical end-of-file marker. POSIX (IEEE Std 1003.1, 2004 Edition) allows this. The -l and -i options appear in the 1997 version of the POSIX standard, but do not appear in the 2004 version of the standard. Therefore you should use -L and -I instead, respectively. The -o option is an extension to the POSIX standard for better compatibility with BSD. The POSIX standard allows implementations to have a limit on the size of arguments to the exec functions. This limit could be as low as 4096 bytes including the size of the environment. For scripts to be portable, they must not rely on a larger value. However, I know of no implementation whose actual limit is that small. The --show-limits option can be used to discover the actual limits in force on the current system. HISTORY top The xargs program was invented by Herb Gellis at Bell Labs. See the Texinfo manual for findutils, Finding Files, for more information. BUGS top It is not possible for xargs to be used securely, since there will always be a time gap between the production of the list of input files and their use in the commands that xargs issues. If other users have access to the system, they can manipulate the filesystem during this time window to force the action of the commands xargs runs to apply to files that you didn't intend. For a more detailed discussion of this and related problems, please refer to the ``Security Considerations'' chapter in the findutils Texinfo documentation. The -execdir option of find can often be used as a more secure alternative. When you use the -I option, each line read from the input is buffered internally. This means that there is an upper limit on the length of input line that xargs will accept when used with the -I option. To work around this limitation, you can use the -s option to increase the amount of buffer space that xargs uses, and you can also use an extra invocation of xargs to ensure that very long lines do not occur. For example: somecommand | xargs -s 50000 echo | xargs -I '{}' -s 100000 rm '{}' Here, the first invocation of xargs has no input line length limit because it doesn't use the -i option. The second invocation of xargs does have such a limit, but we have ensured that it never encounters a line which is longer than it can handle. This is not an ideal solution. Instead, the -i option should not impose a line length limit, which is why this discussion appears in the BUGS section. The problem doesn't occur with the output of find(1) because it emits just one filename per line. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 19902023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top find(1), kill(1), locate(1), updatedb(1), fork(2), execvp(3), locatedb(5), signal(7) Full documentation <https://www.gnu.org/software/findutils/xargs> or available locally via: info xargs COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org XARGS(1) Pages that refer to this page: dpkg-name(1), find(1), grep(1), locate(1), updatedb(1), lsof(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. cp(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training cp(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON CP(1) User Commands CP(1) NAME top cp - copy files and directories SYNOPSIS top cp [OPTION]... [-T] SOURCE DEST cp [OPTION]... SOURCE... DIRECTORY cp [OPTION]... -t DIRECTORY SOURCE... DESCRIPTION top Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY. Mandatory arguments to long options are mandatory for short options too. -a, --archive same as -dR --preserve=all --attributes-only don't copy the file data, just the attributes --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument --copy-contents copy contents of special files when recursive -d same as --no-dereference --preserve=links --debug explain how a file is copied. Implies -v -f, --force if an existing destination file cannot be opened, remove it and try again (this option is ignored when the -n option is also used) -i, --interactive prompt before overwrite (overrides a previous -n option) -H follow command-line symbolic links in SOURCE -l, --link hard link files instead of copying -L, --dereference always follow symbolic links in SOURCE -n, --no-clobber do not overwrite an existing file (overrides a -u or previous -i option). See also --update -P, --no-dereference never follow symbolic links in SOURCE -p same as --preserve=mode,ownership,timestamps --preserve[=ATTR_LIST] preserve the specified attributes --no-preserve=ATTR_LIST don't preserve the specified attributes --parents use full source file name under DIRECTORY -R, -r, --recursive copy directories recursively --reflink[=WHEN] control clone/CoW copies. See below --remove-destination remove each existing destination file before attempting to open it (contrast with --force) --sparse=WHEN control creation of sparse files. See below --strip-trailing-slashes remove any trailing slashes from each SOURCE argument -s, --symbolic-link make symbolic links instead of copying -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY copy all SOURCE arguments into DIRECTORY -T, --no-target-directory treat DEST as a normal file --update[=UPDATE] control which existing files are updated; UPDATE={all,none,older(default)}. See below -u equivalent to --update[=older] -v, --verbose explain what is being done -x, --one-file-system stay on this file system -Z set SELinux security context of destination file to default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit ATTR_LIST is a comma-separated list of attributes. Attributes are 'mode' for permissions (including any ACL and xattr permissions), 'ownership' for user and group, 'timestamps' for file timestamps, 'links' for hard links, 'context' for security context, 'xattr' for extended attributes, and 'all' for all attributes. By default, sparse SOURCE files are detected by a crude heuristic and the corresponding DEST file is made sparse as well. That is the behavior selected by --sparse=auto. Specify --sparse=always to create a sparse DEST file whenever the SOURCE file contains a long enough sequence of zero bytes. Use --sparse=never to inhibit creation of sparse files. UPDATE controls which existing files in the destination are replaced. 'all' is the default operation when an --update option is not specified, and results in all existing files in the destination being replaced. 'none' is similar to the --no-clobber option, in that no files in the destination are replaced, but also skipped files do not induce a failure. 'older' is the default operation when --update is specified, and results in files being replaced if they're older than the corresponding source file. When --reflink[=always] is specified, perform a lightweight copy, where the data blocks are copied only when modified. If this is not possible the copy fails, or if --reflink=auto is specified, fall back to a standard copy. Use --reflink=never to ensure a standard copy is performed. The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups As a special case, cp makes a backup of SOURCE when the force and backup options are given and SOURCE and DEST are the same name for an existing, regular file. AUTHOR top Written by Torbjorn Granlund, David MacKenzie, and Jim Meyering. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top install(1) Full documentation <https://www.gnu.org/software/coreutils/cp> or available locally via: info '(coreutils) cp invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 CP(1) Pages that refer to this page: install(1), pmlogmv(1), rsync(1), cpuset(7), symlink(7), e2image(8), readprofile(8), swapon(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a copy of index.html in all directories in current directory, pausing for confirmation before overwriting any existing files - names may not contain spaces - names may not contain spaces. Bash Command:<START>find . -mindepth 1 -maxdepth 1 -type d| xargs -n 1 cp -i index.html<END> |
Create a directory named 'alpha_real' in the current directory | mkdir alpha_real | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create a directory named 'alpha_real' in the current directory Bash Command:<START>mkdir alpha_real<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create a directory named 'alpha_real' in the current directory Bash Command:<START>mkdir alpha_real<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a directory named 'alpha_real' in the current directory Bash Command:<START>mkdir alpha_real<END> |
Create a full path symbolic link "$newlink" from a relative path symbolic link "$origlink" | ln -s $(readlink -f $origlink) $newlink | ['readlink', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a full path symbolic link "$newlink" from a relative path symbolic link "$origlink" Bash Command:<START>ln -s $(readlink -f $origlink) $newlink<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # readlink\n\n> Follow symlinks and get symlink information.\n> More information: <https://www.gnu.org/software/coreutils/readlink>.\n\n- Get the actual file to which the symlink points:\n\n`readlink {{path/to/file}}`\n\n- Get the absolute path to a file:\n\n`readlink -f {{path/to/file}}`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a full path symbolic link "$newlink" from a relative path symbolic link "$origlink" Bash Command:<START>ln -s $(readlink -f $origlink) $newlink<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: readlink(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training readlink(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON READLINK(1) User Commands READLINK(1) NAME top readlink - print resolved symbolic links or canonical file names SYNOPSIS top readlink [OPTION]... FILE... DESCRIPTION top Note realpath(1) is the preferred command to use for canonicalization functionality. Print value of a symbolic link or canonical file name -f, --canonicalize canonicalize by following every symlink in every component of the given name recursively; all but the last component must exist -e, --canonicalize-existing canonicalize by following every symlink in every component of the given name recursively, all components must exist -m, --canonicalize-missing canonicalize by following every symlink in every component of the given name recursively, without requirements on components existence -n, --no-newline do not output the trailing delimiter -q, --quiet -s, --silent suppress most error messages (on by default) -v, --verbose report error messages -z, --zero end each output line with NUL, not newline --help display this help and exit --version output version information and exit AUTHOR top Written by Dmitry V. Levin. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top readlink(2), realpath(1), realpath(3) Full documentation <https://www.gnu.org/software/coreutils/readlink> or available locally via: info '(coreutils) readlink invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 READLINK(1) Pages that refer to this page: basename(1), dirname(1), dpkg-realpath(1), realpath(1), unshare(1), mount(2), readlink(2), unshare(2), namespaces(7), mount(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a full path symbolic link "$newlink" from a relative path symbolic link "$origlink" Bash Command:<START>ln -s $(readlink -f $origlink) $newlink<END> |
Create a gzip archive file ($tarFile) of all *.log files under $sourcePath | find $sourcePath -type f -name "*.log" -exec tar -uvf $tarFile {} \; | ['find', 'tar'] | Output a Bash command to accomplish the following task. Task: Create a gzip archive file ($tarFile) of all *.log files under $sourcePath Bash Command:<START>find $sourcePath -type f -name "*.log" -exec tar -uvf $tarFile {} \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # tar\n\n> Archiving utility.\n> Often combined with a compression method, such as `gzip` or `bzip2`.\n> More information: <https://www.gnu.org/software/tar>.\n\n- [c]reate an archive and write it to a [f]ile:\n\n`tar cf {{path/to/target.tar}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive and write it to a [f]ile:\n\n`tar czf {{path/to/target.tar.gz}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive from a directory using relative paths:\n\n`tar czf {{path/to/target.tar.gz}} --directory={{path/to/directory}} .`\n\n- E[x]tract a (compressed) archive [f]ile into the current directory [v]erbosely:\n\n`tar xvf {{path/to/source.tar[.gz|.bz2|.xz]}}`\n\n- E[x]tract a (compressed) archive [f]ile into the target directory:\n\n`tar xf {{path/to/source.tar[.gz|.bz2|.xz]}} --directory={{path/to/directory}}`\n\n- [c]reate a compressed archive and write it to a [f]ile, using the file extension to [a]utomatically determine the compression program:\n\n`tar caf {{path/to/target.tar.xz}} {{path/to/file1 path/to/file2 ...}}`\n\n- Lis[t] the contents of a tar [f]ile [v]erbosely:\n\n`tar tvf {{path/to/source.tar}}`\n\n- E[x]tract files matching a pattern from an archive [f]ile:\n\n`tar xf {{path/to/source.tar}} --wildcards "{{*.html}}"`\n Task: Create a gzip archive file ($tarFile) of all *.log files under $sourcePath Bash Command:<START>find $sourcePath -type f -name "*.log" -exec tar -uvf $tarFile {} \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. tar(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training tar(1) Linux manual page NAME | SYNOPSIS | NOTE | DESCRIPTION | OPTIONS | RETURN VALUE | SEE ALSO | BUG REPORTS | COPYRIGHT | COLOPHON TAR(1) GNU TAR Manual TAR(1) NAME top tar - an archiving utility SYNOPSIS top Traditional usage tar {A|c|d|r|t|u|x}[GnSkUWOmpsMBiajJzZhPlRvwo] [ARG...] UNIX-style usage tar -A [OPTIONS] -f ARCHIVE ARCHIVE... tar -c [-f ARCHIVE] [OPTIONS] [FILE...] tar -d [-f ARCHIVE] [OPTIONS] [FILE...] tar -r [-f ARCHIVE] [OPTIONS] [FILE...] tar -t [-f ARCHIVE] [OPTIONS] [MEMBER...] tar -u [-f ARCHIVE] [OPTIONS] [FILE...] tar -x [-f ARCHIVE] [OPTIONS] [MEMBER...] GNU-style usage tar {--catenate|--concatenate} [OPTIONS] --file ARCHIVE ARCHIVE... tar --create [--file ARCHIVE] [OPTIONS] [FILE...] tar {--diff|--compare} [--file ARCHIVE] [OPTIONS] [FILE...] tar --delete [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --append [--file ARCHIVE] [OPTIONS] [FILE...] tar --list [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --test-label [--file ARCHIVE] [OPTIONS] [LABEL...] tar --update [--file ARCHIVE] [OPTIONS] [FILE...] tar {--extract|--get} [--file ARCHIVE] [OPTIONS] [MEMBER...] NOTE top This manpage is a short description of GNU tar. For a detailed discussion, including examples and usage recommendations, refer to the GNU Tar Manual available in texinfo format. If the info reader and the tar documentation are properly installed on your system, the command info tar should give you access to the complete manual. You can also view the manual using the info mode in emacs(1), or find it in various formats online at https://www.gnu.org/software/tar/manual If any discrepancies occur between this manpage and the GNU Tar Manual, the later shall be considered the authoritative source. DESCRIPTION top GNU tar is an archiving program designed to store multiple files in a single file (an archive), and to manipulate such archives. The archive can be either a regular file or a device (e.g. a tape drive, hence the name of the program, which stands for tape archiver), which can be located either on the local or on a remote machine. Option styles Options to GNU tar can be given in three different styles. In traditional style, the first argument is a cluster of option letters and all subsequent arguments supply arguments to those options that require them. The arguments are read in the same order as the option letters. Any command line words that remain after all options have been processed are treated as non-option arguments: file or archive member names. For example, the c option requires creating the archive, the v option requests the verbose operation, and the f option takes an argument that sets the name of the archive to operate upon. The following command, written in the traditional style, instructs tar to store all files from the directory /etc into the archive file etc.tar, verbosely listing the files being archived: tar cfv etc.tar /etc In UNIX or short-option style, each option letter is prefixed with a single dash, as in other command line utilities. If an option takes an argument, the argument follows it, either as a separate command line word, or immediately following the option. However, if the option takes an optional argument, the argument must follow the option letter without any intervening whitespace, as in -g/tmp/snar.db. Any number of options not taking arguments can be clustered together after a single dash, e.g. -vkp. An option that takes an argument (whether mandatory or optional) can appear at the end of such a cluster, e.g. -vkpf a.tar. The example command above written in the short-option style could look like: tar -cvf etc.tar /etc or tar -c -v -f etc.tar /etc In GNU or long-option style, each option begins with two dashes and has a meaningful name, consisting of lower-case letters and dashes. When used, the long option can be abbreviated to its initial letters, provided that this does not create ambiguity. Arguments to long options are supplied either as a separate command line word, immediately following the option, or separated from the option by an equals sign with no intervening whitespace. Optional arguments must always use the latter method. Here are several ways of writing the example command in this style: tar --create --file etc.tar --verbose /etc or (abbreviating some options): tar --cre --file=etc.tar --verb /etc The options in all three styles can be intermixed, although doing so with old options is not encouraged. Operation mode The options listed in the table below tell GNU tar what operation it is to perform. Exactly one of them must be given. The meaning of non-option arguments depends on the operation mode requested. -A, --catenate, --concatenate Append archives to the end of another archive. The arguments are treated as the names of archives to append. All archives must be of the same format as the archive they are appended to, otherwise the resulting archive might be unusable with non-GNU implementations of tar. Notice also that when more than one archive is given, the members from archives other than the first one will be accessible in the resulting archive only when using the -i (--ignore-zeros) option. Compressed archives cannot be concatenated. -c, --create Create a new archive. Arguments supply the names of the files to be archived. Directories are archived recursively, unless the --no-recursion option is given. -d, --diff, --compare Find differences between archive and file system. The arguments are optional and specify archive members to compare. If not given, the current working directory is assumed. --delete Delete from the archive. The arguments supply names of the archive members to be removed. At least one argument must be given. This option does not operate on compressed archives. There is no short option equivalent. -r, --append Append files to the end of an archive. Arguments have the same meaning as for -c (--create). -t, --list List the contents of an archive. Arguments are optional. When given, they specify the names of the members to list. --test-label Test the archive volume label and exit. When used without arguments, it prints the volume label (if any) and exits with status 0. When one or more command line arguments are given. tar compares the volume label with each argument. It exits with code 0 if a match is found, and with code 1 otherwise. No output is displayed, unless used together with the -v (--verbose) option. There is no short option equivalent for this option. -u, --update Append files which are newer than the corresponding copy in the archive. Arguments have the same meaning as with the -c and -r options. Notice, that newer files don't replace their old archive copies, but instead are appended to the end of archive. The resulting archive can thus contain several members of the same name, corresponding to various versions of the same file. -x, --extract, --get Extract files from an archive. Arguments are optional. When given, they specify names of the archive members to be extracted. --show-defaults Show built-in defaults for various tar options and exit. -?, --help Display a short option summary and exit. --usage Display a list of available options and exit. --version Print program version and copyright information and exit. OPTIONS top Operation modifiers --check-device Check device numbers when creating incremental archives (default). -g, --listed-incremental=FILE Handle new GNU-format incremental backups. FILE is the name of a snapshot file, where tar stores additional information which is used to decide which files changed since the previous incremental dump and, consequently, must be dumped again. If FILE does not exist when creating an archive, it will be created and all files will be added to the resulting archive (the level 0 dump). To create incremental archives of non-zero level N, you need a copy of the snapshot file created for level N-1, and use it as FILE. When listing or extracting, the actual content of FILE is not inspected, it is needed only due to syntactical requirements. It is therefore common practice to use /dev/null in its place. --hole-detection=METHOD Use METHOD to detect holes in sparse files. This option implies --sparse. Valid values for METHOD are seek and raw. Default is seek with fallback to raw when not applicable. -G, --incremental Handle old GNU-format incremental backups. --ignore-failed-read Do not exit with nonzero on unreadable files. --level=NUMBER Set dump level for a created listed-incremental archive. Currently only --level=0 is meaningful: it instructs tar to truncate the snapshot file before dumping, thereby forcing a level 0 dump. -n, --seek Assume the archive is seekable. Normally tar determines automatically whether the archive can be seeked or not. This option is intended for use in cases when such recognition fails. It takes effect only if the archive is open for reading (e.g. with --list or --extract options). --no-check-device Do not check device numbers when creating incremental archives. --no-seek Assume the archive is not seekable. --occurrence[=N] Process only the Nth occurrence of each file in the archive. This option is valid only when used with one of the following subcommands: --delete, --diff, --extract or --list and when a list of files is given either on the command line or via the -T option. The default N is 1. --restrict Disable the use of some potentially harmful options. --sparse-version=MAJOR[.MINOR] Set which version of the sparse format to use. This option implies --sparse. Valid argument values are 0.0, 0.1, and 1.0. For a detailed discussion of sparse formats, refer to the GNU Tar Manual, appendix D, "Sparse Formats". Using the info reader, it can be accessed running the following command: info tar 'Sparse Formats'. -S, --sparse Handle sparse files efficiently. Some files in the file system may have segments which were actually never written (quite often these are database files created by such systems as DBM). When given this option, tar attempts to determine if the file is sparse prior to archiving it, and if so, to reduce the resulting archive size by not dumping empty parts of the file. Overwrite control These options control tar actions when extracting a file over an existing copy on disk. -k, --keep-old-files Don't replace existing files when extracting. --keep-newer-files Don't replace existing files that are newer than their archive copies. --keep-directory-symlink Don't replace existing symlinks to directories when extracting. --no-overwrite-dir Preserve metadata of existing directories. --one-top-level[=DIR] Extract all files into DIR, or, if used without argument, into a subdirectory named by the base name of the archive (minus standard compression suffixes recognizable by --auto-compress). --overwrite Overwrite existing files when extracting. --overwrite-dir Overwrite metadata of existing directories when extracting (default). --recursive-unlink Recursively remove all files in the directory prior to extracting it. --remove-files Remove files from disk after adding them to the archive. --skip-old-files Don't replace existing files when extracting, silently skip over them. -U, --unlink-first Remove each file prior to extracting over it. -W, --verify Verify the archive after writing it. Output stream selection --ignore-command-error Ignore subprocess exit codes. --no-ignore-command-error Treat non-zero exit codes of children as error (default). -O, --to-stdout Extract files to standard output. --to-command=COMMAND Pipe extracted files to COMMAND. The argument is the pathname of an external program, optionally with command line arguments. The program will be invoked and the contents of the file being extracted supplied to it on its standard input. Additional data will be supplied via the following environment variables: TAR_FILETYPE Type of the file. It is a single letter with the following meaning: f Regular file d Directory l Symbolic link h Hard link b Block device c Character device Currently only regular files are supported. TAR_MODE File mode, an octal number. TAR_FILENAME The name of the file. TAR_REALNAME Name of the file as stored in the archive. TAR_UNAME Name of the file owner. TAR_GNAME Name of the file owner group. TAR_ATIME Time of last access. It is a decimal number, representing seconds since the Epoch. If the archive provides times with nanosecond precision, the nanoseconds are appended to the timestamp after a decimal point. TAR_MTIME Time of last modification. TAR_CTIME Time of last status change. TAR_SIZE Size of the file. TAR_UID UID of the file owner. TAR_GID GID of the file owner. Additionally, the following variables contain information about tar operation mode and the archive being processed: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. Handling of file attributes --atime-preserve[=METHOD] Preserve access times on dumped files, either by restoring the times after reading (METHOD=replace, this is the default) or by not setting the times in the first place (METHOD=system). --delay-directory-restore Delay setting modification times and permissions of extracted directories until the end of extraction. Use this option when extracting from an archive which has unusual member ordering. --group=NAME[:GID] Force NAME as group for added files. If GID is not supplied, NAME can be either a user name or numeric GID. In this case the missing part (GID or name) will be inferred from the current host's group database. When used with --group-map=FILE, affects only those files whose owner group is not listed in FILE. --group-map=FILE Read group translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single group. It must consist of two fields, delimited by any amount of whitespace: OLDGRP NEWGRP[:NEWGID] OLDGRP is either a valid group name or a GID prefixed with +. Unless NEWGID is supplied, NEWGRP must also be either a valid group name or a +GID. Otherwise, both NEWGRP and NEWGID need not be listed in the system group database. As a result, each input file with owner group OLDGRP will be stored in archive with owner group NEWGRP and GID NEWGID. --mode=CHANGES Force symbolic mode CHANGES for added files. --mtime=DATE-OR-FILE Set mtime for added files. DATE-OR-FILE is either a date/time in almost arbitrary format, or the name of an existing file. In the latter case the mtime of that file will be used. -m, --touch Don't extract file modified time. --no-delay-directory-restore Cancel the effect of the prior --delay-directory-restore option. --no-same-owner Extract files as yourself (default for ordinary users). --no-same-permissions Apply the user's umask when extracting permissions from the archive (default for ordinary users). --numeric-owner Always use numbers for user/group names. --owner=NAME[:UID] Force NAME as owner for added files. If UID is not supplied, NAME can be either a user name or numeric UID. In this case the missing part (UID or name) will be inferred from the current host's user database. When used with --owner-map=FILE, affects only those files whose owner is not listed in FILE. --owner-map=FILE Read owner translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single UID. It must consist of two fields, delimited by any amount of whitespace: OLDUSR NEWUSR[:NEWUID] OLDUSR is either a valid user name or a UID prefixed with +. Unless NEWUID is supplied, NEWUSR must also be either a valid user name or a +UID. Otherwise, both NEWUSR and NEWUID need not be listed in the system user database. As a result, each input file owned by OLDUSR will be stored in archive with owner name NEWUSR and UID NEWUID. -p, --preserve-permissions, --same-permissions Set permissions of extracted files to those recorded in the archive (default for superuser). --same-owner Try extracting files with the same ownership as exists in the archive (default for superuser). -s, --preserve-order, --same-order Tell tar that the list of file names to process is sorted in the same order as the files in the archive. --sort=ORDER When creating an archive, sort directory entries according to ORDER, which is one of none, name, or inode. The default is --sort=none, which stores archive members in the same order as returned by the operating system. Using --sort=name ensures the member ordering in the created archive is uniform and reproducible. Using --sort=inode reduces the number of disk seeks made when creating the archive and thus can considerably speed up archivation. This sorting order is supported only if the underlying system provides the necessary information. Extended file attributes --acls Enable POSIX ACLs support. --no-acls Disable POSIX ACLs support. --selinux Enable SELinux context support. --no-selinux Disable SELinux context support. --xattrs Enable extended attributes support. --no-xattrs Disable extended attributes support. --xattrs-exclude=PATTERN Specify the exclude pattern for xattr keys. PATTERN is a globbing pattern, e.g. --xattrs-exclude='user.*' to include only attributes from the user namespace. --xattrs-include=PATTERN Specify the include pattern for xattr keys. PATTERN is a globbing pattern. Device selection and switching -f, --file=ARCHIVE Use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable `TAPE'. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default. The default value can be inspected either using the --show-defaults option, or at the end of the tar --help output. An archive name that has a colon in it specifies a file or device on a remote machine. The part before the colon is taken as the machine name or IP address, and the part after it as the file or device pathname, e.g.: --file=remotehost:/dev/sr0 An optional username can be prefixed to the hostname, placing a @ sign between them. By default, the remote host is accessed via the rsh(1) command. Nowadays it is common to use ssh(1) instead. You can do so by giving the following command line option: --rsh-command=/usr/bin/ssh The remote machine should have the rmt(8) command installed. If its pathname does not match tar's default, you can inform tar about the correct pathname using the --rmt-command option. --force-local Archive file is local even if it has a colon. -F, --info-script=COMMAND, --new-volume-script=COMMAND Run COMMAND at the end of each tape (implies -M). The command can include arguments. When started, it will inherit tar's environment plus the following variables: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. TAR_FD File descriptor which can be used to communicate the new volume name to tar. If the info script fails, tar exits; otherwise, it begins writing the next volume. -L, --tape-length=N Change tape after writing Nx1024 bytes. If N is followed by a size suffix (see the subsection Size suffixes below), the suffix specifies the multiplicative factor to be used instead of 1024. This option implies -M. -M, --multi-volume Create/list/extract multi-volume archive. --rmt-command=COMMAND Use COMMAND instead of rmt when accessing remote archives. See the description of the -f option, above. --rsh-command=COMMAND Use COMMAND instead of rsh when accessing remote archives. See the description of the -f option, above. --volno-file=FILE When this option is used in conjunction with --multi-volume, tar will keep track of which volume of a multi-volume archive it is working in FILE. Device blocking -b, --blocking-factor=BLOCKS Set record size to BLOCKSx512 bytes. -B, --read-full-records When listing or extracting, accept incomplete input records after end-of-file marker. -i, --ignore-zeros Ignore zeroed blocks in archive. Normally two consecutive 512-blocks filled with zeroes mean EOF and tar stops reading after encountering them. This option instructs it to read further and is useful when reading archives created with the -A option. --record-size=NUMBER Set record size. NUMBER is the number of bytes per record. It must be multiple of 512. It can can be suffixed with a size suffix, e.g. --record-size=10K, for 10 Kilobytes. See the subsection Size suffixes, for a list of valid suffixes. Archive format selection -H, --format=FORMAT Create archive of the given format. Valid formats are: gnu GNU tar 1.13.x format oldgnu GNU format as per tar <= 1.12. pax, posix POSIX 1003.1-2001 (pax) format. ustar POSIX 1003.1-1988 (ustar) format. v7 Old V7 tar format. --old-archive, --portability Same as --format=v7. --pax-option=keyword[[:]=value][,keyword[[:]=value]]... Control pax keywords when creating PAX archives (-H pax). This option is equivalent to the -o option of the pax(1) utility. --posix Same as --format=posix. -V, --label=TEXT Create archive with volume name TEXT. If listing or extracting, use TEXT as a globbing pattern for volume name. Compression options -a, --auto-compress Use archive suffix to determine the compression program. -I, --use-compress-program=COMMAND Filter data through COMMAND. It must accept the -d option, for decompression. The argument can contain command line options. -j, --bzip2 Filter the archive through bzip2(1). -J, --xz Filter the archive through xz(1). --lzip Filter the archive through lzip(1). --lzma Filter the archive through lzma(1). --lzop Filter the archive through lzop(1). --no-auto-compress Do not use archive suffix to determine the compression program. -z, --gzip, --gunzip, --ungzip Filter the archive through gzip(1). -Z, --compress, --uncompress Filter the archive through compress(1). --zstd Filter the archive through zstd(1). Local file selection --add-file=FILE Add FILE to the archive (useful if its name starts with a dash). --backup[=CONTROL] Backup before removal. The CONTROL argument, if supplied, controls the backup policy. Its valid values are: none, off Never make backups. t, numbered Make numbered backups. nil, existing Make numbered backups if numbered backups exist, simple backups otherwise. never, simple Always make simple backups If CONTROL is not given, the value is taken from the VERSION_CONTROL environment variable. If it is not set, existing is assumed. -C, --directory=DIR Change to DIR before performing any operations. This option is order-sensitive, i.e. it affects all options that follow. --exclude=PATTERN Exclude files matching PATTERN, a glob(3)-style wildcard pattern. --exclude-backups Exclude backup and lock files. --exclude-caches Exclude contents of directories containing file CACHEDIR.TAG, except for the tag file itself. --exclude-caches-all Exclude directories containing file CACHEDIR.TAG and the file itself. --exclude-caches-under Exclude everything under directories containing CACHEDIR.TAG --exclude-ignore=FILE Before dumping a directory, see if it contains FILE. If so, read exclusion patterns from this file. The patterns affect only the directory itself. --exclude-ignore-recursive=FILE Same as --exclude-ignore, except that patterns from FILE affect both the directory and all its subdirectories. --exclude-tag=FILE Exclude contents of directories containing FILE, except for FILE itself. --exclude-tag-all=FILE Exclude directories containing FILE. --exclude-tag-under=FILE Exclude everything under directories containing FILE. --exclude-vcs Exclude version control system directories. --exclude-vcs-ignores Exclude files that match patterns read from VCS-specific ignore files. Supported files are: .cvsignore, .gitignore, .bzrignore, and .hgignore. -h, --dereference Follow symlinks; archive and dump the files they point to. --hard-dereference Follow hard links; archive and dump the files they refer to. -K, --starting-file=MEMBER Begin at the given member in the archive. --newer-mtime=DATE Work on files whose data changed after the DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --no-null Disable the effect of the previous --null option. --no-recursion Avoid descending automatically in directories. --no-unquote Do not unquote input file or member names. --no-verbatim-files-from Treat each line read from a file list as if it were supplied in the command line. I.e., leading and trailing whitespace is removed and, if the resulting string begins with a dash, it is treated as tar command line option. This is the default behavior. The --no-verbatim-files-from option is provided as a way to restore it after --verbatim-files-from option. This option is positional: it affects all --files-from options that occur after it in, until --verbatim-files-from option or end of line, whichever occurs first. It is implied by the --no-null option. --null Instruct subsequent -T options to read null-terminated names verbatim (disables special handling of names that start with a dash). See also --verbatim-files-from. -N, --newer=DATE, --after-date=DATE Only store files newer than DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --one-file-system Stay in local file system when creating archive. -P, --absolute-names Don't strip leading slashes from file names when creating archives. --recursion Recurse into directories (default). --suffix=STRING Backup before removal, override usual suffix. Default suffix is ~, unless overridden by environment variable SIMPLE_BACKUP_SUFFIX. -T, --files-from=FILE Get names to extract or create from FILE. Unless specified otherwise, the FILE must contain a list of names separated by ASCII LF (i.e. one name per line). The names read are handled the same way as command line arguments. They undergo quote removal and word splitting, and any string that starts with a - is handled as tar command line option. If this behavior is undesirable, it can be turned off using the --verbatim-files-from option. The --null option instructs tar that the names in FILE are separated by ASCII NUL character, instead of LF. It is useful if the list is generated by find(1) -print0 predicate. --unquote Unquote file or member names (default). --verbatim-files-from Treat each line obtained from a file list as a file name, even if it starts with a dash. File lists are supplied with the --files-from (-T) option. The default behavior is to handle names supplied in file lists as if they were typed in the command line, i.e. any names starting with a dash are treated as tar options. The --verbatim-files-from option disables this behavior. This option affects all --files-from options that occur after it in the command line. Its effect is reverted by the --no-verbatim-files-from option. This option is implied by the --null option. See also --add-file. -X, --exclude-from=FILE Exclude files matching patterns listed in FILE. File name transformations --strip-components=NUMBER Strip NUMBER leading components from file names on extraction. --transform=EXPRESSION, --xform=EXPRESSION Use sed replace EXPRESSION to transform file names. File name matching options These options affect both exclude and include patterns. --anchored Patterns match file name start. --ignore-case Ignore case. --no-anchored Patterns match after any / (default for exclusion). --no-ignore-case Case sensitive matching (default). --no-wildcards Verbatim string matching. --no-wildcards-match-slash Wildcards do not match /. --wildcards Use wildcards (default for exclusion). --wildcards-match-slash Wildcards match / (default for exclusion). Informative output --checkpoint[=N] Display progress messages every Nth record (default 10). --checkpoint-action=ACTION Run ACTION on each checkpoint. --clamp-mtime Only set time when the file is more recent than what was given with --mtime. --full-time Print file time to its full resolution. --index-file=FILE Send verbose output to FILE. -l, --check-links Print a message if not all links are dumped. --no-quote-chars=STRING Disable quoting for characters from STRING. --quote-chars=STRING Additionally quote characters from STRING. --quoting-style=STYLE Set quoting style for file and member names. Valid values for STYLE are literal, shell, shell-always, c, c-maybe, escape, locale, clocale. -R, --block-number Show block number within archive with each message. --show-omitted-dirs When listing or extracting, list each directory that does not match search criteria. --show-transformed-names, --show-stored-names Show file or archive names after transformation by --strip and --transform options. --totals[=SIGNAL] Print total bytes after processing the archive. If SIGNAL is given, print total bytes when this signal is delivered. Allowed signals are: SIGHUP, SIGQUIT, SIGINT, SIGUSR1, and SIGUSR2. The SIG prefix can be omitted. --utc Print file modification times in UTC. -v, --verbose Verbosely list files processed. Each instance of this option on the command line increases the verbosity level by one. The maximum verbosity level is 3. For a detailed discussion of how various verbosity levels affect tar's output, please refer to GNU Tar Manual, subsection 2.5.2 "The '--verbose' Option". --warning=KEYWORD Enable or disable warning messages identified by KEYWORD. The messages are suppressed if KEYWORD is prefixed with no- and enabled otherwise. Multiple --warning options accumulate. Keywords controlling general tar operation: all Enable all warning messages. This is the default. none Disable all warning messages. filename-with-nuls "%s: file name read contains nul character" alone-zero-block "A lone zero block at %s" Keywords applicable for tar --create: cachedir "%s: contains a cache directory tag %s; %s" file-shrank "%s: File shrank by %s bytes; padding with zeros" xdev "%s: file is on a different filesystem; not dumped" file-ignored "%s: Unknown file type; file ignored" "%s: socket ignored" "%s: door ignored" file-unchanged "%s: file is unchanged; not dumped" ignore-archive "%s: archive cannot contain itself; not dumped" file-removed "%s: File removed before we read it" file-changed "%s: file changed as we read it" failed-read Suppresses warnings about unreadable files or directories. This keyword applies only if used together with the --ignore-failed-read option. Keywords applicable for tar --extract: existing-file "%s: skipping existing file" timestamp "%s: implausibly old time stamp %s" "%s: time stamp %s is %s s in the future" contiguous-cast "Extracting contiguous files as regular files" symlink-cast "Attempting extraction of symbolic links as hard links" unknown-cast "%s: Unknown file type '%c', extracted as normal file" ignore-newer "Current %s is newer or same age" unknown-keyword "Ignoring unknown extended header keyword '%s'" decompress-program Controls verbose description of failures occurring when trying to run alternative decompressor programs. This warning is disabled by default (unless --verbose is used). A common example of what you can get when using this warning is: $ tar --warning=decompress-program -x -f archive.Z tar (child): cannot run compress: No such file or directory tar (child): trying gzip This means that tar first tried to decompress archive.Z using compress, and, when that failed, switched to gzip. record-size "Record size = %lu blocks" Keywords controlling incremental extraction: rename-directory "%s: Directory has been renamed from %s" "%s: Directory has been renamed" new-directory "%s: Directory is new" xdev "%s: directory is on a different device: not purging" bad-dumpdir "Malformed dumpdir: 'X' never used" -w, --interactive, --confirmation Ask for confirmation for every action. Compatibility options -o When creating, same as --old-archive. When extracting, same as --no-same-owner. Size suffixes Suffix Units Byte Equivalent b Blocks SIZE x 512 B Kilobytes SIZE x 1024 c Bytes SIZE G Gigabytes SIZE x 1024^3 K Kilobytes SIZE x 1024 k Kilobytes SIZE x 1024 M Megabytes SIZE x 1024^2 P Petabytes SIZE x 1024^5 T Terabytes SIZE x 1024^4 w Words SIZE x 2 RETURN VALUE top Tar's exit code indicates whether it was able to successfully perform the requested operation, and if not, what kind of error occurred. 0 Successful termination. 1 Some files differ. If tar was invoked with the --compare (--diff, -d) command line option, this means that some files in the archive differ from their disk counterparts. If tar was given one of the --create, --append or --update options, this exit code means that some files were changed while being archived and so the resulting archive does not contain the exact copy of the file set. 2 Fatal error. This means that some fatal, unrecoverable error occurred. If a subprocess that had been invoked by tar exited with a nonzero exit code, tar itself exits with that code as well. This can happen, for example, if a compression option (e.g. -z) was used and the external compressor program failed. Another example is rmt failure during backup to a remote device. SEE ALSO top bzip2(1), compress(1), gzip(1), lzma(1), lzop(1), rmt(8), symlink(7), xz(1), zstd(1). Complete tar manual: run info tar or use emacs(1) info mode to read it. Online copies of GNU tar documentation in various formats can be found at: https://www.gnu.org/software/tar/manual BUG REPORTS top Report bugs to <bug-tar@gnu.org>. COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. COLOPHON top This page is part of the tar (an archiver program) project. Information about the project can be found at http://savannah.gnu.org/projects/tar/. If you have a bug report for this manual page, see http://savannah.gnu.org/bugs/?group=tar. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/tar.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-09-12.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org TAR July 11, 2022 TAR(1) Pages that refer to this page: attr(1), dpkg-deb(1), dpkg-source(1), machinectl(1), rsync(1), st(4), suffixes(7), symlink(7), cupsd-helper(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a gzip archive file ($tarFile) of all *.log files under $sourcePath Bash Command:<START>find $sourcePath -type f -name "*.log" -exec tar -uvf $tarFile {} \;<END> |
Create a hard link named "my-hard-link" to "myfile.txt" | ln myfile.txt my-hard-link | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a hard link named "my-hard-link" to "myfile.txt" Bash Command:<START>ln myfile.txt my-hard-link<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a hard link named "my-hard-link" to "myfile.txt" Bash Command:<START>ln myfile.txt my-hard-link<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a hard link named "my-hard-link" to "myfile.txt" Bash Command:<START>ln myfile.txt my-hard-link<END> |
Create a local SSH tunnel from "localhost" port 16379 to "localhost" port 6379 using key "keyfile.rsa" and disables the interactive shell | ssh -i keyfile.rsa -T -N -L 16379:localhost:6379 someuser@somehost | ['ssh'] | Output a Bash command to accomplish the following task. Task: Create a local SSH tunnel from "localhost" port 16379 to "localhost" port 6379 using key "keyfile.rsa" and disables the interactive shell Bash Command:<START>ssh -i keyfile.rsa -T -N -L 16379:localhost:6379 someuser@somehost<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh\n\n> Secure Shell is a protocol used to securely log onto remote systems.\n> It can be used for logging or executing commands on a remote server.\n> More information: <https://man.openbsd.org/ssh>.\n\n- Connect to a remote server:\n\n`ssh {{username}}@{{remote_host}}`\n\n- Connect to a remote server with a specific identity (private key):\n\n`ssh -i {{path/to/key_file}} {{username}}@{{remote_host}}`\n\n- Connect to a remote server using a specific [p]ort:\n\n`ssh {{username}}@{{remote_host}} -p {{2222}}`\n\n- Run a command on a remote server with a [t]ty allocation allowing interaction with the remote command:\n\n`ssh {{username}}@{{remote_host}} -t {{command}} {{command_arguments}}`\n\n- SSH tunneling: [D]ynamic port forwarding (SOCKS proxy on `localhost:1080`):\n\n`ssh -D {{1080}} {{username}}@{{remote_host}}`\n\n- SSH tunneling: Forward a specific port (`localhost:9999` to `example.org:80`) along with disabling pseudo-[T]ty allocation and executio[N] of remote commands:\n\n`ssh -L {{9999}}:{{example.org}}:{{80}} -N -T {{username}}@{{remote_host}}`\n\n- SSH [J]umping: Connect through a jumphost to a remote server (Multiple jump hops may be specified separated by comma characters):\n\n`ssh -J {{username}}@{{jump_host}} {{username}}@{{remote_host}}`\n\n- Agent forwarding: Forward the authentication information to the remote machine (see `man ssh_config` for available options):\n\n`ssh -A {{username}}@{{remote_host}}`\n Task: Create a local SSH tunnel from "localhost" port 16379 to "localhost" port 6379 using key "keyfile.rsa" and disables the interactive shell Bash Command:<START>ssh -i keyfile.rsa -T -N -L 16379:localhost:6379 someuser@somehost<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHENTICATION | ESCAPE CHARACTERS | TCP FORWARDING | X11 FORWARDING | VERIFYING HOST KEYS | SSH-BASED VIRTUAL PRIVATE NETWORKS | ENVIRONMENT | FILES | EXIT STATUS | SEE ALSO | STANDARDS | AUTHORS | COLOPHON SSH(1) General Commands Manual SSH(1) NAME top ssh OpenSSH remote login client SYNOPSIS top ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface] [-b bind_address] [-c cipher_spec] [-D [bind_address:]port] [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11] [-i identity_file] [-J destination] [-L address] [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-P tag] [-p port] [-R address] [-S ctl_path] [-W host:port] [-w local_tun[:remote_tun]] destination [command [argument ...]] [-Q query_option] DESCRIPTION top (SSH client) is a program for logging into a remote machine and for executing commands on a remote machine. It is intended to provide secure encrypted communications between two untrusted hosts over an insecure network. X11 connections, arbitrary TCP ports and Unix-domain sockets can also be forwarded over the secure channel. connects and logs into the specified destination, which may be specified as either [user@]hostname or a URI of the form ssh://[user@]hostname[:port]. The user must prove their identity to the remote machine using one of several methods (see below). If a command is specified, it will be executed on the remote host instead of a login shell. A complete command line may be specified as command, or it may have additional arguments. If supplied, the arguments will be appended to the command, separated by spaces, before it is sent to the server to be executed. The options are as follows: -4 Forces to use IPv4 addresses only. -6 Forces to use IPv6 addresses only. -A Enables forwarding of connections from an authentication agent such as ssh-agent(1). This can also be specified on a per-host basis in a configuration file. Agent forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the agent's Unix-domain socket) can access the local agent through the forwarded connection. An attacker cannot obtain key material from the agent, however they can perform operations on the keys that enable them to authenticate using the identities loaded into the agent. A safer alternative may be to use a jump host (see -J). -a Disables forwarding of the authentication agent connection. -B bind_interface Bind to the address of bind_interface before attempting to connect to the destination host. This is only useful on systems with more than one address. -b bind_address Use bind_address on the local machine as the source address of the connection. Only useful on systems with more than one address. -C Requests compression of all data (including stdin, stdout, stderr, and data for forwarded X11, TCP and Unix-domain connections). The compression algorithm is the same used by gzip(1). Compression is desirable on modem lines and other slow connections, but will only slow down things on fast networks. The default value can be set on a host-by-host basis in the configuration files; see the Compression option in ssh_config(5). -c cipher_spec Selects the cipher specification for encrypting the session. cipher_spec is a comma-separated list of ciphers listed in order of preference. See the Ciphers keyword in ssh_config(5) for more information. -D [bind_address:]port Specifies a local dynamic application-level port forwarding. This works by allocating a socket to listen to port on the local side, optionally bound to the specified bind_address. Whenever a connection is made to this port, the connection is forwarded over the secure channel, and the application protocol is then used to determine where to connect to from the remote machine. Currently the SOCKS4 and SOCKS5 protocols are supported, and will act as a SOCKS server. Only root can forward privileged ports. Dynamic port forwardings can also be specified in the configuration file. IPv6 addresses can be specified by enclosing the address in square brackets. Only the superuser can forward privileged ports. By default, the local port is bound in accordance with the GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a specific address. The bind_address of localhost indicates that the listening port be bound for local use only, while an empty address or * indicates that the port should be available from all interfaces. -E log_file Append debug logs to log_file instead of standard error. -e escape_char Sets the escape character for sessions with a pty (default: ~). The escape character is only recognized at the beginning of a line. The escape character followed by a dot (.) closes the connection; followed by control-Z suspends the connection; and followed by itself sends the escape character once. Setting the character to none disables any escapes and makes the session fully transparent. -F configfile Specifies an alternative per-user configuration file. If a configuration file is given on the command line, the system-wide configuration file (/etc/ssh/ssh_config) will be ignored. The default for the per-user configuration file is ~/.ssh/config. If set to none, no configuration files will be read. -f Requests to go to background just before command execution. This is useful if is going to ask for passwords or passphrases, but the user wants it in the background. This implies -n. The recommended way to start X11 programs at a remote site is with something like ssh -f host xterm. If the ExitOnForwardFailure configuration option is set to yes, then a client started with -f will wait for all remote port forwards to be successfully established before placing itself in the background. Refer to the description of ForkAfterAuthentication in ssh_config(5) for details. -G Causes to print its configuration after evaluating Host and Match blocks and exit. -g Allows remote hosts to connect to local forwarded ports. If used on a multiplexed connection, then this option must be specified on the master process. -I pkcs11 Specify the PKCS#11 shared library should use to communicate with a PKCS#11 token providing keys for user authentication. -i identity_file Selects a file from which the identity (private key) for public key authentication is read. You can also specify a public key file to use the corresponding private key that is loaded in ssh-agent(1) when the private key file is not present locally. The default is ~/.ssh/id_rsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk and ~/.ssh/id_dsa. Identity files may also be specified on a per-host basis in the configuration file. It is possible to have multiple -i options (and multiple identities specified in configuration files). If no certificates have been explicitly specified by the CertificateFile directive, will also try to load certificate information from the filename obtained by appending -cert.pub to identity filenames. -J destination Connect to the target host by first making an connection to the jump host described by destination and then establishing a TCP forwarding to the ultimate destination from there. Multiple jump hops may be specified separated by comma characters. This is a shortcut to specify a ProxyJump configuration directive. Note that configuration directives supplied on the command-line generally apply to the destination host and not any specified jump hosts. Use ~/.ssh/config to specify configuration for jump hosts. -K Enables GSSAPI-based authentication and forwarding (delegation) of GSSAPI credentials to the server. -k Disables forwarding (delegation) of GSSAPI credentials to the server. -L [bind_address:]port:host:hostport -L [bind_address:]port:remote_socket -L local_socket:host:hostport -L local_socket:remote_socket Specifies that connections to the given TCP port or Unix socket on the local (client) host are to be forwarded to the given host and port, or Unix socket, on the remote side. This works by allocating a socket to listen to either a TCP port on the local side, optionally bound to the specified bind_address, or to a Unix socket. Whenever a connection is made to the local port or socket, the connection is forwarded over the secure channel, and a connection is made to either host port hostport, or the Unix socket remote_socket, from the remote machine. Port forwardings can also be specified in the configuration file. Only the superuser can forward privileged ports. IPv6 addresses can be specified by enclosing the address in square brackets. By default, the local port is bound in accordance with the GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a specific address. The bind_address of localhost indicates that the listening port be bound for local use only, while an empty address or * indicates that the port should be available from all interfaces. -l login_name Specifies the user to log in as on the remote machine. This also may be specified on a per-host basis in the configuration file. -M Places the client into master mode for connection sharing. Multiple -M options places into master mode but with confirmation required using ssh-askpass(1) before each operation that changes the multiplexing state (e.g. opening a new session). Refer to the description of ControlMaster in ssh_config(5) for details. -m mac_spec A comma-separated list of MAC (message authentication code) algorithms, specified in order of preference. See the MACs keyword in ssh_config(5) for more information. -N Do not execute a remote command. This is useful for just forwarding ports. Refer to the description of SessionType in ssh_config(5) for details. -n Redirects stdin from /dev/null (actually, prevents reading from stdin). This must be used when is run in the background. A common trick is to use this to run X11 programs on a remote machine. For example, ssh -n shadows.cs.hut.fi emacs & will start an emacs on shadows.cs.hut.fi, and the X11 connection will be automatically forwarded over an encrypted channel. The program will be put in the background. (This does not work if needs to ask for a password or passphrase; see also the -f option.) Refer to the description of StdinNull in ssh_config(5) for details. -O ctl_cmd Control an active connection multiplexing master process. When the -O option is specified, the ctl_cmd argument is interpreted and passed to the master process. Valid commands are: check (check that the master process is running), forward (request forwardings without command execution), cancel (cancel forwardings), exit (request the master to exit), and stop (request the master to stop accepting further multiplexing requests). -o option Can be used to give options in the format used in the configuration file. This is useful for specifying options for which there is no separate command-line flag. For full details of the options listed below, and their possible values, see ssh_config(5). AddKeysToAgent AddressFamily BatchMode BindAddress CanonicalDomains CanonicalizeFallbackLocal CanonicalizeHostname CanonicalizeMaxDots CanonicalizePermittedCNAMEs CASignatureAlgorithms CertificateFile CheckHostIP Ciphers ClearAllForwardings Compression ConnectionAttempts ConnectTimeout ControlMaster ControlPath ControlPersist DynamicForward EnableEscapeCommandline EscapeChar ExitOnForwardFailure FingerprintHash ForkAfterAuthentication ForwardAgent ForwardX11 ForwardX11Timeout ForwardX11Trusted GatewayPorts GlobalKnownHostsFile GSSAPIAuthentication GSSAPIDelegateCredentials HashKnownHosts Host HostbasedAcceptedAlgorithms HostbasedAuthentication HostKeyAlgorithms HostKeyAlias Hostname IdentitiesOnly IdentityAgent IdentityFile IPQoS KbdInteractiveAuthentication KbdInteractiveDevices KexAlgorithms KnownHostsCommand LocalCommand LocalForward LogLevel MACs Match NoHostAuthenticationForLocalhost NumberOfPasswordPrompts PasswordAuthentication PermitLocalCommand PermitRemoteOpen PKCS11Provider Port PreferredAuthentications ProxyCommand ProxyJump ProxyUseFdpass PubkeyAcceptedAlgorithms PubkeyAuthentication RekeyLimit RemoteCommand RemoteForward RequestTTY RequiredRSASize SendEnv ServerAliveInterval ServerAliveCountMax SessionType SetEnv StdinNull StreamLocalBindMask StreamLocalBindUnlink StrictHostKeyChecking TCPKeepAlive Tunnel TunnelDevice UpdateHostKeys User UserKnownHostsFile VerifyHostKeyDNS VisualHostKey XAuthLocation -P tag Specify a tag name that may be used to select configuration in ssh_config(5). Refer to the Tag and Match keywords in ssh_config(5) for more information. -p port Port to connect to on the remote host. This can be specified on a per-host basis in the configuration file. -Q query_option Queries for the algorithms supported by one of the following features: cipher (supported symmetric ciphers), cipher-auth (supported symmetric ciphers that support authenticated encryption), help (supported query terms for use with the -Q flag), mac (supported message integrity codes), kex (key exchange algorithms), key (key types), key-ca-sign (valid CA signature algorithms for certificates), key-cert (certificate key types), key-plain (non-certificate key types), key-sig (all key types and signature algorithms), protocol-version (supported SSH protocol versions), and sig (supported signature algorithms). Alternatively, any keyword from ssh_config(5) or sshd_config(5) that takes an algorithm list may be used as an alias for the corresponding query_option. -q Quiet mode. Causes most warning and diagnostic messages to be suppressed. -R [bind_address:]port:host:hostport -R [bind_address:]port:local_socket -R remote_socket:host:hostport -R remote_socket:local_socket -R [bind_address:]port Specifies that connections to the given TCP port or Unix socket on the remote (server) host are to be forwarded to the local side. This works by allocating a socket to listen to either a TCP port or to a Unix socket on the remote side. Whenever a connection is made to this port or Unix socket, the connection is forwarded over the secure channel, and a connection is made from the local machine to either an explicit destination specified by host port hostport, or local_socket, or, if no explicit destination was specified, will act as a SOCKS 4/5 proxy and forward connections to the destinations requested by the remote SOCKS client. Port forwardings can also be specified in the configuration file. Privileged ports can be forwarded only when logging in as root on the remote machine. IPv6 addresses can be specified by enclosing the address in square brackets. By default, TCP listening sockets on the server will be bound to the loopback interface only. This may be overridden by specifying a bind_address. An empty bind_address, or the address *, indicates that the remote socket should listen on all interfaces. Specifying a remote bind_address will only succeed if the server's GatewayPorts option is enabled (see sshd_config(5)). If the port argument is 0, the listen port will be dynamically allocated on the server and reported to the client at run time. When used together with -O forward, the allocated port will be printed to the standard output. -S ctl_path Specifies the location of a control socket for connection sharing, or the string none to disable connection sharing. Refer to the description of ControlPath and ControlMaster in ssh_config(5) for details. -s May be used to request invocation of a subsystem on the remote system. Subsystems facilitate the use of SSH as a secure transport for other applications (e.g. sftp(1)). The subsystem is specified as the remote command. Refer to the description of SessionType in ssh_config(5) for details. -T Disable pseudo-terminal allocation. -t Force pseudo-terminal allocation. This can be used to execute arbitrary screen-based programs on a remote machine, which can be very useful, e.g. when implementing menu services. Multiple -t options force tty allocation, even if has no local tty. -V Display the version number and exit. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful in debugging connection, authentication, and configuration problems. Multiple -v options increase the verbosity. The maximum is 3. -W host:port Requests that standard input and output on the client be forwarded to host on port over the secure channel. Implies -N, -T, ExitOnForwardFailure and ClearAllForwardings, though these can be overridden in the configuration file or using -o command line options. -w local_tun[:remote_tun] Requests tunnel device forwarding with the specified tun(4) devices between the client (local_tun) and the server (remote_tun). The devices may be specified by numerical ID or the keyword any, which uses the next available tunnel device. If remote_tun is not specified, it defaults to any. See also the Tunnel and TunnelDevice directives in ssh_config(5). If the Tunnel directive is unset, it will be set to the default tunnel mode, which is point-to-point. If a different Tunnel forwarding mode it desired, then it should be specified before -w. -X Enables X11 forwarding. This can also be specified on a per-host basis in a configuration file. X11 forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the user's X authorization database) can access the local X11 display through the forwarded connection. An attacker may then be able to perform activities such as keystroke monitoring. For this reason, X11 forwarding is subjected to X11 SECURITY extension restrictions by default. Refer to the -Y option and the ForwardX11Trusted directive in ssh_config(5) for more information. -x Disables X11 forwarding. -Y Enables trusted X11 forwarding. Trusted X11 forwardings are not subjected to the X11 SECURITY extension controls. -y Send log information using the syslog(3) system module. By default this information is sent to stderr. may additionally obtain configuration data from a per-user configuration file and a system-wide configuration file. The file format and configuration options are described in ssh_config(5). AUTHENTICATION top The OpenSSH SSH client supports SSH protocol 2. The methods available for authentication are: GSSAPI-based authentication, host-based authentication, public key authentication, keyboard-interactive authentication, and password authentication. Authentication methods are tried in the order specified above, though PreferredAuthentications can be used to change the default order. Host-based authentication works as follows: If the machine the user logs in from is listed in /etc/hosts.equiv or /etc/shosts.equiv on the remote machine, the user is non-root and the user names are the same on both sides, or if the files ~/.rhosts or ~/.shosts exist in the user's home directory on the remote machine and contain a line containing the name of the client machine and the name of the user on that machine, the user is considered for login. Additionally, the server must be able to verify the client's host key (see the description of /etc/ssh/ssh_known_hosts and ~/.ssh/known_hosts, below) for login to be permitted. This authentication method closes security holes due to IP spoofing, DNS spoofing, and routing spoofing. [Note to the administrator: /etc/hosts.equiv, ~/.rhosts, and the rlogin/rsh protocol in general, are inherently insecure and should be disabled if security is desired.] Public key authentication works as follows: The scheme is based on public-key cryptography, using cryptosystems where encryption and decryption are done using separate keys, and it is unfeasible to derive the decryption key from the encryption key. The idea is that each user creates a public/private key pair for authentication purposes. The server knows the public key, and only the user knows the private key. implements public key authentication protocol automatically, using one of the DSA, ECDSA, Ed25519 or RSA algorithms. The HISTORY section of ssl(8) contains a brief discussion of the DSA and RSA algorithms. The file ~/.ssh/authorized_keys lists the public keys that are permitted for logging in. When the user logs in, the program tells the server which key pair it would like to use for authentication. The client proves that it has access to the private key and the server checks that the corresponding public key is authorized to accept the account. The server may inform the client of errors that prevented public key authentication from succeeding after authentication completes using a different method. These may be viewed by increasing the LogLevel to DEBUG or higher (e.g. by using the -v flag). The user creates their key pair by running ssh-keygen(1). This stores the private key in ~/.ssh/id_dsa (DSA), ~/.ssh/id_ecdsa (ECDSA), ~/.ssh/id_ecdsa_sk (authenticator-hosted ECDSA), ~/.ssh/id_ed25519 (Ed25519), ~/.ssh/id_ed25519_sk (authenticator- hosted Ed25519), or ~/.ssh/id_rsa (RSA) and stores the public key in ~/.ssh/id_dsa.pub (DSA), ~/.ssh/id_ecdsa.pub (ECDSA), ~/.ssh/id_ecdsa_sk.pub (authenticator-hosted ECDSA), ~/.ssh/id_ed25519.pub (Ed25519), ~/.ssh/id_ed25519_sk.pub (authenticator-hosted Ed25519), or ~/.ssh/id_rsa.pub (RSA) in the user's home directory. The user should then copy the public key to ~/.ssh/authorized_keys in their home directory on the remote machine. The authorized_keys file corresponds to the conventional ~/.rhosts file, and has one key per line, though the lines can be very long. After this, the user can log in without giving the password. A variation on public key authentication is available in the form of certificate authentication: instead of a set of public/private keys, signed certificates are used. This has the advantage that a single trusted certification authority can be used in place of many public/private keys. See the CERTIFICATES section of ssh-keygen(1) for more information. The most convenient way to use public key or certificate authentication may be with an authentication agent. See ssh-agent(1) and (optionally) the AddKeysToAgent directive in ssh_config(5) for more information. Keyboard-interactive authentication works as follows: The server sends an arbitrary "challenge" text and prompts for a response, possibly multiple times. Examples of keyboard-interactive authentication include BSD Authentication (see login.conf(5)) and PAM (some non-OpenBSD systems). Finally, if other authentication methods fail, prompts the user for a password. The password is sent to the remote host for checking; however, since all communications are encrypted, the password cannot be seen by someone listening on the network. automatically maintains and checks a database containing identification for all hosts it has ever been used with. Host keys are stored in ~/.ssh/known_hosts in the user's home directory. Additionally, the file /etc/ssh/ssh_known_hosts is automatically checked for known hosts. Any new hosts are automatically added to the user's file. If a host's identification ever changes, warns about this and disables password authentication to prevent server spoofing or man-in-the- middle attacks, which could otherwise be used to circumvent the encryption. The StrictHostKeyChecking option can be used to control logins to machines whose host key is not known or has changed. When the user's identity has been accepted by the server, the server either executes the given command in a non-interactive session or, if no command has been specified, logs into the machine and gives the user a normal shell as an interactive session. All communication with the remote command or shell will be automatically encrypted. If an interactive session is requested, by default will only request a pseudo-terminal (pty) for interactive sessions when the client has one. The flags -T and -t can be used to override this behaviour. If a pseudo-terminal has been allocated, the user may use the escape characters noted below. If no pseudo-terminal has been allocated, the session is transparent and can be used to reliably transfer binary data. On most systems, setting the escape character to none will also make the session transparent even if a tty is used. The session terminates when the command or shell on the remote machine exits and all X11 and TCP connections have been closed. ESCAPE CHARACTERS top When a pseudo-terminal has been requested, supports a number of functions through the use of an escape character. A single tilde character can be sent as ~~ or by following the tilde by a character other than those described below. The escape character must always follow a newline to be interpreted as special. The escape character can be changed in configuration files using the EscapeChar configuration directive or on the command line by the -e option. The supported escapes (assuming the default ~) are: ~. Disconnect. ~^Z Background . ~# List forwarded connections. ~& Background at logout when waiting for forwarded connection / X11 sessions to terminate. ~? Display a list of escape characters. ~B Send a BREAK to the remote system (only useful if the peer supports it). ~C Open command line. Currently this allows the addition of port forwardings using the -L, -R and -D options (see above). It also allows the cancellation of existing port-forwardings with -KL[bind_address:]port for local, -KR[bind_address:]port for remote and -KD[bind_address:]port for dynamic port-forwardings. !command allows the user to execute a local command if the PermitLocalCommand option is enabled in ssh_config(5). Basic help is available, using the -h option. ~R Request rekeying of the connection (only useful if the peer supports it). ~V Decrease the verbosity (LogLevel) when errors are being written to stderr. ~v Increase the verbosity (LogLevel) when errors are being written to stderr. TCP FORWARDING top Forwarding of arbitrary TCP connections over a secure channel can be specified either on the command line or in a configuration file. One possible application of TCP forwarding is a secure connection to a mail server; another is going through firewalls. In the example below, we look at encrypting communication for an IRC client, even though the IRC server it connects to does not directly support encrypted communication. This works as follows: the user connects to the remote host using , specifying the ports to be used to forward the connection. After that it is possible to start the program locally, and will encrypt and forward the connection to the remote server. The following example tunnels an IRC session from the client to an IRC server at server.example.com, joining channel #users, nickname pinky, using the standard IRC port, 6667: $ ssh -f -L 6667:localhost:6667 server.example.com sleep 10 $ irc -c '#users' pinky IRC/127.0.0.1 The -f option backgrounds and the remote command sleep 10 is specified to allow an amount of time (10 seconds, in the example) to start the program which is going to use the tunnel. If no connections are made within the time specified, will exit. X11 FORWARDING top If the ForwardX11 variable is set to yes (or see the description of the -X, -x, and -Y options above) and the user is using X11 (the DISPLAY environment variable is set), the connection to the X11 display is automatically forwarded to the remote side in such a way that any X11 programs started from the shell (or command) will go through the encrypted channel, and the connection to the real X server will be made from the local machine. The user should not manually set DISPLAY. Forwarding of X11 connections can be configured on the command line or in configuration files. The DISPLAY value set by will point to the server machine, but with a display number greater than zero. This is normal, and happens because creates a proxy X server on the server machine for forwarding the connections over the encrypted channel. will also automatically set up Xauthority data on the server machine. For this purpose, it will generate a random authorization cookie, store it in Xauthority on the server, and verify that any forwarded connections carry this cookie and replace it by the real cookie when the connection is opened. The real authentication cookie is never sent to the server machine (and no cookies are sent in the plain). If the ForwardAgent variable is set to yes (or see the description of the -A and -a options above) and the user is using an authentication agent, the connection to the agent is automatically forwarded to the remote side. VERIFYING HOST KEYS top When connecting to a server for the first time, a fingerprint of the server's public key is presented to the user (unless the option StrictHostKeyChecking has been disabled). Fingerprints can be determined using ssh-keygen(1): $ ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key If the fingerprint is already known, it can be matched and the key can be accepted or rejected. If only legacy (MD5) fingerprints for the server are available, the ssh-keygen(1) -E option may be used to downgrade the fingerprint algorithm to match. Because of the difficulty of comparing host keys just by looking at fingerprint strings, there is also support to compare host keys visually, using random art. By setting the VisualHostKey option to yes, a small ASCII graphic gets displayed on every login to a server, no matter if the session itself is interactive or not. By learning the pattern a known server produces, a user can easily find out that the host key has changed when a completely different pattern is displayed. Because these patterns are not unambiguous however, a pattern that looks similar to the pattern remembered only gives a good probability that the host key is the same, not guaranteed proof. To get a listing of the fingerprints along with their random art for all known hosts, the following command line can be used: $ ssh-keygen -lv -f ~/.ssh/known_hosts If the fingerprint is unknown, an alternative method of verification is available: SSH fingerprints verified by DNS. An additional resource record (RR), SSHFP, is added to a zonefile and the connecting client is able to match the fingerprint with that of the key presented. In this example, we are connecting a client to a server, host.example.com. The SSHFP resource records should first be added to the zonefile for host.example.com: $ ssh-keygen -r host.example.com. The output lines will have to be added to the zonefile. To check that the zone is answering fingerprint queries: $ dig -t SSHFP host.example.com Finally the client connects: $ ssh -o "VerifyHostKeyDNS ask" host.example.com [...] Matching host key fingerprint found in DNS. Are you sure you want to continue connecting (yes/no)? See the VerifyHostKeyDNS option in ssh_config(5) for more information. SSH-BASED VIRTUAL PRIVATE NETWORKS top contains support for Virtual Private Network (VPN) tunnelling using the tun(4) network pseudo-device, allowing two networks to be joined securely. The sshd_config(5) configuration option PermitTunnel controls whether the server supports this, and at what level (layer 2 or 3 traffic). The following example would connect client network 10.0.50.0/24 with remote network 10.0.99.0/24 using a point-to-point connection from 10.1.1.1 to 10.1.1.2, provided that the SSH server running on the gateway to the remote network, at 192.168.1.15, allows it. On the client: # ssh -f -w 0:1 192.168.1.15 true # ifconfig tun0 10.1.1.1 10.1.1.2 netmask 255.255.255.252 # route add 10.0.99.0/24 10.1.1.2 On the server: # ifconfig tun1 10.1.1.2 10.1.1.1 netmask 255.255.255.252 # route add 10.0.50.0/24 10.1.1.1 Client access may be more finely tuned via the /root/.ssh/authorized_keys file (see below) and the PermitRootLogin server option. The following entry would permit connections on tun(4) device 1 from user jane and on tun device 2 from user john, if PermitRootLogin is set to forced-commands-only: tunnel="1",command="sh /etc/netstart tun1" ssh-rsa ... jane tunnel="2",command="sh /etc/netstart tun2" ssh-rsa ... john Since an SSH-based setup entails a fair amount of overhead, it may be more suited to temporary setups, such as for wireless VPNs. More permanent VPNs are better provided by tools such as ipsecctl(8) and isakmpd(8). ENVIRONMENT top will normally set the following environment variables: DISPLAY The DISPLAY variable indicates the location of the X11 server. It is automatically set by to point to a value of the form hostname:n, where hostname indicates the host where the shell runs, and n is an integer 1. uses this special value to forward X11 connections over the secure channel. The user should normally not set DISPLAY explicitly, as that will render the X11 connection insecure (and will require the user to manually copy any required authorization cookies). HOME Set to the path of the user's home directory. LOGNAME Synonym for USER; set for compatibility with systems that use this variable. MAIL Set to the path of the user's mailbox. PATH Set to the default PATH, as specified when compiling . SSH_ASKPASS If needs a passphrase, it will read the passphrase from the current terminal if it was run from a terminal. If does not have a terminal associated with it but DISPLAY and SSH_ASKPASS are set, it will execute the program specified by SSH_ASKPASS and open an X11 window to read the passphrase. This is particularly useful when calling from a .xsession or related script. (Note that on some machines it may be necessary to redirect the input from /dev/null to make this work.) SSH_ASKPASS_REQUIRE Allows further control over the use of an askpass program. If this variable is set to never then will never attempt to use one. If it is set to prefer, then will prefer to use the askpass program instead of the TTY when requesting passwords. Finally, if the variable is set to force, then the askpass program will be used for all passphrase input regardless of whether DISPLAY is set. SSH_AUTH_SOCK Identifies the path of a Unix-domain socket used to communicate with the agent. SSH_CONNECTION Identifies the client and server ends of the connection. The variable contains four space-separated values: client IP address, client port number, server IP address, and server port number. SSH_ORIGINAL_COMMAND This variable contains the original command line if a forced command is executed. It can be used to extract the original arguments. SSH_TTY This is set to the name of the tty (path to the device) associated with the current shell or command. If the current session has no tty, this variable is not set. SSH_TUNNEL Optionally set by sshd(8) to contain the interface names assigned if tunnel forwarding was requested by the client. SSH_USER_AUTH Optionally set by sshd(8), this variable may contain a pathname to a file that lists the authentication methods successfully used when the session was established, including any public keys that were used. TZ This variable is set to indicate the present time zone if it was set when the daemon was started (i.e. the daemon passes the value on to new connections). USER Set to the name of the user logging in. Additionally, reads ~/.ssh/environment, and adds lines of the format VARNAME=value to the environment if the file exists and users are allowed to change their environment. For more information, see the PermitUserEnvironment option in sshd_config(5). FILES top ~/.rhosts This file is used for host-based authentication (see above). On some machines this file may need to be world- readable if the user's home directory is on an NFS partition, because sshd(8) reads it as root. Additionally, this file must be owned by the user, and must not have write permissions for anyone else. The recommended permission for most machines is read/write for the user, and not accessible by others. ~/.shosts This file is used in exactly the same way as .rhosts, but allows host-based authentication without permitting login with rlogin/rsh. ~/.ssh/ This directory is the default location for all user- specific configuration and authentication information. There is no general requirement to keep the entire contents of this directory secret, but the recommended permissions are read/write/execute for the user, and not accessible by others. ~/.ssh/authorized_keys Lists the public keys (DSA, ECDSA, Ed25519, RSA) that can be used for logging in as this user. The format of this file is described in the sshd(8) manual page. This file is not highly sensitive, but the recommended permissions are read/write for the user, and not accessible by others. ~/.ssh/config This is the per-user configuration file. The file format and configuration options are described in ssh_config(5). Because of the potential for abuse, this file must have strict permissions: read/write for the user, and not writable by others. ~/.ssh/environment Contains additional definitions for environment variables; see ENVIRONMENT, above. ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the private key for authentication. These files contain sensitive data and should be readable by the user but not accessible by others (read/write/execute). will simply ignore a private key file if it is accessible by others. It is possible to specify a passphrase when generating the key which will be used to encrypt the sensitive part of this file using AES-128. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the public key for authentication. These files are not sensitive and can (but need not) be readable by anyone. ~/.ssh/known_hosts Contains a list of host keys for all hosts the user has logged into that are not already in the systemwide list of known host keys. See sshd(8) for further details of the format of this file. ~/.ssh/rc Commands in this file are executed by when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information. /etc/hosts.equiv This file is for host-based authentication (see above). It should only be writable by root. /etc/shosts.equiv This file is used in exactly the same way as hosts.equiv, but allows host-based authentication without permitting login with rlogin/rsh. /etc/ssh/ssh_config Systemwide configuration file. The file format and configuration options are described in ssh_config(5). /etc/ssh/ssh_host_key /etc/ssh/ssh_host_dsa_key /etc/ssh/ssh_host_ecdsa_key /etc/ssh/ssh_host_ed25519_key /etc/ssh/ssh_host_rsa_key These files contain the private parts of the host keys and are used for host-based authentication. /etc/ssh/ssh_known_hosts Systemwide list of known host keys. This file should be prepared by the system administrator to contain the public host keys of all machines in the organization. It should be world-readable. See sshd(8) for further details of the format of this file. /etc/ssh/sshrc Commands in this file are executed by when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information. EXIT STATUS top exits with the exit status of the remote command or with 255 if an error occurred. SEE ALSO top scp(1), sftp(1), ssh-add(1), ssh-agent(1), ssh-keygen(1), ssh-keyscan(1), tun(4), ssh_config(5), ssh-keysign(8), sshd(8) STANDARDS top S. Lehtinen and C. Lonvick, The Secure Shell (SSH) Protocol Assigned Numbers, RFC 4250, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Protocol Architecture, RFC 4251, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Authentication Protocol, RFC 4252, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Transport Layer Protocol, RFC 4253, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Connection Protocol, RFC 4254, January 2006. J. Schlyter and W. Griffin, Using DNS to Securely Publish Secure Shell (SSH) Key Fingerprints, RFC 4255, January 2006. F. Cusack and M. Forssen, Generic Message Exchange Authentication for the Secure Shell Protocol (SSH), RFC 4256, January 2006. J. Galbraith and P. Remaker, The Secure Shell (SSH) Session Channel Break Extension, RFC 4335, January 2006. M. Bellare, T. Kohno, and C. Namprempre, The Secure Shell (SSH) Transport Layer Encryption Modes, RFC 4344, January 2006. B. Harris, Improved Arcfour Modes for the Secure Shell (SSH) Transport Layer Protocol, RFC 4345, January 2006. M. Friedl, N. Provos, and W. Simpson, Diffie-Hellman Group Exchange for the Secure Shell (SSH) Transport Layer Protocol, RFC 4419, March 2006. J. Galbraith and R. Thayer, The Secure Shell (SSH) Public Key File Format, RFC 4716, November 2006. D. Stebila and J. Green, Elliptic Curve Algorithm Integration in the Secure Shell Transport Layer, RFC 5656, December 2009. A. Perrig and D. Song, Hash Visualization: a New Technique to improve Real-World Security, 1999, International Workshop on Cryptographic Techniques and E-Commerce (CrypTEC '99). AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU October 11, 2023 SSH(1) Pages that refer to this page: stap-jupyter(1), systemd-stdio-bridge(1), tar(1), sd_bus_default(3), environment.d(5), proc(5), user@.service(5), pty(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a local SSH tunnel from "localhost" port 16379 to "localhost" port 6379 using key "keyfile.rsa" and disables the interactive shell Bash Command:<START>ssh -i keyfile.rsa -T -N -L 16379:localhost:6379 someuser@somehost<END> |
Create a new RSA key for ssh with no passphrase, store it in ~/.ssh/id_rsa without prompting to overwrite if this file exists, and minimize output from ssh-keygen. | echo -e 'y\n'|ssh-keygen -q -t rsa -N "" -f ~/.ssh/id_rsa | ['echo', 'ssh-keygen'] | Output a Bash command to accomplish the following task. Task: Create a new RSA key for ssh with no passphrase, store it in ~/.ssh/id_rsa without prompting to overwrite if this file exists, and minimize output from ssh-keygen. Bash Command:<START>echo -e 'y\n'|ssh-keygen -q -t rsa -N "" -f ~/.ssh/id_rsa<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # echo\n\n> Print given arguments.\n> More information: <https://www.gnu.org/software/coreutils/echo>.\n\n- Print a text message. Note: quotes are optional:\n\n`echo "{{Hello World}}"`\n\n- Print a message with environment variables:\n\n`echo "{{My path is $PATH}}"`\n\n- Print a message without the trailing newline:\n\n`echo -n "{{Hello World}}"`\n\n- Append a message to the file:\n\n`echo "{{Hello World}}" >> {{file.txt}}`\n\n- Enable interpretation of backslash escapes (special characters):\n\n`echo -e "{{Column 1\tColumn 2}}"`\n\n- Print the exit status of the last executed command (Note: In Windows Command Prompt and PowerShell the equivalent commands are `echo %errorlevel%` and `$lastexitcode` respectively):\n\n`echo $?`\n # ssh-keygen\n\n> Generate SSH keys used for authentication, password-less logins, and other things.\n> More information: <https://man.openbsd.org/ssh-keygen>.\n\n- Generate a key interactively:\n\n`ssh-keygen`\n\n- Generate an ed25519 key with 32 key derivation function rounds and save the key to a specific file:\n\n`ssh-keygen -t {{ed25519}} -a {{32}} -f {{~/.ssh/filename}}`\n\n- Generate an RSA 4096-bit key with email as a comment:\n\n`ssh-keygen -t {{rsa}} -b {{4096}} -C "{{comment|email}}"`\n\n- Remove the keys of a host from the known_hosts file (useful when a known host has a new key):\n\n`ssh-keygen -R {{remote_host}}`\n\n- Retrieve the fingerprint of a key in MD5 Hex:\n\n`ssh-keygen -l -E {{md5}} -f {{~/.ssh/filename}}`\n\n- Change the password of a key:\n\n`ssh-keygen -p -f {{~/.ssh/filename}}`\n\n- Change the type of the key format (for example from OPENSSH format to PEM), the file will be rewritten in-place:\n\n`ssh-keygen -p -N "" -m {{PEM}} -f {{~/.ssh/OpenSSH_private_key}}`\n\n- Retrieve public key from secret key:\n\n`ssh-keygen -y -f {{~/.ssh/OpenSSH_private_key}}`\n Task: Create a new RSA key for ssh with no passphrase, store it in ~/.ssh/id_rsa without prompting to overwrite if this file exists, and minimize output from ssh-keygen. Bash Command:<START>echo -e 'y\n'|ssh-keygen -q -t rsa -N "" -f ~/.ssh/id_rsa<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: echo(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training echo(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON ECHO(1) User Commands ECHO(1) NAME top echo - display a line of text SYNOPSIS top echo [SHORT-OPTION]... [STRING]... echo LONG-OPTION DESCRIPTION top Echo the STRING(s) to standard output. -n do not output the trailing newline -e enable interpretation of backslash escapes -E disable interpretation of backslash escapes (default) --help display this help and exit --version output version information and exit If -e is in effect, the following sequences are recognized: \\ backslash \a alert (BEL) \b backspace \c produce no further output \e escape \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \0NNN byte with octal value NNN (1 to 3 digits) \xHH byte with hexadecimal value HH (1 to 2 digits) NOTE: your shell may have its own version of echo, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. NOTE: printf(1) is a preferred alternative, which does not have issues outputting option-like strings. AUTHOR top Written by Brian Fox and Chet Ramey. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top printf(1) Full documentation <https://www.gnu.org/software/coreutils/echo> or available locally via: info '(coreutils) echo invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 ECHO(1) Pages that refer to this page: ldapcompare(1), systemd-ask-password(1), systemd-run(1), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ssh-keygen(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh-keygen(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | MODULI GENERATION | CERTIFICATES | FIDO AUTHENTICATOR | KEY REVOCATION LISTS | ALLOWED SIGNERS | ENVIRONMENT | FILES | SEE ALSO | AUTHORS | COLOPHON SSH-KEYGEN(1) General Commands Manual SSH-KEYGEN(1) NAME top ssh-keygen OpenSSH authentication key utility SYNOPSIS top ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile] [-m format] [-N new_passphrase] [-O option] [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa] [-w provider] [-Z cipher] ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase] [-P old_passphrase] [-Z cipher] ssh-keygen -i [-f input_keyfile] [-m key_format] ssh-keygen -e [-f input_keyfile] [-m key_format] ssh-keygen -y [-f input_keyfile] ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase] ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile] ssh-keygen -B [-f input_keyfile] ssh-keygen -D pkcs11 ssh-keygen -F hostname [-lv] [-f known_hosts_file] ssh-keygen -H [-f known_hosts_file] ssh-keygen -K [-a rounds] [-w provider] ssh-keygen -R hostname [-f known_hosts_file] ssh-keygen -r hostname [-g] [-f input_keyfile] ssh-keygen -M generate [-O option] output_file ssh-keygen -M screen [-f input_file] [-O option] output_file ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider] [-n principals] [-O option] [-V validity_interval] [-z serial_number] file ... ssh-keygen -L [-f input_keyfile] ssh-keygen -A [-a rounds] [-f prefix_path] ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number] file ... ssh-keygen -Q [-l] -f krl_file file ... ssh-keygen -Y find-principals [-O option] -s signature_file -f allowed_signers_file ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file ssh-keygen -Y check-novalidate [-O option] -n namespace -s signature_file ssh-keygen -Y sign [-O option] -f key_file -n namespace file ... ssh-keygen -Y verify [-O option] -f allowed_signers_file -I signer_identity -n namespace -s signature_file [-r revocation_file] DESCRIPTION top generates, manages and converts authentication keys for ssh(1). can create keys for use by SSH protocol version 2. The type of key to be generated is specified with the -t option. If invoked without any arguments, will generate an Ed25519 key. is also used to generate groups for use in Diffie-Hellman group exchange (DH-GEX). See the MODULI GENERATION section for details. Finally, can be used to generate and update Key Revocation Lists, and to test whether given keys have been revoked by one. See the KEY REVOCATION LISTS section for details. Normally each user wishing to use SSH with public key authentication runs this once to create the authentication key in ~/.ssh/id_dsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk or ~/.ssh/id_rsa. Additionally, the system administrator may use this to generate host keys, as seen in /etc/rc. Normally this program generates the key and asks for a file in which to store the private key. The public key is stored in a file with the same name but .pub appended. The program also asks for a passphrase. The passphrase may be empty to indicate no passphrase (host keys must have an empty passphrase), or it may be a string of arbitrary length. A passphrase is similar to a password, except it can be a phrase with a series of words, punctuation, numbers, whitespace, or any string of characters you want. Good passphrases are 10-30 characters long, are not simple sentences or otherwise easily guessable (English prose has only 1-2 bits of entropy per character, and provides very bad passphrases), and contain a mix of upper and lowercase letters, numbers, and non-alphanumeric characters. The passphrase can be changed later by using the -p option. There is no way to recover a lost passphrase. If the passphrase is lost or forgotten, a new key must be generated and the corresponding public key copied to other machines. will by default write keys in an OpenSSH-specific format. This format is preferred as it offers better protection for keys at rest as well as allowing storage of key comments within the private key file itself. The key comment may be useful to help identify the key. The comment is initialized to user@host when the key is created, but can be changed using the -c option. It is still possible for to write the previously-used PEM format private keys using the -m flag. This may be used when generating new keys, and existing new-format keys may be converted using this option in conjunction with the -p (change passphrase) flag. After a key is generated, will ask where the keys should be placed to be activated. The options are as follows: -A Generate host keys of all default key types (rsa, ecdsa, and ed25519) if they do not already exist. The host keys are generated with the default key file path, an empty passphrase, default bits for the key type, and default comment. If -f has also been specified, its argument is used as a prefix to the default path for the resulting host key files. This is used by /etc/rc to generate new host keys. -a rounds When saving a private key, this option specifies the number of KDF (key derivation function, currently bcrypt_pbkdf(3)) rounds used. Higher numbers result in slower passphrase verification and increased resistance to brute-force password cracking (should the keys be stolen). The default is 16 rounds. -B Show the bubblebabble digest of specified private or public key file. -b bits Specifies the number of bits in the key to create. For RSA keys, the minimum size is 1024 bits and the default is 3072 bits. Generally, 3072 bits is considered sufficient. DSA keys must be exactly 1024 bits as specified by FIPS 186-2. For ECDSA keys, the -b flag determines the key length by selecting from one of three elliptic curve sizes: 256, 384 or 521 bits. Attempting to use bit lengths other than these three values for ECDSA keys will fail. ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the -b flag will be ignored. -C comment Provides a new comment. -c Requests changing the comment in the private and public key files. The program will prompt for the file containing the private keys, for the passphrase if the key has one, and for the new comment. -D pkcs11 Download the public keys provided by the PKCS#11 shared library pkcs11. When used in combination with -s, this option indicates that a CA key resides in a PKCS#11 token (see the CERTIFICATES section for details). -E fingerprint_hash Specifies the hash algorithm used when displaying key fingerprints. Valid options are: md5 and sha256. The default is sha256. -e This option will read a private or public OpenSSH key file and print to stdout a public key in one of the formats specified by the -m option. The default export format is RFC4716. This option allows exporting OpenSSH keys for use by other programs, including several commercial SSH implementations. -F hostname | [hostname]:port Search for the specified hostname (with optional port number) in a known_hosts file, listing any occurrences found. This option is useful to find hashed host names or addresses and may also be used in conjunction with the -H option to print found keys in a hashed format. -f filename Specifies the filename of the key file. -g Use generic DNS format when printing fingerprint resource records using the -r command. -H Hash a known_hosts file. This replaces all hostnames and addresses with hashed representations within the specified file; the original content is moved to a file with a .old suffix. These hashes may be used normally by ssh and sshd, but they do not reveal identifying information should the file's contents be disclosed. This option will not modify existing hashed hostnames and is therefore safe to use on files that mix hashed and non-hashed names. -h When signing a key, create a host certificate instead of a user certificate. See the CERTIFICATES section for details. -I certificate_identity Specify the key identity when signing a public key. See the CERTIFICATES section for details. -i This option will read an unencrypted private (or public) key file in the format specified by the -m option and print an OpenSSH compatible private (or public) key to stdout. This option allows importing keys from other software, including several commercial SSH implementations. The default import format is RFC4716. -K Download resident keys from a FIDO authenticator. Public and private key files will be written to the current directory for each downloaded key. If multiple FIDO authenticators are attached, keys will be downloaded from the first touched authenticator. See the FIDO AUTHENTICATOR section for more information. -k Generate a KRL file. In this mode, will generate a KRL file at the location specified via the -f flag that revokes every key or certificate presented on the command line. Keys/certificates to be revoked may be specified by public key file or using the format described in the KEY REVOCATION LISTS section. -L Prints the contents of one or more certificates. -l Show fingerprint of specified public key file. For RSA and DSA keys tries to find the matching public key file and prints its fingerprint. If combined with -v, a visual ASCII art representation of the key is supplied with the fingerprint. -M generate Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for eventual use by the diffie-hellman-group-exchange-* key exchange methods. The numbers generated by this operation must be further screened before use. See the MODULI GENERATION section for more information. -M screen Screen candidate parameters for Diffie-Hellman Group Exchange. This will accept a list of candidate numbers and test that they are safe (Sophie Germain) primes with acceptable group generators. The results of this operation may be added to the /etc/moduli file. See the MODULI GENERATION section for more information. -m key_format Specify a key format for key generation, the -i (import), -e (export) conversion options, and the -p change passphrase operation. The latter may be used to convert between OpenSSH private key and PEM private key formats. The supported key formats are: RFC4716 (RFC 4716/SSH2 public or private key), PKCS8 (PKCS8 public or private key) or PEM (PEM public key). By default OpenSSH will write newly-generated private keys in its own format, but when converting public keys for export the default format is RFC4716. Setting a format of PEM when generating or updating a supported private key type will cause the key to be stored in the legacy PEM private key format. -N new_passphrase Provides the new passphrase. -n principals Specify one or more principals (user or host names) to be included in a certificate when signing a key. Multiple principals may be specified, separated by commas. See the CERTIFICATES section for details. -O option Specify a key/value option. These are specific to the operation that has been requested to perform. When signing certificates, one of the options listed in the CERTIFICATES section may be specified here. When performing moduli generation or screening, one of the options listed in the MODULI GENERATION section may be specified. When generating FIDO authenticator-backed keys, the options listed in the FIDO AUTHENTICATOR section may be specified. When performing signature-related options using the -Y flag, the following options are accepted: hashalg=algorithm Selects the hash algorithm to use for hashing the message to be signed. Valid algorithms are sha256 and sha512. The default is sha512. print-pubkey Print the full public key to standard output after signature verification. verify-time=timestamp Specifies a time to use when validating signatures instead of the current time. The time may be specified as a date or time in the YYYYMMDD[Z] or in YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. When generating SSHFP DNS records from public keys using the -r flag, the following options are accepted: hashalg=algorithm Selects a hash algorithm to use when printing SSHFP records using the -D flag. Valid algorithms are sha1 and sha256. The default is to print both. The -O option may be specified multiple times. -P passphrase Provides the (old) passphrase. -p Requests changing the passphrase of a private key file instead of creating a new private key. The program will prompt for the file containing the private key, for the old passphrase, and twice for the new passphrase. -Q Test whether keys have been revoked in a KRL. If the -l option is also specified then the contents of the KRL will be printed. -q Silence ssh-keygen. -R hostname | [hostname]:port Removes all keys belonging to the specified hostname (with optional port number) from a known_hosts file. This option is useful to delete hashed hosts (see the -H option above). -r hostname Print the SSHFP fingerprint resource record named hostname for the specified public key file. -s ca_key Certify (sign) a public key using the specified CA key. See the CERTIFICATES section for details. When generating a KRL, -s specifies a path to a CA public key file used to revoke certificates directly by key ID or serial number. See the KEY REVOCATION LISTS section for details. -t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa Specifies the type of key to create. The possible values are dsa, ecdsa, ecdsa-sk, ed25519, ed25519-sk, or rsa. This flag may also be used to specify the desired signature type when signing certificates using an RSA CA key. The available RSA signature variants are ssh-rsa (SHA1 signatures, not recommended), rsa-sha2-256, and rsa-sha2-512 (the default). -U When used in combination with -s or -Y sign, this option indicates that a CA key resides in a ssh-agent(1). See the CERTIFICATES section for more information. -u Update a KRL. When specified with -k, keys listed via the command line are added to the existing KRL rather than a new KRL being created. -V validity_interval Specify a validity interval when signing a certificate. A validity interval may consist of a single time, indicating that the certificate is valid beginning now and expiring at that time, or may consist of two times separated by a colon to indicate an explicit time interval. The start time may be specified as: The string always to indicate the certificate has no specified start time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time before the current system time consisting of a minus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. The end time may be specified similarly to the start time: The string forever to indicate the certificate has no specified end time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time after the current system time consisting of a plus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. For example: +52w1d Valid from now to 52 weeks and one day from now. -4w:+4w Valid from four weeks ago to four weeks from now. 20100101123000:20110101123000 Valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011. 20100101123000Z:20110101123000Z Similar, but interpreted in the UTC time zone rather than the system time zone. -1d:20110101 Valid from yesterday to midnight, January 1st, 2011. 0x1:0x2000000000 Valid from roughly early 1970 to May 2033. -1m:forever Valid from one minute ago and never expiring. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful for debugging moduli generation. Multiple -v options increase the verbosity. The maximum is 3. -w provider Specifies a path to a library that will be used when creating FIDO authenticator-hosted keys, overriding the default of using the internal USB HID support. -Y find-principals Find the principal(s) associated with the public key of a signature, provided using the -s flag in an authorized signers file provided using the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. If one or more matching principals are found, they are returned on standard output. -Y match-principals Find principal matching the principal name provided using the -I flag in the authorized signers file specified using the -f flag. If one or more matching principals are found, they are returned on standard output. -Y check-novalidate Checks that a signature generated using -Y sign has a valid structure. This does not validate if a signature comes from an authorized signer. When testing a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag. Successful testing of the signature is signalled by returning a zero exit status. -Y sign Cryptographically sign a file or some data using an SSH key. When signing, accepts zero or more files to sign on the command-line - if no files are specified then will sign data presented on standard input. Signatures are written to the path of the input file with .sig appended, or to standard output if the message to be signed was read from standard input. The key used for signing is specified using the -f option and may refer to either a private key, or a public key with the private half available via ssh-agent(1). An additional signature namespace, used to prevent signature confusion across different domains of use (e.g. file signing vs email signing) must be provided via the -n flag. Namespaces are arbitrary strings, and may include: file for file signing, email for email signing. For custom uses, it is recommended to use names following a NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces. -Y verify Request to verify a signature generated using -Y sign as described above. When verifying a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag, along with the identity of the signer using -I and a list of allowed signers via the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. A file containing revoked keys can be passed using the -r flag. The revocation file may be a KRL or a one-per-line list of public keys. Successful verification by an authorized signer is signalled by returning a zero exit status. -y This option will read a private OpenSSH format file and print an OpenSSH public key to stdout. -Z cipher Specifies the cipher to use for encryption when writing an OpenSSH-format private key file. The list of available ciphers may be obtained using "ssh -Q cipher". The default is aes256-ctr. -z serial_number Specifies a serial number to be embedded in the certificate to distinguish this certificate from others from the same CA. If the serial_number is prefixed with a + character, then the serial number will be incremented for each certificate signed on a single command-line. The default serial number is zero. When generating a KRL, the -z flag is used to specify a KRL version number. MODULI GENERATION top may be used to generate groups for the Diffie-Hellman Group Exchange (DH-GEX) protocol. Generating these groups is a two- step process: first, candidate primes are generated using a fast, but memory intensive process. These candidate primes are then tested for suitability (a CPU-intensive process). Generation of primes is performed using the -M generate option. The desired length of the primes may be specified by the -O bits option. For example: # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates By default, the search for primes begins at a random point in the desired length range. This may be overridden using the -O start option, which specifies a different start point (in hex). Once a set of candidates have been generated, they must be screened for suitability. This may be performed using the -M screen option. In this mode will read candidates from standard input (or a file specified using the -f option). For example: # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048 By default, each candidate will be subjected to 100 primality tests. This may be overridden using the -O prime-tests option. The DH generator value will be chosen automatically for the prime under consideration. If a specific generator is desired, it may be requested using the -O generator option. Valid generator values are 2, 3, and 5. Screened DH groups may be installed in /etc/moduli. It is important that this file contains moduli of a range of bit lengths. A number of options are available for moduli generation and screening via the -O flag: lines=number Exit after screening the specified number of lines while performing DH candidate screening. start-line=line-number Start screening at the specified line number while performing DH candidate screening. checkpoint=filename Write the last line processed to the specified file while performing DH candidate screening. This will be used to skip lines in the input file that have already been processed if the job is restarted. memory=mbytes Specify the amount of memory to use (in megabytes) when generating candidate moduli for DH-GEX. start=hex-value Specify start point (in hex) when generating candidate moduli for DH-GEX. generator=value Specify desired generator (in decimal) when testing candidate moduli for DH-GEX. CERTIFICATES top supports signing of keys to produce certificates that may be used for user or host authentication. Certificates consist of a public key, some identity information, zero or more principal (user or host) names and a set of options that are signed by a Certification Authority (CA) key. Clients or servers may then trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys. Note that OpenSSH certificates are a different, and much simpler, format to the X.509 certificates used in ssl(8). supports two types of certificates: user and host. User certificates authenticate users to servers, whereas host certificates authenticate server hosts to users. To generate a user certificate: $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub The resultant certificate will be placed in /path/to/user_key-cert.pub. A host certificate requires the -h option: $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub The host certificate will be output to /path/to/host_key-cert.pub. It is possible to sign using a CA key stored in a PKCS#11 token by providing the token library using -D and identifying the CA key by providing its public half as an argument to -s: $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub Similarly, it is possible for the CA key to be hosted in a ssh-agent(1). This is indicated by the -U flag and, again, the CA key must be identified by its public half. $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub In all cases, key_id is a "key identifier" that is logged by the server when the certificate is used for authentication. Certificates may be limited to be valid for a set of principal (user/host) names. By default, generated certificates are valid for all users or hosts. To generate a certificate for a specified set of principals: $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub $ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub Additional limitations on the validity and use of user certificates may be specified through certificate options. A certificate option may disable features of the SSH session, may be valid only when presented from particular source addresses or may force the use of a specific command. The options that are valid for user certificates are: clear Clear all enabled permissions. This is useful for clearing the default set of permissions so permissions may be added individually. critical:name[=contents] extension:name[=contents] Includes an arbitrary certificate critical option or extension. The specified name should include a domain suffix, e.g. name@example.com. If contents is specified then it is included as the contents of the extension/option encoded as a string, otherwise the extension/option is created with no contents (usually indicating a flag). Extensions may be ignored by a client or server that does not recognise them, whereas unknown critical options will cause the certificate to be refused. force-command=command Forces the execution of command instead of any shell or command specified by the user when the certificate is used for authentication. no-agent-forwarding Disable ssh-agent(1) forwarding (permitted by default). no-port-forwarding Disable port forwarding (permitted by default). no-pty Disable PTY allocation (permitted by default). no-user-rc Disable execution of ~/.ssh/rc by sshd(8) (permitted by default). no-x11-forwarding Disable X11 forwarding (permitted by default). permit-agent-forwarding Allows ssh-agent(1) forwarding. permit-port-forwarding Allows port forwarding. permit-pty Allows PTY allocation. permit-user-rc Allows execution of ~/.ssh/rc by sshd(8). permit-X11-forwarding Allows X11 forwarding. no-touch-required Do not require signatures made using this key include demonstration of user presence (e.g. by having the user touch the authenticator). This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. source-address=address_list Restrict the source addresses from which the certificate is considered valid. The address_list is a comma- separated list of one or more address/netmask pairs in CIDR format. verify-required Require signatures made using this key indicate that the user was first verified. This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. At present, no standard options are valid for host keys. Finally, certificates may be defined with a validity lifetime. The -V option allows specification of certificate start and end times. A certificate that is presented at a time outside this range will not be considered valid. By default, certificates are valid from the Unix Epoch to the distant future. For certificates to be used for user or host authentication, the CA public key must be trusted by sshd(8) or ssh(1). Refer to those manual pages for details. FIDO AUTHENTICATOR top is able to generate FIDO authenticator-backed keys, after which they may be used much like any other key type supported by OpenSSH, so long as the hardware authenticator is attached when the keys are used. FIDO authenticators generally require the user to explicitly authorise operations by touching or tapping them. FIDO keys consist of two parts: a key handle part stored in the private key file on disk, and a per-device private key that is unique to each FIDO authenticator and that cannot be exported from the authenticator hardware. These are combined by the hardware at authentication time to derive the real key that is used to sign authentication challenges. Supported key types are ecdsa-sk and ed25519-sk. The options that are valid for FIDO keys are: application Override the default FIDO application/origin string of ssh:. This may be useful when generating host or domain-specific resident keys. The specified application string must begin with ssh:. challenge=path Specifies a path to a challenge string that will be passed to the FIDO authenticator during key generation. The challenge string may be used as part of an out-of- band protocol for key enrollment (a random challenge is used by default). device Explicitly specify a fido(4) device to use, rather than letting the authenticator middleware select one. no-touch-required Indicate that the generated private key should not require touch events (user presence) when making signatures. Note that sshd(8) will refuse such signatures by default, unless overridden via an authorized_keys option. resident Indicate that the key handle should be stored on the FIDO authenticator itself. This makes it easier to use the authenticator on multiple computers. Resident keys may be supported on FIDO2 authenticators and typically require that a PIN be set on the authenticator prior to generation. Resident keys may be loaded off the authenticator using ssh-add(1). Storing both parts of a key on a FIDO authenticator increases the likelihood of an attacker being able to use a stolen authenticator device. user A username to be associated with a resident key, overriding the empty default username. Specifying a username may be useful when generating multiple resident keys for the same application name. verify-required Indicate that this private key should require user verification for each signature. Not all FIDO authenticators support this option. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. write-attestation=path May be used at key generation time to record the attestation data returned from FIDO authenticators during key generation. This information is potentially sensitive. By default, this information is discarded. KEY REVOCATION LISTS top is able to manage OpenSSH format Key Revocation Lists (KRLs). These binary files specify keys or certificates to be revoked using a compact format, taking as little as one bit per certificate if they are being revoked by serial number. KRLs may be generated using the -k flag. This option reads one or more files from the command line and generates a new KRL. The files may either contain a KRL specification (see below) or public keys, listed one per line. Plain public keys are revoked by listing their hash or contents in the KRL and certificates revoked by serial number or key ID (if the serial is zero or not available). Revoking keys using a KRL specification offers explicit control over the types of record used to revoke keys and may be used to directly revoke certificates by serial number or key ID without having the complete original certificate on hand. A KRL specification consists of lines containing one of the following directives followed by a colon and some directive-specific information. serial: serial_number[-serial_number] Revokes a certificate with the specified serial number. Serial numbers are 64-bit values, not including zero and may be expressed in decimal, hex or octal. If two serial numbers are specified separated by a hyphen, then the range of serial numbers including and between each is revoked. The CA key must have been specified on the command line using the -s option. id: key_id Revokes a certificate with the specified key ID string. The CA key must have been specified on the command line using the -s option. key: public_key Revokes the specified key. If a certificate is listed, then it is revoked as a plain public key. sha1: public_key Revokes the specified key by including its SHA1 hash in the KRL. sha256: public_key Revokes the specified key by including its SHA256 hash in the KRL. KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions prior to 7.9. hash: fingerprint Revokes a key using a fingerprint hash, as obtained from a sshd(8) authentication log message or the -l flag. Only SHA256 fingerprints are supported here and resultant KRLs are not supported by OpenSSH versions prior to 7.9. KRLs may be updated using the -u flag in addition to -k. When this option is specified, keys listed via the command line are merged into the KRL, adding to those already there. It is also possible, given a KRL, to test whether it revokes a particular key (or keys). The -Q flag will query an existing KRL, testing each key specified on the command line. If any key listed on the command line has been revoked (or an error encountered) then will exit with a non-zero exit status. A zero exit status will only be returned if no key was revoked. ALLOWED SIGNERS top When verifying signatures, uses a simple list of identities and keys to determine whether a signature comes from an authorized source. This "allowed signers" file uses a format patterned after the AUTHORIZED_KEYS FILE FORMAT described in sshd(8). Each line of the file contains the following space-separated fields: principals, options, keytype, base64-encoded key. Empty lines and lines starting with a # are ignored as comments. The principals field is a pattern-list (see PATTERNS in ssh_config(5)) consisting of one or more comma-separated USER@DOMAIN identity patterns that are accepted for signing. When verifying, the identity presented via the -I option must match a principals pattern in order for the corresponding key to be considered acceptable for verification. The options (if present) consist of comma-separated option specifications. No spaces are permitted, except within double quotes. The following option specifications are supported (note that option keywords are case-insensitive): cert-authority Indicates that this key is accepted as a certificate authority (CA) and that certificates signed by this CA may be accepted for verification. namespaces=namespace-list Specifies a pattern-list of namespaces that are accepted for this key. If this option is present, the signature namespace embedded in the signature object and presented on the verification command-line must match the specified list before the key will be considered acceptable. valid-after=timestamp Indicates that the key is valid for use at or after the specified timestamp, which may be a date or time in the YYYYMMDD[Z] or YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. valid-before=timestamp Indicates that the key is valid for use at or before the specified timestamp. When verifying signatures made by certificates, the expected principal name must match both the principals pattern in the allowed signers file and the principals embedded in the certificate itself. An example allowed signers file: # Comments allowed at start of line user1@example.com,user2@example.com ssh-rsa AAAAX1... # A certificate authority, trusted for all principals in a domain. *@example.com cert-authority ssh-ed25519 AAAB4... # A key that is accepted only for file signing. user2@example.com namespaces="file" ssh-ed25519 AAA41... ENVIRONMENT top SSH_SK_PROVIDER Specifies a path to a library that will be used when loading any FIDO authenticator-hosted keys, overriding the default of using the built-in USB HID support. FILES top ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specify a passphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 128-bit AES. This file is not automatically accessed by but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machines where the user wishes to log in using public key authentication. There is no need to keep the contents of this file secret. /etc/moduli Contains Diffie-Hellman groups used for DH-GEX. The file format is described in moduli(5). SEE ALSO top ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU September 4, 2023 SSH-KEYGEN(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a new RSA key for ssh with no passphrase, store it in ~/.ssh/id_rsa without prompting to overwrite if this file exists, and minimize output from ssh-keygen. Bash Command:<START>echo -e 'y\n'|ssh-keygen -q -t rsa -N "" -f ~/.ssh/id_rsa<END> |
Create a new directory "existing-dir/new-dir/" on host "node" | rsync /dev/null node:existing-dir/new-dir/ | ['rsync'] | Output a Bash command to accomplish the following task. Task: Create a new directory "existing-dir/new-dir/" on host "node" Bash Command:<START>rsync /dev/null node:existing-dir/new-dir/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # rsync\n\n> Transfer files either to or from a remote host (but not between two remote hosts), by default using SSH.\n> To specify a remote path, use `user@host:path/to/file_or_directory`.\n> More information: <https://download.samba.org/pub/rsync/rsync.1>.\n\n- Transfer a file:\n\n`rsync {{path/to/source}} {{path/to/destination}}`\n\n- Use archive mode (recursively copy directories, copy symlinks without resolving, and preserve permissions, ownership and modification times):\n\n`rsync --archive {{path/to/source}} {{path/to/destination}}`\n\n- Compress the data as it is sent to the destination, display verbose and human-readable progress, and keep partially transferred files if interrupted:\n\n`rsync --compress --verbose --human-readable --partial --progress {{path/to/source}} {{path/to/destination}}`\n\n- Recursively copy directories:\n\n`rsync --recursive {{path/to/source}} {{path/to/destination}}`\n\n- Transfer directory contents, but not the directory itself:\n\n`rsync --recursive {{path/to/source}}/ {{path/to/destination}}`\n\n- Use archive mode, resolve symlinks and skip files that are newer on the destination:\n\n`rsync --archive --update --copy-links {{path/to/source}} {{path/to/destination}}`\n\n- Transfer a directory to a remote host running `rsyncd` and delete files on the destination that do not exist on the source:\n\n`rsync --recursive --delete rsync://{{host}}:{{path/to/source}} {{path/to/destination}}`\n\n- Transfer a file over SSH using a different port than the default (22) and show global progress:\n\n`rsync --rsh 'ssh -p {{port}}' --info=progress2 {{host}}:{{path/to/source}} {{path/to/destination}}`\n Task: Create a new directory "existing-dir/new-dir/" on host "node" Bash Command:<START>rsync /dev/null node:existing-dir/new-dir/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: rsync(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training rsync(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | GENERAL | SETUP | USAGE | COPYING TO A DIFFERENT NAME | SORTED TRANSFER ORDER | MULTI-HOST SECURITY | ADVANCED USAGE | CONNECTING TO AN RSYNC DAEMON | USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION | STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS | EXAMPLES | OPTION SUMMARY | OPTIONS | DAEMON OPTIONS | FILTER RULES | TRANSFER RULES | BATCH MODE | SYMBOLIC LINKS | DIAGNOSTICS | EXIT VALUES | ENVIRONMENT VARIABLES | FILES | SEE ALSO | BUGS | VERSION | INTERNAL OPTIONS | CREDITS | THANKS | AUTHOR | COLOPHON rsync(1) User Commands rsync(1) NAME top rsync - a fast, versatile, remote (and local) file-copying tool SYNOPSIS top Local: rsync [OPTION...] SRC... [DEST] Access via remote shell: Pull: rsync [OPTION...] [USER@]HOST:SRC... [DEST] Push: rsync [OPTION...] SRC... [USER@]HOST:DEST Access via rsync daemon: Pull: rsync [OPTION...] [USER@]HOST::SRC... [DEST] rsync [OPTION...] rsync://[USER@]HOST[:PORT]/SRC... [DEST] Push: rsync [OPTION...] SRC... [USER@]HOST::DEST rsync [OPTION...] SRC... rsync://[USER@]HOST[:PORT]/DEST) Usages with just one SRC arg and no DEST arg will list the source files instead of copying. The online version of this manpage (that includes cross-linking of topics) is available at https://download.samba.org/pub/rsync/rsync.1. DESCRIPTION top Rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. It offers a large number of options that control every aspect of its behavior and permit very flexible specification of the set of files to be copied. It is famous for its delta-transfer algorithm, which reduces the amount of data sent over the network by sending only the differences between the source files and the existing files in the destination. Rsync is widely used for backups and mirroring and as an improved copy command for everyday use. Rsync finds files that need to be transferred using a "quick check" algorithm (by default) that looks for files that have changed in size or in last-modified time. Any changes in the other preserved attributes (as requested by options) are made on the destination file directly when the quick check indicates that the file's data does not need to be updated. Some of the additional features of rsync are: o support for copying links, devices, owners, groups, and permissions o exclude and exclude-from options similar to GNU tar o a CVS exclude mode for ignoring the same files that CVS would ignore o can use any transparent remote shell, including ssh or rsh o does not require super-user privileges o pipelining of file transfers to minimize latency costs o support for anonymous or authenticated rsync daemons (ideal for mirroring) GENERAL top Rsync copies files either to or from a remote host, or locally on the current host (it does not support copying files between two remote hosts). There are two different ways for rsync to contact a remote system: using a remote-shell program as the transport (such as ssh or rsh) or contacting an rsync daemon directly via TCP. The remote-shell transport is used whenever the source or destination path contains a single colon (:) separator after a host specification. Contacting an rsync daemon directly happens when the source or destination path contains a double colon (::) separator after a host specification, OR when an rsync:// URL is specified (see also the USING RSYNC-DAEMON FEATURES VIA A REMOTE- SHELL CONNECTION section for an exception to this latter rule). As a special case, if a single source arg is specified without a destination, the files are listed in an output format similar to "ls -l". As expected, if neither the source or destination path specify a remote host, the copy occurs locally (see also the --list-only option). Rsync refers to the local side as the client and the remote side as the server. Don't confuse server with an rsync daemon. A daemon is always a server, but a server can be either a daemon or a remote-shell spawned process. SETUP top See the file README.md for installation instructions. Once installed, you can use rsync to any machine that you can access via a remote shell (as well as some that you can access using the rsync daemon-mode protocol). For remote transfers, a modern rsync uses ssh for its communications, but it may have been configured to use a different remote shell by default, such as rsh or remsh. You can also specify any remote shell you like, either by using the -e command line option, or by setting the RSYNC_RSH environment variable. Note that rsync must be installed on both the source and destination machines. USAGE top You use rsync in the same way you use rcp. You must specify a source and a destination, one of which may be remote. Perhaps the best way to explain the syntax is with some examples: rsync -t *.c foo:src/ This would transfer all files matching the pattern *.c from the current directory to the directory src on the machine foo. If any of the files already exist on the remote system then the rsync remote-update protocol is used to update the file by sending only the differences in the data. Note that the expansion of wildcards on the command-line (*.c) into a list of files is handled by the shell before it runs rsync and not by rsync itself (exactly the same as all other Posix-style programs). rsync -avz foo:src/bar /data/tmp This would recursively transfer all files from the directory src/bar on the machine foo into the /data/tmp/bar directory on the local machine. The files are transferred in archive mode, which ensures that symbolic links, devices, attributes, permissions, ownerships, etc. are preserved in the transfer. Additionally, compression will be used to reduce the size of data portions of the transfer. rsync -avz foo:src/bar/ /data/tmp A trailing slash on the source changes this behavior to avoid creating an additional directory level at the destination. You can think of a trailing / on a source as meaning "copy the contents of this directory" as opposed to "copy the directory by name", but in both cases the attributes of the containing directory are transferred to the containing directory on the destination. In other words, each of the following commands copies the files in the same way, including their setting of the attributes of /dest/foo: rsync -av /src/foo /dest rsync -av /src/foo/ /dest/foo Note also that host and module references don't require a trailing slash to copy the contents of the default directory. For example, both of these copy the remote directory's contents into "/dest": rsync -av host: /dest rsync -av host::module /dest You can also use rsync in local-only mode, where both the source and destination don't have a ':' in the name. In this case it behaves like an improved copy command. Finally, you can list all the (listable) modules available from a particular rsync daemon by leaving off the module name: rsync somehost.mydomain.com:: COPYING TO A DIFFERENT NAME top When you want to copy a directory to a different name, use a trailing slash on the source directory to put the contents of the directory into any destination directory you like: rsync -ai foo/ bar/ Rsync also has the ability to customize a destination file's name when copying a single item. The rules for this are: o The transfer list must consist of a single item (either a file or an empty directory) o The final element of the destination path must not exist as a directory o The destination path must not have been specified with a trailing slash Under those circumstances, rsync will set the name of the destination's single item to the last element of the destination path. Keep in mind that it is best to only use this idiom when copying a file and use the above trailing-slash idiom when copying a directory. The following example copies the foo.c file as bar.c in the save dir (assuming that bar.c isn't a directory): rsync -ai src/foo.c save/bar.c The single-item copy rule might accidentally bite you if you unknowingly copy a single item and specify a destination dir that doesn't exist (without using a trailing slash). For example, if src/*.c matches one file and save/dir doesn't exist, this will confuse you by naming the destination file save/dir: rsync -ai src/*.c save/dir To prevent such an accident, either make sure the destination dir exists or specify the destination path with a trailing slash: rsync -ai src/*.c save/dir/ SORTED TRANSFER ORDER top Rsync always sorts the specified filenames into its internal transfer list. This handles the merging together of the contents of identically named directories, makes it easy to remove duplicate filenames. It can, however, confuse someone when the files are transferred in a different order than what was given on the command-line. If you need a particular file to be transferred prior to another, either separate the files into different rsync calls, or consider using --delay-updates (which doesn't affect the sorted transfer order, but does make the final file-updating phase happen much more rapidly). MULTI-HOST SECURITY top Rsync takes steps to ensure that the file requests that are shared in a transfer are protected against various security issues. Most of the potential problems arise on the receiving side where rsync takes steps to ensure that the list of files being transferred remains within the bounds of what was requested. Toward this end, rsync 3.1.2 and later have aborted when a file list contains an absolute or relative path that tries to escape out of the top of the transfer. Also, beginning with version 3.2.5, rsync does two more safety checks of the file list to (1) ensure that no extra source arguments were added into the transfer other than those that the client requested and (2) ensure that the file list obeys the exclude rules that were sent to the sender. For those that don't yet have a 3.2.5 client rsync (or those that want to be extra careful), it is safest to do a copy into a dedicated destination directory for the remote files when you don't trust the remote host. For example, instead of doing an rsync copy into your home directory: rsync -aiv host1:dir1 ~ Dedicate a "host1-files" dir to the remote content: rsync -aiv host1:dir1 ~/host1-files See the --trust-sender option for additional details. CAUTION: it is not particularly safe to use rsync to copy files from a case-preserving filesystem to a case-ignoring filesystem. If you must perform such a copy, you should either disable symlinks via --no-links or enable the munging of symlinks via --munge-links (and make sure you use the right local or remote option). This will prevent rsync from doing potentially dangerous things if a symlink name overlaps with a file or directory. It does not, however, ensure that you get a full copy of all the files (since that may not be possible when the names overlap). A potentially better solution is to list all the source files and create a safe list of filenames that you pass to the --files-from option. Any files that conflict in name would need to be copied to different destination directories using more than one copy. While a copy of a case-ignoring filesystem to a case-ignoring filesystem can work out fairly well, if no --delete-during or --delete-before option is active, rsync can potentially update an existing file on the receiveing side without noticing that the upper-/lower-case of the filename should be changed to match the sender. ADVANCED USAGE top The syntax for requesting multiple files from a remote host is done by specifying additional remote-host args in the same style as the first, or with the hostname omitted. For instance, all these work: rsync -aiv host:file1 :file2 host:file{3,4} /dest/ rsync -aiv host::modname/file{1,2} host::modname/extra /dest/ rsync -aiv host::modname/first ::extra-file{1,2} /dest/ Note that a daemon connection only supports accessing one module per copy command, so if the start of a follow-up path doesn't begin with the modname of the first path, it is assumed to be a path in the module (such as the extra-file1 & extra-file2 that are grabbed above). Really old versions of rsync (2.6.9 and before) only allowed specifying one remote-source arg, so some people have instead relied on the remote-shell performing space splitting to break up an arg into multiple paths. Such unintuitive behavior is no longer supported by default (though you can request it, as described below). Starting in 3.2.4, filenames are passed to a remote shell in such a way as to preserve the characters you give it. Thus, if you ask for a file with spaces in the name, that's what the remote rsync looks for: rsync -aiv host:'a simple file.pdf' /dest/ If you use scripts that have been written to manually apply extra quoting to the remote rsync args (or to require remote arg splitting), you can ask rsync to let your script handle the extra escaping. This is done by either adding the --old-args option to the rsync runs in the script (which requires a new rsync) or exporting RSYNC_OLD_ARGS=1 and RSYNC_PROTECT_ARGS=0 (which works with old or new rsync versions). CONNECTING TO AN RSYNC DAEMON top It is also possible to use rsync without a remote shell as the transport. In this case you will directly connect to a remote rsync daemon, typically using TCP port 873. (This obviously requires the daemon to be running on the remote system, so refer to the STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS section below for information on that.) Using rsync in this way is the same as using it with a remote shell except that: o Use either double-colon syntax or rsync:// URL syntax instead of the single-colon (remote shell) syntax. o The first element of the "path" is actually a module name. o Additional remote source args can use an abbreviated syntax that omits the hostname and/or the module name, as discussed in ADVANCED USAGE. o The remote daemon may print a "message of the day" when you connect. o If you specify only the host (with no module or path) then a list of accessible modules on the daemon is output. o If you specify a remote source path but no destination, a listing of the matching files on the remote daemon is output. o The --rsh (-e) option must be omitted to avoid changing the connection style from using a socket connection to USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION. An example that copies all the files in a remote module named "src": rsync -av host::src /dest Some modules on the remote daemon may require authentication. If so, you will receive a password prompt when you connect. You can avoid the password prompt by setting the environment variable RSYNC_PASSWORD to the password you want to use or using the --password-file option. This may be useful when scripting rsync. WARNING: On some systems environment variables are visible to all users. On those systems using --password-file is recommended. You may establish the connection via a web proxy by setting the environment variable RSYNC_PROXY to a hostname:port pair pointing to your web proxy. Note that your web proxy's configuration must support proxy connections to port 873. You may also establish a daemon connection using a program as a proxy by setting the environment variable RSYNC_CONNECT_PROG to the commands you wish to run in place of making a direct socket connection. The string may contain the escape "%H" to represent the hostname specified in the rsync command (so use "%%" if you need a single "%" in your string). For example: export RSYNC_CONNECT_PROG='ssh proxyhost nc %H 873' rsync -av targethost1::module/src/ /dest/ rsync -av rsync://targethost2/module/src/ /dest/ The command specified above uses ssh to run nc (netcat) on a proxyhost, which forwards all data to port 873 (the rsync daemon) on the targethost (%H). Note also that if the RSYNC_SHELL environment variable is set, that program will be used to run the RSYNC_CONNECT_PROG command instead of using the default shell of the system() call. USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION top It is sometimes useful to use various features of an rsync daemon (such as named modules) without actually allowing any new socket connections into a system (other than what is already required to allow remote-shell access). Rsync supports connecting to a host using a remote shell and then spawning a single-use "daemon" server that expects to read its config file in the home dir of the remote user. This can be useful if you want to encrypt a daemon-style transfer's data, but since the daemon is started up fresh by the remote user, you may not be able to use features such as chroot or change the uid used by the daemon. (For another way to encrypt a daemon transfer, consider using ssh to tunnel a local port to a remote machine and configure a normal rsync daemon on that remote host to only allow connections from "localhost".) From the user's perspective, a daemon transfer via a remote-shell connection uses nearly the same command-line syntax as a normal rsync-daemon transfer, with the only exception being that you must explicitly set the remote shell program on the command-line with the --rsh=COMMAND option. (Setting the RSYNC_RSH in the environment will not turn on this functionality.) For example: rsync -av --rsh=ssh host::module /dest If you need to specify a different remote-shell user, keep in mind that the user@ prefix in front of the host is specifying the rsync-user value (for a module that requires user-based authentication). This means that you must give the '-l user' option to ssh when specifying the remote-shell, as in this example that uses the short version of the --rsh option: rsync -av -e "ssh -l ssh-user" rsync-user@host::module /dest The "ssh-user" will be used at the ssh level; the "rsync-user" will be used to log-in to the "module". In this setup, the daemon is started by the ssh command that is accessing the system (which can be forced via the ~/.ssh/authorized_keys file, if desired). However, when accessing a daemon directly, it needs to be started beforehand. STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS top In order to connect to an rsync daemon, the remote system needs to have a daemon already running (or it needs to have configured something like inetd to spawn an rsync daemon for incoming connections on a particular port). For full information on how to start a daemon that will handling incoming socket connections, see the rsyncd.conf(5) manpage -- that is the config file for the daemon, and it contains the full details for how to run the daemon (including stand-alone and inetd configurations). If you're using one of the remote-shell transports for the transfer, there is no need to manually start an rsync daemon. EXAMPLES top Here are some examples of how rsync can be used. To backup a home directory, which consists of large MS Word files and mail folders, a per-user cron job can be used that runs this each day: rsync -aiz . bkhost:backup/joe/ To move some files from a remote host to the local host, you could run: rsync -aiv --remove-source-files rhost:/tmp/{file1,file2}.c ~/src/ OPTION SUMMARY top Here is a short summary of the options available in rsync. Each option also has its own detailed description later in this manpage. --verbose, -v increase verbosity --info=FLAGS fine-grained informational verbosity --debug=FLAGS fine-grained debug verbosity --stderr=e|a|c change stderr output mode (default: errors) --quiet, -q suppress non-error messages --no-motd suppress daemon-mode MOTD --checksum, -c skip based on checksum, not mod-time & size --archive, -a archive mode is -rlptgoD (no -A,-X,-U,-N,-H) --no-OPTION turn off an implied OPTION (e.g. --no-D) --recursive, -r recurse into directories --relative, -R use relative path names --no-implied-dirs don't send implied dirs with --relative --backup, -b make backups (see --suffix & --backup-dir) --backup-dir=DIR make backups into hierarchy based in DIR --suffix=SUFFIX backup suffix (default ~ w/o --backup-dir) --update, -u skip files that are newer on the receiver --inplace update destination files in-place --append append data onto shorter files --append-verify --append w/old data in file checksum --dirs, -d transfer directories without recursing --old-dirs, --old-d works like --dirs when talking to old rsync --mkpath create destination's missing path components --links, -l copy symlinks as symlinks --copy-links, -L transform symlink into referent file/dir --copy-unsafe-links only "unsafe" symlinks are transformed --safe-links ignore symlinks that point outside the tree --munge-links munge symlinks to make them safe & unusable --copy-dirlinks, -k transform symlink to dir into referent dir --keep-dirlinks, -K treat symlinked dir on receiver as dir --hard-links, -H preserve hard links --perms, -p preserve permissions --executability, -E preserve executability --chmod=CHMOD affect file and/or directory permissions --acls, -A preserve ACLs (implies --perms) --xattrs, -X preserve extended attributes --owner, -o preserve owner (super-user only) --group, -g preserve group --devices preserve device files (super-user only) --copy-devices copy device contents as a regular file --write-devices write to devices as files (implies --inplace) --specials preserve special files -D same as --devices --specials --times, -t preserve modification times --atimes, -U preserve access (use) times --open-noatime avoid changing the atime on opened files --crtimes, -N preserve create times (newness) --omit-dir-times, -O omit directories from --times --omit-link-times, -J omit symlinks from --times --super receiver attempts super-user activities --fake-super store/recover privileged attrs using xattrs --sparse, -S turn sequences of nulls into sparse blocks --preallocate allocate dest files before writing them --dry-run, -n perform a trial run with no changes made --whole-file, -W copy files whole (w/o delta-xfer algorithm) --checksum-choice=STR choose the checksum algorithm (aka --cc) --one-file-system, -x don't cross filesystem boundaries --block-size=SIZE, -B force a fixed checksum block-size --rsh=COMMAND, -e specify the remote shell to use --rsync-path=PROGRAM specify the rsync to run on remote machine --existing skip creating new files on receiver --ignore-existing skip updating files that exist on receiver --remove-source-files sender removes synchronized files (non-dir) --del an alias for --delete-during --delete delete extraneous files from dest dirs --delete-before receiver deletes before xfer, not during --delete-during receiver deletes during the transfer --delete-delay find deletions during, delete after --delete-after receiver deletes after transfer, not during --delete-excluded also delete excluded files from dest dirs --ignore-missing-args ignore missing source args without error --delete-missing-args delete missing source args from destination --ignore-errors delete even if there are I/O errors --force force deletion of dirs even if not empty --max-delete=NUM don't delete more than NUM files --max-size=SIZE don't transfer any file larger than SIZE --min-size=SIZE don't transfer any file smaller than SIZE --max-alloc=SIZE change a limit relating to memory alloc --partial keep partially transferred files --partial-dir=DIR put a partially transferred file into DIR --delay-updates put all updated files into place at end --prune-empty-dirs, -m prune empty directory chains from file-list --numeric-ids don't map uid/gid values by user/group name --usermap=STRING custom username mapping --groupmap=STRING custom groupname mapping --chown=USER:GROUP simple username/groupname mapping --timeout=SECONDS set I/O timeout in seconds --contimeout=SECONDS set daemon connection timeout in seconds --ignore-times, -I don't skip files that match size and time --size-only skip files that match in size --modify-window=NUM, -@ set the accuracy for mod-time comparisons --temp-dir=DIR, -T create temporary files in directory DIR --fuzzy, -y find similar file for basis if no dest file --compare-dest=DIR also compare destination files relative to DIR --copy-dest=DIR ... and include copies of unchanged files --link-dest=DIR hardlink to files in DIR when unchanged --compress, -z compress file data during the transfer --compress-choice=STR choose the compression algorithm (aka --zc) --compress-level=NUM explicitly set compression level (aka --zl) --skip-compress=LIST skip compressing files with suffix in LIST --cvs-exclude, -C auto-ignore files in the same way CVS does --filter=RULE, -f add a file-filtering RULE -F same as --filter='dir-merge /.rsync-filter' repeated: --filter='- .rsync-filter' --exclude=PATTERN exclude files matching PATTERN --exclude-from=FILE read exclude patterns from FILE --include=PATTERN don't exclude files matching PATTERN --include-from=FILE read include patterns from FILE --files-from=FILE read list of source-file names from FILE --from0, -0 all *-from/filter files are delimited by 0s --old-args disable the modern arg-protection idiom --secluded-args, -s use the protocol to safely send the args --trust-sender trust the remote sender's file list --copy-as=USER[:GROUP] specify user & optional group for the copy --address=ADDRESS bind address for outgoing socket to daemon --port=PORT specify double-colon alternate port number --sockopts=OPTIONS specify custom TCP options --blocking-io use blocking I/O for the remote shell --outbuf=N|L|B set out buffering to None, Line, or Block --stats give some file-transfer stats --8-bit-output, -8 leave high-bit chars unescaped in output --human-readable, -h output numbers in a human-readable format --progress show progress during transfer -P same as --partial --progress --itemize-changes, -i output a change-summary for all updates --remote-option=OPT, -M send OPTION to the remote side only --out-format=FORMAT output updates using the specified FORMAT --log-file=FILE log what we're doing to the specified FILE --log-file-format=FMT log updates using the specified FMT --password-file=FILE read daemon-access password from FILE --early-input=FILE use FILE for daemon's early exec input --list-only list the files instead of copying them --bwlimit=RATE limit socket I/O bandwidth --stop-after=MINS Stop rsync after MINS minutes have elapsed --stop-at=y-m-dTh:m Stop rsync at the specified point in time --fsync fsync every written file --write-batch=FILE write a batched update to FILE --only-write-batch=FILE like --write-batch but w/o updating dest --read-batch=FILE read a batched update from FILE --protocol=NUM force an older protocol version to be used --iconv=CONVERT_SPEC request charset conversion of filenames --checksum-seed=NUM set block/file checksum seed (advanced) --ipv4, -4 prefer IPv4 --ipv6, -6 prefer IPv6 --version, -V print the version + other info and exit --help, -h (*) show this help (* -h is help only on its own) Rsync can also be run as a daemon, in which case the following options are accepted: --daemon run as an rsync daemon --address=ADDRESS bind to the specified address --bwlimit=RATE limit socket I/O bandwidth --config=FILE specify alternate rsyncd.conf file --dparam=OVERRIDE, -M override global daemon config parameter --no-detach do not detach from the parent --port=PORT listen on alternate port number --log-file=FILE override the "log file" setting --log-file-format=FMT override the "log format" setting --sockopts=OPTIONS specify custom TCP options --verbose, -v increase verbosity --ipv4, -4 prefer IPv4 --ipv6, -6 prefer IPv6 --help, -h show this help (when used with --daemon) OPTIONS top Rsync accepts both long (double-dash + word) and short (single- dash + letter) options. The full list of the available options are described below. If an option can be specified in more than one way, the choices are comma-separated. Some options only have a long variant, not a short. If the option takes a parameter, the parameter is only listed after the long variant, even though it must also be specified for the short. When specifying a parameter, you can either use the form --option=param, --option param, -o=param, -o param, or -oparam (the latter choices assume that your option has a short variant). The parameter may need to be quoted in some manner for it to survive the shell's command-line parsing. Also keep in mind that a leading tilde (~) in a pathname is substituted by your shell, so make sure that you separate the option name from the pathname using a space if you want the local shell to expand it. --help Print a short help page describing the options available in rsync and exit. You can also use -h for --help when it is used without any other options (since it normally means --human-readable). --version, -V Print the rsync version plus other info and exit. When repeated, the information is output is a JSON format that is still fairly readable (client side only). The output includes a list of compiled-in capabilities, a list of optimizations, the default list of checksum algorithms, the default list of compression algorithms, the default list of daemon auth digests, a link to the rsync web site, and a few other items. --verbose, -v This option increases the amount of information you are given during the transfer. By default, rsync works silently. A single -v will give you information about what files are being transferred and a brief summary at the end. Two -v options will give you information on what files are being skipped and slightly more information at the end. More than two -v options should only be used if you are debugging rsync. The end-of-run summary tells you the number of bytes sent to the remote rsync (which is the receiving side on a local copy), the number of bytes received from the remote host, and the average bytes per second of the transferred data computed over the entire length of the rsync run. The second line shows the total size (in bytes), which is the sum of all the file sizes that rsync considered transferring. It also shows a "speedup" value, which is a ratio of the total file size divided by the sum of the sent and received bytes (which is really just a feel-good bigger-is-better number). Note that these byte values can be made more (or less) human-readable by using the --human-readable (or --no-human-readable) options. In a modern rsync, the -v option is equivalent to the setting of groups of --info and --debug options. You can choose to use these newer options in addition to, or in place of using --verbose, as any fine-grained settings override the implied settings of -v. Both --info and --debug have a way to ask for help that tells you exactly what flags are set for each increase in verbosity. However, do keep in mind that a daemon's "max verbosity" setting will limit how high of a level the various individual flags can be set on the daemon side. For instance, if the max is 2, then any info and/or debug flag that is set to a higher value than what would be set by -vv will be downgraded to the -vv level in the daemon's logging. --info=FLAGS This option lets you have fine-grained control over the information output you want to see. An individual flag name may be followed by a level number, with 0 meaning to silence that output, 1 being the default output level, and higher numbers increasing the output of that flag (for those that support higher levels). Use --info=help to see all the available flag names, what they output, and what flag names are added for each increase in the verbose level. Some examples: rsync -a --info=progress2 src/ dest/ rsync -avv --info=stats2,misc1,flist0 src/ dest/ Note that --info=name's output is affected by the --out- format and --itemize-changes (-i) options. See those options for more information on what is output and when. This option was added to 3.1.0, so an older rsync on the server side might reject your attempts at fine-grained control (if one or more flags needed to be send to the server and the server was too old to understand them). See also the "max verbosity" caveat above when dealing with a daemon. --debug=FLAGS This option lets you have fine-grained control over the debug output you want to see. An individual flag name may be followed by a level number, with 0 meaning to silence that output, 1 being the default output level, and higher numbers increasing the output of that flag (for those that support higher levels). Use --debug=help to see all the available flag names, what they output, and what flag names are added for each increase in the verbose level. Some examples: rsync -avvv --debug=none src/ dest/ rsync -avA --del --debug=del2,acl src/ dest/ Note that some debug messages will only be output when the --stderr=all option is specified, especially those pertaining to I/O and buffer debugging. Beginning in 3.2.0, this option is no longer auto- forwarded to the server side in order to allow you to specify different debug values for each side of the transfer, as well as to specify a new debug option that is only present in one of the rsync versions. If you want to duplicate the same option on both sides, using brace expansion is an easy way to save you some typing. This works in zsh and bash: rsync -aiv {-M,}--debug=del2 src/ dest/ --stderr=errors|all|client This option controls which processes output to stderr and if info messages are also changed to stderr. The mode strings can be abbreviated, so feel free to use a single letter value. The 3 possible choices are: o errors - (the default) causes all the rsync processes to send an error directly to stderr, even if the process is on the remote side of the transfer. Info messages are sent to the client side via the protocol stream. If stderr is not available (i.e. when directly connecting with a daemon via a socket) errors fall back to being sent via the protocol stream. o all - causes all rsync messages (info and error) to get written directly to stderr from all (possible) processes. This causes stderr to become line- buffered (instead of raw) and eliminates the ability to divide up the info and error messages by file handle. For those doing debugging or using several levels of verbosity, this option can help to avoid clogging up the transfer stream (which should prevent any chance of a deadlock bug hanging things up). It also allows --debug to enable some extra I/O related messages. o client - causes all rsync messages to be sent to the client side via the protocol stream. One client process outputs all messages, with errors on stderr and info messages on stdout. This was the default in older rsync versions, but can cause error delays when a lot of transfer data is ahead of the messages. If you're pushing files to an older rsync, you may want to use --stderr=all since that idiom has been around for several releases. This option was added in rsync 3.2.3. This version also began the forwarding of a non-default setting to the remote side, though rsync uses the backward-compatible options --msgs2stderr and --no-msgs2stderr to represent the all and client settings, respectively. A newer rsync will continue to accept these older option names to maintain compatibility. --quiet, -q This option decreases the amount of information you are given during the transfer, notably suppressing information messages from the remote server. This option is useful when invoking rsync from cron. --no-motd This option affects the information that is output by the client at the start of a daemon transfer. This suppresses the message-of-the-day (MOTD) text, but it also affects the list of modules that the daemon sends in response to the "rsync host::" request (due to a limitation in the rsync protocol), so omit this option if you want to request the list of modules from the daemon. --ignore-times, -I Normally rsync will skip any files that are already the same size and have the same modification timestamp. This option turns off this "quick check" behavior, causing all files to be updated. This option can be confusing compared to --ignore-existing and --ignore-non-existing in that that they cause rsync to transfer fewer files, while this option causes rsync to transfer more files. --size-only This modifies rsync's "quick check" algorithm for finding files that need to be transferred, changing it from the default of transferring files with either a changed size or a changed last-modified time to just looking for files that have changed in size. This is useful when starting to use rsync after using another mirroring system which may not preserve timestamps exactly. --modify-window=NUM, -@ When comparing two timestamps, rsync treats the timestamps as being equal if they differ by no more than the modify- window value. The default is 0, which matches just integer seconds. If you specify a negative value (and the receiver is at least version 3.1.3) then nanoseconds will also be taken into account. Specifying 1 is useful for copies to/from MS Windows FAT filesystems, because FAT represents times with a 2-second resolution (allowing times to differ from the original by up to 1 second). If you want all your transfers to default to comparing nanoseconds, you can create a ~/.popt file and put these lines in it: rsync alias -a -a@-1 rsync alias -t -t@-1 With that as the default, you'd need to specify --modify- window=0 (aka -@0) to override it and ignore nanoseconds, e.g. if you're copying between ext3 and ext4, or if the receiving rsync is older than 3.1.3. --checksum, -c This changes the way rsync checks if the files have been changed and are in need of a transfer. Without this option, rsync uses a "quick check" that (by default) checks if each file's size and time of last modification match between the sender and receiver. This option changes this to compare a 128-bit checksum for each file that has a matching size. Generating the checksums means that both sides will expend a lot of disk I/O reading all the data in the files in the transfer, so this can slow things down significantly (and this is prior to any reading that will be done to transfer changed files) The sending side generates its checksums while it is doing the file-system scan that builds the list of the available files. The receiver generates its checksums when it is scanning for changed files, and will checksum any file that has the same size as the corresponding sender's file: files with either a changed size or a changed checksum are selected for transfer. Note that rsync always verifies that each transferred file was correctly reconstructed on the receiving side by checking a whole-file checksum that is generated as the file is transferred, but that automatic after-the-transfer verification has nothing to do with this option's before- the-transfer "Does this file need to be updated?" check. The checksum used is auto-negotiated between the client and the server, but can be overridden using either the --checksum-choice (--cc) option or an environment variable that is discussed in that option's section. --archive, -a This is equivalent to -rlptgoD. It is a quick way of saying you want recursion and want to preserve almost everything. Be aware that it does not include preserving ACLs (-A), xattrs (-X), atimes (-U), crtimes (-N), nor the finding and preserving of hardlinks (-H). The only exception to the above equivalence is when --files-from is specified, in which case -r is not implied. --no-OPTION You may turn off one or more implied options by prefixing the option name with "no-". Not all positive options have a negated opposite, but a lot do, including those that can be used to disable an implied option (e.g. --no-D, --no- perms) or have different defaults in various circumstances (e.g. --no-whole-file, --no-blocking-io, --no-dirs). Every valid negated option accepts both the short and the long option name after the "no-" prefix (e.g. --no-R is the same as --no-relative). As an example, if you want to use --archive (-a) but don't want --owner (-o), instead of converting -a into -rlptgD, you can specify -a --no-o (aka --archive --no-owner). The order of the options is important: if you specify --no-r -a, the -r option would end up being turned on, the opposite of -a --no-r. Note also that the side-effects of the --files-from option are NOT positional, as it affects the default state of several options and slightly changes the meaning of -a (see the --files-from option for more details). --recursive, -r This tells rsync to copy directories recursively. See also --dirs (-d) for an option that allows the scanning of a single directory. See the --inc-recursive option for a discussion of the incremental recursion for creating the list of files to transfer. --inc-recursive, --i-r This option explicitly enables on incremental recursion when scanning for files, which is enabled by default when using the --recursive option and both sides of the transfer are running rsync 3.0.0 or newer. Incremental recursion uses much less memory than non- incremental, while also beginning the transfer more quickly (since it doesn't need to scan the entire transfer hierarchy before it starts transferring files). If no recursion is enabled in the source files, this option has no effect. Some options require rsync to know the full file list, so these options disable the incremental recursion mode. These include: o --delete-before (the old default of --delete) o --delete-after o --prune-empty-dirs o --delay-updates In order to make --delete compatible with incremental recursion, rsync 3.0.0 made --delete-during the default delete mode (which was first added in 2.6.4). One side-effect of incremental recursion is that any missing sub-directories inside a recursively-scanned directory are (by default) created prior to recursing into the sub-dirs. This earlier creation point (compared to a non-incremental recursion) allows rsync to then set the modify time of the finished directory right away (without having to delay that until a bunch of recursive copying has finished). However, these early directories don't yet have their completed mode, mtime, or ownership set -- they have more restrictive rights until the subdirectory's copying actually begins. This early-creation idiom can be avoided by using the --omit-dir-times option. Incremental recursion can be disabled using the --no-inc- recursive (--no-i-r) option. --no-inc-recursive, --no-i-r Disables the new incremental recursion algorithm of the --recursive option. This makes rsync scan the full file list before it begins to transfer files. See --inc- recursive for more info. --relative, -R Use relative paths. This means that the full path names specified on the command line are sent to the server rather than just the last parts of the filenames. This is particularly useful when you want to send several different directories at the same time. For example, if you used this command: rsync -av /foo/bar/baz.c remote:/tmp/ would create a file named baz.c in /tmp/ on the remote machine. If instead you used rsync -avR /foo/bar/baz.c remote:/tmp/ then a file named /tmp/foo/bar/baz.c would be created on the remote machine, preserving its full path. These extra path elements are called "implied directories" (i.e. the "foo" and the "foo/bar" directories in the above example). Beginning with rsync 3.0.0, rsync always sends these implied directories as real directories in the file list, even if a path element is really a symlink on the sending side. This prevents some really unexpected behaviors when copying the full path of a file that you didn't realize had a symlink in its path. If you want to duplicate a server-side symlink, include both the symlink via its path, and referent directory via its real path. If you're dealing with an older rsync on the sending side, you may need to use the --no-implied-dirs option. It is also possible to limit the amount of path information that is sent as implied directories for each path you specify. With a modern rsync on the sending side (beginning with 2.6.7), you can insert a dot and a slash into the source path, like this: rsync -avR /foo/./bar/baz.c remote:/tmp/ That would create /tmp/bar/baz.c on the remote machine. (Note that the dot must be followed by a slash, so "/foo/." would not be abbreviated.) For older rsync versions, you would need to use a chdir to limit the source path. For example, when pushing files: (cd /foo; rsync -avR bar/baz.c remote:/tmp/) (Note that the parens put the two commands into a sub- shell, so that the "cd" command doesn't remain in effect for future commands.) If you're pulling files from an older rsync, use this idiom (but only for a non-daemon transfer): rsync -avR --rsync-path="cd /foo; rsync" \ remote:bar/baz.c /tmp/ --no-implied-dirs This option affects the default behavior of the --relative option. When it is specified, the attributes of the implied directories from the source names are not included in the transfer. This means that the corresponding path elements on the destination system are left unchanged if they exist, and any missing implied directories are created with default attributes. This even allows these implied path elements to have big differences, such as being a symlink to a directory on the receiving side. For instance, if a command-line arg or a files-from entry told rsync to transfer the file "path/foo/file", the directories "path" and "path/foo" are implied when --relative is used. If "path/foo" is a symlink to "bar" on the destination system, the receiving rsync would ordinarily delete "path/foo", recreate it as a directory, and receive the file into the new directory. With --no- implied-dirs, the receiving rsync updates "path/foo/file" using the existing path elements, which means that the file ends up being created in "path/bar". Another way to accomplish this link preservation is to use the --keep- dirlinks option (which will also affect symlinks to directories in the rest of the transfer). When pulling files from an rsync older than 3.0.0, you may need to use this option if the sending side has a symlink in the path you request and you wish the implied directories to be transferred as normal directories. --backup, -b With this option, preexisting destination files are renamed as each file is transferred or deleted. You can control where the backup file goes and what (if any) suffix gets appended using the --backup-dir and --suffix options. If you don't specify --backup-dir: 1. the --omit-dir-times option will be forced on 2. the use of --delete (without --delete-excluded), causes rsync to add a "protect" filter-rule for the backup suffix to the end of all your existing filters that looks like this: -f "P *~". This rule prevents previously backed-up files from being deleted. Note that if you are supplying your own filter rules, you may need to manually insert your own exclude/protect rule somewhere higher up in the list so that it has a high enough priority to be effective (e.g. if your rules specify a trailing inclusion/exclusion of *, the auto- added rule would never be reached). --backup-dir=DIR This implies the --backup option, and tells rsync to store all backups in the specified directory on the receiving side. This can be used for incremental backups. You can additionally specify a backup suffix using the --suffix option (otherwise the files backed up in the specified directory will keep their original filenames). Note that if you specify a relative path, the backup directory will be relative to the destination directory, so you probably want to specify either an absolute path or a path that starts with "../". If an rsync daemon is the receiver, the backup dir cannot go outside the module's path hierarchy, so take extra care not to delete it or copy into it. --suffix=SUFFIX This option allows you to override the default backup suffix used with the --backup (-b) option. The default suffix is a ~ if no --backup-dir was specified, otherwise it is an empty string. --update, -u This forces rsync to skip any files which exist on the destination and have a modified time that is newer than the source file. (If an existing destination file has a modification time equal to the source file's, it will be updated if the sizes are different.) Note that this does not affect the copying of dirs, symlinks, or other special files. Also, a difference of file format between the sender and receiver is always considered to be important enough for an update, no matter what date is on the objects. In other words, if the source has a directory where the destination has a file, the transfer would occur regardless of the timestamps. This option is a TRANSFER RULE, so don't expect any exclude side effects. A caution for those that choose to combine --inplace with --update: an interrupted transfer will leave behind a partial file on the receiving side that has a very recent modified time, so re-running the transfer will probably not continue the interrupted file. As such, it is usually best to avoid combining this with --inplace unless you have implemented manual steps to handle any interrupted in-progress files. --inplace This option changes how rsync transfers a file when its data needs to be updated: instead of the default method of creating a new copy of the file and moving it into place when it is complete, rsync instead writes the updated data directly to the destination file. This has several effects: o Hard links are not broken. This means the new data will be visible through other hard links to the destination file. Moreover, attempts to copy differing source files onto a multiply-linked destination file will result in a "tug of war" with the destination data changing back and forth. o In-use binaries cannot be updated (either the OS will prevent this from happening, or binaries that attempt to swap-in their data will misbehave or crash). o The file's data will be in an inconsistent state during the transfer and will be left that way if the transfer is interrupted or if an update fails. o A file that rsync cannot write to cannot be updated. While a super user can update any file, a normal user needs to be granted write permission for the open of the file for writing to be successful. o The efficiency of rsync's delta-transfer algorithm may be reduced if some data in the destination file is overwritten before it can be copied to a position later in the file. This does not apply if you use --backup, since rsync is smart enough to use the backup file as the basis file for the transfer. WARNING: you should not use this option to update files that are being accessed by others, so be careful when choosing to use this for a copy. This option is useful for transferring large files with block-based changes or appended data, and also on systems that are disk bound, not network bound. It can also help keep a copy-on-write filesystem snapshot from diverging the entire contents of a file that only has minor changes. The option implies --partial (since an interrupted transfer does not delete the file), but conflicts with --partial-dir and --delay-updates. Prior to rsync 2.6.4 --inplace was also incompatible with --compare-dest and --link-dest. --append This special copy mode only works to efficiently update files that are known to be growing larger where any existing content on the receiving side is also known to be the same as the content on the sender. The use of --append can be dangerous if you aren't 100% sure that all the files in the transfer are shared, growing files. You should thus use filter rules to ensure that you weed out any files that do not fit this criteria. Rsync updates these growing file in-place without verifying any of the existing content in the file (it only verifies the content that it is appending). Rsync skips any files that exist on the receiving side that are not shorter than the associated file on the sending side (which means that new files are transferred). It also skips any files whose size on the sending side gets shorter during the send negotiations (rsync warns about a "diminished" file when this happens). This does not interfere with the updating of a file's non- content attributes (e.g. permissions, ownership, etc.) when the file does not need to be transferred, nor does it affect the updating of any directories or non-regular files. --append-verify This special copy mode works like --append except that all the data in the file is included in the checksum verification (making it less efficient but also potentially safer). This option can be dangerous if you aren't 100% sure that all the files in the transfer are shared, growing files. See the --append option for more details. Note: prior to rsync 3.0.0, the --append option worked like --append-verify, so if you are interacting with an older rsync (or the transfer is using a protocol prior to 30), specifying either append option will initiate an --append-verify transfer. --dirs, -d Tell the sending side to include any directories that are encountered. Unlike --recursive, a directory's contents are not copied unless the directory name specified is "." or ends with a trailing slash (e.g. ".", "dir/.", "dir/", etc.). Without this option or the --recursive option, rsync will skip all directories it encounters (and output a message to that effect for each one). If you specify both --dirs and --recursive, --recursive takes precedence. The --dirs option is implied by the --files-from option or the --list-only option (including an implied --list-only usage) if --recursive wasn't specified (so that directories are seen in the listing). Specify --no-dirs (or --no-d) if you want to turn this off. There is also a backward-compatibility helper option, --old-dirs (--old-d) that tells rsync to use a hack of -r --exclude='/*/*' to get an older rsync to list a single directory without recursing. --mkpath Create all missing path components of the destination path. By default, rsync allows only the final component of the destination path to not exist, which is an attempt to help you to validate your destination path. With this option, rsync creates all the missing destination-path components, just as if mkdir -p $DEST_PATH had been run on the receiving side. When specifying a destination path, including a trailing slash ensures that the whole path is treated as directory names to be created, even when the file list has a single item. See the COPYING TO A DIFFERENT NAME section for full details on how rsync decides if a final destination-path component should be created as a directory or not. If you would like the newly-created destination dirs to match the dirs on the sending side, you should be using --relative (-R) instead of --mkpath. For instance, the following two commands result in the same destination tree, but only the second command ensures that the "some/extra/path" components match the dirs on the sending side: rsync -ai --mkpath host:some/extra/path/*.c some/extra/path/ rsync -aiR host:some/extra/path/*.c ./ --links, -l Add symlinks to the transferred files instead of noisily ignoring them with a "non-regular file" warning for each symlink encountered. You can alternately silence the warning by specifying --info=nonreg0. The default handling of symlinks is to recreate each symlink's unchanged value on the receiving side. See the SYMBOLIC LINKS section for multi-option info. --copy-links, -L The sender transforms each symlink encountered in the transfer into the referent item, following the symlink chain to the file or directory that it references. If a symlink chain is broken, an error is output and the file is dropped from the transfer. This option supersedes any other options that affect symlinks in the transfer, since there are no symlinks left in the transfer. This option does not change the handling of existing symlinks on the receiving side, unlike versions of rsync prior to 2.6.3 which had the side-effect of telling the receiving side to also follow symlinks. A modern rsync won't forward this option to a remote receiver (since only the sender needs to know about it), so this caveat should only affect someone using an rsync client older than 2.6.7 (which is when -L stopped being forwarded to the receiver). See the --keep-dirlinks (-K) if you need a symlink to a directory to be treated as a real directory on the receiving side. See the SYMBOLIC LINKS section for multi-option info. --copy-unsafe-links This tells rsync to copy the referent of symbolic links that point outside the copied tree. Absolute symlinks are also treated like ordinary files, and so are any symlinks in the source path itself when --relative is used. Note that the cut-off point is the top of the transfer, which is the part of the path that rsync isn't mentioning in the verbose output. If you copy "/src/subdir" to "/dest/" then the "subdir" directory is a name inside the transfer tree, not the top of the transfer (which is /src) so it is legal for created relative symlinks to refer to other names inside the /src and /dest directories. If you instead copy "/src/subdir/" (with a trailing slash) to "/dest/subdir" that would not allow symlinks to any files outside of "subdir". Note that safe symlinks are only copied if --links was also specified or implied. The --copy-unsafe-links option has no extra effect when combined with --copy-links. See the SYMBOLIC LINKS section for multi-option info. --safe-links This tells the receiving rsync to ignore any symbolic links in the transfer which point outside the copied tree. All absolute symlinks are also ignored. Since this ignoring is happening on the receiving side, it will still be effective even when the sending side has munged symlinks (when it is using --munge-links). It also affects deletions, since the file being present in the transfer prevents any matching file on the receiver from being deleted when the symlink is deemed to be unsafe and is skipped. This option must be combined with --links (or --archive) to have any symlinks in the transfer to conditionally ignore. Its effect is superseded by --copy-unsafe-links. Using this option in conjunction with --relative may give unexpected results. See the SYMBOLIC LINKS section for multi-option info. --munge-links This option affects just one side of the transfer and tells rsync to munge symlink values when it is receiving files or unmunge symlink values when it is sending files. The munged values make the symlinks unusable on disk but allows the original contents of the symlinks to be recovered. The server-side rsync often enables this option without the client's knowledge, such as in an rsync daemon's configuration file or by an option given to the rrsync (restricted rsync) script. When specified on the client side, specify the option normally if it is the client side that has/needs the munged symlinks, or use -M--munge-links to give the option to the server when it has/needs the munged symlinks. Note that on a local transfer, the client is the sender, so specifying the option directly unmunges symlinks while specifying it as a remote option munges symlinks. This option has no effect when sent to a daemon via --remote-option because the daemon configures whether it wants munged symlinks via its "munge symlinks" parameter. The symlink value is munged/unmunged once it is in the transfer, so any option that transforms symlinks into non- symlinks occurs prior to the munging/unmunging except for --safe-links, which is a choice that the receiver makes, so it bases its decision on the munged/unmunged value. This does mean that if a receiver has munging enabled, that using --safe-links will cause all symlinks to be ignored (since they are all absolute). The method that rsync uses to munge the symlinks is to prefix each one's value with the string "/rsyncd-munged/". This prevents the links from being used as long as the directory does not exist. When this option is enabled, rsync will refuse to run if that path is a directory or a symlink to a directory (though it only checks at startup). See also the "munge-symlinks" python script in the support directory of the source code for a way to munge/unmunge one or more symlinks in-place. --copy-dirlinks, -k This option causes the sending side to treat a symlink to a directory as though it were a real directory. This is useful if you don't want symlinks to non-directories to be affected, as they would be using --copy-links. Without this option, if the sending side has replaced a directory with a symlink to a directory, the receiving side will delete anything that is in the way of the new symlink, including a directory hierarchy (as long as --force or --delete is in effect). See also --keep-dirlinks for an analogous option for the receiving side. --copy-dirlinks applies to all symlinks to directories in the source. If you want to follow only a few specified symlinks, a trick you can use is to pass them as additional source args with a trailing slash, using --relative to make the paths match up right. For example: rsync -r --relative src/./ src/./follow-me/ dest/ This works because rsync calls lstat(2) on the source arg as given, and the trailing slash makes lstat(2) follow the symlink, giving rise to a directory in the file-list which overrides the symlink found during the scan of "src/./". See the SYMBOLIC LINKS section for multi-option info. --keep-dirlinks, -K This option causes the receiving side to treat a symlink to a directory as though it were a real directory, but only if it matches a real directory from the sender. Without this option, the receiver's symlink would be deleted and replaced with a real directory. For example, suppose you transfer a directory "foo" that contains a file "file", but "foo" is a symlink to directory "bar" on the receiver. Without --keep-dirlinks, the receiver deletes symlink "foo", recreates it as a directory, and receives the file into the new directory. With --keep-dirlinks, the receiver keeps the symlink and "file" ends up in "bar". One note of caution: if you use --keep-dirlinks, you must trust all the symlinks in the copy or enable the --munge- links option on the receiving side! If it is possible for an untrusted user to create their own symlink to any real directory, the user could then (on a subsequent copy) replace the symlink with a real directory and affect the content of whatever directory the symlink references. For backup copies, you are better off using something like a bind mount instead of a symlink to modify your receiving hierarchy. See also --copy-dirlinks for an analogous option for the sending side. See the SYMBOLIC LINKS section for multi-option info. --hard-links, -H This tells rsync to look for hard-linked files in the source and link together the corresponding files on the destination. Without this option, hard-linked files in the source are treated as though they were separate files. This option does NOT necessarily ensure that the pattern of hard links on the destination exactly matches that on the source. Cases in which the destination may end up with extra hard links include the following: o If the destination contains extraneous hard-links (more linking than what is present in the source file list), the copying algorithm will not break them explicitly. However, if one or more of the paths have content differences, the normal file- update process will break those extra links (unless you are using the --inplace option). o If you specify a --link-dest directory that contains hard links, the linking of the destination files against the --link-dest files can cause some paths in the destination to become linked together due to the --link-dest associations. Note that rsync can only detect hard links between files that are inside the transfer set. If rsync updates a file that has extra hard-link connections to files outside the transfer, that linkage will be broken. If you are tempted to use the --inplace option to avoid this breakage, be very careful that you know how your files are being updated so that you are certain that no unintended changes happen due to lingering hard links (and see the --inplace option for more caveats). If incremental recursion is active (see --inc-recursive), rsync may transfer a missing hard-linked file before it finds that another link for that contents exists elsewhere in the hierarchy. This does not affect the accuracy of the transfer (i.e. which files are hard-linked together), just its efficiency (i.e. copying the data for a new, early copy of a hard-linked file that could have been found later in the transfer in another member of the hard- linked set of files). One way to avoid this inefficiency is to disable incremental recursion using the --no-inc- recursive option. --perms, -p This option causes the receiving rsync to set the destination permissions to be the same as the source permissions. (See also the --chmod option for a way to modify what rsync considers to be the source permissions.) When this option is off, permissions are set as follows: o Existing files (including updated files) retain their existing permissions, though the --executability option might change just the execute permission for the file. o New files get their "normal" permission bits set to the source file's permissions masked with the receiving directory's default permissions (either the receiving process's umask, or the permissions specified via the destination directory's default ACL), and their special permission bits disabled except in the case where a new directory inherits a setgid bit from its parent directory. Thus, when --perms and --executability are both disabled, rsync's behavior is the same as that of other file-copy utilities, such as cp(1) and tar(1). In summary: to give destination files (both old and new) the source permissions, use --perms. To give new files the destination-default permissions (while leaving existing files unchanged), make sure that the --perms option is off and use --chmod=ugo=rwX (which ensures that all non-masked bits get enabled). If you'd care to make this latter behavior easier to type, you could define a popt alias for it, such as putting this line in the file ~/.popt (the following defines the -Z option, and includes --no-g to use the default group of the destination dir): rsync alias -Z --no-p --no-g --chmod=ugo=rwX You could then use this new option in a command such as this one: rsync -avZ src/ dest/ (Caveat: make sure that -a does not follow -Z, or it will re-enable the two --no-* options mentioned above.) The preservation of the destination's setgid bit on newly- created directories when --perms is off was added in rsync 2.6.7. Older rsync versions erroneously preserved the three special permission bits for newly-created files when --perms was off, while overriding the destination's setgid bit setting on a newly-created directory. Default ACL observance was added to the ACL patch for rsync 2.6.7, so older (or non-ACL-enabled) rsyncs use the umask even if default ACLs are present. (Keep in mind that it is the version of the receiving rsync that affects these behaviors.) --executability, -E This option causes rsync to preserve the executability (or non-executability) of regular files when --perms is not enabled. A regular file is considered to be executable if at least one 'x' is turned on in its permissions. When an existing destination file's executability differs from that of the corresponding source file, rsync modifies the destination file's permissions as follows: o To make a file non-executable, rsync turns off all its 'x' permissions. o To make a file executable, rsync turns on each 'x' permission that has a corresponding 'r' permission enabled. If --perms is enabled, this option is ignored. --acls, -A This option causes rsync to update the destination ACLs to be the same as the source ACLs. The option also implies --perms. The source and destination systems must have compatible ACL entries for this option to work properly. See the --fake-super option for a way to backup and restore ACLs that are not compatible. --xattrs, -X This option causes rsync to update the destination extended attributes to be the same as the source ones. For systems that support extended-attribute namespaces, a copy being done by a super-user copies all namespaces except system.*. A normal user only copies the user.* namespace. To be able to backup and restore non-user namespaces as a normal user, see the --fake-super option. The above name filtering can be overridden by using one or more filter options with the x modifier. When you specify an xattr-affecting filter rule, rsync requires that you do your own system/user filtering, as well as any additional filtering for what xattr names are copied and what names are allowed to be deleted. For example, to skip the system namespace, you could specify: --filter='-x system.*' To skip all namespaces except the user namespace, you could specify a negated-user match: --filter='-x! user.*' To prevent any attributes from being deleted, you could specify a receiver-only rule that excludes all names: --filter='-xr *' Note that the -X option does not copy rsync's special xattr values (e.g. those used by --fake-super) unless you repeat the option (e.g. -XX). This "copy all xattrs" mode cannot be used with --fake-super. --chmod=CHMOD This option tells rsync to apply one or more comma- separated "chmod" modes to the permission of the files in the transfer. The resulting value is treated as though it were the permissions that the sending side supplied for the file, which means that this option can seem to have no effect on existing files if --perms is not enabled. In addition to the normal parsing rules specified in the chmod(1) manpage, you can specify an item that should only apply to a directory by prefixing it with a 'D', or specify an item that should only apply to a file by prefixing it with a 'F'. For example, the following will ensure that all directories get marked set-gid, that no files are other-writable, that both are user-writable and group-writable, and that both have consistent executability across all bits: --chmod=Dg+s,ug+w,Fo-w,+X Using octal mode numbers is also allowed: --chmod=D2775,F664 It is also legal to specify multiple --chmod options, as each additional option is just appended to the list of changes to make. See the --perms and --executability options for how the resulting permission value can be applied to the files in the transfer. --owner, -o This option causes rsync to set the owner of the destination file to be the same as the source file, but only if the receiving rsync is being run as the super-user (see also the --super and --fake-super options). Without this option, the owner of new and/or transferred files are set to the invoking user on the receiving side. The preservation of ownership will associate matching names by default, but may fall back to using the ID number in some circumstances (see also the --numeric-ids option for a full discussion). --group, -g This option causes rsync to set the group of the destination file to be the same as the source file. If the receiving program is not running as the super-user (or if --no-super was specified), only groups that the invoking user on the receiving side is a member of will be preserved. Without this option, the group is set to the default group of the invoking user on the receiving side. The preservation of group information will associate matching names by default, but may fall back to using the ID number in some circumstances (see also the --numeric- ids option for a full discussion). --devices This option causes rsync to transfer character and block device files to the remote system to recreate these devices. If the receiving rsync is not being run as the super-user, rsync silently skips creating the device files (see also the --super and --fake-super options). By default, rsync generates a "non-regular file" warning for each device file encountered when this option is not set. You can silence the warning by specifying --info=nonreg0. --specials This option causes rsync to transfer special files, such as named sockets and fifos. If the receiving rsync is not being run as the super-user, rsync silently skips creating the special files (see also the --super and --fake-super options). By default, rsync generates a "non-regular file" warning for each special file encountered when this option is not set. You can silence the warning by specifying --info=nonreg0. -D The -D option is equivalent to "--devices --specials". --copy-devices This tells rsync to treat a device on the sending side as a regular file, allowing it to be copied to a normal destination file (or another device if --write-devices was also specified). This option is refused by default by an rsync daemon. --write-devices This tells rsync to treat a device on the receiving side as a regular file, allowing the writing of file data into a device. This option implies the --inplace option. Be careful using this, as you should know what devices are present on the receiving side of the transfer, especially when running rsync as root. This option is refused by default by an rsync daemon. --times, -t This tells rsync to transfer modification times along with the files and update them on the remote system. Note that if this option is not used, the optimization that excludes files that have not been modified cannot be effective; in other words, a missing -t (or -a) will cause the next transfer to behave as if it used --ignore-times (-I), causing all files to be updated (though rsync's delta- transfer algorithm will make the update fairly efficient if the files haven't actually changed, you're much better off using -t). A modern rsync that is using transfer protocol 30 or 31 conveys a modify time using up to 8-bytes. If rsync is forced to speak an older protocol (perhaps due to the remote rsync being older than 3.0.0) a modify time is conveyed using 4-bytes. Prior to 3.2.7, these shorter values could convey a date range of 13-Dec-1901 to 19-Jan-2038. Beginning with 3.2.7, these 4-byte values now convey a date range of 1-Jan-1970 to 7-Feb-2106. If you have files dated older than 1970, make sure your rsync executables are upgraded so that the full range of dates can be conveyed. --atimes, -U This tells rsync to set the access (use) times of the destination files to the same value as the source files. If repeated, it also sets the --open-noatime option, which can help you to make the sending and receiving systems have the same access times on the transferred files without needing to run rsync an extra time after a file is transferred. Note that some older rsync versions (prior to 3.2.0) may have been built with a pre-release --atimes patch that does not imply --open-noatime when this option is repeated. --open-noatime This tells rsync to open files with the O_NOATIME flag (on systems that support it) to avoid changing the access time of the files that are being transferred. If your OS does not support the O_NOATIME flag then rsync will silently ignore this option. Note also that some filesystems are mounted to avoid updating the atime on read access even without the O_NOATIME flag being set. --crtimes, -N, This tells rsync to set the create times (newness) of the destination files to the same value as the source files. --omit-dir-times, -O This tells rsync to omit directories when it is preserving modification, access, and create times. If NFS is sharing the directories on the receiving side, it is a good idea to use -O. This option is inferred if you use --backup without --backup-dir. This option also has the side-effect of avoiding early creation of missing sub-directories when incremental recursion is enabled, as discussed in the --inc-recursive section. --omit-link-times, -J This tells rsync to omit symlinks when it is preserving modification, access, and create times. --super This tells the receiving side to attempt super-user activities even if the receiving rsync wasn't run by the super-user. These activities include: preserving users via the --owner option, preserving all groups (not just the current user's groups) via the --group option, and copying devices via the --devices option. This is useful for systems that allow such activities without being the super-user, and also for ensuring that you will get errors if the receiving side isn't being run as the super-user. To turn off super-user activities, the super-user can use --no-super. --fake-super When this option is enabled, rsync simulates super-user activities by saving/restoring the privileged attributes via special extended attributes that are attached to each file (as needed). This includes the file's owner and group (if it is not the default), the file's device info (device & special files are created as empty text files), and any permission bits that we won't allow to be set on the real file (e.g. the real file gets u-s,g-s,o-t for safety) or that would limit the owner's access (since the real super-user can always access/change a file, the files we create can always be accessed/changed by the creating user). This option also handles ACLs (if --acls was specified) and non-user extended attributes (if --xattrs was specified). This is a good way to backup data without using a super- user, and to store ACLs from incompatible systems. The --fake-super option only affects the side where the option is used. To affect the remote side of a remote- shell connection, use the --remote-option (-M) option: rsync -av -M--fake-super /src/ host:/dest/ For a local copy, this option affects both the source and the destination. If you wish a local copy to enable this option just for the destination files, specify -M--fake- super. If you wish a local copy to enable this option just for the source files, combine --fake-super with -M--super. This option is overridden by both --super and --no-super. See also the fake super setting in the daemon's rsyncd.conf file. --sparse, -S Try to handle sparse files efficiently so they take up less space on the destination. If combined with --inplace the file created might not end up with sparse blocks with some combinations of kernel version and/or filesystem type. If --whole-file is in effect (e.g. for a local copy) then it will always work because rsync truncates the file prior to writing out the updated version. Note that versions of rsync older than 3.1.3 will reject the combination of --sparse and --inplace. --preallocate This tells the receiver to allocate each destination file to its eventual size before writing data to the file. Rsync will only use the real filesystem-level preallocation support provided by Linux's fallocate(2) system call or Cygwin's posix_fallocate(3), not the slow glibc implementation that writes a null byte into each block. Without this option, larger files may not be entirely contiguous on the filesystem, but with this option rsync will probably copy more slowly. If the destination is not an extent-supporting filesystem (such as ext4, xfs, NTFS, etc.), this option may have no positive effect at all. If combined with --sparse, the file will only have sparse blocks (as opposed to allocated sequences of null bytes) if the kernel version and filesystem type support creating holes in the allocated data. --dry-run, -n This makes rsync perform a trial run that doesn't make any changes (and produces mostly the same output as a real run). It is most commonly used in combination with the --verbose (-v) and/or --itemize-changes (-i) options to see what an rsync command is going to do before one actually runs it. The output of --itemize-changes is supposed to be exactly the same on a dry run and a subsequent real run (barring intentional trickery and system call failures); if it isn't, that's a bug. Other output should be mostly unchanged, but may differ in some areas. Notably, a dry run does not send the actual data for file transfers, so --progress has no effect, the "bytes sent", "bytes received", "literal data", and "matched data" statistics are too small, and the "speedup" value is equivalent to a run where no file transfers were needed. --whole-file, -W This option disables rsync's delta-transfer algorithm, which causes all transferred files to be sent whole. The transfer may be faster if this option is used when the bandwidth between the source and destination machines is higher than the bandwidth to disk (especially when the "disk" is actually a networked filesystem). This is the default when both the source and destination are specified as local paths, but only if no batch-writing option is in effect. --no-whole-file, --no-W Disable whole-file updating when it is enabled by default for a local transfer. This usually slows rsync down, but it can be useful if you are trying to minimize the writes to the destination file (if combined with --inplace) or for testing the checksum-based update algorithm. See also the --whole-file option. --checksum-choice=STR, --cc=STR This option overrides the checksum algorithms. If one algorithm name is specified, it is used for both the transfer checksums and (assuming --checksum is specified) the pre-transfer checksums. If two comma-separated names are supplied, the first name affects the transfer checksums, and the second name affects the pre-transfer checksums (-c). The checksum options that you may be able to use are: o auto (the default automatic choice) o xxh128 o xxh3 o xxh64 (aka xxhash) o md5 o md4 o sha1 o none Run rsync --version to see the default checksum list compiled into your version (which may differ from the list above). If "none" is specified for the first (or only) name, the --whole-file option is forced on and no checksum verification is performed on the transferred data. If "none" is specified for the second (or only) name, the --checksum option cannot be used. The "auto" option is the default, where rsync bases its algorithm choice on a negotiation between the client and the server as follows: When both sides of the transfer are at least 3.2.0, rsync chooses the first algorithm in the client's list of choices that is also in the server's list of choices. If no common checksum choice is found, rsync exits with an error. If the remote rsync is too old to support checksum negotiation, a value is chosen based on the protocol version (which chooses between MD5 and various flavors of MD4 based on protocol age). The default order can be customized by setting the environment variable RSYNC_CHECKSUM_LIST to a space- separated list of acceptable checksum names. If the string contains a "&" character, it is separated into the "client string & server string", otherwise the same string applies to both. If the string (or string portion) contains no non-whitespace characters, the default checksum list is used. This method does not allow you to specify the transfer checksum separately from the pre- transfer checksum, and it discards "auto" and all unknown checksum names. A list with only invalid names results in a failed negotiation. The use of the --checksum-choice option overrides this environment list. --one-file-system, -x This tells rsync to avoid crossing a filesystem boundary when recursing. This does not limit the user's ability to specify items to copy from multiple filesystems, just rsync's recursion through the hierarchy of each directory that the user specified, and also the analogous recursion on the receiving side during deletion. Also keep in mind that rsync treats a "bind" mount to the same device as being on the same filesystem. If this option is repeated, rsync omits all mount-point directories from the copy. Otherwise, it includes an empty directory at each mount-point it encounters (using the attributes of the mounted directory because those of the underlying mount-point directory are inaccessible). If rsync has been told to collapse symlinks (via --copy- links or --copy-unsafe-links), a symlink to a directory on another device is treated like a mount-point. Symlinks to non-directories are unaffected by this option. --ignore-non-existing, --existing This tells rsync to skip creating files (including directories) that do not exist yet on the destination. If this option is combined with the --ignore-existing option, no files will be updated (which can be useful if all you want to do is delete extraneous files). This option is a TRANSFER RULE, so don't expect any exclude side effects. --ignore-existing This tells rsync to skip updating files that already exist on the destination (this does not ignore existing directories, or nothing would get done). See also --ignore-non-existing. This option is a TRANSFER RULE, so don't expect any exclude side effects. This option can be useful for those doing backups using the --link-dest option when they need to continue a backup run that got interrupted. Since a --link-dest run is copied into a new directory hierarchy (when it is used properly), using [--ignore-existing will ensure that the already-handled files don't get tweaked (which avoids a change in permissions on the hard-linked files). This does mean that this option is only looking at the existing files in the destination hierarchy itself. When --info=skip2 is used rsync will output "FILENAME exists (INFO)" messages where the INFO indicates one of "type change", "sum change" (requires -c), "file change" (based on the quick check), "attr change", or "uptodate". Using --info=skip1 (which is also implied by 2 -v options) outputs the exists message without the INFO suffix. --remove-source-files This tells rsync to remove from the sending side the files (meaning non-directories) that are a part of the transfer and have been successfully duplicated on the receiving side. Note that you should only use this option on source files that are quiescent. If you are using this to move files that show up in a particular directory over to another host, make sure that the finished files get renamed into the source directory, not directly written into it, so that rsync can't possibly transfer a file that is not yet fully written. If you can't first write the files into a different directory, you should use a naming idiom that lets rsync avoid transferring files that are not yet finished (e.g. name the file "foo.new" when it is written, rename it to "foo" when it is done, and then use the option --exclude='*.new' for the rsync transfer). Starting with 3.1.0, rsync will skip the sender-side removal (and output an error) if the file's size or modify time has not stayed unchanged. Starting with 3.2.6, a local rsync copy will ensure that the sender does not remove a file the receiver just verified, such as when the user accidentally makes the source and destination directory the same path. --delete This tells rsync to delete extraneous files from the receiving side (ones that aren't on the sending side), but only for the directories that are being synchronized. You must have asked rsync to send the whole directory (e.g. "dir" or "dir/") without using a wildcard for the directory's contents (e.g. "dir/*") since the wildcard is expanded by the shell and rsync thus gets a request to transfer individual files, not the files' parent directory. Files that are excluded from the transfer are also excluded from being deleted unless you use the --delete-excluded option or mark the rules as only matching on the sending side (see the include/exclude modifiers in the FILTER RULES section). Prior to rsync 2.6.7, this option would have no effect unless --recursive was enabled. Beginning with 2.6.7, deletions will also occur when --dirs (-d) is enabled, but only for directories whose contents are being copied. This option can be dangerous if used incorrectly! It is a very good idea to first try a run using the --dry-run (-n) option to see what files are going to be deleted. If the sending side detects any I/O errors, then the deletion of any files at the destination will be automatically disabled. This is to prevent temporary filesystem failures (such as NFS errors) on the sending side from causing a massive deletion of files on the destination. You can override this with the --ignore- errors option. The --delete option may be combined with one of the --delete-WHEN options without conflict, as well as --delete-excluded. However, if none of the --delete-WHEN options are specified, rsync will choose the --delete- during algorithm when talking to rsync 3.0.0 or newer, or the --delete-before algorithm when talking to an older rsync. See also --delete-delay and --delete-after. --delete-before Request that the file-deletions on the receiving side be done before the transfer starts. See --delete (which is implied) for more details on file-deletion. Deleting before the transfer is helpful if the filesystem is tight for space and removing extraneous files would help to make the transfer possible. However, it does introduce a delay before the start of the transfer, and this delay might cause the transfer to timeout (if --timeout was specified). It also forces rsync to use the old, non-incremental recursion algorithm that requires rsync to scan all the files in the transfer into memory at once (see --recursive). --delete-during, --del Request that the file-deletions on the receiving side be done incrementally as the transfer happens. The per- directory delete scan is done right before each directory is checked for updates, so it behaves like a more efficient --delete-before, including doing the deletions prior to any per-directory filter files being updated. This option was first added in rsync version 2.6.4. See --delete (which is implied) for more details on file- deletion. --delete-delay Request that the file-deletions on the receiving side be computed during the transfer (like --delete-during), and then removed after the transfer completes. This is useful when combined with --delay-updates and/or --fuzzy, and is more efficient than using --delete-after (but can behave differently, since --delete-after computes the deletions in a separate pass after all updates are done). If the number of removed files overflows an internal buffer, a temporary file will be created on the receiving side to hold the names (it is removed while open, so you shouldn't see it during the transfer). If the creation of the temporary file fails, rsync will try to fall back to using --delete-after (which it cannot do if --recursive is doing an incremental scan). See --delete (which is implied) for more details on file-deletion. --delete-after Request that the file-deletions on the receiving side be done after the transfer has completed. This is useful if you are sending new per-directory merge files as a part of the transfer and you want their exclusions to take effect for the delete phase of the current transfer. It also forces rsync to use the old, non-incremental recursion algorithm that requires rsync to scan all the files in the transfer into memory at once (see --recursive). See --delete (which is implied) for more details on file- deletion. See also the --delete-delay option that might be a faster choice for those that just want the deletions to occur at the end of the transfer. --delete-excluded This option turns any unqualified exclude/include rules into server-side rules that do not affect the receiver's deletions. By default, an exclude or include has both a server-side effect (to "hide" and "show" files when building the server's file list) and a receiver-side effect (to "protect" and "risk" files when deletions are occurring). Any rule that has no modifier to specify what sides it is executed on will be instead treated as if it were a server-side rule only, avoiding any "protect" effects of the rules. A rule can still apply to both sides even with this option specified if the rule is given both the sender & receiver modifier letters (e.g., -f'-sr foo'). Receiver-side protect/risk rules can also be explicitly specified to limit the deletions. This saves you from having to edit a bunch of -f'- foo' rules into -f'-s foo' (aka -f'H foo') rules (not to mention the corresponding includes). See the FILTER RULES section for more information. See --delete (which is implied) for more details on deletion. --ignore-missing-args When rsync is first processing the explicitly requested source files (e.g. command-line arguments or --files-from entries), it is normally an error if the file cannot be found. This option suppresses that error, and does not try to transfer the file. This does not affect subsequent vanished-file errors if a file was initially found to be present and later is no longer there. --delete-missing-args This option takes the behavior of the (implied) --ignore- missing-args option a step farther: each missing arg will become a deletion request of the corresponding destination file on the receiving side (should it exist). If the destination file is a non-empty directory, it will only be successfully deleted if --force or --delete are in effect. Other than that, this option is independent of any other type of delete processing. The missing source files are represented by special file- list entries which display as a "*missing" entry in the --list-only output. --ignore-errors Tells --delete to go ahead and delete files even when there are I/O errors. --force This option tells rsync to delete a non-empty directory when it is to be replaced by a non-directory. This is only relevant if deletions are not active (see --delete for details). Note for older rsync versions: --force used to still be required when using --delete-after, and it used to be non- functional unless the --recursive option was also enabled. --max-delete=NUM This tells rsync not to delete more than NUM files or directories. If that limit is exceeded, all further deletions are skipped through the end of the transfer. At the end, rsync outputs a warning (including a count of the skipped deletions) and exits with an error code of 25 (unless some more important error condition also occurred). Beginning with version 3.0.0, you may specify --max- delete=0 to be warned about any extraneous files in the destination without removing any of them. Older clients interpreted this as "unlimited", so if you don't know what version the client is, you can use the less obvious --max- delete=-1 as a backward-compatible way to specify that no deletions be allowed (though really old versions didn't warn when the limit was exceeded). --max-size=SIZE This tells rsync to avoid transferring any file that is larger than the specified SIZE. A numeric value can be suffixed with a string to indicate the numeric units or left unqualified to specify bytes. Feel free to use a fractional value along with the units, such as --max- size=1.5m. This option is a TRANSFER RULE, so don't expect any exclude side effects. The first letter of a units string can be B (bytes), K (kilo), M (mega), G (giga), T (tera), or P (peta). If the string is a single char or has "ib" added to it (e.g. "G" or "GiB") then the units are multiples of 1024. If you use a two-letter suffix that ends with a "B" (e.g. "kb") then you get units that are multiples of 1000. The string's letters can be any mix of upper and lower-case that you want to use. Finally, if the string ends with either "+1" or "-1", it is offset by one byte in the indicated direction. The largest possible value is usually 8192P-1. Examples: --max-size=1.5mb-1 is 1499999 bytes, and --max- size=2g+1 is 2147483649 bytes. Note that rsync versions prior to 3.1.0 did not allow --max-size=0. --min-size=SIZE This tells rsync to avoid transferring any file that is smaller than the specified SIZE, which can help in not transferring small, junk files. See the --max-size option for a description of SIZE and other info. Note that rsync versions prior to 3.1.0 did not allow --min-size=0. --max-alloc=SIZE By default rsync limits an individual malloc/realloc to about 1GB in size. For most people this limit works just fine and prevents a protocol error causing rsync to request massive amounts of memory. However, if you have many millions of files in a transfer, a large amount of server memory, and you don't want to split up your transfer into multiple parts, you can increase the per- allocation limit to something larger and rsync will consume more memory. Keep in mind that this is not a limit on the total size of allocated memory. It is a sanity-check value for each individual allocation. See the --max-size option for a description of how SIZE can be specified. The default suffix if none is given is bytes. Beginning in 3.2.3, a value of 0 specifies no limit. You can set a default value using the environment variable RSYNC_MAX_ALLOC using the same SIZE values as supported by this option. If the remote rsync doesn't understand the --max-alloc option, you can override an environmental value by specifying --max-alloc=1g, which will make rsync avoid sending the option to the remote side (because "1G" is the default). --block-size=SIZE, -B This forces the block size used in rsync's delta-transfer algorithm to a fixed value. It is normally selected based on the size of each file being updated. See the technical report for details. Beginning in 3.2.3 the SIZE can be specified with a suffix as detailed in the --max-size option. Older versions only accepted a byte count. --rsh=COMMAND, -e This option allows you to choose an alternative remote shell program to use for communication between the local and remote copies of rsync. Typically, rsync is configured to use ssh by default, but you may prefer to use rsh on a local network. If this option is used with [user@]host::module/path, then the remote shell COMMAND will be used to run an rsync daemon on the remote host, and all data will be transmitted through that remote shell connection, rather than through a direct socket connection to a running rsync daemon on the remote host. See the USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION section above. Beginning with rsync 3.2.0, the RSYNC_PORT environment variable will be set when a daemon connection is being made via a remote-shell connection. It is set to 0 if the default daemon port is being assumed, or it is set to the value of the rsync port that was specified via either the --port option or a non-empty port value in an rsync:// URL. This allows the script to discern if a non-default port is being requested, allowing for things such as an SSL or stunnel helper script to connect to a default or alternate port. Command-line arguments are permitted in COMMAND provided that COMMAND is presented to rsync as a single argument. You must use spaces (not tabs or other whitespace) to separate the command and args from each other, and you can use single- and/or double-quotes to preserve spaces in an argument (but not backslashes). Note that doubling a single-quote inside a single-quoted string gives you a single-quote; likewise for double-quotes (though you need to pay attention to which quotes your shell is parsing and which quotes rsync is parsing). Some examples: -e 'ssh -p 2234' -e 'ssh -o "ProxyCommand nohup ssh firewall nc -w1 %h %p"' (Note that ssh users can alternately customize site- specific connect options in their .ssh/config file.) You can also choose the remote shell program using the RSYNC_RSH environment variable, which accepts the same range of values as -e. See also the --blocking-io option which is affected by this option. --rsync-path=PROGRAM Use this to specify what program is to be run on the remote machine to start-up rsync. Often used when rsync is not in the default remote-shell's path (e.g. --rsync- path=/usr/local/bin/rsync). Note that PROGRAM is run with the help of a shell, so it can be any program, script, or command sequence you'd care to run, so long as it does not corrupt the standard-in & standard-out that rsync is using to communicate. One tricky example is to set a different default directory on the remote machine for use with the --relative option. For instance: rsync -avR --rsync-path="cd /a/b && rsync" host:c/d /e/ --remote-option=OPTION, -M This option is used for more advanced situations where you want certain effects to be limited to one side of the transfer only. For instance, if you want to pass --log- file=FILE and --fake-super to the remote system, specify it like this: rsync -av -M --log-file=foo -M--fake-super src/ dest/ If you want to have an option affect only the local side of a transfer when it normally affects both sides, send its negation to the remote side. Like this: rsync -av -x -M--no-x src/ dest/ Be cautious using this, as it is possible to toggle an option that will cause rsync to have a different idea about what data to expect next over the socket, and that will make it fail in a cryptic fashion. Note that you should use a separate -M option for each remote option you want to pass. On older rsync versions, the presence of any spaces in the remote-option arg could cause it to be split into separate remote args, but this requires the use of --old-args in a modern rsync. When performing a local transfer, the "local" side is the sender and the "remote" side is the receiver. Note some versions of the popt option-parsing library have a bug in them that prevents you from using an adjacent arg with an equal in it next to a short option letter (e.g. -M--log-file=/tmp/foo). If this bug affects your version of popt, you can use the version of popt that is included with rsync. --cvs-exclude, -C This is a useful shorthand for excluding a broad range of files that you often don't want to transfer between systems. It uses a similar algorithm to CVS to determine if a file should be ignored. The exclude list is initialized to exclude the following items (these initial items are marked as perishable -- see the FILTER RULES section): RCS SCCS CVS CVS.adm RCSLOG cvslog.* tags TAGS .make.state .nse_depinfo *~ #* .#* ,* _$* *$ *.old *.bak *.BAK *.orig *.rej .del-* *.a *.olb *.o *.obj *.so *.exe *.Z *.elc *.ln core .svn/ .git/ .hg/ .bzr/ then, files listed in a $HOME/.cvsignore are added to the list and any files listed in the CVSIGNORE environment variable (all cvsignore names are delimited by whitespace). Finally, any file is ignored if it is in the same directory as a .cvsignore file and matches one of the patterns listed therein. Unlike rsync's filter/exclude files, these patterns are split on whitespace. See the cvs(1) manual for more information. If you're combining -C with your own --filter rules, you should note that these CVS excludes are appended at the end of your own rules, regardless of where the -C was placed on the command-line. This makes them a lower priority than any rules you specified explicitly. If you want to control where these CVS excludes get inserted into your filter rules, you should omit the -C as a command- line option and use a combination of --filter=:C and --filter=-C (either on your command-line or by putting the ":C" and "-C" rules into a filter file with your other rules). The first option turns on the per-directory scanning for the .cvsignore file. The second option does a one-time import of the CVS excludes mentioned above. --filter=RULE, -f This option allows you to add rules to selectively exclude certain files from the list of files to be transferred. This is most useful in combination with a recursive transfer. You may use as many --filter options on the command line as you like to build up the list of files to exclude. If the filter contains whitespace, be sure to quote it so that the shell gives the rule to rsync as a single argument. The text below also mentions that you can use an underscore to replace the space that separates a rule from its arg. See the FILTER RULES section for detailed information on this option. -F The -F option is a shorthand for adding two --filter rules to your command. The first time it is used is a shorthand for this rule: --filter='dir-merge /.rsync-filter' This tells rsync to look for per-directory .rsync-filter files that have been sprinkled through the hierarchy and use their rules to filter the files in the transfer. If -F is repeated, it is a shorthand for this rule: --filter='exclude .rsync-filter' This filters out the .rsync-filter files themselves from the transfer. See the FILTER RULES section for detailed information on how these options work. --exclude=PATTERN This option is a simplified form of the --filter option that specifies an exclude rule and does not allow the full rule-parsing syntax of normal filter rules. This is equivalent to specifying -f'- PATTERN'. See the FILTER RULES section for detailed information on this option. --exclude-from=FILE This option is related to the --exclude option, but it specifies a FILE that contains exclude patterns (one per line). Blank lines in the file are ignored, as are whole- line comments that start with ';' or '#' (filename rules that contain those characters are unaffected). If a line begins with "- " (dash, space) or "+ " (plus, space), then the type of rule is being explicitly specified as an exclude or an include (respectively). Any rules without such a prefix are taken to be an exclude. If a line consists of just "!", then the current filter rules are cleared before adding any further rules. If FILE is '-', the list will be read from standard input. --include=PATTERN This option is a simplified form of the --filter option that specifies an include rule and does not allow the full rule-parsing syntax of normal filter rules. This is equivalent to specifying -f'+ PATTERN'. See the FILTER RULES section for detailed information on this option. --include-from=FILE This option is related to the --include option, but it specifies a FILE that contains include patterns (one per line). Blank lines in the file are ignored, as are whole- line comments that start with ';' or '#' (filename rules that contain those characters are unaffected). If a line begins with "- " (dash, space) or "+ " (plus, space), then the type of rule is being explicitly specified as an exclude or an include (respectively). Any rules without such a prefix are taken to be an include. If a line consists of just "!", then the current filter rules are cleared before adding any further rules. If FILE is '-', the list will be read from standard input. --files-from=FILE Using this option allows you to specify the exact list of files to transfer (as read from the specified FILE or '-' for standard input). It also tweaks the default behavior of rsync to make transferring just the specified files and directories easier: o The --relative (-R) option is implied, which preserves the path information that is specified for each item in the file (use --no-relative or --no-R if you want to turn that off). o The --dirs (-d) option is implied, which will create directories specified in the list on the destination rather than noisily skipping them (use --no-dirs or --no-d if you want to turn that off). o The --archive (-a) option's behavior does not imply --recursive (-r), so specify it explicitly, if you want it. o These side-effects change the default state of rsync, so the position of the --files-from option on the command-line has no bearing on how other options are parsed (e.g. -a works the same before or after --files-from, as does --no-R and all other options). The filenames that are read from the FILE are all relative to the source dir -- any leading slashes are removed and no ".." references are allowed to go higher than the source dir. For example, take this command: rsync -a --files-from=/tmp/foo /usr remote:/backup If /tmp/foo contains the string "bin" (or even "/bin"), the /usr/bin directory will be created as /backup/bin on the remote host. If it contains "bin/" (note the trailing slash), the immediate contents of the directory would also be sent (without needing to be explicitly mentioned in the file -- this began in version 2.6.4). In both cases, if the -r option was enabled, that dir's entire hierarchy would also be transferred (keep in mind that -r needs to be specified explicitly with --files-from, since it is not implied by -a. Also note that the effect of the (enabled by default) -r option is to duplicate only the path info that is read from the file -- it does not force the duplication of the source-spec path (/usr in this case). In addition, the --files-from file can be read from the remote host instead of the local host if you specify a "host:" in front of the file (the host must match one end of the transfer). As a short-cut, you can specify just a prefix of ":" to mean "use the remote end of the transfer". For example: rsync -a --files-from=:/path/file-list src:/ /tmp/copy This would copy all the files specified in the /path/file- list file that was located on the remote "src" host. If the --iconv and --secluded-args options are specified and the --files-from filenames are being sent from one host to another, the filenames will be translated from the sending host's charset to the receiving host's charset. NOTE: sorting the list of files in the --files-from input helps rsync to be more efficient, as it will avoid re- visiting the path elements that are shared between adjacent entries. If the input is not sorted, some path elements (implied directories) may end up being scanned multiple times, and rsync will eventually unduplicate them after they get turned into file-list elements. --from0, -0 This tells rsync that the rules/filenames it reads from a file are terminated by a null ('\0') character, not a NL, CR, or CR+LF. This affects --exclude-from, --include- from, --files-from, and any merged files specified in a --filter rule. It does not affect --cvs-exclude (since all names read from a .cvsignore file are split on whitespace). --old-args This option tells rsync to stop trying to protect the arg values on the remote side from unintended word-splitting or other misinterpretation. It also allows the client to treat an empty arg as a "." instead of generating an error. The default in a modern rsync is for "shell-active" characters (including spaces) to be backslash-escaped in the args that are sent to the remote shell. The wildcard characters *, ?, [, & ] are not escaped in filename args (allowing them to expand into multiple filenames) while being protected in option args, such as --usermap. If you have a script that wants to use old-style arg splitting in its filenames, specify this option once. If the remote shell has a problem with any backslash escapes at all, specify this option twice. You may also control this setting via the RSYNC_OLD_ARGS environment variable. If it has the value "1", rsync will default to a single-option setting. If it has the value "2" (or more), rsync will default to a repeated-option setting. If it is "0", you'll get the default escaping behavior. The environment is always overridden by manually specified positive or negative options (the negative is --no-old-args). Note that this option also disables the extra safety check added in 3.2.5 that ensures that a remote sender isn't including extra top-level items in the file-list that you didn't request. This side-effect is necessary because we can't know for sure what names to expect when the remote shell is interpreting the args. This option conflicts with the --secluded-args option. --secluded-args, -s This option sends all filenames and most options to the remote rsync via the protocol (not the remote shell command line) which avoids letting the remote shell modify them. Wildcards are expanded on the remote host by rsync instead of a shell. This is similar to the default backslash-escaping of args that was added in 3.2.4 (see --old-args) in that it prevents things like space splitting and unwanted special- character side-effects. However, it has the drawbacks of being incompatible with older rsync versions (prior to 3.0.0) and of being refused by restricted shells that want to be able to inspect all the option values for safety. This option is useful for those times that you need the argument's character set to be converted for the remote host, if the remote shell is incompatible with the default backslash-escpaing method, or there is some other reason that you want the majority of the options and arguments to bypass the command-line of the remote shell. If you combine this option with --iconv, the args related to the remote side will be translated from the local to the remote character-set. The translation happens before wild-cards are expanded. See also the --files-from option. You may also control this setting via the RSYNC_PROTECT_ARGS environment variable. If it has a non- zero value, this setting will be enabled by default, otherwise it will be disabled by default. Either state is overridden by a manually specified positive or negative version of this option (note that --no-s and --no- secluded-args are the negative versions). This environment variable is also superseded by a non-zero RSYNC_OLD_ARGS export. This option conflicts with the --old-args option. This option used to be called --protect-args (before 3.2.6) and that older name can still be used (though specifying it as -s is always the easiest and most compatible choice). --trust-sender This option disables two extra validation checks that a local client performs on the file list generated by a remote sender. This option should only be used if you trust the sender to not put something malicious in the file list (something that could possibly be done via a modified rsync, a modified shell, or some other similar manipulation). Normally, the rsync client (as of version 3.2.5) runs two extra validation checks when pulling files from a remote rsync: o It verifies that additional arg items didn't get added at the top of the transfer. o It verifies that none of the items in the file list are names that should have been excluded (if filter rules were specified). Note that various options can turn off one or both of these checks if the option interferes with the validation. For instance: o Using a per-directory filter file reads filter rules that only the server knows about, so the filter checking is disabled. o Using the --old-args option allows the sender to manipulate the requested args, so the arg checking is disabled. o Reading the files-from list from the server side means that the client doesn't know the arg list, so the arg checking is disabled. o Using --read-batch disables both checks since the batch file's contents will have been verified when it was created. This option may help an under-powered client server if the extra pattern matching is slowing things down on a huge transfer. It can also be used to work around a currently- unknown bug in the verification logic for a transfer from a trusted sender. When using this option it is a good idea to specify a dedicated destination directory, as discussed in the MULTI-HOST SECURITY section. --copy-as=USER[:GROUP] This option instructs rsync to use the USER and (if specified after a colon) the GROUP for the copy operations. This only works if the user that is running rsync has the ability to change users. If the group is not specified then the user's default groups are used. This option can help to reduce the risk of an rsync being run as root into or out of a directory that might have live changes happening to it and you want to make sure that root-level read or write actions of system files are not possible. While you could alternatively run all of rsync as the specified user, sometimes you need the root- level host-access credentials to be used, so this allows rsync to drop root for the copying part of the operation after the remote-shell or daemon connection is established. The option only affects one side of the transfer unless the transfer is local, in which case it affects both sides. Use the --remote-option to affect the remote side, such as -M--copy-as=joe. For a local transfer, the lsh (or lsh.sh) support file provides a local-shell helper script that can be used to allow a "localhost:" or "lh:" host-spec to be specified without needing to setup any remote shells, allowing you to specify remote options that affect the side of the transfer that is using the host- spec (and using hostname "lh" avoids the overriding of the remote directory to the user's home dir). For example, the following rsync writes the local files as user "joe": sudo rsync -aiv --copy-as=joe host1:backups/joe/ /home/joe/ This makes all files owned by user "joe", limits the groups to those that are available to that user, and makes it impossible for the joe user to do a timed exploit of the path to induce a change to a file that the joe user has no permissions to change. The following command does a local copy into the "dest/" dir as user "joe" (assuming you've installed support/lsh into a dir on your $PATH): sudo rsync -aive lsh -M--copy-as=joe src/ lh:dest/ --temp-dir=DIR, -T This option instructs rsync to use DIR as a scratch directory when creating temporary copies of the files transferred on the receiving side. The default behavior is to create each temporary file in the same directory as the associated destination file. Beginning with rsync 3.1.1, the temp-file names inside the specified DIR will not be prefixed with an extra dot (though they will still have a random suffix added). This option is most often used when the receiving disk partition does not have enough free space to hold a copy of the largest file in the transfer. In this case (i.e. when the scratch directory is on a different disk partition), rsync will not be able to rename each received temporary file over the top of the associated destination file, but instead must copy it into place. Rsync does this by copying the file over the top of the destination file, which means that the destination file will contain truncated data during this copy. If this were not done this way (even if the destination file were first removed, the data locally copied to a temporary file in the destination directory, and then renamed into place) it would be possible for the old file to continue taking up disk space (if someone had it open), and thus there might not be enough room to fit the new version on the disk at the same time. If you are using this option for reasons other than a shortage of disk space, you may wish to combine it with the --delay-updates option, which will ensure that all copied files get put into subdirectories in the destination hierarchy, awaiting the end of the transfer. If you don't have enough room to duplicate all the arriving files on the destination partition, another way to tell rsync that you aren't overly concerned about disk space is to use the --partial-dir option with a relative path; because this tells rsync that it is OK to stash off a copy of a single file in a subdir in the destination hierarchy, rsync will use the partial-dir as a staging area to bring over the copied file, and then rename it into place from there. (Specifying a --partial-dir with an absolute path does not have this side-effect.) --fuzzy, -y This option tells rsync that it should look for a basis file for any destination file that is missing. The current algorithm looks in the same directory as the destination file for either a file that has an identical size and modified-time, or a similarly-named file. If found, rsync uses the fuzzy basis file to try to speed up the transfer. If the option is repeated, the fuzzy scan will also be done in any matching alternate destination directories that are specified via --compare-dest, --copy-dest, or --link-dest. Note that the use of the --delete option might get rid of any potential fuzzy-match files, so either use --delete- after or specify some filename exclusions if you need to prevent this. --compare-dest=DIR This option instructs rsync to use DIR on the destination machine as an additional hierarchy to compare destination files against doing transfers (if the files are missing in the destination directory). If a file is found in DIR that is identical to the sender's file, the file will NOT be transferred to the destination directory. This is useful for creating a sparse backup of just files that have changed from an earlier backup. This option is typically used to copy into an empty (or newly created) directory. Beginning in version 2.6.4, multiple --compare-dest directories may be provided, which will cause rsync to search the list in the order specified for an exact match. If a match is found that differs only in attributes, a local copy is made and the attributes updated. If a match is not found, a basis file from one of the DIRs will be selected to try to speed up the transfer. If DIR is a relative path, it is relative to the destination directory. See also --copy-dest and --link- dest. NOTE: beginning with version 3.1.0, rsync will remove a file from a non-empty destination hierarchy if an exact match is found in one of the compare-dest hierarchies (making the end result more closely match a fresh copy). --copy-dest=DIR This option behaves like --compare-dest, but rsync will also copy unchanged files found in DIR to the destination directory using a local copy. This is useful for doing transfers to a new destination while leaving existing files intact, and then doing a flash-cutover when all files have been successfully transferred. Multiple --copy-dest directories may be provided, which will cause rsync to search the list in the order specified for an unchanged file. If a match is not found, a basis file from one of the DIRs will be selected to try to speed up the transfer. If DIR is a relative path, it is relative to the destination directory. See also --compare-dest and --link-dest. --link-dest=DIR This option behaves like --copy-dest, but unchanged files are hard linked from DIR to the destination directory. The files must be identical in all preserved attributes (e.g. permissions, possibly ownership) in order for the files to be linked together. An example: rsync -av --link-dest=$PWD/prior_dir host:src_dir/ new_dir/ If files aren't linking, double-check their attributes. Also check if some attributes are getting forced outside of rsync's control, such a mount option that squishes root to a single user, or mounts a removable drive with generic ownership (such as OS X's "Ignore ownership on this volume" option). Beginning in version 2.6.4, multiple --link-dest directories may be provided, which will cause rsync to search the list in the order specified for an exact match (there is a limit of 20 such directories). If a match is found that differs only in attributes, a local copy is made and the attributes updated. If a match is not found, a basis file from one of the DIRs will be selected to try to speed up the transfer. This option works best when copying into an empty destination hierarchy, as existing files may get their attributes tweaked, and that can affect alternate destination files via hard-links. Also, itemizing of changes can get a bit muddled. Note that prior to version 3.1.0, an alternate-directory exact match would never be found (nor linked into the destination) when a destination file already exists. Note that if you combine this option with --ignore-times, rsync will not link any files together because it only links identical files together as a substitute for transferring the file, never as an additional check after the file is updated. If DIR is a relative path, it is relative to the destination directory. See also --compare-dest and --copy-dest. Note that rsync versions prior to 2.6.1 had a bug that could prevent --link-dest from working properly for a non- super-user when --owner (-o) was specified (or implied). You can work-around this bug by avoiding the -o option (or using --no-o) when sending to an old rsync. --compress, -z With this option, rsync compresses the file data as it is sent to the destination machine, which reduces the amount of data being transmitted -- something that is useful over a slow connection. Rsync supports multiple compression methods and will choose one for you unless you force the choice using the --compress-choice (--zc) option. Run rsync --version to see the default compress list compiled into your version. When both sides of the transfer are at least 3.2.0, rsync chooses the first algorithm in the client's list of choices that is also in the server's list of choices. If no common compress choice is found, rsync exits with an error. If the remote rsync is too old to support checksum negotiation, its list is assumed to be "zlib". The default order can be customized by setting the environment variable RSYNC_COMPRESS_LIST to a space- separated list of acceptable compression names. If the string contains a "&" character, it is separated into the "client string & server string", otherwise the same string applies to both. If the string (or string portion) contains no non-whitespace characters, the default compress list is used. Any unknown compression names are discarded from the list, but a list with only invalid names results in a failed negotiation. There are some older rsync versions that were configured to reject a -z option and require the use of -zz because their compression library was not compatible with the default zlib compression method. You can usually ignore this weirdness unless the rsync server complains and tells you to specify -zz. --compress-choice=STR, --zc=STR This option can be used to override the automatic negotiation of the compression algorithm that occurs when --compress is used. The option implies --compress unless "none" was specified, which instead implies --no-compress. The compression options that you may be able to use are: o zstd o lz4 o zlibx o zlib o none Run rsync --version to see the default compress list compiled into your version (which may differ from the list above). Note that if you see an error about an option named --old- compress or --new-compress, this is rsync trying to send the --compress-choice=zlib or --compress-choice=zlibx option in a backward-compatible manner that more rsync versions understand. This error indicates that the older rsync version on the server will not allow you to force the compression type. Note that the "zlibx" compression algorithm is just the "zlib" algorithm with matched data excluded from the compression stream (to try to make it more compatible with an external zlib implementation). --compress-level=NUM, --zl=NUM Explicitly set the compression level to use (see --compress, -z) instead of letting it default. The --compress option is implied as long as the level chosen is not a "don't compress" level for the compression algorithm that is in effect (e.g. zlib compression treats level 0 as "off"). The level values vary depending on the checksum in effect. Because rsync will negotiate a checksum choice by default (when the remote rsync is new enough), it can be good to combine this option with a --compress-choice (--zc) option unless you're sure of the choice in effect. For example: rsync -aiv --zc=zstd --zl=22 host:src/ dest/ For zlib & zlibx compression the valid values are from 1 to 9 with 6 being the default. Specifying --zl=0 turns compression off, and specifying --zl=-1 chooses the default level of 6. For zstd compression the valid values are from -131072 to 22 with 3 being the default. Specifying 0 chooses the default of 3. For lz4 compression there are no levels, so the value is always 0. If you specify a too-large or too-small value, the number is silently limited to a valid value. This allows you to specify something like --zl=999999999 and be assured that you'll end up with the maximum compression level no matter what algorithm was chosen. If you want to know the compression level that is in effect, specify --debug=nstr to see the "negotiated string" results. This will report something like "Client compress: zstd (level 3)" (along with the checksum choice in effect). --skip-compress=LIST NOTE: no compression method currently supports per-file compression changes, so this option has no effect. Override the list of file suffixes that will be compressed as little as possible. Rsync sets the compression level on a per-file basis based on the file's suffix. If the compression algorithm has an "off" level, then no compression occurs for those files. Other algorithms that support changing the streaming level on-the-fly will have the level minimized to reduces the CPU usage as much as possible for a matching file. The LIST should be one or more file suffixes (without the dot) separated by slashes (/). You may specify an empty string to indicate that no files should be skipped. Simple character-class matching is supported: each must consist of a list of letters inside the square brackets (e.g. no special classes, such as "[:alpha:]", are supported, and '-' has no special meaning). The characters asterisk (*) and question-mark (?) have no special meaning. Here's an example that specifies 6 suffixes to skip (since 1 of the 5 rules matches 2 suffixes): --skip-compress=gz/jpg/mp[34]/7z/bz2 The default file suffixes in the skip-compress list in this version of rsync are: 3g2 3gp 7z aac ace apk avi bz2 deb dmg ear f4v flac flv gpg gz iso jar jpeg jpg lrz lz lz4 lzma lzo m1a m1v m2a m2ts m2v m4a m4b m4p m4r m4v mka mkv mov mp1 mp2 mp3 mp4 mpa mpeg mpg mpv mts odb odf odg odi odm odp ods odt oga ogg ogm ogv ogx opus otg oth otp ots ott oxt png qt rar rpm rz rzip spx squashfs sxc sxd sxg sxm sxw sz tbz tbz2 tgz tlz ts txz tzo vob war webm webp xz z zip zst This list will be replaced by your --skip-compress list in all but one situation: a copy from a daemon rsync will add your skipped suffixes to its list of non-compressing files (and its list may be configured to a different default). --numeric-ids With this option rsync will transfer numeric group and user IDs rather than using user and group names and mapping them at both ends. By default rsync will use the username and groupname to determine what ownership to give files. The special uid 0 and the special group 0 are never mapped via user/group names even if the --numeric-ids option is not specified. If a user or group has no name on the source system or it has no match on the destination system, then the numeric ID from the source system is used instead. See also the use chroot setting in the rsyncd.conf manpage for some comments on how the chroot setting affects rsync's ability to look up the names of the users and groups and what you can do about it. --usermap=STRING, --groupmap=STRING These options allow you to specify users and groups that should be mapped to other values by the receiving side. The STRING is one or more FROM:TO pairs of values separated by commas. Any matching FROM value from the sender is replaced with a TO value from the receiver. You may specify usernames or user IDs for the FROM and TO values, and the FROM value may also be a wild-card string, which will be matched against the sender's names (wild- cards do NOT match against ID numbers, though see below for why a '*' matches everything). You may instead specify a range of ID numbers via an inclusive range: LOW- HIGH. For example: --usermap=0-99:nobody,wayne:admin,*:normal --groupmap=usr:1,1:usr The first match in the list is the one that is used. You should specify all your user mappings using a single --usermap option, and/or all your group mappings using a single --groupmap option. Note that the sender's name for the 0 user and group are not transmitted to the receiver, so you should either match these values using a 0, or use the names in effect on the receiving side (typically "root"). All other FROM names match those in use on the sending side. All TO names match those in use on the receiving side. Any IDs that do not have a name on the sending side are treated as having an empty name for the purpose of matching. This allows them to be matched via a "*" or using an empty name. For instance: --usermap=:nobody --groupmap=*:nobody When the --numeric-ids option is used, the sender does not send any names, so all the IDs are treated as having an empty name. This means that you will need to specify numeric FROM values if you want to map these nameless IDs to different values. For the --usermap option to work, the receiver will need to be running as a super-user (see also the --super and --fake-super options). For the --groupmap option to work, the receiver will need to have permissions to set that group. Starting with rsync 3.2.4, the --usermap option implies the --owner (-o) option while the --groupmap option implies the --group (-g) option (since rsync needs to have those options enabled for the mapping options to work). An older rsync client may need to use -s to avoid a complaint about wildcard characters, but a modern rsync handles this automatically. --chown=USER:GROUP This option forces all files to be owned by USER with group GROUP. This is a simpler interface than using --usermap & --groupmap directly, but it is implemented using those options internally so they cannot be mixed. If either the USER or GROUP is empty, no mapping for the omitted user/group will occur. If GROUP is empty, the trailing colon may be omitted, but if USER is empty, a leading colon must be supplied. If you specify "--chown=foo:bar", this is exactly the same as specifying "--usermap=*:foo --groupmap=*:bar", only easier (and with the same implied --owner and/or --group options). An older rsync client may need to use -s to avoid a complaint about wildcard characters, but a modern rsync handles this automatically. --timeout=SECONDS This option allows you to set a maximum I/O timeout in seconds. If no data is transferred for the specified time then rsync will exit. The default is 0, which means no timeout. --contimeout=SECONDS This option allows you to set the amount of time that rsync will wait for its connection to an rsync daemon to succeed. If the timeout is reached, rsync exits with an error. --address=ADDRESS By default rsync will bind to the wildcard address when connecting to an rsync daemon. The --address option allows you to specify a specific IP address (or hostname) to bind to. See also the daemon version of the --address option. --port=PORT This specifies an alternate TCP port number to use rather than the default of 873. This is only needed if you are using the double-colon (::) syntax to connect with an rsync daemon (since the URL syntax has a way to specify the port as a part of the URL). See also the daemon version of the --port option. --sockopts=OPTIONS This option can provide endless fun for people who like to tune their systems to the utmost degree. You can set all sorts of socket options which may make transfers faster (or slower!). Read the manpage for the setsockopt() system call for details on some of the options you may be able to set. By default no special socket options are set. This only affects direct socket connections to a remote rsync daemon. See also the daemon version of the --sockopts option. --blocking-io This tells rsync to use blocking I/O when launching a remote shell transport. If the remote shell is either rsh or remsh, rsync defaults to using blocking I/O, otherwise it defaults to using non-blocking I/O. (Note that ssh prefers non-blocking I/O.) --outbuf=MODE This sets the output buffering mode. The mode can be None (aka Unbuffered), Line, or Block (aka Full). You may specify as little as a single letter for the mode, and use upper or lower case. The main use of this option is to change Full buffering to Line buffering when rsync's output is going to a file or pipe. --itemize-changes, -i Requests a simple itemized list of the changes that are being made to each file, including attribute changes. This is exactly the same as specifying --out- format='%i %n%L'. If you repeat the option, unchanged files will also be output, but only if the receiving rsync is at least version 2.6.7 (you can use -vv with older versions of rsync, but that also turns on the output of other verbose messages). The "%i" escape has a cryptic output that is 11 letters long. The general format is like the string YXcstpoguax, where Y is replaced by the type of update being done, X is replaced by the file-type, and the other letters represent attributes that may be output if they are being modified. The update types that replace the Y are as follows: o A < means that a file is being transferred to the remote host (sent). o A > means that a file is being transferred to the local host (received). o A c means that a local change/creation is occurring for the item (such as the creation of a directory or the changing of a symlink, etc.). o A h means that the item is a hard link to another item (requires --hard-links). o A . means that the item is not being updated (though it might have attributes that are being modified). o A * means that the rest of the itemized-output area contains a message (e.g. "deleting"). The file-types that replace the X are: f for a file, a d for a directory, an L for a symlink, a D for a device, and a S for a special file (e.g. named sockets and fifos). The other letters in the string indicate if some attributes of the file have changed, as follows: o "." - the attribute is unchanged. o "+" - the file is newly created. o " " - all the attributes are unchanged (all dots turn to spaces). o "?" - the change is unknown (when the remote rsync is old). o A letter indicates an attribute is being updated. The attribute that is associated with each letter is as follows: o A c means either that a regular file has a different checksum (requires --checksum) or that a symlink, device, or special file has a changed value. Note that if you are sending files to an rsync prior to 3.0.1, this change flag will be present only for checksum-differing regular files. o A s means the size of a regular file is different and will be updated by the file transfer. o A t means the modification time is different and is being updated to the sender's value (requires --times). An alternate value of T means that the modification time will be set to the transfer time, which happens when a file/symlink/device is updated without --times and when a symlink is changed and the receiver can't set its time. (Note: when using an rsync 3.0.0 client, you might see the s flag combined with t instead of the proper T flag for this time-setting failure.) o A p means the permissions are different and are being updated to the sender's value (requires --perms). o An o means the owner is different and is being updated to the sender's value (requires --owner and super-user privileges). o A g means the group is different and is being updated to the sender's value (requires --group and the authority to set the group). o o A u|n|b indicates the following information: u means the access (use) time is different and is being updated to the sender's value (requires --atimes) o n means the create time (newness) is different and is being updated to the sender's value (requires --crtimes) o b means that both the access and create times are being updated o The a means that the ACL information is being changed. o The x means that the extended attribute information is being changed. One other output is possible: when deleting files, the "%i" will output the string "*deleting" for each item that is being removed (assuming that you are talking to a recent enough rsync that it logs deletions instead of outputting them as a verbose message). --out-format=FORMAT This allows you to specify exactly what the rsync client outputs to the user on a per-update basis. The format is a text string containing embedded single-character escape sequences prefixed with a percent (%) character. A default format of "%n%L" is assumed if either --info=name or -v is specified (this tells you just the name of the file and, if the item is a link, where it points). For a full list of the possible escape characters, see the log format setting in the rsyncd.conf manpage. Specifying the --out-format option implies the --info=name option, which will mention each file, dir, etc. that gets updated in a significant way (a transferred file, a recreated symlink/device, or a touched directory). In addition, if the itemize-changes escape (%i) is included in the string (e.g. if the --itemize-changes option was used), the logging of names increases to mention any item that is changed in any way (as long as the receiving side is at least 2.6.4). See the --itemize-changes option for a description of the output of "%i". Rsync will output the out-format string prior to a file's transfer unless one of the transfer-statistic escapes is requested, in which case the logging is done at the end of the file's transfer. When this late logging is in effect and --progress is also specified, rsync will also output the name of the file being transferred prior to its progress information (followed, of course, by the out- format output). --log-file=FILE This option causes rsync to log what it is doing to a file. This is similar to the logging that a daemon does, but can be requested for the client side and/or the server side of a non-daemon transfer. If specified as a client option, transfer logging will be enabled with a default format of "%i %n%L". See the --log-file-format option if you wish to override this. Here's an example command that requests the remote side to log what is happening: rsync -av --remote-option=--log-file=/tmp/rlog src/ dest/ This is very useful if you need to debug why a connection is closing unexpectedly. See also the daemon version of the --log-file option. --log-file-format=FORMAT This allows you to specify exactly what per-update logging is put into the file specified by the --log-file option (which must also be specified for this option to have any effect). If you specify an empty string, updated files will not be mentioned in the log file. For a list of the possible escape characters, see the log format setting in the rsyncd.conf manpage. The default FORMAT used if --log-file is specified and this option is not is '%i %n%L'. See also the daemon version of the --log-file-format option. --stats This tells rsync to print a verbose set of statistics on the file transfer, allowing you to tell how effective rsync's delta-transfer algorithm is for your data. This option is equivalent to --info=stats2 if combined with 0 or 1 -v options, or --info=stats3 if combined with 2 or more -v options. The current statistics are as follows: o Number of files is the count of all "files" (in the generic sense), which includes directories, symlinks, etc. The total count will be followed by a list of counts by filetype (if the total is non- zero). For example: "(reg: 5, dir: 3, link: 2, dev: 1, special: 1)" lists the totals for regular files, directories, symlinks, devices, and special files. If any of value is 0, it is completely omitted from the list. o Number of created files is the count of how many "files" (generic sense) were created (as opposed to updated). The total count will be followed by a list of counts by filetype (if the total is non- zero). o Number of deleted files is the count of how many "files" (generic sense) were deleted. The total count will be followed by a list of counts by filetype (if the total is non-zero). Note that this line is only output if deletions are in effect, and only if protocol 31 is being used (the default for rsync 3.1.x). o Number of regular files transferred is the count of normal files that were updated via rsync's delta- transfer algorithm, which does not include dirs, symlinks, etc. Note that rsync 3.1.0 added the word "regular" into this heading. o Total file size is the total sum of all file sizes in the transfer. This does not count any size for directories or special files, but does include the size of symlinks. o Total transferred file size is the total sum of all files sizes for just the transferred files. o Literal data is how much unmatched file-update data we had to send to the receiver for it to recreate the updated files. o Matched data is how much data the receiver got locally when recreating the updated files. o File list size is how big the file-list data was when the sender sent it to the receiver. This is smaller than the in-memory size for the file list due to some compressing of duplicated data when rsync sends the list. o File list generation time is the number of seconds that the sender spent creating the file list. This requires a modern rsync on the sending side for this to be present. o File list transfer time is the number of seconds that the sender spent sending the file list to the receiver. o Total bytes sent is the count of all the bytes that rsync sent from the client side to the server side. o Total bytes received is the count of all non- message bytes that rsync received by the client side from the server side. "Non-message" bytes means that we don't count the bytes for a verbose message that the server sent to us, which makes the stats more consistent. --8-bit-output, -8 This tells rsync to leave all high-bit characters unescaped in the output instead of trying to test them to see if they're valid in the current locale and escaping the invalid ones. All control characters (but never tabs) are always escaped, regardless of this option's setting. The escape idiom that started in 2.6.7 is to output a literal backslash (\) and a hash (#), followed by exactly 3 octal digits. For example, a newline would output as "\#012". A literal backslash that is in a filename is not escaped unless it is followed by a hash and 3 digits (0-9). --human-readable, -h Output numbers in a more human-readable format. There are 3 possible levels: 1. output numbers with a separator between each set of 3 digits (either a comma or a period, depending on if the decimal point is represented by a period or a comma). 2. output numbers in units of 1000 (with a character suffix for larger units -- see below). 3. output numbers in units of 1024. The default is human-readable level 1. Each -h option increases the level by one. You can take the level down to 0 (to output numbers as pure digits) by specifying the --no-human-readable (--no-h) option. The unit letters that are appended in levels 2 and 3 are: K (kilo), M (mega), G (giga), T (tera), or P (peta). For example, a 1234567-byte file would output as 1.23M in level-2 (assuming that a period is your local decimal point). Backward compatibility note: versions of rsync prior to 3.1.0 do not support human-readable level 1, and they default to level 0. Thus, specifying one or two -h options will behave in a comparable manner in old and new versions as long as you didn't specify a --no-h option prior to one or more -h options. See the --list-only option for one difference. --partial By default, rsync will delete any partially transferred file if the transfer is interrupted. In some circumstances it is more desirable to keep partially transferred files. Using the --partial option tells rsync to keep the partial file which should make a subsequent transfer of the rest of the file much faster. --partial-dir=DIR This option modifies the behavior of the --partial option while also implying that it be enabled. This enhanced partial-file method puts any partially transferred files into the specified DIR instead of writing the partial file out to the destination file. On the next transfer, rsync will use a file found in this dir as data to speed up the resumption of the transfer and then delete it after it has served its purpose. Note that if --whole-file is specified (or implied), any partial-dir files that are found for a file that is being updated will simply be removed (since rsync is sending files without using rsync's delta-transfer algorithm). Rsync will create the DIR if it is missing, but just the last dir -- not the whole path. This makes it easy to use a relative path (such as "--partial-dir=.rsync-partial") to have rsync create the partial-directory in the destination file's directory when it is needed, and then remove it again when the partial file is deleted. Note that this directory removal is only done for a relative pathname, as it is expected that an absolute path is to a directory that is reserved for partial-dir work. If the partial-dir value is not an absolute path, rsync will add an exclude rule at the end of all your existing excludes. This will prevent the sending of any partial- dir files that may exist on the sending side, and will also prevent the untimely deletion of partial-dir items on the receiving side. An example: the above --partial-dir option would add the equivalent of this "perishable" exclude at the end of any other filter rules: -f '-p .rsync-partial/' If you are supplying your own exclude rules, you may need to add your own exclude/hide/protect rule for the partial- dir because: 1. the auto-added rule may be ineffective at the end of your other rules, or 2. you may wish to override rsync's exclude choice. For instance, if you want to make rsync clean-up any left- over partial-dirs that may be lying around, you should specify --delete-after and add a "risk" filter rule, e.g. -f 'R .rsync-partial/'. Avoid using --delete-before or --delete-during unless you don't need rsync to use any of the left-over partial-dir data during the current run. IMPORTANT: the --partial-dir should not be writable by other users or it is a security risk! E.g. AVOID "/tmp"! You can also set the partial-dir value the RSYNC_PARTIAL_DIR environment variable. Setting this in the environment does not force --partial to be enabled, but rather it affects where partial files go when --partial is specified. For instance, instead of using --partial-dir=.rsync-tmp along with --progress, you could set RSYNC_PARTIAL_DIR=.rsync-tmp in your environment and then use the -P option to turn on the use of the .rsync- tmp dir for partial transfers. The only times that the --partial option does not look for this environment value are: 1. when --inplace was specified (since --inplace conflicts with --partial-dir), and 2. when --delay-updates was specified (see below). When a modern rsync resumes the transfer of a file in the partial-dir, that partial file is now updated in-place instead of creating yet another tmp-file copy (so it maxes out at dest + tmp instead of dest + partial + tmp). This requires both ends of the transfer to be at least version 3.2.0. For the purposes of the daemon-config's "refuse options" setting, --partial-dir does not imply --partial. This is so that a refusal of the --partial option can be used to disallow the overwriting of destination files with a partial transfer, while still allowing the safer idiom provided by --partial-dir. --delay-updates This option puts the temporary file from each updated file into a holding directory until the end of the transfer, at which time all the files are renamed into place in rapid succession. This attempts to make the updating of the files a little more atomic. By default the files are placed into a directory named .~tmp~ in each file's destination directory, but if you've specified the --partial-dir option, that directory will be used instead. See the comments in the --partial-dir section for a discussion of how this .~tmp~ dir will be excluded from the transfer, and what you can do if you want rsync to cleanup old .~tmp~ dirs that might be lying around. Conflicts with --inplace and --append. This option implies --no-inc-recursive since it needs the full file list in memory in order to be able to iterate over it at the end. This option uses more memory on the receiving side (one bit per file transferred) and also requires enough free disk space on the receiving side to hold an additional copy of all the updated files. Note also that you should not use an absolute path to --partial-dir unless: 1. there is no chance of any of the files in the transfer having the same name (since all the updated files will be put into a single directory if the path is absolute), and 2. there are no mount points in the hierarchy (since the delayed updates will fail if they can't be renamed into place). See also the "atomic-rsync" python script in the "support" subdir for an update algorithm that is even more atomic (it uses --link-dest and a parallel hierarchy of files). --prune-empty-dirs, -m This option tells the receiving rsync to get rid of empty directories from the file-list, including nested directories that have no non-directory children. This is useful for avoiding the creation of a bunch of useless directories when the sending rsync is recursively scanning a hierarchy of files using include/exclude/filter rules. This option can still leave empty directories on the receiving side if you make use of TRANSFER_RULES. Because the file-list is actually being pruned, this option also affects what directories get deleted when a delete is active. However, keep in mind that excluded files and directories can prevent existing items from being deleted due to an exclude both hiding source files and protecting destination files. See the perishable filter-rule option for how to avoid this. You can prevent the pruning of certain empty directories from the file-list by using a global "protect" filter. For instance, this option would ensure that the directory "emptydir" was kept in the file-list: --filter 'protect emptydir/' Here's an example that copies all .pdf files in a hierarchy, only creating the necessary destination directories to hold the .pdf files, and ensures that any superfluous files and directories in the destination are removed (note the hide filter of non-directories being used instead of an exclude): rsync -avm --del --include='*.pdf' -f 'hide,! */' src/ dest If you didn't want to remove superfluous destination files, the more time-honored options of --include='*/' --exclude='*' would work fine in place of the hide-filter (if that is more natural to you). --progress This option tells rsync to print information showing the progress of the transfer. This gives a bored user something to watch. With a modern rsync this is the same as specifying --info=flist2,name,progress, but any user- supplied settings for those info flags takes precedence (e.g. --info=flist0 --progress). While rsync is transferring a regular file, it updates a progress line that looks like this: 782448 63% 110.64kB/s 0:00:04 In this example, the receiver has reconstructed 782448 bytes or 63% of the sender's file, which is being reconstructed at a rate of 110.64 kilobytes per second, and the transfer will finish in 4 seconds if the current rate is maintained until the end. These statistics can be misleading if rsync's delta- transfer algorithm is in use. For example, if the sender's file consists of the basis file followed by additional data, the reported rate will probably drop dramatically when the receiver gets to the literal data, and the transfer will probably take much longer to finish than the receiver estimated as it was finishing the matched part of the file. When the file transfer finishes, rsync replaces the progress line with a summary line that looks like this: 1,238,099 100% 146.38kB/s 0:00:08 (xfr#5, to-chk=169/396) In this example, the file was 1,238,099 bytes long in total, the average rate of transfer for the whole file was 146.38 kilobytes per second over the 8 seconds that it took to complete, it was the 5th transfer of a regular file during the current rsync session, and there are 169 more files for the receiver to check (to see if they are up-to-date or not) remaining out of the 396 total files in the file-list. In an incremental recursion scan, rsync won't know the total number of files in the file-list until it reaches the ends of the scan, but since it starts to transfer files during the scan, it will display a line with the text "ir-chk" (for incremental recursion check) instead of "to-chk" until the point that it knows the full size of the list, at which point it will switch to using "to-chk". Thus, seeing "ir-chk" lets you know that the total count of files in the file list is still going to increase (and each time it does, the count of files left to check will increase by the number of the files added to the list). -P The -P option is equivalent to "--partial --progress". Its purpose is to make it much easier to specify these two options for a long transfer that may be interrupted. There is also a --info=progress2 option that outputs statistics based on the whole transfer, rather than individual files. Use this flag without outputting a filename (e.g. avoid -v or specify --info=name0) if you want to see how the transfer is doing without scrolling the screen with a lot of names. (You don't need to specify the --progress option in order to use --info=progress2.) Finally, you can get an instant progress report by sending rsync a signal of either SIGINFO or SIGVTALRM. On BSD systems, a SIGINFO is generated by typing a Ctrl+T (Linux doesn't currently support a SIGINFO signal). When the client-side process receives one of those signals, it sets a flag to output a single progress report which is output when the current file transfer finishes (so it may take a little time if a big file is being handled when the signal arrives). A filename is output (if needed) followed by the --info=progress2 format of progress info. If you don't know which of the 3 rsync processes is the client process, it's OK to signal all of them (since the non- client processes ignore the signal). CAUTION: sending SIGVTALRM to an older rsync (pre-3.2.0) will kill it. --password-file=FILE This option allows you to provide a password for accessing an rsync daemon via a file or via standard input if FILE is -. The file should contain just the password on the first line (all other lines are ignored). Rsync will exit with an error if FILE is world readable or if a root-run rsync command finds a non-root-owned file. This option does not supply a password to a remote shell transport such as ssh; to learn how to do that, consult the remote shell's documentation. When accessing an rsync daemon using a remote shell as the transport, this option only comes into effect after the remote shell finishes its authentication (i.e. if you have also specified a password in the daemon's config file). --early-input=FILE This option allows rsync to send up to 5K of data to the "early exec" script on its stdin. One possible use of this data is to give the script a secret that can be used to mount an encrypted filesystem (which you should unmount in the the "post-xfer exec" script). The daemon must be at least version 3.2.1. --list-only This option will cause the source files to be listed instead of transferred. This option is inferred if there is a single source arg and no destination specified, so its main uses are: 1. to turn a copy command that includes a destination arg into a file-listing command, or 2. to be able to specify more than one source arg. Note: be sure to include the destination. CAUTION: keep in mind that a source arg with a wild-card is expanded by the shell into multiple args, so it is never safe to try to specify a single wild-card arg to try to infer this option. A safe example is: rsync -av --list-only foo* dest/ This option always uses an output format that looks similar to this: drwxrwxr-x 4,096 2022/09/30 12:53:11 support -rw-rw-r-- 80 2005/01/11 10:37:37 support/Makefile The only option that affects this output style is (as of 3.1.0) the --human-readable (-h) option. The default is to output sizes as byte counts with digit separators (in a 14-character-width column). Specifying at least one -h option makes the sizes output with unit suffixes. If you want old-style bytecount sizes without digit separators (and an 11-character-width column) use --no-h. Compatibility note: when requesting a remote listing of files from an rsync that is version 2.6.3 or older, you may encounter an error if you ask for a non-recursive listing. This is because a file listing implies the --dirs option w/o --recursive, and older rsyncs don't have that option. To avoid this problem, either specify the --no-dirs option (if you don't need to expand a directory's content), or turn on recursion and exclude the content of subdirectories: -r --exclude='/*/*'. --bwlimit=RATE This option allows you to specify the maximum transfer rate for the data sent over the socket, specified in units per second. The RATE value can be suffixed with a string to indicate a size multiplier, and may be a fractional value (e.g. --bwlimit=1.5m). If no suffix is specified, the value will be assumed to be in units of 1024 bytes (as if "K" or "KiB" had been appended). See the --max-size option for a description of all the available suffixes. A value of 0 specifies no limit. For backward-compatibility reasons, the rate limit will be rounded to the nearest KiB unit, so no rate smaller than 1024 bytes per second is possible. Rsync writes data over the socket in blocks, and this option both limits the size of the blocks that rsync writes, and tries to keep the average transfer rate at the requested limit. Some burstiness may be seen where rsync writes out a block of data and then sleeps to bring the average rate into compliance. Due to the internal buffering of data, the --progress option may not be an accurate reflection on how fast the data is being sent. This is because some files can show up as being rapidly sent when the data is quickly buffered, while other can show up as very slow when the flushing of the output buffer occurs. This may be fixed in a future version. See also the daemon version of the --bwlimit option. --stop-after=MINS, (--time-limit=MINS) This option tells rsync to stop copying when the specified number of minutes has elapsed. For maximal flexibility, rsync does not communicate this option to the remote rsync since it is usually enough that one side of the connection quits as specified. This allows the option's use even when only one side of the connection supports it. You can tell the remote side about the time limit using --remote-option (-M), should the need arise. The --time-limit version of this option is deprecated. --stop-at=y-m-dTh:m This option tells rsync to stop copying when the specified point in time has been reached. The date & time can be fully specified in a numeric format of year-month- dayThour:minute (e.g. 2000-12-31T23:59) in the local timezone. You may choose to separate the date numbers using slashes instead of dashes. The value can also be abbreviated in a variety of ways, such as specifying a 2-digit year and/or leaving off various values. In all cases, the value will be taken to be the next possible point in time where the supplied information matches. If the value specifies the current time or a past time, rsync exits with an error. For example, "1-30" specifies the next January 30th (at midnight local time), "14:00" specifies the next 2 P.M., "1" specifies the next 1st of the month at midnight, "31" specifies the next month where we can stop on its 31st day, and ":59" specifies the next 59th minute after the hour. For maximal flexibility, rsync does not communicate this option to the remote rsync since it is usually enough that one side of the connection quits as specified. This allows the option's use even when only one side of the connection supports it. You can tell the remote side about the time limit using --remote-option (-M), should the need arise. Do keep in mind that the remote host may have a different default timezone than your local host. --fsync Cause the receiving side to fsync each finished file. This may slow down the transfer, but can help to provide peace of mind when updating critical files. --write-batch=FILE Record a file that can later be applied to another identical destination with --read-batch. See the "BATCH MODE" section for details, and also the --only-write-batch option. This option overrides the negotiated checksum & compress lists and always negotiates a choice based on old-school md5/md4/zlib choices. If you want a more modern choice, use the --checksum-choice (--cc) and/or --compress-choice (--zc) options. --only-write-batch=FILE Works like --write-batch, except that no updates are made on the destination system when creating the batch. This lets you transport the changes to the destination system via some other means and then apply the changes via --read-batch. Note that you can feel free to write the batch directly to some portable media: if this media fills to capacity before the end of the transfer, you can just apply that partial transfer to the destination and repeat the whole process to get the rest of the changes (as long as you don't mind a partially updated destination system while the multi-update cycle is happening). Also note that you only save bandwidth when pushing changes to a remote system because this allows the batched data to be diverted from the sender into the batch file without having to flow over the wire to the receiver (when pulling, the sender is remote, and thus can't write the batch). --read-batch=FILE Apply all of the changes stored in FILE, a file previously generated by --write-batch. If FILE is -, the batch data will be read from standard input. See the "BATCH MODE" section for details. --protocol=NUM Force an older protocol version to be used. This is useful for creating a batch file that is compatible with an older version of rsync. For instance, if rsync 2.6.4 is being used with the --write-batch option, but rsync 2.6.3 is what will be used to run the --read-batch option, you should use "--protocol=28" when creating the batch file to force the older protocol version to be used in the batch file (assuming you can't upgrade the rsync on the reading system). --iconv=CONVERT_SPEC Rsync can convert filenames between character sets using this option. Using a CONVERT_SPEC of "." tells rsync to look up the default character-set via the locale setting. Alternately, you can fully specify what conversion to do by giving a local and a remote charset separated by a comma in the order --iconv=LOCAL,REMOTE, e.g. --iconv=utf8,iso88591. This order ensures that the option will stay the same whether you're pushing or pulling files. Finally, you can specify either --no-iconv or a CONVERT_SPEC of "-" to turn off any conversion. The default setting of this option is site-specific, and can also be affected via the RSYNC_ICONV environment variable. For a list of what charset names your local iconv library supports, you can run "iconv --list". If you specify the --secluded-args (-s) option, rsync will translate the filenames you specify on the command-line that are being sent to the remote host. See also the --files-from option. Note that rsync does not do any conversion of names in filter files (including include/exclude files). It is up to you to ensure that you're specifying matching rules that can match on both sides of the transfer. For instance, you can specify extra include/exclude rules if there are filename differences on the two sides that need to be accounted for. When you pass an --iconv option to an rsync daemon that allows it, the daemon uses the charset specified in its "charset" configuration parameter regardless of the remote charset you actually pass. Thus, you may feel free to specify just the local charset for a daemon transfer (e.g. --iconv=utf8). --ipv4, -4 or --ipv6, -6 Tells rsync to prefer IPv4/IPv6 when creating sockets or running ssh. This affects sockets that rsync has direct control over, such as the outgoing socket when directly contacting an rsync daemon, as well as the forwarding of the -4 or -6 option to ssh when rsync can deduce that ssh is being used as the remote shell. For other remote shells you'll need to specify the "--rsh SHELL -4" option directly (or whatever IPv4/IPv6 hint options it uses). See also the daemon version of these options. If rsync was compiled without support for IPv6, the --ipv6 option will have no effect. The rsync --version output will contain "no IPv6" if is the case. --checksum-seed=NUM Set the checksum seed to the integer NUM. This 4 byte checksum seed is included in each block and MD4 file checksum calculation (the more modern MD5 file checksums don't use a seed). By default the checksum seed is generated by the server and defaults to the current time(). This option is used to set a specific checksum seed, which is useful for applications that want repeatable block checksums, or in the case where the user wants a more random checksum seed. Setting NUM to 0 causes rsync to use the default of time() for checksum seed. DAEMON OPTIONS top The options allowed when starting an rsync daemon are as follows: --daemon This tells rsync that it is to run as a daemon. The daemon you start running may be accessed using an rsync client using the host::module or rsync://host/module/ syntax. If standard input is a socket then rsync will assume that it is being run via inetd, otherwise it will detach from the current terminal and become a background daemon. The daemon will read the config file (rsyncd.conf) on each connect made by a client and respond to requests accordingly. See the rsyncd.conf(5) manpage for more details. --address=ADDRESS By default rsync will bind to the wildcard address when run as a daemon with the --daemon option. The --address option allows you to specify a specific IP address (or hostname) to bind to. This makes virtual hosting possible in conjunction with the --config option. See also the address global option in the rsyncd.conf manpage and the client version of the --address option. --bwlimit=RATE This option allows you to specify the maximum transfer rate for the data the daemon sends over the socket. The client can still specify a smaller --bwlimit value, but no larger value will be allowed. See the client version of the --bwlimit option for some extra details. --config=FILE This specifies an alternate config file than the default. This is only relevant when --daemon is specified. The default is /etc/rsyncd.conf unless the daemon is running over a remote shell program and the remote user is not the super-user; in that case the default is rsyncd.conf in the current directory (typically $HOME). --dparam=OVERRIDE, -M This option can be used to set a daemon-config parameter when starting up rsync in daemon mode. It is equivalent to adding the parameter at the end of the global settings prior to the first module's definition. The parameter names can be specified without spaces, if you so desire. For instance: rsync --daemon -M pidfile=/path/rsync.pid --no-detach When running as a daemon, this option instructs rsync to not detach itself and become a background process. This option is required when running as a service on Cygwin, and may also be useful when rsync is supervised by a program such as daemontools or AIX's System Resource Controller. --no-detach is also recommended when rsync is run under a debugger. This option has no effect if rsync is run from inetd or sshd. --port=PORT This specifies an alternate TCP port number for the daemon to listen on rather than the default of 873. See also the client version of the --port option and the port global setting in the rsyncd.conf manpage. --log-file=FILE This option tells the rsync daemon to use the given log- file name instead of using the "log file" setting in the config file. See also the client version of the --log-file option. --log-file-format=FORMAT This option tells the rsync daemon to use the given FORMAT string instead of using the "log format" setting in the config file. It also enables "transfer logging" unless the string is empty, in which case transfer logging is turned off. See also the client version of the --log-file-format option. --sockopts This overrides the socket options setting in the rsyncd.conf file and has the same syntax. See also the client version of the --sockopts option. --verbose, -v This option increases the amount of information the daemon logs during its startup phase. After the client connects, the daemon's verbosity level will be controlled by the options that the client used and the "max verbosity" setting in the module's config section. See also the client version of the --verbose option. --ipv4, -4 or --ipv6, -6 Tells rsync to prefer IPv4/IPv6 when creating the incoming sockets that the rsync daemon will use to listen for connections. One of these options may be required in older versions of Linux to work around an IPv6 bug in the kernel (if you see an "address already in use" error when nothing else is using the port, try specifying --ipv6 or --ipv4 when starting the daemon). See also the client version of these options. If rsync was compiled without support for IPv6, the --ipv6 option will have no effect. The rsync --version output will contain "no IPv6" if is the case. --help, -h When specified after --daemon, print a short help page describing the options available for starting an rsync daemon. FILTER RULES top The filter rules allow for custom control of several aspects of how files are handled: o Control which files the sending side puts into the file list that describes the transfer hierarchy o Control which files the receiving side protects from deletion when the file is not in the sender's file list o Control which extended attribute names are skipped when copying xattrs The rules are either directly specified via option arguments or they can be read in from one or more files. The filter-rule files can even be a part of the hierarchy of files being copied, affecting different parts of the tree in different ways. SIMPLE INCLUDE/EXCLUDE RULES We will first cover the basics of how include & exclude rules affect what files are transferred, ignoring any deletion side- effects. Filter rules mainly affect the contents of directories that rsync is "recursing" into, but they can also affect a top- level item in the transfer that was specified as a argument. The default for any unmatched file/dir is for it to be included in the transfer, which puts the file/dir into the sender's file list. The use of an exclude rule causes one or more matching files/dirs to be left out of the sender's file list. An include rule can be used to limit the effect of an exclude rule that is matching too many files. The order of the rules is important because the first rule that matches is the one that takes effect. Thus, if an early rule excludes a file, no include rule that comes after it can have any effect. This means that you must place any include overrides somewhere prior to the exclude that it is intended to limit. When a directory is excluded, all its contents and sub-contents are also excluded. The sender doesn't scan through any of it at all, which can save a lot of time when skipping large unneeded sub-trees. It is also important to understand that the include/exclude rules are applied to every file and directory that the sender is recursing into. Thus, if you want a particular deep file to be included, you have to make sure that none of the directories that must be traversed on the way down to that file are excluded or else the file will never be discovered to be included. As an example, if the directory "a/path" was given as a transfer argument and you want to ensure that the file "a/path/down/deep/wanted.txt" is a part of the transfer, then the sender must not exclude the directories "a/path", "a/path/down", or "a/path/down/deep" as it makes it way scanning through the file tree. When you are working on the rules, it can be helpful to ask rsync to tell you what is being excluded/included and why. Specifying --debug=FILTER or (when pulling files) -M--debug=FILTER turns on level 1 of the FILTER debug information that will output a message any time that a file or directory is included or excluded and which rule it matched. Beginning in 3.2.4 it will also warn if a filter rule has trailing whitespace, since an exclude of "foo " (with a trailing space) will not exclude a file named "foo". Exclude and include rules can specify wildcard PATTERN MATCHING RULES (similar to shell wildcards) that allow you to match things like a file suffix or a portion of a filename. A rule can be limited to only affecting a directory by putting a trailing slash onto the filename. SIMPLE INCLUDE/EXCLUDE EXAMPLE With the following file tree created on the sending side: mkdir x/ touch x/file.txt mkdir x/y/ touch x/y/file.txt touch x/y/zzz.txt mkdir x/z/ touch x/z/file.txt Then the following rsync command will transfer the file "x/y/file.txt" and the directories needed to hold it, resulting in the path "/tmp/x/y/file.txt" existing on the remote host: rsync -ai -f'+ x/' -f'+ x/y/' -f'+ x/y/file.txt' -f'- *' x host:/tmp/ Aside: this copy could also have been accomplished using the -R option (though the 2 commands behave differently if deletions are enabled): rsync -aiR x/y/file.txt host:/tmp/ The following command does not need an include of the "x" directory because it is not a part of the transfer (note the traililng slash). Running this command would copy just "/tmp/x/file.txt" because the "y" and "z" dirs get excluded: rsync -ai -f'+ file.txt' -f'- *' x/ host:/tmp/x/ This command would omit the zzz.txt file while copying "x" and everything else it contains: rsync -ai -f'- zzz.txt' x host:/tmp/ FILTER RULES WHEN DELETING By default the include & exclude filter rules affect both the sender (as it creates its file list) and the receiver (as it creates its file lists for calculating deletions). If no delete option is in effect, the receiver skips creating the delete- related file lists. This two-sided default can be manually overridden so that you are only specifying sender rules or receiver rules, as described in the FILTER RULES IN DEPTH section. When deleting, an exclude protects a file from being removed on the receiving side while an include overrides that protection (putting the file at risk of deletion). The default is for a file to be at risk -- its safety depends on it matching a corresponding file from the sender. An example of the two-sided exclude effect can be illustrated by the copying of a C development directory between 2 systems. When doing a touch-up copy, you might want to skip copying the built executable and the .o files (sender hide) so that the receiving side can build their own and not lose any object files that are already correct (receiver protect). For instance: rsync -ai --del -f'- *.o' -f'- cmd' src host:/dest/ Note that using -f'-p *.o' is even better than -f'- *.o' if there is a chance that the directory structure may have changed. The "p" modifier is discussed in FILTER RULE MODIFIERS. One final note, if your shell doesn't mind unexpanded wildcards, you could simplify the typing of the filter options by using an underscore in place of the space and leaving off the quotes. For instance, -f -_*.o -f -_cmd (and similar) could be used instead of the filter options above. FILTER RULES IN DEPTH Rsync supports old-style include/exclude rules and new-style filter rules. The older rules are specified using --include and --exclude as well as the --include-from and --exclude-from. These are limited in behavior but they don't require a "-" or "+" prefix. An old-style exclude rule is turned into a "- name" filter rule (with no modifiers) and an old-style include rule is turned into a "+ name" filter rule (with no modifiers). Rsync builds an ordered list of filter rules as specified on the command-line and/or read-in from files. New style filter rules have the following syntax: RULE [PATTERN_OR_FILENAME] RULE,MODIFIERS [PATTERN_OR_FILENAME] You have your choice of using either short or long RULE names, as described below. If you use a short-named rule, the ',' separating the RULE from the MODIFIERS is optional. The PATTERN or FILENAME that follows (when present) must come after either a single space or an underscore (_). Any additional spaces and/or underscores are considered to be a part of the pattern name. Here are the available rule prefixes: exclude, '-' specifies an exclude pattern that (by default) is both a hide and a protect. include, '+' specifies an include pattern that (by default) is both a show and a risk. merge, '.' specifies a merge-file on the client side to read for more rules. dir-merge, ':' specifies a per-directory merge-file. Using this kind of filter rule requires that you trust the sending side's filter checking, so it has the side-effect mentioned under the --trust-sender option. hide, 'H' specifies a pattern for hiding files from the transfer. Equivalent to a sender-only exclude, so -f'H foo' could also be specified as -f'-s foo'. show, 'S' files that match the pattern are not hidden. Equivalent to a sender-only include, so -f'S foo' could also be specified as -f'+s foo'. protect, 'P' specifies a pattern for protecting files from deletion. Equivalent to a receiver-only exclude, so -f'P foo' could also be specified as -f'-r foo'. risk, 'R' files that match the pattern are not protected. Equivalent to a receiver-only include, so -f'R foo' could also be specified as -f'+r foo'. clear, '!' clears the current include/exclude list (takes no arg) When rules are being read from a file (using merge or dir-merge), empty lines are ignored, as are whole-line comments that start with a '#' (filename rules that contain a hash character are unaffected). Note also that the --filter, --include, and --exclude options take one rule/pattern each. To add multiple ones, you can repeat the options on the command-line, use the merge-file syntax of the --filter option, or the --include-from / --exclude-from options. PATTERN MATCHING RULES Most of the rules mentioned above take an argument that specifies what the rule should match. If rsync is recursing through a directory hierarchy, keep in mind that each pattern is matched against the name of every directory in the descent path as rsync finds the filenames to send. The matching rules for the pattern argument take several forms: o If a pattern contains a / (not counting a trailing slash) or a "**" (which can match a slash), then the pattern is matched against the full pathname, including any leading directories within the transfer. If the pattern doesn't contain a (non-trailing) / or a "**", then it is matched only against the final component of the filename or pathname. For example, foo means that the final path component must be "foo" while foo/bar would match the last 2 elements of the path (as long as both elements are within the transfer). o A pattern that ends with a / only matches a directory, not a regular file, symlink, or device. o A pattern that starts with a / is anchored to the start of the transfer path instead of the end. For example, /foo/** or /foo/bar/** match only leading elements in the path. If the rule is read from a per-directory filter file, the transfer path being matched will begin at the level of the filter file instead of the top of the transfer. See the section on ANCHORING INCLUDE/EXCLUDE PATTERNS for a full discussion of how to specify a pattern that matches at the root of the transfer. Rsync chooses between doing a simple string match and wildcard matching by checking if the pattern contains one of these three wildcard characters: '*', '?', and '[' : o a '?' matches any single character except a slash (/). o a '*' matches zero or more non-slash characters. o a '**' matches zero or more characters, including slashes. o a '[' introduces a character class, such as [a-z] or [[:alpha:]], that must match one character. o a trailing *** in the pattern is a shorthand that allows you to match a directory and all its contents using a single rule. For example, specifying "dir_name/***" will match both the "dir_name" directory (as if "dir_name/" had been specified) and everything in the directory (as if "dir_name/**" had been specified). o a backslash can be used to escape a wildcard character, but it is only interpreted as an escape character if at least one wildcard character is present in the match pattern. For instance, the pattern "foo\bar" matches that single backslash literally, while the pattern "foo\bar*" would need to be changed to "foo\\bar*" to avoid the "\b" becoming just "b". Here are some examples of exclude/include matching: o Option -f'- *.o' would exclude all filenames ending with .o o Option -f'- /foo' would exclude a file (or directory) named foo in the transfer-root directory o Option -f'- foo/' would exclude any directory named foo o Option -f'- foo/*/bar' would exclude any file/dir named bar which is at two levels below a directory named foo (if foo is in the transfer) o Option -f'- /foo/**/bar' would exclude any file/dir named bar that was two or more levels below a top-level directory named foo (note that /foo/bar is not excluded by this) o Options -f'+ */' -f'+ *.c' -f'- *' would include all directories and .c source files but nothing else o Options -f'+ foo/' -f'+ foo/bar.c' -f'- *' would include only the foo directory and foo/bar.c (the foo directory must be explicitly included or it would be excluded by the "- *") FILTER RULE MODIFIERS The following modifiers are accepted after an include (+) or exclude (-) rule: o A / specifies that the include/exclude rule should be matched against the absolute pathname of the current item. For example, -f'-/ /etc/passwd' would exclude the passwd file any time the transfer was sending files from the "/etc" directory, and "-/ subdir/foo" would always exclude "foo" when it is in a dir named "subdir", even if "foo" is at the root of the current transfer. o A ! specifies that the include/exclude should take effect if the pattern fails to match. For instance, -f'-! */' would exclude all non-directories. o A C is used to indicate that all the global CVS-exclude rules should be inserted as excludes in place of the "-C". No arg should follow. o An s is used to indicate that the rule applies to the sending side. When a rule affects the sending side, it affects what files are put into the sender's file list. The default is for a rule to affect both sides unless --delete-excluded was specified, in which case default rules become sender-side only. See also the hide (H) and show (S) rules, which are an alternate way to specify sending-side includes/excludes. o An r is used to indicate that the rule applies to the receiving side. When a rule affects the receiving side, it prevents files from being deleted. See the s modifier for more info. See also the protect (P) and risk (R) rules, which are an alternate way to specify receiver-side includes/excludes. o A p indicates that a rule is perishable, meaning that it is ignored in directories that are being deleted. For instance, the --cvs-exclude (-C) option's default rules that exclude things like "CVS" and "*.o" are marked as perishable, and will not prevent a directory that was removed on the source from being deleted on the destination. o An x indicates that a rule affects xattr names in xattr copy/delete operations (and is thus ignored when matching file/dir names). If no xattr-matching rules are specified, a default xattr filtering rule is used (see the --xattrs option). MERGE-FILE FILTER RULES You can merge whole files into your filter rules by specifying either a merge (.) or a dir-merge (:) filter rule (as introduced in the FILTER RULES section above). There are two kinds of merged files -- single-instance ('.') and per-directory (':'). A single-instance merge file is read one time, and its rules are incorporated into the filter list in the place of the "." rule. For per-directory merge files, rsync will scan every directory that it traverses for the named file, merging its contents when the file exists into the current list of inherited rules. These per-directory rule files must be created on the sending side because it is the sending side that is being scanned for the available files to transfer. These rule files may also need to be transferred to the receiving side if you want them to affect what files don't get deleted (see PER- DIRECTORY RULES AND DELETE below). Some examples: merge /etc/rsync/default.rules . /etc/rsync/default.rules dir-merge .per-dir-filter dir-merge,n- .non-inherited-per-dir-excludes :n- .non-inherited-per-dir-excludes The following modifiers are accepted after a merge or dir-merge rule: o A - specifies that the file should consist of only exclude patterns, with no other rule-parsing except for in-file comments. o A + specifies that the file should consist of only include patterns, with no other rule-parsing except for in-file comments. o A C is a way to specify that the file should be read in a CVS-compatible manner. This turns on 'n', 'w', and '-', but also allows the list-clearing token (!) to be specified. If no filename is provided, ".cvsignore" is assumed. o A e will exclude the merge-file name from the transfer; e.g. "dir-merge,e .rules" is like "dir-merge .rules" and "- .rules". o An n specifies that the rules are not inherited by subdirectories. o A w specifies that the rules are word-split on whitespace instead of the normal line-splitting. This also turns off comments. Note: the space that separates the prefix from the rule is treated specially, so "- foo + bar" is parsed as two rules (assuming that prefix-parsing wasn't also disabled). o You may also specify any of the modifiers for the "+" or "-" rules (above) in order to have the rules that are read in from the file default to having that modifier set (except for the ! modifier, which would not be useful). For instance, "merge,-/ .excl" would treat the contents of .excl as absolute-path excludes, while "dir-merge,s .filt" and ":sC" would each make all their per-directory rules apply only on the sending side. If the merge rule specifies sides to affect (via the s or r modifier or both), then the rules in the file must not specify sides (via a modifier or a rule prefix such as hide). Per-directory rules are inherited in all subdirectories of the directory where the merge-file was found unless the 'n' modifier was used. Each subdirectory's rules are prefixed to the inherited per-directory rules from its parents, which gives the newest rules a higher priority than the inherited rules. The entire set of dir-merge rules are grouped together in the spot where the merge-file was specified, so it is possible to override dir-merge rules via a rule that got specified earlier in the list of global rules. When the list-clearing rule ("!") is read from a per-directory file, it only clears the inherited rules for the current merge file. Another way to prevent a single rule from a dir-merge file from being inherited is to anchor it with a leading slash. Anchored rules in a per-directory merge-file are relative to the merge- file's directory, so a pattern "/foo" would only match the file "foo" in the directory where the dir-merge filter file was found. Here's an example filter file which you'd specify via --filter=". file": merge /home/user/.global-filter - *.gz dir-merge .rules + *.[ch] - *.o - foo* This will merge the contents of the /home/user/.global-filter file at the start of the list and also turns the ".rules" filename into a per-directory filter file. All rules read in prior to the start of the directory scan follow the global anchoring rules (i.e. a leading slash matches at the root of the transfer). If a per-directory merge-file is specified with a path that is a parent directory of the first transfer directory, rsync will scan all the parent dirs from that starting point to the transfer directory for the indicated per-directory file. For instance, here is a common filter (see -F): --filter=': /.rsync-filter' That rule tells rsync to scan for the file .rsync-filter in all directories from the root down through the parent directory of the transfer prior to the start of the normal directory scan of the file in the directories that are sent as a part of the transfer. (Note: for an rsync daemon, the root is always the same as the module's "path".) Some examples of this pre-scanning for per-directory files: rsync -avF /src/path/ /dest/dir rsync -av --filter=': ../../.rsync-filter' /src/path/ /dest/dir rsync -av --filter=': .rsync-filter' /src/path/ /dest/dir The first two commands above will look for ".rsync-filter" in "/" and "/src" before the normal scan begins looking for the file in "/src/path" and its subdirectories. The last command avoids the parent-dir scan and only looks for the ".rsync-filter" files in each directory that is a part of the transfer. If you want to include the contents of a ".cvsignore" in your patterns, you should use the rule ":C", which creates a dir-merge of the .cvsignore file, but parsed in a CVS-compatible manner. You can use this to affect where the --cvs-exclude (-C) option's inclusion of the per-directory .cvsignore file gets placed into your rules by putting the ":C" wherever you like in your filter rules. Without this, rsync would add the dir-merge rule for the .cvsignore file at the end of all your other rules (giving it a lower priority than your command-line rules). For example: cat <<EOT | rsync -avC --filter='. -' a/ b + foo.o :C - *.old EOT rsync -avC --include=foo.o -f :C --exclude='*.old' a/ b Both of the above rsync commands are identical. Each one will merge all the per-directory .cvsignore rules in the middle of the list rather than at the end. This allows their dir-specific rules to supersede the rules that follow the :C instead of being subservient to all your rules. To affect the other CVS exclude rules (i.e. the default list of exclusions, the contents of $HOME/.cvsignore, and the value of $CVSIGNORE) you should omit the -C command-line option and instead insert a "-C" rule into your filter rules; e.g. "--filter=-C". LIST-CLEARING FILTER RULE You can clear the current include/exclude list by using the "!" filter rule (as introduced in the FILTER RULES section above). The "current" list is either the global list of rules (if the rule is encountered while parsing the filter options) or a set of per-directory rules (which are inherited in their own sub-list, so a subdirectory can use this to clear out the parent's rules). ANCHORING INCLUDE/EXCLUDE PATTERNS As mentioned earlier, global include/exclude patterns are anchored at the "root of the transfer" (as opposed to per- directory patterns, which are anchored at the merge-file's directory). If you think of the transfer as a subtree of names that are being sent from sender to receiver, the transfer-root is where the tree starts to be duplicated in the destination directory. This root governs where patterns that start with a / match. Because the matching is relative to the transfer-root, changing the trailing slash on a source path or changing your use of the --relative option affects the path you need to use in your matching (in addition to changing how much of the file tree is duplicated on the destination host). The following examples demonstrate this. Let's say that we want to match two source files, one with an absolute path of "/home/me/foo/bar", and one with a path of "/home/you/bar/baz". Here is how the various command choices differ for a 2-source transfer: Example cmd: rsync -a /home/me /home/you /dest +/- pattern: /me/foo/bar +/- pattern: /you/bar/baz Target file: /dest/me/foo/bar Target file: /dest/you/bar/baz Example cmd: rsync -a /home/me/ /home/you/ /dest +/- pattern: /foo/bar (note missing "me") +/- pattern: /bar/baz (note missing "you") Target file: /dest/foo/bar Target file: /dest/bar/baz Example cmd: rsync -a --relative /home/me/ /home/you /dest +/- pattern: /home/me/foo/bar (note full path) +/- pattern: /home/you/bar/baz (ditto) Target file: /dest/home/me/foo/bar Target file: /dest/home/you/bar/baz Example cmd: cd /home; rsync -a --relative me/foo you/ /dest +/- pattern: /me/foo/bar (starts at specified path) +/- pattern: /you/bar/baz (ditto) Target file: /dest/me/foo/bar Target file: /dest/you/bar/baz The easiest way to see what name you should filter is to just look at the output when using --verbose and put a / in front of the name (use the --dry-run option if you're not yet ready to copy any files). PER-DIRECTORY RULES AND DELETE Without a delete option, per-directory rules are only relevant on the sending side, so you can feel free to exclude the merge files themselves without affecting the transfer. To make this easy, the 'e' modifier adds this exclude for you, as seen in these two equivalent commands: rsync -av --filter=': .excl' --exclude=.excl host:src/dir /dest rsync -av --filter=':e .excl' host:src/dir /dest However, if you want to do a delete on the receiving side AND you want some files to be excluded from being deleted, you'll need to be sure that the receiving side knows what files to exclude. The easiest way is to include the per-directory merge files in the transfer and use --delete-after, because this ensures that the receiving side gets all the same exclude rules as the sending side before it tries to delete anything: rsync -avF --delete-after host:src/dir /dest However, if the merge files are not a part of the transfer, you'll need to either specify some global exclude rules (i.e. specified on the command line), or you'll need to maintain your own per-directory merge files on the receiving side. An example of the first is this (assume that the remote .rules files exclude themselves): rsync -av --filter=': .rules' --filter='. /my/extra.rules' --delete host:src/dir /dest In the above example the extra.rules file can affect both sides of the transfer, but (on the sending side) the rules are subservient to the rules merged from the .rules files because they were specified after the per-directory merge rule. In one final example, the remote side is excluding the .rsync- filter files from the transfer, but we want to use our own .rsync-filter files to control what gets deleted on the receiving side. To do this we must specifically exclude the per-directory merge files (so that they don't get deleted) and then put rules into the local files to control what else should not get deleted. Like one of these commands: rsync -av --filter=':e /.rsync-filter' --delete \ host:src/dir /dest rsync -avFF --delete host:src/dir /dest TRANSFER RULES top In addition to the FILTER RULES that affect the recursive file scans that generate the file list on the sending and (when deleting) receiving sides, there are transfer rules. These rules affect which files the generator decides need to be transferred without the side effects of an exclude filter rule. Transfer rules affect only files and never directories. Because a transfer rule does not affect what goes into the sender's (and receiver's) file list, it cannot have any effect on which files get deleted on the receiving side. For example, if the file "foo" is present in the sender's list but its size is such that it is omitted due to a transfer rule, the receiving side does not request the file. However, its presence in the file list means that a delete pass will not remove a matching file named "foo" on the receiving side. On the other hand, a server-side exclude (hide) of the file "foo" leaves the file out of the server's file list, and absent a receiver-side exclude (protect) the receiver will remove a matching file named "foo" if deletions are requested. Given that the files are still in the sender's file list, the --prune-empty-dirs option will not judge a directory as being empty even if it contains only files that the transfer rules omitted. Similarly, a transfer rule does not have any extra effect on which files are deleted on the receiving side, so setting a maximum file size for the transfer does not prevent big files from being deleted. Examples of transfer rules include the default "quick check" algorithm (which compares size & modify time), the --update option, the --max-size option, the --ignore-non-existing option, and a few others. BATCH MODE top Batch mode can be used to apply the same set of updates to many identical systems. Suppose one has a tree which is replicated on a number of hosts. Now suppose some changes have been made to this source tree and those changes need to be propagated to the other hosts. In order to do this using batch mode, rsync is run with the write-batch option to apply the changes made to the source tree to one of the destination trees. The write-batch option causes the rsync client to store in a "batch file" all the information needed to repeat this operation against other, identical destination trees. Generating the batch file once saves having to perform the file status, checksum, and data block generation more than once when updating multiple destination trees. Multicast transport protocols can be used to transfer the batch update files in parallel to many hosts at once, instead of sending the same data to every host individually. To apply the recorded changes to another destination tree, run rsync with the read-batch option, specifying the name of the same batch file, and the destination tree. Rsync updates the destination tree using the information stored in the batch file. For your convenience, a script file is also created when the write-batch option is used: it will be named the same as the batch file with ".sh" appended. This script file contains a command-line suitable for updating a destination tree using the associated batch file. It can be executed using a Bourne (or Bourne-like) shell, optionally passing in an alternate destination tree pathname which is then used instead of the original destination path. This is useful when the destination tree path on the current host differs from the one used to create the batch file. Examples: $ rsync --write-batch=foo -a host:/source/dir/ /adest/dir/ $ scp foo* remote: $ ssh remote ./foo.sh /bdest/dir/ $ rsync --write-batch=foo -a /source/dir/ /adest/dir/ $ ssh remote rsync --read-batch=- -a /bdest/dir/ <foo In these examples, rsync is used to update /adest/dir/ from /source/dir/ and the information to repeat this operation is stored in "foo" and "foo.sh". The host "remote" is then updated with the batched data going into the directory /bdest/dir. The differences between the two examples reveals some of the flexibility you have in how you deal with batches: o The first example shows that the initial copy doesn't have to be local -- you can push or pull data to/from a remote host using either the remote-shell syntax or rsync daemon syntax, as desired. o The first example uses the created "foo.sh" file to get the right rsync options when running the read-batch command on the remote host. o The second example reads the batch data via standard input so that the batch file doesn't need to be copied to the remote machine first. This example avoids the foo.sh script because it needed to use a modified --read-batch option, but you could edit the script file if you wished to make use of it (just be sure that no other option is trying to use standard input, such as the --exclude-from=- option). Caveats: The read-batch option expects the destination tree that it is updating to be identical to the destination tree that was used to create the batch update fileset. When a difference between the destination trees is encountered the update might be discarded with a warning (if the file appears to be up-to-date already) or the file-update may be attempted and then, if the file fails to verify, the update discarded with an error. This means that it should be safe to re-run a read-batch operation if the command got interrupted. If you wish to force the batched-update to always be attempted regardless of the file's size and date, use the -I option (when reading the batch). If an error occurs, the destination tree will probably be in a partially updated state. In that case, rsync can be used in its regular (non-batch) mode of operation to fix up the destination tree. The rsync version used on all destinations must be at least as new as the one used to generate the batch file. Rsync will die with an error if the protocol version in the batch file is too new for the batch-reading rsync to handle. See also the --protocol option for a way to have the creating rsync generate a batch file that an older rsync can understand. (Note that batch files changed format in version 2.6.3, so mixing versions older than that with newer versions will not work.) When reading a batch file, rsync will force the value of certain options to match the data in the batch file if you didn't set them to the same as the batch-writing command. Other options can (and should) be changed. For instance --write-batch changes to --read-batch, --files-from is dropped, and the --filter / --include / --exclude options are not needed unless one of the --delete options is specified. The code that creates the BATCH.sh file transforms any filter/include/exclude options into a single list that is appended as a "here" document to the shell script file. An advanced user can use this to modify the exclude list if a change in what gets deleted by --delete is desired. A normal user can ignore this detail and just use the shell script as an easy way to run the appropriate --read-batch command for the batched data. The original batch mode in rsync was based on "rsync+", but the latest version uses a new implementation. SYMBOLIC LINKS top Three basic behaviors are possible when rsync encounters a symbolic link in the source directory. By default, symbolic links are not transferred at all. A message "skipping non-regular" file is emitted for any symlinks that exist. If --links is specified, then symlinks are added to the transfer (instead of being noisily ignored), and the default handling is to recreate them with the same target on the destination. Note that --archive implies --links. If --copy-links is specified, then symlinks are "collapsed" by copying their referent, rather than the symlink. Rsync can also distinguish "safe" and "unsafe" symbolic links. An example where this might be used is a web site mirror that wishes to ensure that the rsync module that is copied does not include symbolic links to /etc/passwd in the public section of the site. Using --copy-unsafe-links will cause any links to be copied as the file they point to on the destination. Using --safe-links will cause unsafe links to be omitted by the receiver. (Note that you must specify or imply --links for --safe-links to have any effect.) Symbolic links are considered unsafe if they are absolute symlinks (start with /), empty, or if they contain enough ".." components to ascend from the top of the transfer. Here's a summary of how the symlink options are interpreted. The list is in order of precedence, so if your combination of options isn't mentioned, use the first line that is a complete subset of your options: --copy-links Turn all symlinks into normal files and directories (leaving no symlinks in the transfer for any other options to affect). --copy-dirlinks Turn just symlinks to directories into real directories, leaving all other symlinks to be handled as described below. --links --copy-unsafe-links Turn all unsafe symlinks into files and create all safe symlinks. --copy-unsafe-links Turn all unsafe symlinks into files, noisily skip all safe symlinks. --links --safe-links The receiver skips creating unsafe symlinks found in the transfer and creates the safe ones. --links Create all symlinks. For the effect of --munge-links, see the discussion in that option's section. Note that the --keep-dirlinks option does not effect symlinks in the transfer but instead affects how rsync treats a symlink to a directory that already exists on the receiving side. See that option's section for a warning. DIAGNOSTICS top Rsync occasionally produces error messages that may seem a little cryptic. The one that seems to cause the most confusion is "protocol version mismatch -- is your shell clean?". This message is usually caused by your startup scripts or remote shell facility producing unwanted garbage on the stream that rsync is using for its transport. The way to diagnose this problem is to run your remote shell like this: ssh remotehost /bin/true > out.dat then look at out.dat. If everything is working correctly then out.dat should be a zero length file. If you are getting the above error from rsync then you will probably find that out.dat contains some text or data. Look at the contents and try to work out what is producing it. The most common cause is incorrectly configured shell startup scripts (such as .cshrc or .profile) that contain output statements for non-interactive logins. If you are having trouble debugging filter patterns, then try specifying the -vv option. At this level of verbosity rsync will show why each individual file is included or excluded. EXIT VALUES top o 0 - Success o 1 - Syntax or usage error o 2 - Protocol incompatibility o 3 - Errors selecting input/output files, dirs o o 4 - Requested action not supported. Either: an attempt was made to manipulate 64-bit files on a platform that cannot support them o an option was specified that is supported by the client and not by the server o 5 - Error starting client-server protocol o 6 - Daemon unable to append to log-file o 10 - Error in socket I/O o 11 - Error in file I/O o 12 - Error in rsync protocol data stream o 13 - Errors with program diagnostics o 14 - Error in IPC code o 20 - Received SIGUSR1 or SIGINT o 21 - Some error returned by waitpid() o 22 - Error allocating core memory buffers o 23 - Partial transfer due to error o 24 - Partial transfer due to vanished source files o 25 - The --max-delete limit stopped deletions o 30 - Timeout in data send/receive o 35 - Timeout waiting for daemon connection ENVIRONMENT VARIABLES top CVSIGNORE The CVSIGNORE environment variable supplements any ignore patterns in .cvsignore files. See the --cvs-exclude option for more details. RSYNC_ICONV Specify a default --iconv setting using this environment variable. First supported in 3.0.0. RSYNC_OLD_ARGS Specify a "1" if you want the --old-args option to be enabled by default, a "2" (or more) if you want it to be enabled in the repeated-option state, or a "0" to make sure that it is disabled by default. When this environment variable is set to a non-zero value, it supersedes the RSYNC_PROTECT_ARGS variable. This variable is ignored if --old-args, --no-old-args, or --secluded-args is specified on the command line. First supported in 3.2.4. RSYNC_PROTECT_ARGS Specify a non-zero numeric value if you want the --secluded-args option to be enabled by default, or a zero value to make sure that it is disabled by default. This variable is ignored if --secluded-args, --no- secluded-args, or --old-args is specified on the command line. First supported in 3.1.0. Starting in 3.2.4, this variable is ignored if RSYNC_OLD_ARGS is set to a non-zero value. RSYNC_RSH This environment variable allows you to override the default shell used as the transport for rsync. Command line options are permitted after the command name, just as in the --rsh (-e) option. RSYNC_PROXY This environment variable allows you to redirect your rsync client to use a web proxy when connecting to an rsync daemon. You should set RSYNC_PROXY to a hostname:port pair. RSYNC_PASSWORD This environment variable allows you to set the password for an rsync daemon connection, which avoids the password prompt. Note that this does not supply a password to a remote shell transport such as ssh (consult its documentation for how to do that). USER or LOGNAME The USER or LOGNAME environment variables are used to determine the default username sent to an rsync daemon. If neither is set, the username defaults to "nobody". If both are set, USER takes precedence. RSYNC_PARTIAL_DIR This environment variable specifies the directory to use for a --partial transfer without implying that partial transfers be enabled. See the --partial-dir option for full details. RSYNC_COMPRESS_LIST This environment variable allows you to customize the negotiation of the compression algorithm by specifying an alternate order or a reduced list of names. Use the command rsync --version to see the available compression names. See the --compress option for full details. RSYNC_CHECKSUM_LIST This environment variable allows you to customize the negotiation of the checksum algorithm by specifying an alternate order or a reduced list of names. Use the command rsync --version to see the available checksum names. See the --checksum-choice option for full details. RSYNC_MAX_ALLOC This environment variable sets an allocation maximum as if you had used the --max-alloc option. RSYNC_PORT This environment variable is not read by rsync, but is instead set in its sub-environment when rsync is running the remote shell in combination with a daemon connection. This allows a script such as rsync-ssl to be able to know the port number that the user specified on the command line. HOME This environment variable is used to find the user's default .cvsignore file. RSYNC_CONNECT_PROG This environment variable is mainly used in debug setups to set the program to use when making a daemon connection. See CONNECTING TO AN RSYNC DAEMON for full details. RSYNC_SHELL This environment variable is mainly used in debug setups to set the program to use to run the program specified by RSYNC_CONNECT_PROG. See CONNECTING TO AN RSYNC DAEMON for full details. FILES top /etc/rsyncd.conf or rsyncd.conf SEE ALSO top rsync-ssl(1), rsyncd.conf(5), rrsync(1) BUGS top o Times are transferred as *nix time_t values. o When transferring to FAT filesystems rsync may re-sync unmodified files. See the comments on the --modify-window option. o File permissions, devices, etc. are transferred as native numerical values. o See also the comments on the --delete option. Please report bugs! See the web site at https://rsync.samba.org/. VERSION top This manpage is current for version 3.2.7 of rsync. INTERNAL OPTIONS top The options --server and --sender are used internally by rsync, and should never be typed by a user under normal circumstances. Some awareness of these options may be needed in certain scenarios, such as when setting up a login that can only run an rsync command. For instance, the support directory of the rsync distribution has an example script named rrsync (for restricted rsync) that can be used with a restricted ssh login. CREDITS top Rsync is distributed under the GNU General Public License. See the file COPYING for details. An rsync web site is available at https://rsync.samba.org/. The site includes an FAQ-O-Matic which may cover questions unanswered by this manual page. The rsync github project is https://github.com/WayneD/rsync. We would be delighted to hear from you if you like this program. Please contact the mailing-list at rsync@lists.samba.org. This program uses the excellent zlib compression library written by Jean-loup Gailly and Mark Adler. THANKS top Special thanks go out to: John Van Essen, Matt McCutchen, Wesley W. Terpstra, David Dykstra, Jos Backus, Sebastian Krahmer, Martin Pool, and our gone-but-not-forgotten compadre, J.W. Schultz. Thanks also to Richard Brent, Brendan Mackay, Bill Waite, Stephen Rothwell and David Bell. I've probably missed some people, my apologies if I have. AUTHOR top Rsync was originally written by Andrew Tridgell and Paul Mackerras. Many people have later contributed to it. It is currently maintained by Wayne Davison. Mailing lists for support and development are available at https://lists.samba.org/. COLOPHON top This page is part of the rsync (a fast, versatile, remote (and local) file-copying tool) project. Information about the project can be found at https://rsync.samba.org/. If you have a bug report for this manual page, see https://rsync.samba.org/bugzilla.html. This page was obtained from the tarball fetched from https://download.samba.org/pub/rsync/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org rsync 3.2.7 20 Oct 2022 rsync(1) Pages that refer to this page: pmlogger_daily(1), rrsync(1), rsync-ssl(1), rsyncd.conf(5) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a new directory "existing-dir/new-dir/" on host "node" Bash Command:<START>rsync /dev/null node:existing-dir/new-dir/<END> |
Create a report of the contents of a USB drive mounted at find /path/to/drive | find /path/to/drive -type f -exec file -b '{}' \; -printf '%s\n' | awk -F , 'NR%2 {i=$1} NR%2==0 {a[i]+=$1} END {for (i in a) printf("%12u %s\n",a[i],i)}' | sort -nr | ['find', 'awk', 'file', 'sort'] | Output a Bash command to accomplish the following task. Task: Create a report of the contents of a USB drive mounted at find /path/to/drive Bash Command:<START>find /path/to/drive -type f -exec file -b '{}' \; -printf '%s\n' | awk -F , 'NR%2 {i=$1} NR%2==0 {a[i]+=$1} END {for (i in a) printf("%12u %s\n",a[i],i)}' | sort -nr<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # awk\n\n> A versatile programming language for working on files.\n> More information: <https://github.com/onetrueawk/awk>.\n\n- Print the fifth column (a.k.a. field) in a space-separated file:\n\n`awk '{print $5}' {{path/to/file}}`\n\n- Print the second column of the lines containing "foo" in a space-separated file:\n\n`awk '/{{foo}}/ {print $2}' {{path/to/file}}`\n\n- Print the last column of each line in a file, using a comma (instead of space) as a field separator:\n\n`awk -F ',' '{print $NF}' {{path/to/file}}`\n\n- Sum the values in the first column of a file and print the total:\n\n`awk '{s+=$1} END {print s}' {{path/to/file}}`\n\n- Print every third line starting from the first line:\n\n`awk 'NR%3==1' {{path/to/file}}`\n\n- Print different values based on conditions:\n\n`awk '{if ($1 == "foo") print "Exact match foo"; else if ($1 ~ "bar") print "Partial match bar"; else print "Baz"}' {{path/to/file}}`\n\n- Print all lines where the 10th column value equals the specified value:\n\n`awk '($10 == {{value}})'`\n\n- Print all the lines which the 10th column value is between a min and a max:\n\n`awk '($10 >= {{min_value}} && $10 <= {{max_value}})'`\n # file\n\n> Determine file type.\n> More information: <https://manned.org/file>.\n\n- Give a description of the type of the specified file. Works fine for files with no file extension:\n\n`file {{path/to/file}}`\n\n- Look inside a zipped file and determine the file type(s) inside:\n\n`file -z {{foo.zip}}`\n\n- Allow file to work with special or device files:\n\n`file -s {{path/to/file}}`\n\n- Don't stop at first file type match; keep going until the end of the file:\n\n`file -k {{path/to/file}}`\n\n- Determine the MIME encoding type of a file:\n\n`file -i {{path/to/file}}`\n # sort\n\n> Sort lines of text files.\n> More information: <https://www.gnu.org/software/coreutils/sort>.\n\n- Sort a file in ascending order:\n\n`sort {{path/to/file}}`\n\n- Sort a file in descending order:\n\n`sort --reverse {{path/to/file}}`\n\n- Sort a file in case-insensitive way:\n\n`sort --ignore-case {{path/to/file}}`\n\n- Sort a file using numeric rather than alphabetic order:\n\n`sort --numeric-sort {{path/to/file}}`\n\n- Sort `/etc/passwd` by the 3rd field of each line numerically, using ":" as a field separator:\n\n`sort --field-separator={{:}} --key={{3n}} {{/etc/passwd}}`\n\n- Sort a file preserving only unique lines:\n\n`sort --unique {{path/to/file}}`\n\n- Sort a file, printing the output to the specified output file (can be used to sort a file in-place):\n\n`sort --output={{path/to/file}} {{path/to/file}}`\n\n- Sort numbers with exponents:\n\n`sort --general-numeric-sort {{path/to/file}}`\n Task: Create a report of the contents of a USB drive mounted at find /path/to/drive Bash Command:<START>find /path/to/drive -type f -exec file -b '{}' \; -printf '%s\n' | awk -F , 'NR%2 {i=$1} NR%2==0 {a[i]+=$1} END {for (i in a) printf("%12u %s\n",a[i],i)}' | sort -nr<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. awk(1p) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training awk(1p) Linux manual page PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT AWK(1P) POSIX Programmer's Manual AWK(1P) PROLOG top This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux. NAME top awk pattern scanning and processing language SYNOPSIS top awk [-F sepstring] [-v assignment]... program [argument...] awk [-F sepstring] -f progfile [-f progfile]... [-v assignment]... [argument...] DESCRIPTION top The awk utility shall execute programs written in the awk programming language, which is specialized for textual data manipulation. An awk program is a sequence of patterns and corresponding actions. When input is read that matches a pattern, the action associated with that pattern is carried out. Input shall be interpreted as a sequence of records. By default, a record is a line, less its terminating <newline>, but this can be changed by using the RS built-in variable. Each record of input shall be matched in turn against each pattern in the program. For each pattern matched, the associated action shall be executed. The awk utility shall interpret each input record as a sequence of fields where, by default, a field is a string of non-<blank> non-<newline> characters. This default <blank> and <newline> field delimiter can be changed by using the FS built-in variable or the -F sepstring option. The awk utility shall denote the first field in a record $1, the second $2, and so on. The symbol $0 shall refer to the entire record; setting any other field causes the re-evaluation of $0. Assigning to $0 shall reset the values of all other fields and the NF built-in variable. OPTIONS top The awk utility shall conform to the Base Definitions volume of POSIX.12017, Section 12.2, Utility Syntax Guidelines. The following options shall be supported: -F sepstring Define the input field separator. This option shall be equivalent to: -v FS=sepstring except that if -F sepstring and -v FS=sepstring are both used, it is unspecified whether the FS assignment resulting from -F sepstring is processed in command line order or is processed after the last -v FS=sepstring. See the description of the FS built-in variable, and how it is used, in the EXTENDED DESCRIPTION section. -f progfile Specify the pathname of the file progfile containing an awk program. A pathname of '-' shall denote the standard input. If multiple instances of this option are specified, the concatenation of the files specified as progfile in the order specified shall be the awk program. The awk program can alternatively be specified in the command line as a single argument. -v assignment The application shall ensure that the assignment argument is in the same form as an assignment operand. The specified variable assignment shall occur prior to executing the awk program, including the actions associated with BEGIN patterns (if any). Multiple occurrences of this option can be specified. OPERANDS top The following operands shall be supported: program If no -f option is specified, the first operand to awk shall be the text of the awk program. The application shall supply the program operand as a single argument to awk. If the text does not end in a <newline>, awk shall interpret the text as if it did. argument Either of the following two types of argument can be intermixed: file A pathname of a file that contains the input to be read, which is matched against the set of patterns in the program. If no file operands are specified, or if a file operand is '-', the standard input shall be used. assignment An operand that begins with an <underscore> or alphabetic character from the portable character set (see the table in the Base Definitions volume of POSIX.12017, Section 6.1, Portable Character Set), followed by a sequence of underscores, digits, and alphabetics from the portable character set, followed by the '=' character, shall specify a variable assignment rather than a pathname. The characters before the '=' represent the name of an awk variable; if that name is an awk reserved word (see Grammar) the behavior is undefined. The characters following the <equals-sign> shall be interpreted as if they appeared in the awk program preceded and followed by a double-quote ('"') character, as a STRING token (see Grammar), except that if the last character is an unescaped <backslash>, it shall be interpreted as a literal <backslash> rather than as the first character of the sequence "\"". The variable shall be assigned the value of that STRING token and, if appropriate, shall be considered a numeric string (see Expressions in awk), the variable shall also be assigned its numeric value. Each such variable assignment shall occur just prior to the processing of the following file, if any. Thus, an assignment before the first file argument shall be executed after the BEGIN actions (if any), while an assignment after the last file argument shall occur before the END actions (if any). If there are no file arguments, assignments shall be executed before processing the standard input. STDIN top The standard input shall be used only if no file operands are specified, or if a file operand is '-', or if a progfile option- argument is '-'; see the INPUT FILES section. If the awk program contains no actions and no patterns, but is otherwise a valid awk program, standard input and any file operands shall not be read and awk shall exit with a return status of zero. INPUT FILES top Input files to the awk program from any of the following sources shall be text files: * Any file operands or their equivalents, achieved by modifying the awk variables ARGV and ARGC * Standard input in the absence of any file operands * Arguments to the getline function Whether the variable RS is set to a value other than a <newline> or not, for these files, implementations shall support records terminated with the specified separator up to {LINE_MAX} bytes and may support longer records. If -f progfile is specified, the application shall ensure that the files named by each of the progfile option-arguments are text files and their concatenation, in the same order as they appear in the arguments, is an awk program. ENVIRONMENT VARIABLES top The following environment variables shall affect the execution of awk: LANG Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of POSIX.12017, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.) LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE Determine the locale for the behavior of ranges, equivalence classes, and multi-character collating elements within regular expressions and in comparisons of string values. LC_CTYPE Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments and input files), the behavior of character classes within regular expressions, the identification of characters as letters, and the mapping of uppercase and lowercase characters for the toupper and tolower functions. LC_MESSAGES Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error. LC_NUMERIC Determine the radix character used when interpreting numeric input, performing conversions between numeric and string values, and formatting numeric output. Regardless of locale, the <period> character (the decimal-point character of the POSIX locale) is the decimal-point character recognized in processing awk programs (including assignments in command line arguments). NLSPATH Determine the location of message catalogs for the processing of LC_MESSAGES. PATH Determine the search path when looking for commands executed by system(expr), or input and output pipes; see the Base Definitions volume of POSIX.12017, Chapter 8, Environment Variables. In addition, all environment variables shall be visible via the awk variable ENVIRON. ASYNCHRONOUS EVENTS top Default. STDOUT top The nature of the output files depends on the awk program. STDERR top The standard error shall be used only for diagnostic messages. OUTPUT FILES top The nature of the output files depends on the awk program. EXTENDED DESCRIPTION top Overall Program Structure An awk program is composed of pairs of the form: pattern { action } Either the pattern or the action (including the enclosing brace characters) can be omitted. A missing pattern shall match any record of input, and a missing action shall be equivalent to: { print } Execution of the awk program shall start by first executing the actions associated with all BEGIN patterns in the order they occur in the program. Then each file operand (or standard input if no files were specified) shall be processed in turn by reading data from the file until a record separator is seen (<newline> by default). Before the first reference to a field in the record is evaluated, the record shall be split into fields, according to the rules in Regular Expressions, using the value of FS that was current at the time the record was read. Each pattern in the program then shall be evaluated in the order of occurrence, and the action associated with each pattern that matches the current record executed. The action for a matching pattern shall be executed before evaluating subsequent patterns. Finally, the actions associated with all END patterns shall be executed in the order they occur in the program. Expressions in awk Expressions describe computations used in patterns and actions. In the following table, valid expression operations are given in groups from highest precedence first to lowest precedence last, with equal-precedence operators grouped between horizontal lines. In expression evaluation, where the grammar is formally ambiguous, higher precedence operators shall be evaluated before lower precedence operators. In this table expr, expr1, expr2, and expr3 represent any expression, while lvalue represents any entity that can be assigned to (that is, on the left side of an assignment operator). The precise syntax of expressions is given in Grammar. Table 4-1: Expressions in Decreasing Precedence in awk Syntax Name Type of Result Associativity ( expr ) Grouping Type of expr N/A $expr Field reference String N/A lvalue ++ Post-increment Numeric N/A lvalue -- Post-decrement Numeric N/A ++ lvalue Pre-increment Numeric N/A -- lvalue Pre-decrement Numeric N/A expr ^ expr Exponentiation Numeric Right ! expr Logical not Numeric N/A + expr Unary plus Numeric N/A - expr Unary minus Numeric N/A expr * expr Multiplication Numeric Left expr / expr Division Numeric Left expr % expr Modulus Numeric Left expr + expr Addition Numeric Left expr - expr Subtraction Numeric Left expr expr String concatenation String Left expr < expr Less than Numeric None expr <= expr Less than or equal to Numeric None expr != expr Not equal to Numeric None expr == expr Equal to Numeric None expr > expr Greater than Numeric None expr >= expr Greater than or equal to Numeric None expr ~ expr ERE match Numeric None expr !~ expr ERE non-match Numeric None expr in array Array membership Numeric Left ( index ) in array Multi-dimension array Numeric Left membership expr && expr Logical AND Numeric Left expr || expr Logical OR Numeric Left expr1 ? expr2 : expr3Conditional expression Type of selectedRight expr2 or expr3 lvalue ^= expr Exponentiation assignmentNumeric Right lvalue %= expr Modulus assignment Numeric Right lvalue *= expr Multiplication assignmentNumeric Right lvalue /= expr Division assignment Numeric Right lvalue += expr Addition assignment Numeric Right lvalue -= expr Subtraction assignment Numeric Right lvalue = expr Assignment Type of expr Right Each expression shall have either a string value, a numeric value, or both. Except as stated for specific contexts, the value of an expression shall be implicitly converted to the type needed for the context in which it is used. A string value shall be converted to a numeric value either by the equivalent of the following calls to functions defined by the ISO C standard: setlocale(LC_NUMERIC, ""); numeric_value = atof(string_value); or by converting the initial portion of the string to type double representation as follows: The input string is decomposed into two parts: an initial, possibly empty, sequence of white-space characters (as specified by isspace()) and a subject sequence interpreted as a floating-point constant. The expected form of the subject sequence is an optional '+' or '-' sign, then a non-empty sequence of digits optionally containing a <period>, then an optional exponent part. An exponent part consists of 'e' or 'E', followed by an optional sign, followed by one or more decimal digits. The sequence starting with the first digit or the <period> (whichever occurs first) is interpreted as a floating constant of the C language, and if neither an exponent part nor a <period> appears, a <period> is assumed to follow the last digit in the string. If the subject sequence begins with a <hyphen-minus>, the value resulting from the conversion is negated. A numeric value that is exactly equal to the value of an integer (see Section 1.1.2, Concepts Derived from the ISO C Standard) shall be converted to a string by the equivalent of a call to the sprintf function (see String Functions) with the string "%d" as the fmt argument and the numeric value being converted as the first and only expr argument. Any other numeric value shall be converted to a string by the equivalent of a call to the sprintf function with the value of the variable CONVFMT as the fmt argument and the numeric value being converted as the first and only expr argument. The result of the conversion is unspecified if the value of CONVFMT is not a floating-point format specification. This volume of POSIX.12017 specifies no explicit conversions between numbers and strings. An application can force an expression to be treated as a number by adding zero to it, or can force it to be treated as a string by concatenating the null string ("") to it. A string value shall be considered a numeric string if it comes from one of the following: 1. Field variables 2. Input from the getline() function 3. FILENAME 4. ARGV array elements 5. ENVIRON array elements 6. Array elements created by the split() function 7. A command line variable assignment 8. Variable assignment from another numeric string variable and an implementation-dependent condition corresponding to either case (a) or (b) below is met. a. After the equivalent of the following calls to functions defined by the ISO C standard, string_value_end would differ from string_value, and any characters before the terminating null character in string_value_end would be <blank> characters: char *string_value_end; setlocale(LC_NUMERIC, ""); numeric_value = strtod (string_value, &string_value_end); b. After all the following conversions have been applied, the resulting string would lexically be recognized as a NUMBER token as described by the lexical conventions in Grammar: -- All leading and trailing <blank> characters are discarded. -- If the first non-<blank> is '+' or '-', it is discarded. -- Each occurrence of the decimal point character from the current locale is changed to a <period>. In case (a) the numeric value of the numeric string shall be the value that would be returned by the strtod() call. In case (b) if the first non-<blank> is '-', the numeric value of the numeric string shall be the negation of the numeric value of the recognized NUMBER token; otherwise, the numeric value of the numeric string shall be the numeric value of the recognized NUMBER token. Whether or not a string is a numeric string shall be relevant only in contexts where that term is used in this section. When an expression is used in a Boolean context, if it has a numeric value, a value of zero shall be treated as false and any other value shall be treated as true. Otherwise, a string value of the null string shall be treated as false and any other value shall be treated as true. A Boolean context shall be one of the following: * The first subexpression of a conditional expression * An expression operated on by logical NOT, logical AND, or logical OR * The second expression of a for statement * The expression of an if statement * The expression of the while clause in either a while or do...while statement * An expression used as a pattern (as in Overall Program Structure) All arithmetic shall follow the semantics of floating-point arithmetic as specified by the ISO C standard (see Section 1.1.2, Concepts Derived from the ISO C Standard). The value of the expression: expr1 ^ expr2 shall be equivalent to the value returned by the ISO C standard function call: pow(expr1, expr2) The expression: lvalue ^= expr shall be equivalent to the ISO C standard expression: lvalue = pow(lvalue, expr) except that lvalue shall be evaluated only once. The value of the expression: expr1 % expr2 shall be equivalent to the value returned by the ISO C standard function call: fmod(expr1, expr2) The expression: lvalue %= expr shall be equivalent to the ISO C standard expression: lvalue = fmod(lvalue, expr) except that lvalue shall be evaluated only once. Variables and fields shall be set by the assignment statement: lvalue = expression and the type of expression shall determine the resulting variable type. The assignment includes the arithmetic assignments ("+=", "-=", "*=", "/=", "%=", "^=", "++", "--") all of which shall produce a numeric result. The left-hand side of an assignment and the target of increment and decrement operators can be one of a variable, an array with index, or a field selector. The awk language supplies arrays that are used for storing numbers or strings. Arrays need not be declared. They shall initially be empty, and their sizes shall change dynamically. The subscripts, or element identifiers, are strings, providing a type of associative array capability. An array name followed by a subscript within square brackets can be used as an lvalue and thus as an expression, as described in the grammar; see Grammar. Unsubscripted array names can be used in only the following contexts: * A parameter in a function definition or function call * The NAME token following any use of the keyword in as specified in the grammar (see Grammar); if the name used in this context is not an array name, the behavior is undefined A valid array index shall consist of one or more <comma>-separated expressions, similar to the way in which multi- dimensional arrays are indexed in some programming languages. Because awk arrays are really one-dimensional, such a <comma>-separated list shall be converted to a single string by concatenating the string values of the separate expressions, each separated from the other by the value of the SUBSEP variable. Thus, the following two index operations shall be equivalent: var[expr1, expr2, ... exprn] var[expr1 SUBSEP expr2 SUBSEP ... SUBSEP exprn] The application shall ensure that a multi-dimensioned index used with the in operator is parenthesized. The in operator, which tests for the existence of a particular array element, shall not cause that element to exist. Any other reference to a nonexistent array element shall automatically create it. Comparisons (with the '<', "<=", "!=", "==", '>', and ">=" operators) shall be made numerically if both operands are numeric, if one is numeric and the other has a string value that is a numeric string, or if one is numeric and the other has the uninitialized value. Otherwise, operands shall be converted to strings as required and a string comparison shall be made as follows: * For the "!=" and "==" operators, the strings should be compared to check if they are identical but may be compared using the locale-specific collation sequence to check if they collate equally. * For the other operators, the strings shall be compared using the locale-specific collation sequence. The value of the comparison expression shall be 1 if the relation is true, or 0 if the relation is false. Variables and Special Variables Variables can be used in an awk program by referencing them. With the exception of function parameters (see User-Defined Functions), they are not explicitly declared. Function parameter names shall be local to the function; all other variable names shall be global. The same name shall not be used as both a function parameter name and as the name of a function or a special awk variable. The same name shall not be used both as a variable name with global scope and as the name of a function. The same name shall not be used within the same scope both as a scalar variable and as an array. Uninitialized variables, including scalar variables, array elements, and field variables, shall have an uninitialized value. An uninitialized value shall have both a numeric value of zero and a string value of the empty string. Evaluation of variables with an uninitialized value, to either string or numeric, shall be determined by the context in which they are used. Field variables shall be designated by a '$' followed by a number or numerical expression. The effect of the field number expression evaluating to anything other than a non-negative integer is unspecified; uninitialized variables or string values need not be converted to numeric values in this context. New field variables can be created by assigning a value to them. References to nonexistent fields (that is, fields after $NF), shall evaluate to the uninitialized value. Such references shall not create new fields. However, assigning to a nonexistent field (for example, $(NF+2)=5) shall increase the value of NF; create any intervening fields with the uninitialized value; and cause the value of $0 to be recomputed, with the fields being separated by the value of OFS. Each field variable shall have a string value or an uninitialized value when created. Field variables shall have the uninitialized value when created from $0 using FS and the variable does not contain any characters. If appropriate, the field variable shall be considered a numeric string (see Expressions in awk). Implementations shall support the following other special variables that are set by awk: ARGC The number of elements in the ARGV array. ARGV An array of command line arguments, excluding options and the program argument, numbered from zero to ARGC-1. The arguments in ARGV can be modified or added to; ARGC can be altered. As each input file ends, awk shall treat the next non-null element of ARGV, up to the current value of ARGC-1, inclusive, as the name of the next input file. Thus, setting an element of ARGV to null means that it shall not be treated as an input file. The name '-' indicates the standard input. If an argument matches the format of an assignment operand, this argument shall be treated as an assignment rather than a file argument. CONVFMT The printf format for converting numbers to strings (except for output statements, where OFMT is used); "%.6g" by default. ENVIRON An array representing the value of the environment, as described in the exec functions defined in the System Interfaces volume of POSIX.12017. The indices of the array shall be strings consisting of the names of the environment variables, and the value of each array element shall be a string consisting of the value of that variable. If appropriate, the environment variable shall be considered a numeric string (see Expressions in awk); the array element shall also have its numeric value. In all cases where the behavior of awk is affected by environment variables (including the environment of any commands that awk executes via the system function or via pipeline redirections with the print statement, the printf statement, or the getline function), the environment used shall be the environment at the time awk began executing; it is implementation-defined whether any modification of ENVIRON affects this environment. FILENAME A pathname of the current input file. Inside a BEGIN action the value is undefined. Inside an END action the value shall be the name of the last input file processed. FNR The ordinal number of the current record in the current file. Inside a BEGIN action the value shall be zero. Inside an END action the value shall be the number of the last record processed in the last file processed. FS Input field separator regular expression; a <space> by default. NF The number of fields in the current record. Inside a BEGIN action, the use of NF is undefined unless a getline function without a var argument is executed previously. Inside an END action, NF shall retain the value it had for the last record read, unless a subsequent, redirected, getline function without a var argument is performed prior to entering the END action. NR The ordinal number of the current record from the start of input. Inside a BEGIN action the value shall be zero. Inside an END action the value shall be the number of the last record processed. OFMT The printf format for converting numbers to strings in output statements (see Output Statements); "%.6g" by default. The result of the conversion is unspecified if the value of OFMT is not a floating-point format specification. OFS The print statement output field separator; <space> by default. ORS The print statement output record separator; a <newline> by default. RLENGTH The length of the string matched by the match function. RS The first character of the string value of RS shall be the input record separator; a <newline> by default. If RS contains more than one character, the results are unspecified. If RS is null, then records are separated by sequences consisting of a <newline> plus one or more blank lines, leading or trailing blank lines shall not result in empty records at the beginning or end of the input, and a <newline> shall always be a field separator, no matter what the value of FS is. RSTART The starting position of the string matched by the match function, numbering from 1. This shall always be equivalent to the return value of the match function. SUBSEP The subscript separator string for multi-dimensional arrays; the default value is implementation-defined. Regular Expressions The awk utility shall make use of the extended regular expression notation (see the Base Definitions volume of POSIX.12017, Section 9.4, Extended Regular Expressions) except that it shall allow the use of C-language conventions for escaping special characters within the EREs, as specified in the table in the Base Definitions volume of POSIX.12017, Chapter 5, File Format Notation ('\\', '\a', '\b', '\f', '\n', '\r', '\t', '\v') and the following table; these escape sequences shall be recognized both inside and outside bracket expressions. Note that records need not be separated by <newline> characters and string constants can contain <newline> characters, so even the "\n" sequence is valid in awk EREs. Using a <slash> character within an ERE requires the escaping shown in the following table. Table 4-2: Escape Sequences in awk Escape Sequence Description Meaning \" <backslash> <quotation-mark> <quotation-mark> character \/ <backslash> <slash> <slash> character \ddd A <backslash> character followed The character whose encoding is by the longest sequence of one, represented by the one, two, or two, or three octal-digit three-digit octal integer. Multi- characters (01234567). If all of byte characters require multiple, the digits are 0 (that is, concatenated escape sequences of representation of the NUL this type, including the leading character), the behavior is <backslash> for each byte. undefined. \c A <backslash> character followed Undefined by any character not described in this table or in the table in the Base Definitions volume of POSIX.12017, Chapter 5, File Format Notation ('\\', '\a', '\b', '\f', '\n', '\r', '\t', '\v'). A regular expression can be matched against a specific field or string by using one of the two regular expression matching operators, '~' and "!~". These operators shall interpret their right-hand operand as a regular expression and their left-hand operand as a string. If the regular expression matches the string, the '~' expression shall evaluate to a value of 1, and the "!~" expression shall evaluate to a value of 0. (The regular expression matching operation is as defined by the term matched in the Base Definitions volume of POSIX.12017, Section 9.1, Regular Expression Definitions, where a match occurs on any part of the string unless the regular expression is limited with the <circumflex> or <dollar-sign> special characters.) If the regular expression does not match the string, the '~' expression shall evaluate to a value of 0, and the "!~" expression shall evaluate to a value of 1. If the right-hand operand is any expression other than the lexical token ERE, the string value of the expression shall be interpreted as an extended regular expression, including the escape conventions described above. Note that these same escape conventions shall also be applied in determining the value of a string literal (the lexical token STRING), and thus shall be applied a second time when a string literal is used in this context. When an ERE token appears as an expression in any context other than as the right-hand of the '~' or "!~" operator or as one of the built-in function arguments described below, the value of the resulting expression shall be the equivalent of: $0 ~ /ere/ The ere argument to the gsub, match, sub functions, and the fs argument to the split function (see String Functions) shall be interpreted as extended regular expressions. These can be either ERE tokens or arbitrary expressions, and shall be interpreted in the same manner as the right-hand side of the '~' or "!~" operator. An extended regular expression can be used to separate fields by assigning a string containing the expression to the built-in variable FS, either directly or as a consequence of using the -F sepstring option. The default value of the FS variable shall be a single <space>. The following describes FS behavior: 1. If FS is a null string, the behavior is unspecified. 2. If FS is a single character: a. If FS is <space>, skip leading and trailing <blank> and <newline> characters; fields shall be delimited by sets of one or more <blank> or <newline> characters. b. Otherwise, if FS is any other character c, fields shall be delimited by each single occurrence of c. 3. Otherwise, the string value of FS shall be considered to be an extended regular expression. Each occurrence of a sequence matching the extended regular expression shall delimit fields. Except for the '~' and "!~" operators, and in the gsub, match, split, and sub built-in functions, ERE matching shall be based on input records; that is, record separator characters (the first character of the value of the variable RS, <newline> by default) cannot be embedded in the expression, and no expression shall match the record separator character. If the record separator is not <newline>, <newline> characters embedded in the expression can be matched. For the '~' and "!~" operators, and in those four built-in functions, ERE matching shall be based on text strings; that is, any character (including <newline> and the record separator) can be embedded in the pattern, and an appropriate pattern shall match any character. However, in all awk ERE matching, the use of one or more NUL characters in the pattern, input record, or text string produces undefined results. Patterns A pattern is any valid expression, a range specified by two expressions separated by a comma, or one of the two special patterns BEGIN or END. Special Patterns The awk utility shall recognize two special patterns, BEGIN and END. Each BEGIN pattern shall be matched once and its associated action executed before the first record of input is readexcept possibly by use of the getline function (see Input/Output and General Functions) in a prior BEGIN actionand before command line assignment is done. Each END pattern shall be matched once and its associated action executed after the last record of input has been read. These two patterns shall have associated actions. BEGIN and END shall not combine with other patterns. Multiple BEGIN and END patterns shall be allowed. The actions associated with the BEGIN patterns shall be executed in the order specified in the program, as are the END actions. An END pattern can precede a BEGIN pattern in a program. If an awk program consists of only actions with the pattern BEGIN, and the BEGIN action contains no getline function, awk shall exit without reading its input when the last statement in the last BEGIN action is executed. If an awk program consists of only actions with the pattern END or only actions with the patterns BEGIN and END, the input shall be read before the statements in the END actions are executed. Expression Patterns An expression pattern shall be evaluated as if it were an expression in a Boolean context. If the result is true, the pattern shall be considered to match, and the associated action (if any) shall be executed. If the result is false, the action shall not be executed. Pattern Ranges A pattern range consists of two expressions separated by a comma; in this case, the action shall be performed for all records between a match of the first expression and the following match of the second expression, inclusive. At this point, the pattern range can be repeated starting at input records subsequent to the end of the matched range. Actions An action is a sequence of statements as shown in the grammar in Grammar. Any single statement can be replaced by a statement list enclosed in curly braces. The application shall ensure that statements in a statement list are separated by <newline> or <semicolon> characters. Statements in a statement list shall be executed sequentially in the order that they appear. The expression acting as the conditional in an if statement shall be evaluated and if it is non-zero or non-null, the following statement shall be executed; otherwise, if else is present, the statement following the else shall be executed. The if, while, do...while, for, break, and continue statements are based on the ISO C standard (see Section 1.1.2, Concepts Derived from the ISO C Standard), except that the Boolean expressions shall be treated as described in Expressions in awk, and except in the case of: for (variable in array) which shall iterate, assigning each index of array to variable in an unspecified order. The results of adding new elements to array within such a for loop are undefined. If a break or continue statement occurs outside of a loop, the behavior is undefined. The delete statement shall remove an individual array element. Thus, the following code deletes an entire array: for (index in array) delete array[index] The next statement shall cause all further processing of the current input record to be abandoned. The behavior is undefined if a next statement appears or is invoked in a BEGIN or END action. The exit statement shall invoke all END actions in the order in which they occur in the program source and then terminate the program without reading further input. An exit statement inside an END action shall terminate the program without further execution of END actions. If an expression is specified in an exit statement, its numeric value shall be the exit status of awk, unless subsequent errors are encountered or a subsequent exit statement with an expression is executed. Output Statements Both print and printf statements shall write to standard output by default. The output shall be written to the location specified by output_redirection if one is supplied, as follows: > expression >> expression | expression In all cases, the expression shall be evaluated to produce a string that is used as a pathname into which to write (for '>' or ">>") or as a command to be executed (for '|'). Using the first two forms, if the file of that name is not currently open, it shall be opened, creating it if necessary and using the first form, truncating the file. The output then shall be appended to the file. As long as the file remains open, subsequent calls in which expression evaluates to the same string value shall simply append output to the file. The file remains open until the close function (see Input/Output and General Functions) is called with an expression that evaluates to the same string value. The third form shall write output onto a stream piped to the input of a command. The stream shall be created if no stream is currently open with the value of expression as its command name. The stream created shall be equivalent to one created by a call to the popen() function defined in the System Interfaces volume of POSIX.12017 with the value of expression as the command argument and a value of w as the mode argument. As long as the stream remains open, subsequent calls in which expression evaluates to the same string value shall write output to the existing stream. The stream shall remain open until the close function (see Input/Output and General Functions) is called with an expression that evaluates to the same string value. At that time, the stream shall be closed as if by a call to the pclose() function defined in the System Interfaces volume of POSIX.12017. As described in detail by the grammar in Grammar, these output statements shall take a <comma>-separated list of expressions referred to in the grammar by the non-terminal symbols expr_list, print_expr_list, or print_expr_list_opt. This list is referred to here as the expression list, and each member is referred to as an expression argument. The print statement shall write the value of each expression argument onto the indicated output stream separated by the current output field separator (see variable OFS above), and terminated by the output record separator (see variable ORS above). All expression arguments shall be taken as strings, being converted if necessary; this conversion shall be as described in Expressions in awk, with the exception that the printf format in OFMT shall be used instead of the value in CONVFMT. An empty expression list shall stand for the whole input record ($0). The printf statement shall produce output based on a notation similar to the File Format Notation used to describe file formats in this volume of POSIX.12017 (see the Base Definitions volume of POSIX.12017, Chapter 5, File Format Notation). Output shall be produced as specified with the first expression argument as the string format and subsequent expression arguments as the strings arg1 to argn, inclusive, with the following exceptions: 1. The format shall be an actual character string rather than a graphical representation. Therefore, it cannot contain empty character positions. The <space> in the format string, in any context other than a flag of a conversion specification, shall be treated as an ordinary character that is copied to the output. 2. If the character set contains a '' character and that character appears in the format string, it shall be treated as an ordinary character that is copied to the output. 3. The escape sequences beginning with a <backslash> character shall be treated as sequences of ordinary characters that are copied to the output. Note that these same sequences shall be interpreted lexically by awk when they appear in literal strings, but they shall not be treated specially by the printf statement. 4. A field width or precision can be specified as the '*' character instead of a digit string. In this case the next argument from the expression list shall be fetched and its numeric value taken as the field width or precision. 5. The implementation shall not precede or follow output from the d or u conversion specifier characters with <blank> characters not specified by the format string. 6. The implementation shall not precede output from the o conversion specifier character with leading zeros not specified by the format string. 7. For the c conversion specifier character: if the argument has a numeric value, the character whose encoding is that value shall be output. If the value is zero or is not the encoding of any character in the character set, the behavior is undefined. If the argument does not have a numeric value, the first character of the string value shall be output; if the string does not contain any characters, the behavior is undefined. 8. For each conversion specification that consumes an argument, the next expression argument shall be evaluated. With the exception of the c conversion specifier character, the value shall be converted (according to the rules specified in Expressions in awk) to the appropriate type for the conversion specification. 9. If there are insufficient expression arguments to satisfy all the conversion specifications in the format string, the behavior is undefined. 10. If any character sequence in the format string begins with a '%' character, but does not form a valid conversion specification, the behavior is unspecified. Both print and printf can output at least {LINE_MAX} bytes. Functions The awk language has a variety of built-in functions: arithmetic, string, input/output, and general. Arithmetic Functions The arithmetic functions, except for int, shall be based on the ISO C standard (see Section 1.1.2, Concepts Derived from the ISO C Standard). The behavior is undefined in cases where the ISO C standard specifies that an error be returned or that the behavior is undefined. Although the grammar (see Grammar) permits built-in functions to appear with no arguments or parentheses, unless the argument or parentheses are indicated as optional in the following list (by displaying them within the "[]" brackets), such use is undefined. atan2(y,x) Return arctangent of y/x in radians in the range [-,]. cos(x) Return cosine of x, where x is in radians. sin(x) Return sine of x, where x is in radians. exp(x) Return the exponential function of x. log(x) Return the natural logarithm of x. sqrt(x) Return the square root of x. int(x) Return the argument truncated to an integer. Truncation shall be toward 0 when x>0. rand() Return a random number n, such that 0n<1. srand([expr]) Set the seed value for rand to expr or use the time of day if expr is omitted. The previous seed value shall be returned. String Functions The string functions in the following list shall be supported. Although the grammar (see Grammar) permits built-in functions to appear with no arguments or parentheses, unless the argument or parentheses are indicated as optional in the following list (by displaying them within the "[]" brackets), such use is undefined. gsub(ere, repl[, in]) Behave like sub (see below), except that it shall replace all occurrences of the regular expression (like the ed utility global substitute) in $0 or in the in argument, when specified. index(s, t) Return the position, in characters, numbering from 1, in string s where string t first occurs, or zero if it does not occur at all. length[([s])] Return the length, in characters, of its argument taken as a string, or of the whole record, $0, if there is no argument. match(s, ere) Return the position, in characters, numbering from 1, in string s where the extended regular expression ere occurs, or zero if it does not occur at all. RSTART shall be set to the starting position (which is the same as the returned value), zero if no match is found; RLENGTH shall be set to the length of the matched string, -1 if no match is found. split(s, a[, fs ]) Split the string s into array elements a[1], a[2], ..., a[n], and return n. All elements of the array shall be deleted before the split is performed. The separation shall be done with the ERE fs or with the field separator FS if fs is not given. Each array element shall have a string value when created and, if appropriate, the array element shall be considered a numeric string (see Expressions in awk). The effect of a null string as the value of fs is unspecified. sprintf(fmt, expr, expr, ...) Format the expressions according to the printf format given by fmt and return the resulting string. sub(ere, repl[, in ]) Substitute the string repl in place of the first instance of the extended regular expression ERE in string in and return the number of substitutions. An <ampersand> ('&') appearing in the string repl shall be replaced by the string from in that matches the ERE. An <ampersand> preceded with a <backslash> shall be interpreted as the literal <ampersand> character. An occurrence of two consecutive <backslash> characters shall be interpreted as just a single literal <backslash> character. Any other occurrence of a <backslash> (for example, preceding any other character) shall be treated as a literal <backslash> character. Note that if repl is a string literal (the lexical token STRING; see Grammar), the handling of the <ampersand> character occurs after any lexical processing, including any lexical <backslash>-escape sequence processing. If in is specified and it is not an lvalue (see Expressions in awk), the behavior is undefined. If in is omitted, awk shall use the current record ($0) in its place. substr(s, m[, n ]) Return the at most n-character substring of s that begins at position m, numbering from 1. If n is omitted, or if n specifies more characters than are left in the string, the length of the substring shall be limited by the length of the string s. tolower(s) Return a string based on the string s. Each character in s that is an uppercase letter specified to have a tolower mapping by the LC_CTYPE category of the current locale shall be replaced in the returned string by the lowercase letter specified by the mapping. Other characters in s shall be unchanged in the returned string. toupper(s) Return a string based on the string s. Each character in s that is a lowercase letter specified to have a toupper mapping by the LC_CTYPE category of the current locale is replaced in the returned string by the uppercase letter specified by the mapping. Other characters in s are unchanged in the returned string. All of the preceding functions that take ERE as a parameter expect a pattern or a string valued expression that is a regular expression as defined in Regular Expressions. Input/Output and General Functions The input/output and general functions are: close(expression) Close the file or pipe opened by a print or printf statement or a call to getline with the same string- valued expression. The limit on the number of open expression arguments is implementation-defined. If the close was successful, the function shall return zero; otherwise, it shall return non-zero. expression | getline [var] Read a record of input from a stream piped from the output of a command. The stream shall be created if no stream is currently open with the value of expression as its command name. The stream created shall be equivalent to one created by a call to the popen() function with the value of expression as the command argument and a value of r as the mode argument. As long as the stream remains open, subsequent calls in which expression evaluates to the same string value shall read subsequent records from the stream. The stream shall remain open until the close function is called with an expression that evaluates to the same string value. At that time, the stream shall be closed as if by a call to the pclose() function. If var is omitted, $0 and NF shall be set; otherwise, var shall be set and, if appropriate, it shall be considered a numeric string (see Expressions in awk). The getline operator can form ambiguous constructs when there are unparenthesized operators (including concatenate) to the left of the '|' (to the beginning of the expression containing getline). In the context of the '$' operator, '|' shall behave as if it had a lower precedence than '$'. The result of evaluating other operators is unspecified, and conforming applications shall parenthesize properly all such usages. getline Set $0 to the next input record from the current input file. This form of getline shall set the NF, NR, and FNR variables. getline var Set variable var to the next input record from the current input file and, if appropriate, var shall be considered a numeric string (see Expressions in awk). This form of getline shall set the FNR and NR variables. getline [var] < expression Read the next record of input from a named file. The expression shall be evaluated to produce a string that is used as a pathname. If the file of that name is not currently open, it shall be opened. As long as the stream remains open, subsequent calls in which expression evaluates to the same string value shall read subsequent records from the file. The file shall remain open until the close function is called with an expression that evaluates to the same string value. If var is omitted, $0 and NF shall be set; otherwise, var shall be set and, if appropriate, it shall be considered a numeric string (see Expressions in awk). The getline operator can form ambiguous constructs when there are unparenthesized binary operators (including concatenate) to the right of the '<' (up to the end of the expression containing the getline). The result of evaluating such a construct is unspecified, and conforming applications shall parenthesize properly all such usages. system(expression) Execute the command given by expression in a manner equivalent to the system() function defined in the System Interfaces volume of POSIX.12017 and return the exit status of the command. All forms of getline shall return 1 for successful input, zero for end-of-file, and -1 for an error. Where strings are used as the name of a file or pipeline, the application shall ensure that the strings are textually identical. The terminology ``same string value'' implies that ``equivalent strings'', even those that differ only by <space> characters, represent different files. User-Defined Functions The awk language also provides user-defined functions. Such functions can be defined as: function name([parameter, ...]) { statements } A function can be referred to anywhere in an awk program; in particular, its use can precede its definition. The scope of a function is global. Function parameters, if present, can be either scalars or arrays; the behavior is undefined if an array name is passed as a parameter that the function uses as a scalar, or if a scalar expression is passed as a parameter that the function uses as an array. Function parameters shall be passed by value if scalar and by reference if array name. The number of parameters in the function definition need not match the number of parameters in the function call. Excess formal parameters can be used as local variables. If fewer arguments are supplied in a function call than are in the function definition, the extra parameters that are used in the function body as scalars shall evaluate to the uninitialized value until they are otherwise initialized, and the extra parameters that are used in the function body as arrays shall be treated as uninitialized arrays where each element evaluates to the uninitialized value until otherwise initialized. When invoking a function, no white space can be placed between the function name and the opening parenthesis. Function calls can be nested and recursive calls can be made upon functions. Upon return from any nested or recursive function call, the values of all of the calling function's parameters shall be unchanged, except for array parameters passed by reference. The return statement can be used to return a value. If a return statement appears outside of a function definition, the behavior is undefined. In the function definition, <newline> characters shall be optional before the opening brace and after the closing brace. Function definitions can appear anywhere in the program where a pattern-action pair is allowed. Grammar The grammar in this section and the lexical conventions in the following section shall together describe the syntax for awk programs. The general conventions for this style of grammar are described in Section 1.3, Grammar Conventions. A valid program can be represented as the non-terminal symbol program in the grammar. This formal syntax shall take precedence over the preceding text syntax description. %token NAME NUMBER STRING ERE %token FUNC_NAME /* Name followed by '(' without white space. */ /* Keywords */ %token Begin End /* 'BEGIN' 'END' */ %token Break Continue Delete Do Else /* 'break' 'continue' 'delete' 'do' 'else' */ %token Exit For Function If In /* 'exit' 'for' 'function' 'if' 'in' */ %token Next Print Printf Return While /* 'next' 'print' 'printf' 'return' 'while' */ /* Reserved function names */ %token BUILTIN_FUNC_NAME /* One token for the following: * atan2 cos sin exp log sqrt int rand srand * gsub index length match split sprintf sub * substr tolower toupper close system */ %token GETLINE /* Syntactically different from other built-ins. */ /* Two-character tokens. */ %token ADD_ASSIGN SUB_ASSIGN MUL_ASSIGN DIV_ASSIGN MOD_ASSIGN POW_ASSIGN /* '+=' '-=' '*=' '/=' '%=' '^=' */ %token OR AND NO_MATCH EQ LE GE NE INCR DECR APPEND /* '||' '&&' '!~' '==' '<=' '>=' '!=' '++' '--' '>>' */ /* One-character tokens. */ %token '{' '}' '(' ')' '[' ']' ',' ';' NEWLINE %token '+' '-' '*' '%' '^' '!' '>' '<' '|' '?' ':' '~' '$' '=' %start program %% program : item_list | item_list item ; item_list : /* empty */ | item_list item terminator ; item : action | pattern action | normal_pattern | Function NAME '(' param_list_opt ')' newline_opt action | Function FUNC_NAME '(' param_list_opt ')' newline_opt action ; param_list_opt : /* empty */ | param_list ; param_list : NAME | param_list ',' NAME ; pattern : normal_pattern | special_pattern ; normal_pattern : expr | expr ',' newline_opt expr ; special_pattern : Begin | End ; action : '{' newline_opt '}' | '{' newline_opt terminated_statement_list '}' | '{' newline_opt unterminated_statement_list '}' ; terminator : terminator NEWLINE | ';' | NEWLINE ; terminated_statement_list : terminated_statement | terminated_statement_list terminated_statement ; unterminated_statement_list : unterminated_statement | terminated_statement_list unterminated_statement ; terminated_statement : action newline_opt | If '(' expr ')' newline_opt terminated_statement | If '(' expr ')' newline_opt terminated_statement Else newline_opt terminated_statement | While '(' expr ')' newline_opt terminated_statement | For '(' simple_statement_opt ';' expr_opt ';' simple_statement_opt ')' newline_opt terminated_statement | For '(' NAME In NAME ')' newline_opt terminated_statement | ';' newline_opt | terminatable_statement NEWLINE newline_opt | terminatable_statement ';' newline_opt ; unterminated_statement : terminatable_statement | If '(' expr ')' newline_opt unterminated_statement | If '(' expr ')' newline_opt terminated_statement Else newline_opt unterminated_statement | While '(' expr ')' newline_opt unterminated_statement | For '(' simple_statement_opt ';' expr_opt ';' simple_statement_opt ')' newline_opt unterminated_statement | For '(' NAME In NAME ')' newline_opt unterminated_statement ; terminatable_statement : simple_statement | Break | Continue | Next | Exit expr_opt | Return expr_opt | Do newline_opt terminated_statement While '(' expr ')' ; simple_statement_opt : /* empty */ | simple_statement ; simple_statement : Delete NAME '[' expr_list ']' | expr | print_statement ; print_statement : simple_print_statement | simple_print_statement output_redirection ; simple_print_statement : Print print_expr_list_opt | Print '(' multiple_expr_list ')' | Printf print_expr_list | Printf '(' multiple_expr_list ')' ; output_redirection : '>' expr | APPEND expr | '|' expr ; expr_list_opt : /* empty */ | expr_list ; expr_list : expr | multiple_expr_list ; multiple_expr_list : expr ',' newline_opt expr | multiple_expr_list ',' newline_opt expr ; expr_opt : /* empty */ | expr ; expr : unary_expr | non_unary_expr ; unary_expr : '+' expr | '-' expr | unary_expr '^' expr | unary_expr '*' expr | unary_expr '/' expr | unary_expr '%' expr | unary_expr '+' expr | unary_expr '-' expr | unary_expr non_unary_expr | unary_expr '<' expr | unary_expr LE expr | unary_expr NE expr | unary_expr EQ expr | unary_expr '>' expr | unary_expr GE expr | unary_expr '~' expr | unary_expr NO_MATCH expr | unary_expr In NAME | unary_expr AND newline_opt expr | unary_expr OR newline_opt expr | unary_expr '?' expr ':' expr | unary_input_function ; non_unary_expr : '(' expr ')' | '!' expr | non_unary_expr '^' expr | non_unary_expr '*' expr | non_unary_expr '/' expr | non_unary_expr '%' expr | non_unary_expr '+' expr | non_unary_expr '-' expr | non_unary_expr non_unary_expr | non_unary_expr '<' expr | non_unary_expr LE expr | non_unary_expr NE expr | non_unary_expr EQ expr | non_unary_expr '>' expr | non_unary_expr GE expr | non_unary_expr '~' expr | non_unary_expr NO_MATCH expr | non_unary_expr In NAME | '(' multiple_expr_list ')' In NAME | non_unary_expr AND newline_opt expr | non_unary_expr OR newline_opt expr | non_unary_expr '?' expr ':' expr | NUMBER | STRING | lvalue | ERE | lvalue INCR | lvalue DECR | INCR lvalue | DECR lvalue | lvalue POW_ASSIGN expr | lvalue MOD_ASSIGN expr | lvalue MUL_ASSIGN expr | lvalue DIV_ASSIGN expr | lvalue ADD_ASSIGN expr | lvalue SUB_ASSIGN expr | lvalue '=' expr | FUNC_NAME '(' expr_list_opt ')' /* no white space allowed before '(' */ | BUILTIN_FUNC_NAME '(' expr_list_opt ')' | BUILTIN_FUNC_NAME | non_unary_input_function ; print_expr_list_opt : /* empty */ | print_expr_list ; print_expr_list : print_expr | print_expr_list ',' newline_opt print_expr ; print_expr : unary_print_expr | non_unary_print_expr ; unary_print_expr : '+' print_expr | '-' print_expr | unary_print_expr '^' print_expr | unary_print_expr '*' print_expr | unary_print_expr '/' print_expr | unary_print_expr '%' print_expr | unary_print_expr '+' print_expr | unary_print_expr '-' print_expr | unary_print_expr non_unary_print_expr | unary_print_expr '~' print_expr | unary_print_expr NO_MATCH print_expr | unary_print_expr In NAME | unary_print_expr AND newline_opt print_expr | unary_print_expr OR newline_opt print_expr | unary_print_expr '?' print_expr ':' print_expr ; non_unary_print_expr : '(' expr ')' | '!' print_expr | non_unary_print_expr '^' print_expr | non_unary_print_expr '*' print_expr | non_unary_print_expr '/' print_expr | non_unary_print_expr '%' print_expr | non_unary_print_expr '+' print_expr | non_unary_print_expr '-' print_expr | non_unary_print_expr non_unary_print_expr | non_unary_print_expr '~' print_expr | non_unary_print_expr NO_MATCH print_expr | non_unary_print_expr In NAME | '(' multiple_expr_list ')' In NAME | non_unary_print_expr AND newline_opt print_expr | non_unary_print_expr OR newline_opt print_expr | non_unary_print_expr '?' print_expr ':' print_expr | NUMBER | STRING | lvalue | ERE | lvalue INCR | lvalue DECR | INCR lvalue | DECR lvalue | lvalue POW_ASSIGN print_expr | lvalue MOD_ASSIGN print_expr | lvalue MUL_ASSIGN print_expr | lvalue DIV_ASSIGN print_expr | lvalue ADD_ASSIGN print_expr | lvalue SUB_ASSIGN print_expr | lvalue '=' print_expr | FUNC_NAME '(' expr_list_opt ')' /* no white space allowed before '(' */ | BUILTIN_FUNC_NAME '(' expr_list_opt ')' | BUILTIN_FUNC_NAME ; lvalue : NAME | NAME '[' expr_list ']' | '$' expr ; non_unary_input_function : simple_get | simple_get '<' expr | non_unary_expr '|' simple_get ; unary_input_function : unary_expr '|' simple_get ; simple_get : GETLINE | GETLINE lvalue ; newline_opt : /* empty */ | newline_opt NEWLINE ; This grammar has several ambiguities that shall be resolved as follows: * Operator precedence and associativity shall be as described in Table 4-1, Expressions in Decreasing Precedence in awk. * In case of ambiguity, an else shall be associated with the most immediately preceding if that would satisfy the grammar. * In some contexts, a <slash> ('/') that is used to surround an ERE could also be the division operator. This shall be resolved in such a way that wherever the division operator could appear, a <slash> is assumed to be the division operator. (There is no unary division operator.) Each expression in an awk program shall conform to the precedence and associativity rules, even when this is not needed to resolve an ambiguity. For example, because '$' has higher precedence than '++', the string "$x++--" is not a valid awk expression, even though it is unambiguously parsed by the grammar as "$(x++)--". One convention that might not be obvious from the formal grammar is where <newline> characters are acceptable. There are several obvious placements such as terminating a statement, and a <backslash> can be used to escape <newline> characters between any lexical tokens. In addition, <newline> characters without <backslash> characters can follow a comma, an open brace, logical AND operator ("&&"), logical OR operator ("||"), the do keyword, the else keyword, and the closing parenthesis of an if, for, or while statement. For example: { print $1, $2 } Lexical Conventions The lexical conventions for awk programs, with respect to the preceding grammar, shall be as follows: 1. Except as noted, awk shall recognize the longest possible token or delimiter beginning at a given point. 2. A comment shall consist of any characters beginning with the <number-sign> character and terminated by, but excluding the next occurrence of, a <newline>. Comments shall have no effect, except to delimit lexical tokens. 3. The <newline> shall be recognized as the token NEWLINE. 4. A <backslash> character immediately followed by a <newline> shall have no effect. 5. The token STRING shall represent a string constant. A string constant shall begin with the character '"'. Within a string constant, a <backslash> character shall be considered to begin an escape sequence as specified in the table in the Base Definitions volume of POSIX.12017, Chapter 5, File Format Notation ('\\', '\a', '\b', '\f', '\n', '\r', '\t', '\v'). In addition, the escape sequences in Table 4-2, Escape Sequences in awk shall be recognized. A <newline> shall not occur within a string constant. A string constant shall be terminated by the first unescaped occurrence of the character '"' after the one that begins the string constant. The value of the string shall be the sequence of all unescaped characters and values of escape sequences between, but not including, the two delimiting '"' characters. 6. The token ERE represents an extended regular expression constant. An ERE constant shall begin with the <slash> character. Within an ERE constant, a <backslash> character shall be considered to begin an escape sequence as specified in the table in the Base Definitions volume of POSIX.12017, Chapter 5, File Format Notation. In addition, the escape sequences in Table 4-2, Escape Sequences in awk shall be recognized. The application shall ensure that a <newline> does not occur within an ERE constant. An ERE constant shall be terminated by the first unescaped occurrence of the <slash> character after the one that begins the ERE constant. The extended regular expression represented by the ERE constant shall be the sequence of all unescaped characters and values of escape sequences between, but not including, the two delimiting <slash> characters. 7. A <blank> shall have no effect, except to delimit lexical tokens or within STRING or ERE tokens. 8. The token NUMBER shall represent a numeric constant. Its form and numeric value shall either be equivalent to the decimal- floating-constant token as specified by the ISO C standard, or it shall be a sequence of decimal digits and shall be evaluated as an integer constant in decimal. In addition, implementations may accept numeric constants with the form and numeric value equivalent to the hexadecimal-constant and hexadecimal-floating-constant tokens as specified by the ISO C standard. If the value is too large or too small to be representable (see Section 1.1.2, Concepts Derived from the ISO C Standard), the behavior is undefined. 9. A sequence of underscores, digits, and alphabetics from the portable character set (see the Base Definitions volume of POSIX.12017, Section 6.1, Portable Character Set), beginning with an <underscore> or alphabetic character, shall be considered a word. 10. The following words are keywords that shall be recognized as individual tokens; the name of the token is the same as the keyword: BEGIN delete END function in printf break do exit getline next return continue else for if print while 11. The following words are names of built-in functions and shall be recognized as the token BUILTIN_FUNC_NAME: atan2 gsub log split sub toupper close index match sprintf substr cos int rand sqrt system exp length sin srand tolower The above-listed keywords and names of built-in functions are considered reserved words. 12. The token NAME shall consist of a word that is not a keyword or a name of a built-in function and is not followed immediately (without any delimiters) by the '(' character. 13. The token FUNC_NAME shall consist of a word that is not a keyword or a name of a built-in function, followed immediately (without any delimiters) by the '(' character. The '(' character shall not be included as part of the token. 14. The following two-character sequences shall be recognized as the named tokens: Token Name Sequence Token Name Sequence ADD_ASSIGN += NO_MATCH !~ SUB_ASSIGN -= EQ == MUL_ASSIGN *= LE <= DIV_ASSIGN /= GE >= MOD_ASSIGN %= NE != POW_ASSIGN ^= INCR ++ OR || DECR -- AND && APPEND >> 15. The following single characters shall be recognized as tokens whose names are the character: <newline> { } ( ) [ ] , ; + - * % ^ ! > < | ? : ~ $ = There is a lexical ambiguity between the token ERE and the tokens '/' and DIV_ASSIGN. When an input sequence begins with a <slash> character in any syntactic context where the token '/' or DIV_ASSIGN could appear as the next token in a valid program, the longer of those two tokens that can be recognized shall be recognized. In any other syntactic context where the token ERE could appear as the next token in a valid program, the token ERE shall be recognized. EXIT STATUS top The following exit values shall be returned: 0 All input files were processed successfully. >0 An error occurred. The exit status can be altered within the program by using an exit expression. CONSEQUENCES OF ERRORS top If any file operand is specified and the named file cannot be accessed, awk shall write a diagnostic message to standard error and terminate without any further action. If the program specified by either the program operand or a progfile operand is not a valid awk program (as specified in the EXTENDED DESCRIPTION section), the behavior is undefined. The following sections are informative. APPLICATION USAGE top The index, length, match, and substr functions should not be confused with similar functions in the ISO C standard; the awk versions deal with characters, while the ISO C standard deals with bytes. Because the concatenation operation is represented by adjacent expressions rather than an explicit operator, it is often necessary to use parentheses to enforce the proper evaluation precedence. When using awk to process pathnames, it is recommended that LC_ALL, or at least LC_CTYPE and LC_COLLATE, are set to POSIX or C in the environment, since pathnames can contain byte sequences that do not form valid characters in some locales, in which case the utility's behavior would be undefined. In the POSIX locale each byte is a valid single-byte character, and therefore this problem is avoided. On implementations where the "==" operator checks if strings collate equally, applications needing to check whether strings are identical can use: length(a) == length(b) && index(a,b) == 1 On implementations where the "==" operator checks if strings are identical, applications needing to check whether strings collate equally can use: a <= b && a >= b EXAMPLES top The awk program specified in the command line is most easily specified within single-quotes (for example, 'program') for applications using sh, because awk programs commonly contain characters that are special to the shell, including double- quotes. In the cases where an awk program contains single-quote characters, it is usually easiest to specify most of the program as strings within single-quotes concatenated by the shell with quoted single-quote characters. For example: awk '/'\''/ { print "quote:", $0 }' prints all lines from the standard input containing a single- quote character, prefixed with quote:. The following are examples of simple awk programs: 1. Write to the standard output all input lines for which field 3 is greater than 5: $3 > 5 2. Write every tenth line: (NR % 10) == 0 3. Write any line with a substring matching the regular expression: /(G|D)(2[0-9][[:alpha:]]*)/ 4. Print any line with a substring containing a 'G' or 'D', followed by a sequence of digits and characters. This example uses character classes digit and alpha to match language- independent digit and alphabetic characters respectively: /(G|D)([[:digit:][:alpha:]]*)/ 5. Write any line in which the second field matches the regular expression and the fourth field does not: $2 ~ /xyz/ && $4 !~ /xyz/ 6. Write any line in which the second field contains a <backslash>: $2 ~ /\\/ 7. Write any line in which the second field contains a <backslash>. Note that <backslash>-escapes are interpreted twice; once in lexical processing of the string and once in processing the regular expression: $2 ~ "\\\\" 8. Write the second to the last and the last field in each line. Separate the fields by a <colon>: {OFS=":";print $(NF-1), $NF} 9. Write the line number and number of fields in each line. The three strings representing the line number, the <colon>, and the number of fields are concatenated and that string is written to standard output: {print NR ":" NF} 10. Write lines longer than 72 characters: length($0) > 72 11. Write the first two fields in opposite order separated by OFS: { print $2, $1 } 12. Same, with input fields separated by a <comma> or <space> and <tab> characters, or both: BEGIN { FS = ",[ \t]*|[ \t]+" } { print $2, $1 } 13. Add up the first column, print sum, and average: {s += $1 } END {print "sum is ", s, " average is", s/NR} 14. Write fields in reverse order, one per line (many lines out for each line in): { for (i = NF; i > 0; --i) print $i } 15. Write all lines between occurrences of the strings start and stop: /start/, /stop/ 16. Write all lines whose first field is different from the previous one: $1 != prev { print; prev = $1 } 17. Simulate echo: BEGIN { for (i = 1; i < ARGC; ++i) printf("%s%s", ARGV[i], i==ARGC-1?"\n":" ") } 18. Write the path prefixes contained in the PATH environment variable, one per line: BEGIN { n = split (ENVIRON["PATH"], path, ":") for (i = 1; i <= n; ++i) print path[i] } 19. If there is a file named input containing page headers of the form: Page # and a file named program that contains: /Page/ { $2 = n++; } { print } then the command line: awk -f program n=5 input prints the file input, filling in page numbers starting at 5. RATIONALE top This description is based on the new awk, ``nawk'', (see the referenced The AWK Programming Language), which introduced a number of new features to the historical awk: 1. New keywords: delete, do, function, return 2. New built-in functions: atan2, close, cos, gsub, match, rand, sin, srand, sub, system 3. New predefined variables: FNR, ARGC, ARGV, RSTART, RLENGTH, SUBSEP 4. New expression operators: ?, :, ,, ^ 5. The FS variable and the third argument to split, now treated as extended regular expressions. 6. The operator precedence, changed to more closely match the C language. Two examples of code that operate differently are: while ( n /= 10 > 1) ... if (!"wk" ~ /bwk/) ... Several features have been added based on newer implementations of awk: * Multiple instances of -f progfile are permitted. * The new option -v assignment. * The new predefined variable ENVIRON. * New built-in functions toupper and tolower. * More formatting capabilities are added to printf to match the ISO C standard. Earlier versions of this standard required implementations to support multiple adjacent <semicolon>s, lines with one or more <semicolon> before a rule (pattern-action pairs), and lines with only <semicolon>(s). These are not required by this standard and are considered poor programming practice, but can be accepted by an implementation of awk as an extension. The overall awk syntax has always been based on the C language, with a few features from the shell command language and other sources. Because of this, it is not completely compatible with any other language, which has caused confusion for some users. It is not the intent of the standard developers to address such issues. A few relatively minor changes toward making the language more compatible with the ISO C standard were made; most of these changes are based on similar changes in recent implementations, as described above. There remain several C-language conventions that are not in awk. One of the notable ones is the <comma> operator, which is commonly used to specify multiple expressions in the C language for statement. Also, there are various places where awk is more restrictive than the C language regarding the type of expression that can be used in a given context. These limitations are due to the different features that the awk language does provide. Regular expressions in awk have been extended somewhat from historical implementations to make them a pure superset of extended regular expressions, as defined by POSIX.12008 (see the Base Definitions volume of POSIX.12017, Section 9.4, Extended Regular Expressions). The main extensions are internationalization features and interval expressions. Historical implementations of awk have long supported <backslash>-escape sequences as an extension to extended regular expressions, and this extension has been retained despite inconsistency with other utilities. The number of escape sequences recognized in both extended regular expressions and strings has varied (generally increasing with time) among implementations. The set specified by POSIX.12008 includes most sequences known to be supported by popular implementations and by the ISO C standard. One sequence that is not supported is hexadecimal value escapes beginning with '\x'. This would allow values expressed in more than 9 bits to be used within awk as in the ISO C standard. However, because this syntax has a non- deterministic length, it does not permit the subsequent character to be a hexadecimal digit. This limitation can be dealt with in the C language by the use of lexical string concatenation. In the awk language, concatenation could also be a solution for strings, but not for extended regular expressions (either lexical ERE tokens or strings used dynamically as regular expressions). Because of this limitation, the feature has not been added to POSIX.12008. When a string variable is used in a context where an extended regular expression normally appears (where the lexical token ERE is used in the grammar) the string does not contain the literal <slash> characters. Some versions of awk allow the form: func name(args, ... ) { statements } This has been deprecated by the authors of the language, who asked that it not be specified. Historical implementations of awk produce an error if a next statement is executed in a BEGIN action, and cause awk to terminate if a next statement is executed in an END action. This behavior has not been documented, and it was not believed that it was necessary to standardize it. The specification of conversions between string and numeric values is much more detailed than in the documentation of historical implementations or in the referenced The AWK Programming Language. Although most of the behavior is designed to be intuitive, the details are necessary to ensure compatible behavior from different implementations. This is especially important in relational expressions since the types of the operands determine whether a string or numeric comparison is performed. From the perspective of an application developer, it is usually sufficient to expect intuitive behavior and to force conversions (by adding zero or concatenating a null string) when the type of an expression does not obviously match what is needed. The intent has been to specify historical practice in almost all cases. The one exception is that, in historical implementations, variables and constants maintain both string and numeric values after their original value is converted by any use. This means that referencing a variable or constant can have unexpected side-effects. For example, with historical implementations the following program: { a = "+2" b = 2 if (NR % 2) c = a + b if (a == b) print "numeric comparison" else print "string comparison" } would perform a numeric comparison (and output numeric comparison) for each odd-numbered line, but perform a string comparison (and output string comparison) for each even-numbered line. POSIX.12008 ensures that comparisons will be numeric if necessary. With historical implementations, the following program: BEGIN { OFMT = "%e" print 3.14 OFMT = "%f" print 3.14 } would output "3.140000e+00" twice, because in the second print statement the constant "3.14" would have a string value from the previous conversion. POSIX.12008 requires that the output of the second print statement be "3.140000". The behavior of historical implementations was seen as too unintuitive and unpredictable. It was pointed out that with the rules contained in early drafts, the following script would print nothing: BEGIN { y[1.5] = 1 OFMT = "%e" print y[1.5] } Therefore, a new variable, CONVFMT, was introduced. The OFMT variable is now restricted to affecting output conversions of numbers to strings and CONVFMT is used for internal conversions, such as comparisons or array indexing. The default value is the same as that for OFMT, so unless a program changes CONVFMT (which no historical program would do), it will receive the historical behavior associated with internal string conversions. The POSIX awk lexical and syntactic conventions are specified more formally than in other sources. Again the intent has been to specify historical practice. One convention that may not be obvious from the formal grammar as in other verbal descriptions is where <newline> characters are acceptable. There are several obvious placements such as terminating a statement, and a <backslash> can be used to escape <newline> characters between any lexical tokens. In addition, <newline> characters without <backslash> characters can follow a comma, an open brace, a logical AND operator ("&&"), a logical OR operator ("||"), the do keyword, the else keyword, and the closing parenthesis of an if, for, or while statement. For example: { print $1, $2 } The requirement that awk add a trailing <newline> to the program argument text is to simplify the grammar, making it match a text file in form. There is no way for an application or test suite to determine whether a literal <newline> is added or whether awk simply acts as if it did. POSIX.12008 requires several changes from historical implementations in order to support internationalization. Probably the most subtle of these is the use of the decimal-point character, defined by the LC_NUMERIC category of the locale, in representations of floating-point numbers. This locale-specific character is used in recognizing numeric input, in converting between strings and numeric values, and in formatting output. However, regardless of locale, the <period> character (the decimal-point character of the POSIX locale) is the decimal-point character recognized in processing awk programs (including assignments in command line arguments). This is essentially the same convention as the one used in the ISO C standard. The difference is that the C language includes the setlocale() function, which permits an application to modify its locale. Because of this capability, a C application begins executing with its locale set to the C locale, and only executes in the environment-specified locale after an explicit call to setlocale(). However, adding such an elaborate new feature to the awk language was seen as inappropriate for POSIX.12008. It is possible to execute an awk program explicitly in any desired locale by setting the environment in the shell. The undefined behavior resulting from NULs in extended regular expressions allows future extensions for the GNU gawk program to process binary data. The behavior in the case of invalid awk programs (including lexical, syntactic, and semantic errors) is undefined because it was considered overly limiting on implementations to specify. In most cases such errors can be expected to produce a diagnostic and a non-zero exit status. However, some implementations may choose to extend the language in ways that make use of certain invalid constructs. Other invalid constructs might be deemed worthy of a warning, but otherwise cause some reasonable behavior. Still other constructs may be very difficult to detect in some implementations. Also, different implementations might detect a given error during an initial parsing of the program (before reading any input files) while others might detect it when executing the program after reading some input. Implementors should be aware that diagnosing errors as early as possible and producing useful diagnostics can ease debugging of applications, and thus make an implementation more usable. The unspecified behavior from using multi-character RS values is to allow possible future extensions based on extended regular expressions used for record separators. Historical implementations take the first character of the string and ignore the others. Unspecified behavior when split(string,array,<null>) is used is to allow a proposed future extension that would split up a string into an array of individual characters. In the context of the getline function, equally good arguments for different precedences of the | and < operators can be made. Historical practice has been that: getline < "a" "b" is parsed as: ( getline < "a" ) "b" although many would argue that the intent was that the file ab should be read. However: getline < "x" + 1 parses as: getline < ( "x" + 1 ) Similar problems occur with the | version of getline, particularly in combination with $. For example: $"echo hi" | getline (This situation is particularly problematic when used in a print statement, where the |getline part might be a redirection of the print.) Since in most cases such constructs are not (or at least should not) be used (because they have a natural ambiguity for which there is no conventional parsing), the meaning of these constructs has been made explicitly unspecified. (The effect is that a conforming application that runs into the problem must parenthesize to resolve the ambiguity.) There appeared to be few if any actual uses of such constructs. Grammars can be written that would cause an error under these circumstances. Where backwards-compatibility is not a large consideration, implementors may wish to use such grammars. Some historical implementations have allowed some built-in functions to be called without an argument list, the result being a default argument list chosen in some ``reasonable'' way. Use of length as a synonym for length($0) is the only one of these forms that is thought to be widely known or widely used; this particular form is documented in various places (for example, most historical awk reference pages, although not in the referenced The AWK Programming Language) as legitimate practice. With this exception, default argument lists have always been undocumented and vaguely defined, and it is not at all clear how (or if) they should be generalized to user-defined functions. They add no useful functionality and preclude possible future extensions that might need to name functions without calling them. Not standardizing them seems the simplest course. The standard developers considered that length merited special treatment, however, since it has been documented in the past and sees possibly substantial use in historical programs. Accordingly, this usage has been made legitimate, but Issue 5 removed the obsolescent marking for XSI-conforming implementations and many otherwise conforming applications depend on this feature. In sub and gsub, if repl is a string literal (the lexical token STRING), then two consecutive <backslash> characters should be used in the string to ensure a single <backslash> will precede the <ampersand> when the resultant string is passed to the function. (For example, to specify one literal <ampersand> in the replacement string, use gsub(ERE, "\\&").) Historically, the only special character in the repl argument of sub and gsub string functions was the <ampersand> ('&') character and preceding it with the <backslash> character was used to turn off its special meaning. The description in the ISO POSIX2:1993 standard introduced behavior such that the <backslash> character was another special character and it was unspecified whether there were any other special characters. This description introduced several portability problems, some of which are described below, and so it has been replaced with the more historical description. Some of the problems include: * Historically, to create the replacement string, a script could use gsub(ERE, "\\&"), but with the ISO POSIX2:1993 standard wording, it was necessary to use gsub(ERE, "\\\\&"). The <backslash> characters are doubled here because all string literals are subject to lexical analysis, which would reduce each pair of <backslash> characters to a single <backslash> before being passed to gsub. * Since it was unspecified what the special characters were, for portable scripts to guarantee that characters are printed literally, each character had to be preceded with a <backslash>. (For example, a portable script had to use gsub(ERE, "\\h\\i") to produce a replacement string of "hi".) The description for comparisons in the ISO POSIX2:1993 standard did not properly describe historical practice because of the way numeric strings are compared as numbers. The current rules cause the following code: if (0 == "000") print "strange, but true" else print "not true" to do a numeric comparison, causing the if to succeed. It should be intuitively obvious that this is incorrect behavior, and indeed, no historical implementation of awk actually behaves this way. To fix this problem, the definition of numeric string was enhanced to include only those values obtained from specific circumstances (mostly external sources) where it is not possible to determine unambiguously whether the value is intended to be a string or a numeric. Variables that are assigned to a numeric string shall also be treated as a numeric string. (For example, the notion of a numeric string can be propagated across assignments.) In comparisons, all variables having the uninitialized value are to be treated as a numeric operand evaluating to the numeric value zero. Uninitialized variables include all types of variables including scalars, array elements, and fields. The definition of an uninitialized value in Variables and Special Variables is necessary to describe the value placed on uninitialized variables and on fields that are valid (for example, < $NF) but have no characters in them and to describe how these variables are to be used in comparisons. A valid field, such as $1, that has no characters in it can be obtained from an input line of "\t\t" when FS='\t'. Historically, the comparison ($1<10) was done numerically after evaluating $1 to the value zero. The phrase ``... also shall have the numeric value of the numeric string'' was removed from several sections of the ISO POSIX2:1993 standard because is specifies an unnecessary implementation detail. It is not necessary for POSIX.12008 to specify that these objects be assigned two different values. It is only necessary to specify that these objects may evaluate to two different values depending on context. Historical implementations of awk did not parse hexadecimal integer or floating constants like "0xa" and "0xap0". Due to an oversight, the 2001 through 2004 editions of this standard required support for hexadecimal floating constants. This was due to the reference to atof(). This version of the standard allows but does not require implementations to use atof() and includes a description of how floating-point numbers are recognized as an alternative to match historic behavior. The intent of this change is to allow implementations to recognize floating-point constants according to either the ISO/IEC 9899:1990 standard or ISO/IEC 9899:1999 standard, and to allow (but not require) implementations to recognize hexadecimal integer constants. Historical implementations of awk did not support floating-point infinities and NaNs in numeric strings; e.g., "-INF" and "NaN". However, implementations that use the atof() or strtod() functions to do the conversion picked up support for these values if they used a ISO/IEC 9899:1999 standard version of the function instead of a ISO/IEC 9899:1990 standard version. Due to an oversight, the 2001 through 2004 editions of this standard did not allow support for infinities and NaNs, but in this revision support is allowed (but not required). This is a silent change to the behavior of awk programs; for example, in the POSIX locale the expression: ("-INF" + 0 < 0) formerly had the value 0 because "-INF" converted to 0, but now it may have the value 0 or 1. FUTURE DIRECTIONS top A future version of this standard may require the "!=" and "==" operators to perform string comparisons by checking if the strings are identical (and not by checking if they collate equally). SEE ALSO top Section 1.3, Grammar Conventions, grep(1p), lex(1p), sed(1p) The Base Definitions volume of POSIX.12017, Chapter 5, File Format Notation, Section 6.1, Portable Character Set, Chapter 8, Environment Variables, Chapter 9, Regular Expressions, Section 12.2, Utility Syntax Guidelines The System Interfaces volume of POSIX.12017, atof(3p), exec(1p), isspace(3p), popen(3p), setlocale(3p), strtod(3p) COPYRIGHT top Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html . Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html . IEEE/The Open Group 2017 AWK(1P) Pages that refer to this page: bc(1p), colrm(1), join(1p), printf(1p), sed(1p) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. file(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training file(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | FILES | EXIT STATUS | EXAMPLES | SEE ALSO | STANDARDS CONFORMANCE | SECURITY | MAGIC DIRECTORY | HISTORY | LEGAL NOTICE | BUGS | TODO | AVAILABILITY | COLOPHON FILE(1) General Commands Manual FILE(1) NAME top file determine file type SYNOPSIS top [-bcdEhiklLNnprsSvzZ0] [--apple] [--exclude-quiet] [--extension] [--mime-encoding] [--mime-type] [-e testname] [-F separator] [-f namefile] [-m magicfiles] [-P name=value] file ... -C [-m magicfiles] [--help] DESCRIPTION top This manual page documents version 5.45 of the command. tests each argument in an attempt to classify it. There are three sets of tests, performed in this order: filesystem tests, magic tests, and language tests. The first test that succeeds causes the file type to be printed. The type printed will usually contain one of the words text (the file contains only printing characters and a few common control characters and is probably safe to read on an ASCII terminal), executable (the file contains the result of compiling a program in a form understandable to some UNIX kernel or another), or data meaning anything else (data is usually binary or non- printable). Exceptions are well-known file formats (core files, tar archives) that are known to contain binary data. When modifying magic files or the program itself, make sure to preserve these keywords. Users depend on knowing that all the readable files in a directory have the word text printed. Don't do as Berkeley did and change shell commands text to shell script. The filesystem tests are based on examining the return from a stat(2) system call. The program checks to see if the file is empty, or if it's some sort of special file. Any known file types appropriate to the system you are running on (sockets, symbolic links, or named pipes (FIFOs) on those systems that implement them) are intuited if they are defined in the system header file <sys/stat.h>. The magic tests are used to check for files with data in particular fixed formats. The canonical example of this is a binary executable (compiled program) a.out file, whose format is defined in <elf.h>, <a.out.h> and possibly <exec.h> in the standard include directory. These files have a magic number stored in a particular place near the beginning of the file that tells the UNIX operating system that the file is a binary executable, and which of several types thereof. The concept of a magic number has been applied by extension to data files. Any file with some invariant identifier at a small fixed offset into the file can usually be described in this way. The information identifying these files is read from the compiled magic file /usr/local/share/misc/magic.mgc, or the files in the directory /usr/local/share/misc/magic if the compiled file does not exist. In addition, if $HOME/.magic.mgc or $HOME/.magic exists, it will be used in preference to the system magic files. If a file does not match any of the entries in the magic file, it is examined to see if it seems to be a text file. ASCII, ISO-8859-x, non-ISO 8-bit extended-ASCII character sets (such as those used on Macintosh and IBM PC systems), UTF-8-encoded Unicode, UTF-16-encoded Unicode, and EBCDIC character sets can be distinguished by the different ranges and sequences of bytes that constitute printable text in each set. If a file passes any of these tests, its character set is reported. ASCII, ISO-8859-x, UTF-8, and extended-ASCII files are identified as text because they will be mostly readable on nearly any terminal; UTF-16 and EBCDIC are only character data because, while they contain text, it is text that will require translation before it can be read. In addition, will attempt to determine other characteristics of text-type files. If the lines of a file are terminated by CR, CRLF, or NEL, instead of the Unix-standard LF, this will be reported. Files that contain embedded escape sequences or overstriking will also be identified. Once has determined the character set used in a text-type file, it will attempt to determine in what language the file is written. The language tests look for particular strings (cf. <names.h>) that can appear anywhere in the first few blocks of a file. For example, the keyword .br indicates that the file is most likely a troff(1) input file, just as the keyword struct indicates a C program. These tests are less reliable than the previous two groups, so they are performed last. The language test routines also test for some miscellany (such as tar(1) archives, JSON files). Any file that cannot be identified as having been written in any of the character sets listed above is simply said to be data. OPTIONS top --apple Causes the command to output the file type and creator code as used by older MacOS versions. The code consists of eight letters, the first describing the file type, the latter the creator. This option works properly only for file formats that have the apple-style output defined. -b, --brief Do not prepend filenames to output lines (brief mode). -C, --compile Write a magic.mgc output file that contains a pre-parsed version of the magic file or directory. -c, --checking-printout Cause a checking printout of the parsed form of the magic file. This is usually used in conjunction with the -m option to debug a new magic file before installing it. -d Prints internal debugging information to stderr. -E On filesystem errors (file not found etc), instead of handling the error as regular output as POSIX mandates and keep going, issue an error message and exit. -e, --exclude testname Exclude the test named in testname from the list of tests made to determine the file type. Valid test names are: apptype EMX application type (only on EMX). ascii Various types of text files (this test will try to guess the text encoding, irrespective of the setting of the encoding option). encoding Different text encodings for soft magic tests. tokens Ignored for backwards compatibility. cdf Prints details of Compound Document Files. compress Checks for, and looks inside, compressed files. csv Checks Comma Separated Value files. elf Prints ELF file details, provided soft magic tests are enabled and the elf magic is found. json Examines JSON (RFC-7159) files by parsing them for compliance. soft Consults magic files. simh Examines SIMH tape files. tar Examines tar files by verifying the checksum of the 512 byte tar header. Excluding this test can provide more detailed content description by using the soft magic method. text A synonym for ascii. --exclude-quiet Like --exclude but ignore tests that does not know about. This is intended for compatibility with older versions of . --extension Print a slash-separated list of valid extensions for the file type found. -F, --separator separator Use the specified string as the separator between the filename and the file result returned. Defaults to :. -f, --files-from namefile Read the names of the files to be examined from namefile (one per line) before the argument list. Either namefile or at least one filename argument must be present; to test the standard input, use - as a filename argument. Please note that namefile is unwrapped and the enclosed filenames are processed when this option is encountered and before any further options processing is done. This allows one to process multiple lists of files with different command line arguments on the same invocation. Thus if you want to set the delimiter, you need to do it before you specify the list of files, like: -F @ -f namefile, instead of: -f namefile -F @. -h, --no-dereference This option causes symlinks not to be followed (on systems that support symbolic links). This is the default if the environment variable POSIXLY_CORRECT is not defined. -i, --mime Causes the command to output mime type strings rather than the more traditional human readable ones. Thus it may say text/plain; charset=us-ascii rather than ASCII text. --mime-type, --mime-encoding Like -i, but print only the specified element(s). -k, --keep-going Don't stop at the first match, keep going. Subsequent matches will be have the string \012- prepended. (If you want a newline, see the -r option.) The magic pattern with the highest strength (see the -l option) comes first. -l, --list Shows a list of patterns and their strength sorted descending by magic(4) strength which is used for the matching (see also the -k option). -L, --dereference This option causes symlinks to be followed, as the like- named option in ls(1) (on systems that support symbolic links). This is the default if the environment variable POSIXLY_CORRECT is defined. -m, --magic-file magicfiles Specify an alternate list of files and directories containing magic. This can be a single item, or a colon- separated list. If a compiled magic file is found alongside a file or directory, it will be used instead. -N, --no-pad Don't pad filenames so that they align in the output. -n, --no-buffer Force stdout to be flushed after checking each file. This is only useful if checking a list of files. It is intended to be used by programs that want filetype output from a pipe. -p, --preserve-date On systems that support utime(3) or utimes(2), attempt to preserve the access time of files analyzed, to pretend that never read them. -P, --parameter name=value Set various parameter limits. Name Default Explanation bytes 1M max number of bytes to read from file elf_notes 256 max ELF notes processed elf_phnum 2K max ELF program sections processed elf_shnum 32K max ELF sections processed elf_shsize 128MB max ELF section size processed encoding 65K max number of bytes to determine encoding indir 50 recursion limit for indirect magic name 50 use count limit for name/use magic regex 8K length limit for regex searches -r, --raw Don't translate unprintable characters to \ooo. Normally translates unprintable characters to their octal representation. -s, --special-files Normally, only attempts to read and determine the type of argument files which stat(2) reports are ordinary files. This prevents problems, because reading special files may have peculiar consequences. Specifying the -s option causes to also read argument files which are block or character special files. This is useful for determining the filesystem types of the data in raw disk partitions, which are block special files. This option also causes to disregard the file size as reported by stat(2) since on some systems it reports a zero size for raw disk partitions. -S, --no-sandbox On systems where libseccomp (https://github.com/seccomp/libseccomp ) is available, the -S option disables sandboxing which is enabled by default. This option is needed for to execute external decompressing programs, i.e. when the -z option is specified and the built-in decompressors are not available. On systems where sandboxing is not available, this option has no effect. -v, --version Print the version of the program and exit. -z, --uncompress Try to look inside compressed files. -Z, --uncompress-noreport Try to look inside compressed files, but report information about the contents only not the compression. -0, --print0 Output a null character \0 after the end of the filename. Nice to cut(1) the output. This does not affect the separator, which is still printed. If this option is repeated more than once, then prints just the filename followed by a NUL followed by the description (or ERROR: text) followed by a second NUL for each entry. --help Print a help message and exit. ENVIRONMENT top The environment variable MAGIC can be used to set the default magic file name. If that variable is set, then will not attempt to open $HOME/.magic. adds .mgc to the value of this variable as appropriate. The environment variable POSIXLY_CORRECT controls (on systems that support symbolic links), whether will attempt to follow symlinks or not. If set, then follows symlink, otherwise it does not. This is also controlled by the -L and -h options. FILES top /usr/local/share/misc/magic.mgc Default compiled list of magic. /usr/local/share/misc/magic Directory containing default magic files. EXIT STATUS top will exit with 0 if the operation was successful or >0 if an error was encountered. The following errors cause diagnostic messages, but don't affect the program exit code (as POSIX requires), unless -E is specified: A file cannot be found There is no permission to read a file The file type cannot be determined EXAMPLES top $ file file.c file /dev/{wd0a,hda} file.c: C program text file: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), stripped /dev/wd0a: block special (0/0) /dev/hda: block special (3/0) $ file -s /dev/wd0{b,d} /dev/wd0b: data /dev/wd0d: x86 boot sector $ file -s /dev/hda{,1,2,3,4,5,6,7,8,9,10} /dev/hda: x86 boot sector /dev/hda1: Linux/i386 ext2 filesystem /dev/hda2: x86 boot sector /dev/hda3: x86 boot sector, extended partition table /dev/hda4: Linux/i386 ext2 filesystem /dev/hda5: Linux/i386 swap file /dev/hda6: Linux/i386 swap file /dev/hda7: Linux/i386 swap file /dev/hda8: Linux/i386 swap file /dev/hda9: empty /dev/hda10: empty $ file -i file.c file /dev/{wd0a,hda} file.c: text/x-c file: application/x-executable /dev/hda: application/x-not-regular-file /dev/wd0a: application/x-not-regular-file SEE ALSO top hexdump(1), od(1), strings(1), magic(4) STANDARDS CONFORMANCE top This program is believed to exceed the System V Interface Definition of FILE(CMD), as near as one can determine from the vague language contained therein. Its behavior is mostly compatible with the System V program of the same name. This version knows more magic, however, so it will produce different (albeit more accurate) output in many cases. The one significant difference between this version and System V is that this version treats any white space as a delimiter, so that spaces in pattern strings must be escaped. For example, >10 string language impress (imPRESS data) in an existing magic file would have to be changed to >10 string language\ impress (imPRESS data) In addition, in this version, if a pattern string contains a backslash, it must be escaped. For example 0 string \begindata Andrew Toolkit document in an existing magic file would have to be changed to 0 string \\begindata Andrew Toolkit document SunOS releases 3.2 and later from Sun Microsystems include a command derived from the System V one, but with some extensions. This version differs from Sun's only in minor ways. It includes the extension of the & operator, used as, for example, >16 long&0x7fffffff >0 not stripped SECURITY top On systems where libseccomp (https://github.com/seccomp/libseccomp ) is available, is enforces limiting system calls to only the ones necessary for the operation of the program. This enforcement does not provide any security benefit when is asked to decompress input files running external programs with the -z option. To enable execution of external decompressors, one needs to disable sandboxing using the -S option. MAGIC DIRECTORY top The magic file entries have been collected from various sources, mainly USENET, and contributed by various authors. Christos Zoulas (address below) will collect additional or corrected magic file entries. A consolidation of magic file entries will be distributed periodically. The order of entries in the magic file is significant. Depending on what system you are using, the order that they are put together may be incorrect. If your old command uses a magic file, keep the old magic file around for comparison purposes (rename it to /usr/local/share/misc/magic.orig). HISTORY top There has been a command in every UNIX since at least Research Version 4 (man page dated November, 1973). The System V version introduced one significant major change: the external list of magic types. This slowed the program down slightly but made it a lot more flexible. This program, based on the System V version, was written by Ian Darwin ian@darwinsys.com without looking at anybody else's source code. John Gilmore revised the code extensively, making it better than the first version. Geoff Collyer found several inadequacies and provided some magic file entries. Contributions of the & operator by Rob McMahon, cudcv@warwick.ac.uk, 1989. Guy Harris, guy@netapp.com, made many changes from 1993 to the present. Primary development and maintenance from 1990 to the present by Christos Zoulas christos@astron.com. Altered by Chris Lowth chris@lowth.com, 2000: handle the -i option to output mime type strings, using an alternative magic file and internal logic. Altered by Eric Fischer enf@pobox.com, July, 2000, to identify character codes and attempt to identify the languages of non- ASCII files. Altered by Reuben Thomas rrt@sc3d.org, 2007-2011, to improve MIME support, merge MIME and non-MIME magic, support directories as well as files of magic, apply many bug fixes, update and fix a lot of magic, improve the build system, improve the documentation, and rewrite the Python bindings in pure Python. The list of contributors to the magic directory (magic files) is too long to include here. You know who you are; thank you. Many contributors are listed in the source files. LEGAL NOTICE top Copyright (c) Ian F. Darwin, Toronto, Canada, 1986-1999. Covered by the standard Berkeley Software Distribution copyright; see the file COPYING in the source distribution. The files tar.h and is_tar.c were written by John Gilmore from his public-domain tar(1) program, and are not covered by the above license. BUGS top Please report bugs and send patches to the bug tracker at https://bugs.astron.com/ or the mailing list at file@astron.com (visit https://mailman.astron.com/mailman/listinfo/file first to subscribe). TODO top Fix output so that tests for MIME and APPLE flags are not needed all over the place, and actual output is only done in one place. This needs a design. Suggestion: push possible outputs on to a list, then pick the last-pushed (most specific, one hopes) value at the end, or use a default if the list is empty. This should not slow down evaluation. The handling of MAGIC_CONTINUE and printing \012- between entries is clumsy and complicated; refactor and centralize. Some of the encoding logic is hard-coded in encoding.c and can be moved to the magic files if we had a !:charset annotation. Continue to squash all magic bugs. See Debian BTS for a good source. Store arbitrarily long strings, for example for %s patterns, so that they can be printed out. Fixes Debian bug #271672. This can be done by allocating strings in a string pool, storing the string pool at the end of the magic file and converting all the string pointers to relative offsets from the string pool. Add syntax for relative offsets after current level (Debian bug #466037). Make file -ki work, i.e. give multiple MIME types. Add a zip library so we can peek inside Office2007 documents to print more details about their contents. Add an option to print URLs for the sources of the file descriptions. Combine script searches and add a way to map executable names to MIME types (e.g. have a magic value for !:mime which causes the resulting string to be looked up in a table). This would avoid adding the same magic repeatedly for each new hash-bang interpreter. When a file descriptor is available, we can skip and adjust the buffer instead of the hacky buffer management we do now. Fix name and use to check for consistency at compile time (duplicate name, use pointing to undefined name ). Make name / use more efficient by keeping a sorted list of names. Special-case ^ to flip endianness in the parser so that it does not have to be escaped, and document it. If the offsets specified internally in the file exceed the buffer size ( HOWMANY variable in file.h), then we don't seek to that offset, but we give up. It would be better if buffer managements was done when the file descriptor is available so we can seek around the file. One must be careful though because this has performance and thus security considerations, because one can slow down things by repeatedly seeking. There is support now for keeping separate buffers and having offsets from the end of the file, but the internal buffer management still needs an overhaul. AVAILABILITY top You can obtain the original author's latest version by anonymous FTP on ftp.astron.com in the directory /pub/file/file-X.YZ.tar.gz. COLOPHON top This page is part of the file (a file type guesser) project. Information about the project can be found at http://www.darwinsys.com/file/. If you have a bug report for this manual page, see http://bugs.gw.com/my_view_page.php. This page was obtained from the project's upstream Git read-only mirror of the CVS repository https://github.com/glensc/file on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-12-21.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU May 21, 2023 FILE(1) Pages that refer to this page: dh_installmanpages(1), dh_strip(1), ippeveprinter(1), pmcd(1), scr_dump(5), term(5), suffixes(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. sort(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training sort(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON SORT(1) User Commands SORT(1) NAME top sort - sort lines of text files SYNOPSIS top sort [OPTION]... [FILE]... sort [OPTION]... --files0-from=F DESCRIPTION top Write sorted concatenation of all FILE(s) to standard output. With no FILE, or when FILE is -, read standard input. Mandatory arguments to long options are mandatory for short options too. Ordering options: -b, --ignore-leading-blanks ignore leading blanks -d, --dictionary-order consider only blanks and alphanumeric characters -f, --ignore-case fold lower case to upper case characters -g, --general-numeric-sort compare according to general numerical value -i, --ignore-nonprinting consider only printable characters -M, --month-sort compare (unknown) < 'JAN' < ... < 'DEC' -h, --human-numeric-sort compare human readable numbers (e.g., 2K 1G) -n, --numeric-sort compare according to string numerical value -R, --random-sort shuffle, but group identical keys. See shuf(1) --random-source=FILE get random bytes from FILE -r, --reverse reverse the result of comparisons --sort=WORD sort according to WORD: general-numeric -g, human-numeric -h, month -M, numeric -n, random -R, version -V -V, --version-sort natural sort of (version) numbers within text Other options: --batch-size=NMERGE merge at most NMERGE inputs at once; for more use temp files -c, --check, --check=diagnose-first check for sorted input; do not sort -C, --check=quiet, --check=silent like -c, but do not report first bad line --compress-program=PROG compress temporaries with PROG; decompress them with PROG -d --debug annotate the part of the line used to sort, and warn about questionable usage to stderr --files0-from=F read input from the files specified by NUL-terminated names in file F; If F is - then read names from standard input -k, --key=KEYDEF sort via a key; KEYDEF gives location and type -m, --merge merge already sorted files; do not sort -o, --output=FILE write result to FILE instead of standard output -s, --stable stabilize sort by disabling last-resort comparison -S, --buffer-size=SIZE use SIZE for main memory buffer -t, --field-separator=SEP use SEP instead of non-blank to blank transition -T, --temporary-directory=DIR use DIR for temporaries, not $TMPDIR or /tmp; multiple options specify multiple directories --parallel=N change the number of sorts run concurrently to N -u, --unique with -c, check for strict ordering; without -c, output only the first of an equal run -z, --zero-terminated line delimiter is NUL, not newline --help display this help and exit --version output version information and exit KEYDEF is F[.C][OPTS][,F[.C][OPTS]] for start and stop position, where F is a field number and C a character position in the field; both are origin 1, and the stop position defaults to the line's end. If neither -t nor -b is in effect, characters in a field are counted from the beginning of the preceding whitespace. OPTS is one or more single-letter ordering options [bdfgiMhnRrV], which override global ordering options for that key. If no key is given, use the entire line as the key. Use --debug to diagnose incorrect key usage. SIZE may be followed by the following multiplicative suffixes: % 1% of memory, b 1, K 1024 (default), and so on for M, G, T, P, E, Z, Y, R, Q. *** WARNING *** The locale specified by the environment affects sort order. Set LC_ALL=C to get the traditional sort order that uses native byte values. AUTHOR top Written by Mike Haertel and Paul Eggert. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top shuf(1), uniq(1) Full documentation <https://www.gnu.org/software/coreutils/sort> or available locally via: info '(coreutils) sort invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 SORT(1) Pages that refer to this page: column(1), grep(1), look(1), prlimit(1), ps(1), uniq(1), qsort(3), environ(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a report of the contents of a USB drive mounted at find /path/to/drive Bash Command:<START>find /path/to/drive -type f -exec file -b '{}' \; -printf '%s\n' | awk -F , 'NR%2 {i=$1} NR%2==0 {a[i]+=$1} END {for (i in a) printf("%12u %s\n",a[i],i)}' | sort -nr<END> |
Create a rsa key of 2048 bits with comment "michael" and store it in file "key". | ssh-keygen -b 2048 -t rsa -f key -C michael | ['ssh-keygen'] | Output a Bash command to accomplish the following task. Task: Create a rsa key of 2048 bits with comment "michael" and store it in file "key". Bash Command:<START>ssh-keygen -b 2048 -t rsa -f key -C michael<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh-keygen\n\n> Generate SSH keys used for authentication, password-less logins, and other things.\n> More information: <https://man.openbsd.org/ssh-keygen>.\n\n- Generate a key interactively:\n\n`ssh-keygen`\n\n- Generate an ed25519 key with 32 key derivation function rounds and save the key to a specific file:\n\n`ssh-keygen -t {{ed25519}} -a {{32}} -f {{~/.ssh/filename}}`\n\n- Generate an RSA 4096-bit key with email as a comment:\n\n`ssh-keygen -t {{rsa}} -b {{4096}} -C "{{comment|email}}"`\n\n- Remove the keys of a host from the known_hosts file (useful when a known host has a new key):\n\n`ssh-keygen -R {{remote_host}}`\n\n- Retrieve the fingerprint of a key in MD5 Hex:\n\n`ssh-keygen -l -E {{md5}} -f {{~/.ssh/filename}}`\n\n- Change the password of a key:\n\n`ssh-keygen -p -f {{~/.ssh/filename}}`\n\n- Change the type of the key format (for example from OPENSSH format to PEM), the file will be rewritten in-place:\n\n`ssh-keygen -p -N "" -m {{PEM}} -f {{~/.ssh/OpenSSH_private_key}}`\n\n- Retrieve public key from secret key:\n\n`ssh-keygen -y -f {{~/.ssh/OpenSSH_private_key}}`\n Task: Create a rsa key of 2048 bits with comment "michael" and store it in file "key". Bash Command:<START>ssh-keygen -b 2048 -t rsa -f key -C michael<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh-keygen(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh-keygen(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | MODULI GENERATION | CERTIFICATES | FIDO AUTHENTICATOR | KEY REVOCATION LISTS | ALLOWED SIGNERS | ENVIRONMENT | FILES | SEE ALSO | AUTHORS | COLOPHON SSH-KEYGEN(1) General Commands Manual SSH-KEYGEN(1) NAME top ssh-keygen OpenSSH authentication key utility SYNOPSIS top ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile] [-m format] [-N new_passphrase] [-O option] [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa] [-w provider] [-Z cipher] ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase] [-P old_passphrase] [-Z cipher] ssh-keygen -i [-f input_keyfile] [-m key_format] ssh-keygen -e [-f input_keyfile] [-m key_format] ssh-keygen -y [-f input_keyfile] ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase] ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile] ssh-keygen -B [-f input_keyfile] ssh-keygen -D pkcs11 ssh-keygen -F hostname [-lv] [-f known_hosts_file] ssh-keygen -H [-f known_hosts_file] ssh-keygen -K [-a rounds] [-w provider] ssh-keygen -R hostname [-f known_hosts_file] ssh-keygen -r hostname [-g] [-f input_keyfile] ssh-keygen -M generate [-O option] output_file ssh-keygen -M screen [-f input_file] [-O option] output_file ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider] [-n principals] [-O option] [-V validity_interval] [-z serial_number] file ... ssh-keygen -L [-f input_keyfile] ssh-keygen -A [-a rounds] [-f prefix_path] ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number] file ... ssh-keygen -Q [-l] -f krl_file file ... ssh-keygen -Y find-principals [-O option] -s signature_file -f allowed_signers_file ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file ssh-keygen -Y check-novalidate [-O option] -n namespace -s signature_file ssh-keygen -Y sign [-O option] -f key_file -n namespace file ... ssh-keygen -Y verify [-O option] -f allowed_signers_file -I signer_identity -n namespace -s signature_file [-r revocation_file] DESCRIPTION top generates, manages and converts authentication keys for ssh(1). can create keys for use by SSH protocol version 2. The type of key to be generated is specified with the -t option. If invoked without any arguments, will generate an Ed25519 key. is also used to generate groups for use in Diffie-Hellman group exchange (DH-GEX). See the MODULI GENERATION section for details. Finally, can be used to generate and update Key Revocation Lists, and to test whether given keys have been revoked by one. See the KEY REVOCATION LISTS section for details. Normally each user wishing to use SSH with public key authentication runs this once to create the authentication key in ~/.ssh/id_dsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk or ~/.ssh/id_rsa. Additionally, the system administrator may use this to generate host keys, as seen in /etc/rc. Normally this program generates the key and asks for a file in which to store the private key. The public key is stored in a file with the same name but .pub appended. The program also asks for a passphrase. The passphrase may be empty to indicate no passphrase (host keys must have an empty passphrase), or it may be a string of arbitrary length. A passphrase is similar to a password, except it can be a phrase with a series of words, punctuation, numbers, whitespace, or any string of characters you want. Good passphrases are 10-30 characters long, are not simple sentences or otherwise easily guessable (English prose has only 1-2 bits of entropy per character, and provides very bad passphrases), and contain a mix of upper and lowercase letters, numbers, and non-alphanumeric characters. The passphrase can be changed later by using the -p option. There is no way to recover a lost passphrase. If the passphrase is lost or forgotten, a new key must be generated and the corresponding public key copied to other machines. will by default write keys in an OpenSSH-specific format. This format is preferred as it offers better protection for keys at rest as well as allowing storage of key comments within the private key file itself. The key comment may be useful to help identify the key. The comment is initialized to user@host when the key is created, but can be changed using the -c option. It is still possible for to write the previously-used PEM format private keys using the -m flag. This may be used when generating new keys, and existing new-format keys may be converted using this option in conjunction with the -p (change passphrase) flag. After a key is generated, will ask where the keys should be placed to be activated. The options are as follows: -A Generate host keys of all default key types (rsa, ecdsa, and ed25519) if they do not already exist. The host keys are generated with the default key file path, an empty passphrase, default bits for the key type, and default comment. If -f has also been specified, its argument is used as a prefix to the default path for the resulting host key files. This is used by /etc/rc to generate new host keys. -a rounds When saving a private key, this option specifies the number of KDF (key derivation function, currently bcrypt_pbkdf(3)) rounds used. Higher numbers result in slower passphrase verification and increased resistance to brute-force password cracking (should the keys be stolen). The default is 16 rounds. -B Show the bubblebabble digest of specified private or public key file. -b bits Specifies the number of bits in the key to create. For RSA keys, the minimum size is 1024 bits and the default is 3072 bits. Generally, 3072 bits is considered sufficient. DSA keys must be exactly 1024 bits as specified by FIPS 186-2. For ECDSA keys, the -b flag determines the key length by selecting from one of three elliptic curve sizes: 256, 384 or 521 bits. Attempting to use bit lengths other than these three values for ECDSA keys will fail. ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the -b flag will be ignored. -C comment Provides a new comment. -c Requests changing the comment in the private and public key files. The program will prompt for the file containing the private keys, for the passphrase if the key has one, and for the new comment. -D pkcs11 Download the public keys provided by the PKCS#11 shared library pkcs11. When used in combination with -s, this option indicates that a CA key resides in a PKCS#11 token (see the CERTIFICATES section for details). -E fingerprint_hash Specifies the hash algorithm used when displaying key fingerprints. Valid options are: md5 and sha256. The default is sha256. -e This option will read a private or public OpenSSH key file and print to stdout a public key in one of the formats specified by the -m option. The default export format is RFC4716. This option allows exporting OpenSSH keys for use by other programs, including several commercial SSH implementations. -F hostname | [hostname]:port Search for the specified hostname (with optional port number) in a known_hosts file, listing any occurrences found. This option is useful to find hashed host names or addresses and may also be used in conjunction with the -H option to print found keys in a hashed format. -f filename Specifies the filename of the key file. -g Use generic DNS format when printing fingerprint resource records using the -r command. -H Hash a known_hosts file. This replaces all hostnames and addresses with hashed representations within the specified file; the original content is moved to a file with a .old suffix. These hashes may be used normally by ssh and sshd, but they do not reveal identifying information should the file's contents be disclosed. This option will not modify existing hashed hostnames and is therefore safe to use on files that mix hashed and non-hashed names. -h When signing a key, create a host certificate instead of a user certificate. See the CERTIFICATES section for details. -I certificate_identity Specify the key identity when signing a public key. See the CERTIFICATES section for details. -i This option will read an unencrypted private (or public) key file in the format specified by the -m option and print an OpenSSH compatible private (or public) key to stdout. This option allows importing keys from other software, including several commercial SSH implementations. The default import format is RFC4716. -K Download resident keys from a FIDO authenticator. Public and private key files will be written to the current directory for each downloaded key. If multiple FIDO authenticators are attached, keys will be downloaded from the first touched authenticator. See the FIDO AUTHENTICATOR section for more information. -k Generate a KRL file. In this mode, will generate a KRL file at the location specified via the -f flag that revokes every key or certificate presented on the command line. Keys/certificates to be revoked may be specified by public key file or using the format described in the KEY REVOCATION LISTS section. -L Prints the contents of one or more certificates. -l Show fingerprint of specified public key file. For RSA and DSA keys tries to find the matching public key file and prints its fingerprint. If combined with -v, a visual ASCII art representation of the key is supplied with the fingerprint. -M generate Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for eventual use by the diffie-hellman-group-exchange-* key exchange methods. The numbers generated by this operation must be further screened before use. See the MODULI GENERATION section for more information. -M screen Screen candidate parameters for Diffie-Hellman Group Exchange. This will accept a list of candidate numbers and test that they are safe (Sophie Germain) primes with acceptable group generators. The results of this operation may be added to the /etc/moduli file. See the MODULI GENERATION section for more information. -m key_format Specify a key format for key generation, the -i (import), -e (export) conversion options, and the -p change passphrase operation. The latter may be used to convert between OpenSSH private key and PEM private key formats. The supported key formats are: RFC4716 (RFC 4716/SSH2 public or private key), PKCS8 (PKCS8 public or private key) or PEM (PEM public key). By default OpenSSH will write newly-generated private keys in its own format, but when converting public keys for export the default format is RFC4716. Setting a format of PEM when generating or updating a supported private key type will cause the key to be stored in the legacy PEM private key format. -N new_passphrase Provides the new passphrase. -n principals Specify one or more principals (user or host names) to be included in a certificate when signing a key. Multiple principals may be specified, separated by commas. See the CERTIFICATES section for details. -O option Specify a key/value option. These are specific to the operation that has been requested to perform. When signing certificates, one of the options listed in the CERTIFICATES section may be specified here. When performing moduli generation or screening, one of the options listed in the MODULI GENERATION section may be specified. When generating FIDO authenticator-backed keys, the options listed in the FIDO AUTHENTICATOR section may be specified. When performing signature-related options using the -Y flag, the following options are accepted: hashalg=algorithm Selects the hash algorithm to use for hashing the message to be signed. Valid algorithms are sha256 and sha512. The default is sha512. print-pubkey Print the full public key to standard output after signature verification. verify-time=timestamp Specifies a time to use when validating signatures instead of the current time. The time may be specified as a date or time in the YYYYMMDD[Z] or in YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. When generating SSHFP DNS records from public keys using the -r flag, the following options are accepted: hashalg=algorithm Selects a hash algorithm to use when printing SSHFP records using the -D flag. Valid algorithms are sha1 and sha256. The default is to print both. The -O option may be specified multiple times. -P passphrase Provides the (old) passphrase. -p Requests changing the passphrase of a private key file instead of creating a new private key. The program will prompt for the file containing the private key, for the old passphrase, and twice for the new passphrase. -Q Test whether keys have been revoked in a KRL. If the -l option is also specified then the contents of the KRL will be printed. -q Silence ssh-keygen. -R hostname | [hostname]:port Removes all keys belonging to the specified hostname (with optional port number) from a known_hosts file. This option is useful to delete hashed hosts (see the -H option above). -r hostname Print the SSHFP fingerprint resource record named hostname for the specified public key file. -s ca_key Certify (sign) a public key using the specified CA key. See the CERTIFICATES section for details. When generating a KRL, -s specifies a path to a CA public key file used to revoke certificates directly by key ID or serial number. See the KEY REVOCATION LISTS section for details. -t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa Specifies the type of key to create. The possible values are dsa, ecdsa, ecdsa-sk, ed25519, ed25519-sk, or rsa. This flag may also be used to specify the desired signature type when signing certificates using an RSA CA key. The available RSA signature variants are ssh-rsa (SHA1 signatures, not recommended), rsa-sha2-256, and rsa-sha2-512 (the default). -U When used in combination with -s or -Y sign, this option indicates that a CA key resides in a ssh-agent(1). See the CERTIFICATES section for more information. -u Update a KRL. When specified with -k, keys listed via the command line are added to the existing KRL rather than a new KRL being created. -V validity_interval Specify a validity interval when signing a certificate. A validity interval may consist of a single time, indicating that the certificate is valid beginning now and expiring at that time, or may consist of two times separated by a colon to indicate an explicit time interval. The start time may be specified as: The string always to indicate the certificate has no specified start time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time before the current system time consisting of a minus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. The end time may be specified similarly to the start time: The string forever to indicate the certificate has no specified end time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time after the current system time consisting of a plus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. For example: +52w1d Valid from now to 52 weeks and one day from now. -4w:+4w Valid from four weeks ago to four weeks from now. 20100101123000:20110101123000 Valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011. 20100101123000Z:20110101123000Z Similar, but interpreted in the UTC time zone rather than the system time zone. -1d:20110101 Valid from yesterday to midnight, January 1st, 2011. 0x1:0x2000000000 Valid from roughly early 1970 to May 2033. -1m:forever Valid from one minute ago and never expiring. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful for debugging moduli generation. Multiple -v options increase the verbosity. The maximum is 3. -w provider Specifies a path to a library that will be used when creating FIDO authenticator-hosted keys, overriding the default of using the internal USB HID support. -Y find-principals Find the principal(s) associated with the public key of a signature, provided using the -s flag in an authorized signers file provided using the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. If one or more matching principals are found, they are returned on standard output. -Y match-principals Find principal matching the principal name provided using the -I flag in the authorized signers file specified using the -f flag. If one or more matching principals are found, they are returned on standard output. -Y check-novalidate Checks that a signature generated using -Y sign has a valid structure. This does not validate if a signature comes from an authorized signer. When testing a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag. Successful testing of the signature is signalled by returning a zero exit status. -Y sign Cryptographically sign a file or some data using an SSH key. When signing, accepts zero or more files to sign on the command-line - if no files are specified then will sign data presented on standard input. Signatures are written to the path of the input file with .sig appended, or to standard output if the message to be signed was read from standard input. The key used for signing is specified using the -f option and may refer to either a private key, or a public key with the private half available via ssh-agent(1). An additional signature namespace, used to prevent signature confusion across different domains of use (e.g. file signing vs email signing) must be provided via the -n flag. Namespaces are arbitrary strings, and may include: file for file signing, email for email signing. For custom uses, it is recommended to use names following a NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces. -Y verify Request to verify a signature generated using -Y sign as described above. When verifying a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag, along with the identity of the signer using -I and a list of allowed signers via the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. A file containing revoked keys can be passed using the -r flag. The revocation file may be a KRL or a one-per-line list of public keys. Successful verification by an authorized signer is signalled by returning a zero exit status. -y This option will read a private OpenSSH format file and print an OpenSSH public key to stdout. -Z cipher Specifies the cipher to use for encryption when writing an OpenSSH-format private key file. The list of available ciphers may be obtained using "ssh -Q cipher". The default is aes256-ctr. -z serial_number Specifies a serial number to be embedded in the certificate to distinguish this certificate from others from the same CA. If the serial_number is prefixed with a + character, then the serial number will be incremented for each certificate signed on a single command-line. The default serial number is zero. When generating a KRL, the -z flag is used to specify a KRL version number. MODULI GENERATION top may be used to generate groups for the Diffie-Hellman Group Exchange (DH-GEX) protocol. Generating these groups is a two- step process: first, candidate primes are generated using a fast, but memory intensive process. These candidate primes are then tested for suitability (a CPU-intensive process). Generation of primes is performed using the -M generate option. The desired length of the primes may be specified by the -O bits option. For example: # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates By default, the search for primes begins at a random point in the desired length range. This may be overridden using the -O start option, which specifies a different start point (in hex). Once a set of candidates have been generated, they must be screened for suitability. This may be performed using the -M screen option. In this mode will read candidates from standard input (or a file specified using the -f option). For example: # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048 By default, each candidate will be subjected to 100 primality tests. This may be overridden using the -O prime-tests option. The DH generator value will be chosen automatically for the prime under consideration. If a specific generator is desired, it may be requested using the -O generator option. Valid generator values are 2, 3, and 5. Screened DH groups may be installed in /etc/moduli. It is important that this file contains moduli of a range of bit lengths. A number of options are available for moduli generation and screening via the -O flag: lines=number Exit after screening the specified number of lines while performing DH candidate screening. start-line=line-number Start screening at the specified line number while performing DH candidate screening. checkpoint=filename Write the last line processed to the specified file while performing DH candidate screening. This will be used to skip lines in the input file that have already been processed if the job is restarted. memory=mbytes Specify the amount of memory to use (in megabytes) when generating candidate moduli for DH-GEX. start=hex-value Specify start point (in hex) when generating candidate moduli for DH-GEX. generator=value Specify desired generator (in decimal) when testing candidate moduli for DH-GEX. CERTIFICATES top supports signing of keys to produce certificates that may be used for user or host authentication. Certificates consist of a public key, some identity information, zero or more principal (user or host) names and a set of options that are signed by a Certification Authority (CA) key. Clients or servers may then trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys. Note that OpenSSH certificates are a different, and much simpler, format to the X.509 certificates used in ssl(8). supports two types of certificates: user and host. User certificates authenticate users to servers, whereas host certificates authenticate server hosts to users. To generate a user certificate: $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub The resultant certificate will be placed in /path/to/user_key-cert.pub. A host certificate requires the -h option: $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub The host certificate will be output to /path/to/host_key-cert.pub. It is possible to sign using a CA key stored in a PKCS#11 token by providing the token library using -D and identifying the CA key by providing its public half as an argument to -s: $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub Similarly, it is possible for the CA key to be hosted in a ssh-agent(1). This is indicated by the -U flag and, again, the CA key must be identified by its public half. $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub In all cases, key_id is a "key identifier" that is logged by the server when the certificate is used for authentication. Certificates may be limited to be valid for a set of principal (user/host) names. By default, generated certificates are valid for all users or hosts. To generate a certificate for a specified set of principals: $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub $ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub Additional limitations on the validity and use of user certificates may be specified through certificate options. A certificate option may disable features of the SSH session, may be valid only when presented from particular source addresses or may force the use of a specific command. The options that are valid for user certificates are: clear Clear all enabled permissions. This is useful for clearing the default set of permissions so permissions may be added individually. critical:name[=contents] extension:name[=contents] Includes an arbitrary certificate critical option or extension. The specified name should include a domain suffix, e.g. name@example.com. If contents is specified then it is included as the contents of the extension/option encoded as a string, otherwise the extension/option is created with no contents (usually indicating a flag). Extensions may be ignored by a client or server that does not recognise them, whereas unknown critical options will cause the certificate to be refused. force-command=command Forces the execution of command instead of any shell or command specified by the user when the certificate is used for authentication. no-agent-forwarding Disable ssh-agent(1) forwarding (permitted by default). no-port-forwarding Disable port forwarding (permitted by default). no-pty Disable PTY allocation (permitted by default). no-user-rc Disable execution of ~/.ssh/rc by sshd(8) (permitted by default). no-x11-forwarding Disable X11 forwarding (permitted by default). permit-agent-forwarding Allows ssh-agent(1) forwarding. permit-port-forwarding Allows port forwarding. permit-pty Allows PTY allocation. permit-user-rc Allows execution of ~/.ssh/rc by sshd(8). permit-X11-forwarding Allows X11 forwarding. no-touch-required Do not require signatures made using this key include demonstration of user presence (e.g. by having the user touch the authenticator). This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. source-address=address_list Restrict the source addresses from which the certificate is considered valid. The address_list is a comma- separated list of one or more address/netmask pairs in CIDR format. verify-required Require signatures made using this key indicate that the user was first verified. This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. At present, no standard options are valid for host keys. Finally, certificates may be defined with a validity lifetime. The -V option allows specification of certificate start and end times. A certificate that is presented at a time outside this range will not be considered valid. By default, certificates are valid from the Unix Epoch to the distant future. For certificates to be used for user or host authentication, the CA public key must be trusted by sshd(8) or ssh(1). Refer to those manual pages for details. FIDO AUTHENTICATOR top is able to generate FIDO authenticator-backed keys, after which they may be used much like any other key type supported by OpenSSH, so long as the hardware authenticator is attached when the keys are used. FIDO authenticators generally require the user to explicitly authorise operations by touching or tapping them. FIDO keys consist of two parts: a key handle part stored in the private key file on disk, and a per-device private key that is unique to each FIDO authenticator and that cannot be exported from the authenticator hardware. These are combined by the hardware at authentication time to derive the real key that is used to sign authentication challenges. Supported key types are ecdsa-sk and ed25519-sk. The options that are valid for FIDO keys are: application Override the default FIDO application/origin string of ssh:. This may be useful when generating host or domain-specific resident keys. The specified application string must begin with ssh:. challenge=path Specifies a path to a challenge string that will be passed to the FIDO authenticator during key generation. The challenge string may be used as part of an out-of- band protocol for key enrollment (a random challenge is used by default). device Explicitly specify a fido(4) device to use, rather than letting the authenticator middleware select one. no-touch-required Indicate that the generated private key should not require touch events (user presence) when making signatures. Note that sshd(8) will refuse such signatures by default, unless overridden via an authorized_keys option. resident Indicate that the key handle should be stored on the FIDO authenticator itself. This makes it easier to use the authenticator on multiple computers. Resident keys may be supported on FIDO2 authenticators and typically require that a PIN be set on the authenticator prior to generation. Resident keys may be loaded off the authenticator using ssh-add(1). Storing both parts of a key on a FIDO authenticator increases the likelihood of an attacker being able to use a stolen authenticator device. user A username to be associated with a resident key, overriding the empty default username. Specifying a username may be useful when generating multiple resident keys for the same application name. verify-required Indicate that this private key should require user verification for each signature. Not all FIDO authenticators support this option. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. write-attestation=path May be used at key generation time to record the attestation data returned from FIDO authenticators during key generation. This information is potentially sensitive. By default, this information is discarded. KEY REVOCATION LISTS top is able to manage OpenSSH format Key Revocation Lists (KRLs). These binary files specify keys or certificates to be revoked using a compact format, taking as little as one bit per certificate if they are being revoked by serial number. KRLs may be generated using the -k flag. This option reads one or more files from the command line and generates a new KRL. The files may either contain a KRL specification (see below) or public keys, listed one per line. Plain public keys are revoked by listing their hash or contents in the KRL and certificates revoked by serial number or key ID (if the serial is zero or not available). Revoking keys using a KRL specification offers explicit control over the types of record used to revoke keys and may be used to directly revoke certificates by serial number or key ID without having the complete original certificate on hand. A KRL specification consists of lines containing one of the following directives followed by a colon and some directive-specific information. serial: serial_number[-serial_number] Revokes a certificate with the specified serial number. Serial numbers are 64-bit values, not including zero and may be expressed in decimal, hex or octal. If two serial numbers are specified separated by a hyphen, then the range of serial numbers including and between each is revoked. The CA key must have been specified on the command line using the -s option. id: key_id Revokes a certificate with the specified key ID string. The CA key must have been specified on the command line using the -s option. key: public_key Revokes the specified key. If a certificate is listed, then it is revoked as a plain public key. sha1: public_key Revokes the specified key by including its SHA1 hash in the KRL. sha256: public_key Revokes the specified key by including its SHA256 hash in the KRL. KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions prior to 7.9. hash: fingerprint Revokes a key using a fingerprint hash, as obtained from a sshd(8) authentication log message or the -l flag. Only SHA256 fingerprints are supported here and resultant KRLs are not supported by OpenSSH versions prior to 7.9. KRLs may be updated using the -u flag in addition to -k. When this option is specified, keys listed via the command line are merged into the KRL, adding to those already there. It is also possible, given a KRL, to test whether it revokes a particular key (or keys). The -Q flag will query an existing KRL, testing each key specified on the command line. If any key listed on the command line has been revoked (or an error encountered) then will exit with a non-zero exit status. A zero exit status will only be returned if no key was revoked. ALLOWED SIGNERS top When verifying signatures, uses a simple list of identities and keys to determine whether a signature comes from an authorized source. This "allowed signers" file uses a format patterned after the AUTHORIZED_KEYS FILE FORMAT described in sshd(8). Each line of the file contains the following space-separated fields: principals, options, keytype, base64-encoded key. Empty lines and lines starting with a # are ignored as comments. The principals field is a pattern-list (see PATTERNS in ssh_config(5)) consisting of one or more comma-separated USER@DOMAIN identity patterns that are accepted for signing. When verifying, the identity presented via the -I option must match a principals pattern in order for the corresponding key to be considered acceptable for verification. The options (if present) consist of comma-separated option specifications. No spaces are permitted, except within double quotes. The following option specifications are supported (note that option keywords are case-insensitive): cert-authority Indicates that this key is accepted as a certificate authority (CA) and that certificates signed by this CA may be accepted for verification. namespaces=namespace-list Specifies a pattern-list of namespaces that are accepted for this key. If this option is present, the signature namespace embedded in the signature object and presented on the verification command-line must match the specified list before the key will be considered acceptable. valid-after=timestamp Indicates that the key is valid for use at or after the specified timestamp, which may be a date or time in the YYYYMMDD[Z] or YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. valid-before=timestamp Indicates that the key is valid for use at or before the specified timestamp. When verifying signatures made by certificates, the expected principal name must match both the principals pattern in the allowed signers file and the principals embedded in the certificate itself. An example allowed signers file: # Comments allowed at start of line user1@example.com,user2@example.com ssh-rsa AAAAX1... # A certificate authority, trusted for all principals in a domain. *@example.com cert-authority ssh-ed25519 AAAB4... # A key that is accepted only for file signing. user2@example.com namespaces="file" ssh-ed25519 AAA41... ENVIRONMENT top SSH_SK_PROVIDER Specifies a path to a library that will be used when loading any FIDO authenticator-hosted keys, overriding the default of using the built-in USB HID support. FILES top ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specify a passphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 128-bit AES. This file is not automatically accessed by but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machines where the user wishes to log in using public key authentication. There is no need to keep the contents of this file secret. /etc/moduli Contains Diffie-Hellman groups used for DH-GEX. The file format is described in moduli(5). SEE ALSO top ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU September 4, 2023 SSH-KEYGEN(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a rsa key of 2048 bits with comment "michael" and store it in file "key". Bash Command:<START>ssh-keygen -b 2048 -t rsa -f key -C michael<END> |
Create a rsa key with comment specified by variable APP and passphrase specified y SSHKEYPASS. | ssh-keygen -t rsa -C "$APP" -N "$SSHKEYPASS" -f ~/.ssh/id_rsa | ['ssh-keygen'] | Output a Bash command to accomplish the following task. Task: Create a rsa key with comment specified by variable APP and passphrase specified y SSHKEYPASS. Bash Command:<START>ssh-keygen -t rsa -C "$APP" -N "$SSHKEYPASS" -f ~/.ssh/id_rsa<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh-keygen\n\n> Generate SSH keys used for authentication, password-less logins, and other things.\n> More information: <https://man.openbsd.org/ssh-keygen>.\n\n- Generate a key interactively:\n\n`ssh-keygen`\n\n- Generate an ed25519 key with 32 key derivation function rounds and save the key to a specific file:\n\n`ssh-keygen -t {{ed25519}} -a {{32}} -f {{~/.ssh/filename}}`\n\n- Generate an RSA 4096-bit key with email as a comment:\n\n`ssh-keygen -t {{rsa}} -b {{4096}} -C "{{comment|email}}"`\n\n- Remove the keys of a host from the known_hosts file (useful when a known host has a new key):\n\n`ssh-keygen -R {{remote_host}}`\n\n- Retrieve the fingerprint of a key in MD5 Hex:\n\n`ssh-keygen -l -E {{md5}} -f {{~/.ssh/filename}}`\n\n- Change the password of a key:\n\n`ssh-keygen -p -f {{~/.ssh/filename}}`\n\n- Change the type of the key format (for example from OPENSSH format to PEM), the file will be rewritten in-place:\n\n`ssh-keygen -p -N "" -m {{PEM}} -f {{~/.ssh/OpenSSH_private_key}}`\n\n- Retrieve public key from secret key:\n\n`ssh-keygen -y -f {{~/.ssh/OpenSSH_private_key}}`\n Task: Create a rsa key with comment specified by variable APP and passphrase specified y SSHKEYPASS. Bash Command:<START>ssh-keygen -t rsa -C "$APP" -N "$SSHKEYPASS" -f ~/.ssh/id_rsa<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh-keygen(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh-keygen(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | MODULI GENERATION | CERTIFICATES | FIDO AUTHENTICATOR | KEY REVOCATION LISTS | ALLOWED SIGNERS | ENVIRONMENT | FILES | SEE ALSO | AUTHORS | COLOPHON SSH-KEYGEN(1) General Commands Manual SSH-KEYGEN(1) NAME top ssh-keygen OpenSSH authentication key utility SYNOPSIS top ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile] [-m format] [-N new_passphrase] [-O option] [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa] [-w provider] [-Z cipher] ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase] [-P old_passphrase] [-Z cipher] ssh-keygen -i [-f input_keyfile] [-m key_format] ssh-keygen -e [-f input_keyfile] [-m key_format] ssh-keygen -y [-f input_keyfile] ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase] ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile] ssh-keygen -B [-f input_keyfile] ssh-keygen -D pkcs11 ssh-keygen -F hostname [-lv] [-f known_hosts_file] ssh-keygen -H [-f known_hosts_file] ssh-keygen -K [-a rounds] [-w provider] ssh-keygen -R hostname [-f known_hosts_file] ssh-keygen -r hostname [-g] [-f input_keyfile] ssh-keygen -M generate [-O option] output_file ssh-keygen -M screen [-f input_file] [-O option] output_file ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider] [-n principals] [-O option] [-V validity_interval] [-z serial_number] file ... ssh-keygen -L [-f input_keyfile] ssh-keygen -A [-a rounds] [-f prefix_path] ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number] file ... ssh-keygen -Q [-l] -f krl_file file ... ssh-keygen -Y find-principals [-O option] -s signature_file -f allowed_signers_file ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file ssh-keygen -Y check-novalidate [-O option] -n namespace -s signature_file ssh-keygen -Y sign [-O option] -f key_file -n namespace file ... ssh-keygen -Y verify [-O option] -f allowed_signers_file -I signer_identity -n namespace -s signature_file [-r revocation_file] DESCRIPTION top generates, manages and converts authentication keys for ssh(1). can create keys for use by SSH protocol version 2. The type of key to be generated is specified with the -t option. If invoked without any arguments, will generate an Ed25519 key. is also used to generate groups for use in Diffie-Hellman group exchange (DH-GEX). See the MODULI GENERATION section for details. Finally, can be used to generate and update Key Revocation Lists, and to test whether given keys have been revoked by one. See the KEY REVOCATION LISTS section for details. Normally each user wishing to use SSH with public key authentication runs this once to create the authentication key in ~/.ssh/id_dsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk or ~/.ssh/id_rsa. Additionally, the system administrator may use this to generate host keys, as seen in /etc/rc. Normally this program generates the key and asks for a file in which to store the private key. The public key is stored in a file with the same name but .pub appended. The program also asks for a passphrase. The passphrase may be empty to indicate no passphrase (host keys must have an empty passphrase), or it may be a string of arbitrary length. A passphrase is similar to a password, except it can be a phrase with a series of words, punctuation, numbers, whitespace, or any string of characters you want. Good passphrases are 10-30 characters long, are not simple sentences or otherwise easily guessable (English prose has only 1-2 bits of entropy per character, and provides very bad passphrases), and contain a mix of upper and lowercase letters, numbers, and non-alphanumeric characters. The passphrase can be changed later by using the -p option. There is no way to recover a lost passphrase. If the passphrase is lost or forgotten, a new key must be generated and the corresponding public key copied to other machines. will by default write keys in an OpenSSH-specific format. This format is preferred as it offers better protection for keys at rest as well as allowing storage of key comments within the private key file itself. The key comment may be useful to help identify the key. The comment is initialized to user@host when the key is created, but can be changed using the -c option. It is still possible for to write the previously-used PEM format private keys using the -m flag. This may be used when generating new keys, and existing new-format keys may be converted using this option in conjunction with the -p (change passphrase) flag. After a key is generated, will ask where the keys should be placed to be activated. The options are as follows: -A Generate host keys of all default key types (rsa, ecdsa, and ed25519) if they do not already exist. The host keys are generated with the default key file path, an empty passphrase, default bits for the key type, and default comment. If -f has also been specified, its argument is used as a prefix to the default path for the resulting host key files. This is used by /etc/rc to generate new host keys. -a rounds When saving a private key, this option specifies the number of KDF (key derivation function, currently bcrypt_pbkdf(3)) rounds used. Higher numbers result in slower passphrase verification and increased resistance to brute-force password cracking (should the keys be stolen). The default is 16 rounds. -B Show the bubblebabble digest of specified private or public key file. -b bits Specifies the number of bits in the key to create. For RSA keys, the minimum size is 1024 bits and the default is 3072 bits. Generally, 3072 bits is considered sufficient. DSA keys must be exactly 1024 bits as specified by FIPS 186-2. For ECDSA keys, the -b flag determines the key length by selecting from one of three elliptic curve sizes: 256, 384 or 521 bits. Attempting to use bit lengths other than these three values for ECDSA keys will fail. ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the -b flag will be ignored. -C comment Provides a new comment. -c Requests changing the comment in the private and public key files. The program will prompt for the file containing the private keys, for the passphrase if the key has one, and for the new comment. -D pkcs11 Download the public keys provided by the PKCS#11 shared library pkcs11. When used in combination with -s, this option indicates that a CA key resides in a PKCS#11 token (see the CERTIFICATES section for details). -E fingerprint_hash Specifies the hash algorithm used when displaying key fingerprints. Valid options are: md5 and sha256. The default is sha256. -e This option will read a private or public OpenSSH key file and print to stdout a public key in one of the formats specified by the -m option. The default export format is RFC4716. This option allows exporting OpenSSH keys for use by other programs, including several commercial SSH implementations. -F hostname | [hostname]:port Search for the specified hostname (with optional port number) in a known_hosts file, listing any occurrences found. This option is useful to find hashed host names or addresses and may also be used in conjunction with the -H option to print found keys in a hashed format. -f filename Specifies the filename of the key file. -g Use generic DNS format when printing fingerprint resource records using the -r command. -H Hash a known_hosts file. This replaces all hostnames and addresses with hashed representations within the specified file; the original content is moved to a file with a .old suffix. These hashes may be used normally by ssh and sshd, but they do not reveal identifying information should the file's contents be disclosed. This option will not modify existing hashed hostnames and is therefore safe to use on files that mix hashed and non-hashed names. -h When signing a key, create a host certificate instead of a user certificate. See the CERTIFICATES section for details. -I certificate_identity Specify the key identity when signing a public key. See the CERTIFICATES section for details. -i This option will read an unencrypted private (or public) key file in the format specified by the -m option and print an OpenSSH compatible private (or public) key to stdout. This option allows importing keys from other software, including several commercial SSH implementations. The default import format is RFC4716. -K Download resident keys from a FIDO authenticator. Public and private key files will be written to the current directory for each downloaded key. If multiple FIDO authenticators are attached, keys will be downloaded from the first touched authenticator. See the FIDO AUTHENTICATOR section for more information. -k Generate a KRL file. In this mode, will generate a KRL file at the location specified via the -f flag that revokes every key or certificate presented on the command line. Keys/certificates to be revoked may be specified by public key file or using the format described in the KEY REVOCATION LISTS section. -L Prints the contents of one or more certificates. -l Show fingerprint of specified public key file. For RSA and DSA keys tries to find the matching public key file and prints its fingerprint. If combined with -v, a visual ASCII art representation of the key is supplied with the fingerprint. -M generate Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for eventual use by the diffie-hellman-group-exchange-* key exchange methods. The numbers generated by this operation must be further screened before use. See the MODULI GENERATION section for more information. -M screen Screen candidate parameters for Diffie-Hellman Group Exchange. This will accept a list of candidate numbers and test that they are safe (Sophie Germain) primes with acceptable group generators. The results of this operation may be added to the /etc/moduli file. See the MODULI GENERATION section for more information. -m key_format Specify a key format for key generation, the -i (import), -e (export) conversion options, and the -p change passphrase operation. The latter may be used to convert between OpenSSH private key and PEM private key formats. The supported key formats are: RFC4716 (RFC 4716/SSH2 public or private key), PKCS8 (PKCS8 public or private key) or PEM (PEM public key). By default OpenSSH will write newly-generated private keys in its own format, but when converting public keys for export the default format is RFC4716. Setting a format of PEM when generating or updating a supported private key type will cause the key to be stored in the legacy PEM private key format. -N new_passphrase Provides the new passphrase. -n principals Specify one or more principals (user or host names) to be included in a certificate when signing a key. Multiple principals may be specified, separated by commas. See the CERTIFICATES section for details. -O option Specify a key/value option. These are specific to the operation that has been requested to perform. When signing certificates, one of the options listed in the CERTIFICATES section may be specified here. When performing moduli generation or screening, one of the options listed in the MODULI GENERATION section may be specified. When generating FIDO authenticator-backed keys, the options listed in the FIDO AUTHENTICATOR section may be specified. When performing signature-related options using the -Y flag, the following options are accepted: hashalg=algorithm Selects the hash algorithm to use for hashing the message to be signed. Valid algorithms are sha256 and sha512. The default is sha512. print-pubkey Print the full public key to standard output after signature verification. verify-time=timestamp Specifies a time to use when validating signatures instead of the current time. The time may be specified as a date or time in the YYYYMMDD[Z] or in YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. When generating SSHFP DNS records from public keys using the -r flag, the following options are accepted: hashalg=algorithm Selects a hash algorithm to use when printing SSHFP records using the -D flag. Valid algorithms are sha1 and sha256. The default is to print both. The -O option may be specified multiple times. -P passphrase Provides the (old) passphrase. -p Requests changing the passphrase of a private key file instead of creating a new private key. The program will prompt for the file containing the private key, for the old passphrase, and twice for the new passphrase. -Q Test whether keys have been revoked in a KRL. If the -l option is also specified then the contents of the KRL will be printed. -q Silence ssh-keygen. -R hostname | [hostname]:port Removes all keys belonging to the specified hostname (with optional port number) from a known_hosts file. This option is useful to delete hashed hosts (see the -H option above). -r hostname Print the SSHFP fingerprint resource record named hostname for the specified public key file. -s ca_key Certify (sign) a public key using the specified CA key. See the CERTIFICATES section for details. When generating a KRL, -s specifies a path to a CA public key file used to revoke certificates directly by key ID or serial number. See the KEY REVOCATION LISTS section for details. -t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa Specifies the type of key to create. The possible values are dsa, ecdsa, ecdsa-sk, ed25519, ed25519-sk, or rsa. This flag may also be used to specify the desired signature type when signing certificates using an RSA CA key. The available RSA signature variants are ssh-rsa (SHA1 signatures, not recommended), rsa-sha2-256, and rsa-sha2-512 (the default). -U When used in combination with -s or -Y sign, this option indicates that a CA key resides in a ssh-agent(1). See the CERTIFICATES section for more information. -u Update a KRL. When specified with -k, keys listed via the command line are added to the existing KRL rather than a new KRL being created. -V validity_interval Specify a validity interval when signing a certificate. A validity interval may consist of a single time, indicating that the certificate is valid beginning now and expiring at that time, or may consist of two times separated by a colon to indicate an explicit time interval. The start time may be specified as: The string always to indicate the certificate has no specified start time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time before the current system time consisting of a minus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. The end time may be specified similarly to the start time: The string forever to indicate the certificate has no specified end time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time after the current system time consisting of a plus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. For example: +52w1d Valid from now to 52 weeks and one day from now. -4w:+4w Valid from four weeks ago to four weeks from now. 20100101123000:20110101123000 Valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011. 20100101123000Z:20110101123000Z Similar, but interpreted in the UTC time zone rather than the system time zone. -1d:20110101 Valid from yesterday to midnight, January 1st, 2011. 0x1:0x2000000000 Valid from roughly early 1970 to May 2033. -1m:forever Valid from one minute ago and never expiring. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful for debugging moduli generation. Multiple -v options increase the verbosity. The maximum is 3. -w provider Specifies a path to a library that will be used when creating FIDO authenticator-hosted keys, overriding the default of using the internal USB HID support. -Y find-principals Find the principal(s) associated with the public key of a signature, provided using the -s flag in an authorized signers file provided using the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. If one or more matching principals are found, they are returned on standard output. -Y match-principals Find principal matching the principal name provided using the -I flag in the authorized signers file specified using the -f flag. If one or more matching principals are found, they are returned on standard output. -Y check-novalidate Checks that a signature generated using -Y sign has a valid structure. This does not validate if a signature comes from an authorized signer. When testing a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag. Successful testing of the signature is signalled by returning a zero exit status. -Y sign Cryptographically sign a file or some data using an SSH key. When signing, accepts zero or more files to sign on the command-line - if no files are specified then will sign data presented on standard input. Signatures are written to the path of the input file with .sig appended, or to standard output if the message to be signed was read from standard input. The key used for signing is specified using the -f option and may refer to either a private key, or a public key with the private half available via ssh-agent(1). An additional signature namespace, used to prevent signature confusion across different domains of use (e.g. file signing vs email signing) must be provided via the -n flag. Namespaces are arbitrary strings, and may include: file for file signing, email for email signing. For custom uses, it is recommended to use names following a NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces. -Y verify Request to verify a signature generated using -Y sign as described above. When verifying a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag, along with the identity of the signer using -I and a list of allowed signers via the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. A file containing revoked keys can be passed using the -r flag. The revocation file may be a KRL or a one-per-line list of public keys. Successful verification by an authorized signer is signalled by returning a zero exit status. -y This option will read a private OpenSSH format file and print an OpenSSH public key to stdout. -Z cipher Specifies the cipher to use for encryption when writing an OpenSSH-format private key file. The list of available ciphers may be obtained using "ssh -Q cipher". The default is aes256-ctr. -z serial_number Specifies a serial number to be embedded in the certificate to distinguish this certificate from others from the same CA. If the serial_number is prefixed with a + character, then the serial number will be incremented for each certificate signed on a single command-line. The default serial number is zero. When generating a KRL, the -z flag is used to specify a KRL version number. MODULI GENERATION top may be used to generate groups for the Diffie-Hellman Group Exchange (DH-GEX) protocol. Generating these groups is a two- step process: first, candidate primes are generated using a fast, but memory intensive process. These candidate primes are then tested for suitability (a CPU-intensive process). Generation of primes is performed using the -M generate option. The desired length of the primes may be specified by the -O bits option. For example: # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates By default, the search for primes begins at a random point in the desired length range. This may be overridden using the -O start option, which specifies a different start point (in hex). Once a set of candidates have been generated, they must be screened for suitability. This may be performed using the -M screen option. In this mode will read candidates from standard input (or a file specified using the -f option). For example: # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048 By default, each candidate will be subjected to 100 primality tests. This may be overridden using the -O prime-tests option. The DH generator value will be chosen automatically for the prime under consideration. If a specific generator is desired, it may be requested using the -O generator option. Valid generator values are 2, 3, and 5. Screened DH groups may be installed in /etc/moduli. It is important that this file contains moduli of a range of bit lengths. A number of options are available for moduli generation and screening via the -O flag: lines=number Exit after screening the specified number of lines while performing DH candidate screening. start-line=line-number Start screening at the specified line number while performing DH candidate screening. checkpoint=filename Write the last line processed to the specified file while performing DH candidate screening. This will be used to skip lines in the input file that have already been processed if the job is restarted. memory=mbytes Specify the amount of memory to use (in megabytes) when generating candidate moduli for DH-GEX. start=hex-value Specify start point (in hex) when generating candidate moduli for DH-GEX. generator=value Specify desired generator (in decimal) when testing candidate moduli for DH-GEX. CERTIFICATES top supports signing of keys to produce certificates that may be used for user or host authentication. Certificates consist of a public key, some identity information, zero or more principal (user or host) names and a set of options that are signed by a Certification Authority (CA) key. Clients or servers may then trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys. Note that OpenSSH certificates are a different, and much simpler, format to the X.509 certificates used in ssl(8). supports two types of certificates: user and host. User certificates authenticate users to servers, whereas host certificates authenticate server hosts to users. To generate a user certificate: $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub The resultant certificate will be placed in /path/to/user_key-cert.pub. A host certificate requires the -h option: $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub The host certificate will be output to /path/to/host_key-cert.pub. It is possible to sign using a CA key stored in a PKCS#11 token by providing the token library using -D and identifying the CA key by providing its public half as an argument to -s: $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub Similarly, it is possible for the CA key to be hosted in a ssh-agent(1). This is indicated by the -U flag and, again, the CA key must be identified by its public half. $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub In all cases, key_id is a "key identifier" that is logged by the server when the certificate is used for authentication. Certificates may be limited to be valid for a set of principal (user/host) names. By default, generated certificates are valid for all users or hosts. To generate a certificate for a specified set of principals: $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub $ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub Additional limitations on the validity and use of user certificates may be specified through certificate options. A certificate option may disable features of the SSH session, may be valid only when presented from particular source addresses or may force the use of a specific command. The options that are valid for user certificates are: clear Clear all enabled permissions. This is useful for clearing the default set of permissions so permissions may be added individually. critical:name[=contents] extension:name[=contents] Includes an arbitrary certificate critical option or extension. The specified name should include a domain suffix, e.g. name@example.com. If contents is specified then it is included as the contents of the extension/option encoded as a string, otherwise the extension/option is created with no contents (usually indicating a flag). Extensions may be ignored by a client or server that does not recognise them, whereas unknown critical options will cause the certificate to be refused. force-command=command Forces the execution of command instead of any shell or command specified by the user when the certificate is used for authentication. no-agent-forwarding Disable ssh-agent(1) forwarding (permitted by default). no-port-forwarding Disable port forwarding (permitted by default). no-pty Disable PTY allocation (permitted by default). no-user-rc Disable execution of ~/.ssh/rc by sshd(8) (permitted by default). no-x11-forwarding Disable X11 forwarding (permitted by default). permit-agent-forwarding Allows ssh-agent(1) forwarding. permit-port-forwarding Allows port forwarding. permit-pty Allows PTY allocation. permit-user-rc Allows execution of ~/.ssh/rc by sshd(8). permit-X11-forwarding Allows X11 forwarding. no-touch-required Do not require signatures made using this key include demonstration of user presence (e.g. by having the user touch the authenticator). This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. source-address=address_list Restrict the source addresses from which the certificate is considered valid. The address_list is a comma- separated list of one or more address/netmask pairs in CIDR format. verify-required Require signatures made using this key indicate that the user was first verified. This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. At present, no standard options are valid for host keys. Finally, certificates may be defined with a validity lifetime. The -V option allows specification of certificate start and end times. A certificate that is presented at a time outside this range will not be considered valid. By default, certificates are valid from the Unix Epoch to the distant future. For certificates to be used for user or host authentication, the CA public key must be trusted by sshd(8) or ssh(1). Refer to those manual pages for details. FIDO AUTHENTICATOR top is able to generate FIDO authenticator-backed keys, after which they may be used much like any other key type supported by OpenSSH, so long as the hardware authenticator is attached when the keys are used. FIDO authenticators generally require the user to explicitly authorise operations by touching or tapping them. FIDO keys consist of two parts: a key handle part stored in the private key file on disk, and a per-device private key that is unique to each FIDO authenticator and that cannot be exported from the authenticator hardware. These are combined by the hardware at authentication time to derive the real key that is used to sign authentication challenges. Supported key types are ecdsa-sk and ed25519-sk. The options that are valid for FIDO keys are: application Override the default FIDO application/origin string of ssh:. This may be useful when generating host or domain-specific resident keys. The specified application string must begin with ssh:. challenge=path Specifies a path to a challenge string that will be passed to the FIDO authenticator during key generation. The challenge string may be used as part of an out-of- band protocol for key enrollment (a random challenge is used by default). device Explicitly specify a fido(4) device to use, rather than letting the authenticator middleware select one. no-touch-required Indicate that the generated private key should not require touch events (user presence) when making signatures. Note that sshd(8) will refuse such signatures by default, unless overridden via an authorized_keys option. resident Indicate that the key handle should be stored on the FIDO authenticator itself. This makes it easier to use the authenticator on multiple computers. Resident keys may be supported on FIDO2 authenticators and typically require that a PIN be set on the authenticator prior to generation. Resident keys may be loaded off the authenticator using ssh-add(1). Storing both parts of a key on a FIDO authenticator increases the likelihood of an attacker being able to use a stolen authenticator device. user A username to be associated with a resident key, overriding the empty default username. Specifying a username may be useful when generating multiple resident keys for the same application name. verify-required Indicate that this private key should require user verification for each signature. Not all FIDO authenticators support this option. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. write-attestation=path May be used at key generation time to record the attestation data returned from FIDO authenticators during key generation. This information is potentially sensitive. By default, this information is discarded. KEY REVOCATION LISTS top is able to manage OpenSSH format Key Revocation Lists (KRLs). These binary files specify keys or certificates to be revoked using a compact format, taking as little as one bit per certificate if they are being revoked by serial number. KRLs may be generated using the -k flag. This option reads one or more files from the command line and generates a new KRL. The files may either contain a KRL specification (see below) or public keys, listed one per line. Plain public keys are revoked by listing their hash or contents in the KRL and certificates revoked by serial number or key ID (if the serial is zero or not available). Revoking keys using a KRL specification offers explicit control over the types of record used to revoke keys and may be used to directly revoke certificates by serial number or key ID without having the complete original certificate on hand. A KRL specification consists of lines containing one of the following directives followed by a colon and some directive-specific information. serial: serial_number[-serial_number] Revokes a certificate with the specified serial number. Serial numbers are 64-bit values, not including zero and may be expressed in decimal, hex or octal. If two serial numbers are specified separated by a hyphen, then the range of serial numbers including and between each is revoked. The CA key must have been specified on the command line using the -s option. id: key_id Revokes a certificate with the specified key ID string. The CA key must have been specified on the command line using the -s option. key: public_key Revokes the specified key. If a certificate is listed, then it is revoked as a plain public key. sha1: public_key Revokes the specified key by including its SHA1 hash in the KRL. sha256: public_key Revokes the specified key by including its SHA256 hash in the KRL. KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions prior to 7.9. hash: fingerprint Revokes a key using a fingerprint hash, as obtained from a sshd(8) authentication log message or the -l flag. Only SHA256 fingerprints are supported here and resultant KRLs are not supported by OpenSSH versions prior to 7.9. KRLs may be updated using the -u flag in addition to -k. When this option is specified, keys listed via the command line are merged into the KRL, adding to those already there. It is also possible, given a KRL, to test whether it revokes a particular key (or keys). The -Q flag will query an existing KRL, testing each key specified on the command line. If any key listed on the command line has been revoked (or an error encountered) then will exit with a non-zero exit status. A zero exit status will only be returned if no key was revoked. ALLOWED SIGNERS top When verifying signatures, uses a simple list of identities and keys to determine whether a signature comes from an authorized source. This "allowed signers" file uses a format patterned after the AUTHORIZED_KEYS FILE FORMAT described in sshd(8). Each line of the file contains the following space-separated fields: principals, options, keytype, base64-encoded key. Empty lines and lines starting with a # are ignored as comments. The principals field is a pattern-list (see PATTERNS in ssh_config(5)) consisting of one or more comma-separated USER@DOMAIN identity patterns that are accepted for signing. When verifying, the identity presented via the -I option must match a principals pattern in order for the corresponding key to be considered acceptable for verification. The options (if present) consist of comma-separated option specifications. No spaces are permitted, except within double quotes. The following option specifications are supported (note that option keywords are case-insensitive): cert-authority Indicates that this key is accepted as a certificate authority (CA) and that certificates signed by this CA may be accepted for verification. namespaces=namespace-list Specifies a pattern-list of namespaces that are accepted for this key. If this option is present, the signature namespace embedded in the signature object and presented on the verification command-line must match the specified list before the key will be considered acceptable. valid-after=timestamp Indicates that the key is valid for use at or after the specified timestamp, which may be a date or time in the YYYYMMDD[Z] or YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. valid-before=timestamp Indicates that the key is valid for use at or before the specified timestamp. When verifying signatures made by certificates, the expected principal name must match both the principals pattern in the allowed signers file and the principals embedded in the certificate itself. An example allowed signers file: # Comments allowed at start of line user1@example.com,user2@example.com ssh-rsa AAAAX1... # A certificate authority, trusted for all principals in a domain. *@example.com cert-authority ssh-ed25519 AAAB4... # A key that is accepted only for file signing. user2@example.com namespaces="file" ssh-ed25519 AAA41... ENVIRONMENT top SSH_SK_PROVIDER Specifies a path to a library that will be used when loading any FIDO authenticator-hosted keys, overriding the default of using the built-in USB HID support. FILES top ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specify a passphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 128-bit AES. This file is not automatically accessed by but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machines where the user wishes to log in using public key authentication. There is no need to keep the contents of this file secret. /etc/moduli Contains Diffie-Hellman groups used for DH-GEX. The file format is described in moduli(5). SEE ALSO top ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU September 4, 2023 SSH-KEYGEN(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a rsa key with comment specified by variable APP and passphrase specified y SSHKEYPASS. Bash Command:<START>ssh-keygen -t rsa -C "$APP" -N "$SSHKEYPASS" -f ~/.ssh/id_rsa<END> |
Create a ssh key and store it in the file ~/.ssh/apache-rsync | ssh-keygen -f ~/.ssh/apache-rsync | ['ssh-keygen'] | Output a Bash command to accomplish the following task. Task: Create a ssh key and store it in the file ~/.ssh/apache-rsync Bash Command:<START>ssh-keygen -f ~/.ssh/apache-rsync<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh-keygen\n\n> Generate SSH keys used for authentication, password-less logins, and other things.\n> More information: <https://man.openbsd.org/ssh-keygen>.\n\n- Generate a key interactively:\n\n`ssh-keygen`\n\n- Generate an ed25519 key with 32 key derivation function rounds and save the key to a specific file:\n\n`ssh-keygen -t {{ed25519}} -a {{32}} -f {{~/.ssh/filename}}`\n\n- Generate an RSA 4096-bit key with email as a comment:\n\n`ssh-keygen -t {{rsa}} -b {{4096}} -C "{{comment|email}}"`\n\n- Remove the keys of a host from the known_hosts file (useful when a known host has a new key):\n\n`ssh-keygen -R {{remote_host}}`\n\n- Retrieve the fingerprint of a key in MD5 Hex:\n\n`ssh-keygen -l -E {{md5}} -f {{~/.ssh/filename}}`\n\n- Change the password of a key:\n\n`ssh-keygen -p -f {{~/.ssh/filename}}`\n\n- Change the type of the key format (for example from OPENSSH format to PEM), the file will be rewritten in-place:\n\n`ssh-keygen -p -N "" -m {{PEM}} -f {{~/.ssh/OpenSSH_private_key}}`\n\n- Retrieve public key from secret key:\n\n`ssh-keygen -y -f {{~/.ssh/OpenSSH_private_key}}`\n Task: Create a ssh key and store it in the file ~/.ssh/apache-rsync Bash Command:<START>ssh-keygen -f ~/.ssh/apache-rsync<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh-keygen(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh-keygen(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | MODULI GENERATION | CERTIFICATES | FIDO AUTHENTICATOR | KEY REVOCATION LISTS | ALLOWED SIGNERS | ENVIRONMENT | FILES | SEE ALSO | AUTHORS | COLOPHON SSH-KEYGEN(1) General Commands Manual SSH-KEYGEN(1) NAME top ssh-keygen OpenSSH authentication key utility SYNOPSIS top ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile] [-m format] [-N new_passphrase] [-O option] [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa] [-w provider] [-Z cipher] ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase] [-P old_passphrase] [-Z cipher] ssh-keygen -i [-f input_keyfile] [-m key_format] ssh-keygen -e [-f input_keyfile] [-m key_format] ssh-keygen -y [-f input_keyfile] ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase] ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile] ssh-keygen -B [-f input_keyfile] ssh-keygen -D pkcs11 ssh-keygen -F hostname [-lv] [-f known_hosts_file] ssh-keygen -H [-f known_hosts_file] ssh-keygen -K [-a rounds] [-w provider] ssh-keygen -R hostname [-f known_hosts_file] ssh-keygen -r hostname [-g] [-f input_keyfile] ssh-keygen -M generate [-O option] output_file ssh-keygen -M screen [-f input_file] [-O option] output_file ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider] [-n principals] [-O option] [-V validity_interval] [-z serial_number] file ... ssh-keygen -L [-f input_keyfile] ssh-keygen -A [-a rounds] [-f prefix_path] ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number] file ... ssh-keygen -Q [-l] -f krl_file file ... ssh-keygen -Y find-principals [-O option] -s signature_file -f allowed_signers_file ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file ssh-keygen -Y check-novalidate [-O option] -n namespace -s signature_file ssh-keygen -Y sign [-O option] -f key_file -n namespace file ... ssh-keygen -Y verify [-O option] -f allowed_signers_file -I signer_identity -n namespace -s signature_file [-r revocation_file] DESCRIPTION top generates, manages and converts authentication keys for ssh(1). can create keys for use by SSH protocol version 2. The type of key to be generated is specified with the -t option. If invoked without any arguments, will generate an Ed25519 key. is also used to generate groups for use in Diffie-Hellman group exchange (DH-GEX). See the MODULI GENERATION section for details. Finally, can be used to generate and update Key Revocation Lists, and to test whether given keys have been revoked by one. See the KEY REVOCATION LISTS section for details. Normally each user wishing to use SSH with public key authentication runs this once to create the authentication key in ~/.ssh/id_dsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk or ~/.ssh/id_rsa. Additionally, the system administrator may use this to generate host keys, as seen in /etc/rc. Normally this program generates the key and asks for a file in which to store the private key. The public key is stored in a file with the same name but .pub appended. The program also asks for a passphrase. The passphrase may be empty to indicate no passphrase (host keys must have an empty passphrase), or it may be a string of arbitrary length. A passphrase is similar to a password, except it can be a phrase with a series of words, punctuation, numbers, whitespace, or any string of characters you want. Good passphrases are 10-30 characters long, are not simple sentences or otherwise easily guessable (English prose has only 1-2 bits of entropy per character, and provides very bad passphrases), and contain a mix of upper and lowercase letters, numbers, and non-alphanumeric characters. The passphrase can be changed later by using the -p option. There is no way to recover a lost passphrase. If the passphrase is lost or forgotten, a new key must be generated and the corresponding public key copied to other machines. will by default write keys in an OpenSSH-specific format. This format is preferred as it offers better protection for keys at rest as well as allowing storage of key comments within the private key file itself. The key comment may be useful to help identify the key. The comment is initialized to user@host when the key is created, but can be changed using the -c option. It is still possible for to write the previously-used PEM format private keys using the -m flag. This may be used when generating new keys, and existing new-format keys may be converted using this option in conjunction with the -p (change passphrase) flag. After a key is generated, will ask where the keys should be placed to be activated. The options are as follows: -A Generate host keys of all default key types (rsa, ecdsa, and ed25519) if they do not already exist. The host keys are generated with the default key file path, an empty passphrase, default bits for the key type, and default comment. If -f has also been specified, its argument is used as a prefix to the default path for the resulting host key files. This is used by /etc/rc to generate new host keys. -a rounds When saving a private key, this option specifies the number of KDF (key derivation function, currently bcrypt_pbkdf(3)) rounds used. Higher numbers result in slower passphrase verification and increased resistance to brute-force password cracking (should the keys be stolen). The default is 16 rounds. -B Show the bubblebabble digest of specified private or public key file. -b bits Specifies the number of bits in the key to create. For RSA keys, the minimum size is 1024 bits and the default is 3072 bits. Generally, 3072 bits is considered sufficient. DSA keys must be exactly 1024 bits as specified by FIPS 186-2. For ECDSA keys, the -b flag determines the key length by selecting from one of three elliptic curve sizes: 256, 384 or 521 bits. Attempting to use bit lengths other than these three values for ECDSA keys will fail. ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the -b flag will be ignored. -C comment Provides a new comment. -c Requests changing the comment in the private and public key files. The program will prompt for the file containing the private keys, for the passphrase if the key has one, and for the new comment. -D pkcs11 Download the public keys provided by the PKCS#11 shared library pkcs11. When used in combination with -s, this option indicates that a CA key resides in a PKCS#11 token (see the CERTIFICATES section for details). -E fingerprint_hash Specifies the hash algorithm used when displaying key fingerprints. Valid options are: md5 and sha256. The default is sha256. -e This option will read a private or public OpenSSH key file and print to stdout a public key in one of the formats specified by the -m option. The default export format is RFC4716. This option allows exporting OpenSSH keys for use by other programs, including several commercial SSH implementations. -F hostname | [hostname]:port Search for the specified hostname (with optional port number) in a known_hosts file, listing any occurrences found. This option is useful to find hashed host names or addresses and may also be used in conjunction with the -H option to print found keys in a hashed format. -f filename Specifies the filename of the key file. -g Use generic DNS format when printing fingerprint resource records using the -r command. -H Hash a known_hosts file. This replaces all hostnames and addresses with hashed representations within the specified file; the original content is moved to a file with a .old suffix. These hashes may be used normally by ssh and sshd, but they do not reveal identifying information should the file's contents be disclosed. This option will not modify existing hashed hostnames and is therefore safe to use on files that mix hashed and non-hashed names. -h When signing a key, create a host certificate instead of a user certificate. See the CERTIFICATES section for details. -I certificate_identity Specify the key identity when signing a public key. See the CERTIFICATES section for details. -i This option will read an unencrypted private (or public) key file in the format specified by the -m option and print an OpenSSH compatible private (or public) key to stdout. This option allows importing keys from other software, including several commercial SSH implementations. The default import format is RFC4716. -K Download resident keys from a FIDO authenticator. Public and private key files will be written to the current directory for each downloaded key. If multiple FIDO authenticators are attached, keys will be downloaded from the first touched authenticator. See the FIDO AUTHENTICATOR section for more information. -k Generate a KRL file. In this mode, will generate a KRL file at the location specified via the -f flag that revokes every key or certificate presented on the command line. Keys/certificates to be revoked may be specified by public key file or using the format described in the KEY REVOCATION LISTS section. -L Prints the contents of one or more certificates. -l Show fingerprint of specified public key file. For RSA and DSA keys tries to find the matching public key file and prints its fingerprint. If combined with -v, a visual ASCII art representation of the key is supplied with the fingerprint. -M generate Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for eventual use by the diffie-hellman-group-exchange-* key exchange methods. The numbers generated by this operation must be further screened before use. See the MODULI GENERATION section for more information. -M screen Screen candidate parameters for Diffie-Hellman Group Exchange. This will accept a list of candidate numbers and test that they are safe (Sophie Germain) primes with acceptable group generators. The results of this operation may be added to the /etc/moduli file. See the MODULI GENERATION section for more information. -m key_format Specify a key format for key generation, the -i (import), -e (export) conversion options, and the -p change passphrase operation. The latter may be used to convert between OpenSSH private key and PEM private key formats. The supported key formats are: RFC4716 (RFC 4716/SSH2 public or private key), PKCS8 (PKCS8 public or private key) or PEM (PEM public key). By default OpenSSH will write newly-generated private keys in its own format, but when converting public keys for export the default format is RFC4716. Setting a format of PEM when generating or updating a supported private key type will cause the key to be stored in the legacy PEM private key format. -N new_passphrase Provides the new passphrase. -n principals Specify one or more principals (user or host names) to be included in a certificate when signing a key. Multiple principals may be specified, separated by commas. See the CERTIFICATES section for details. -O option Specify a key/value option. These are specific to the operation that has been requested to perform. When signing certificates, one of the options listed in the CERTIFICATES section may be specified here. When performing moduli generation or screening, one of the options listed in the MODULI GENERATION section may be specified. When generating FIDO authenticator-backed keys, the options listed in the FIDO AUTHENTICATOR section may be specified. When performing signature-related options using the -Y flag, the following options are accepted: hashalg=algorithm Selects the hash algorithm to use for hashing the message to be signed. Valid algorithms are sha256 and sha512. The default is sha512. print-pubkey Print the full public key to standard output after signature verification. verify-time=timestamp Specifies a time to use when validating signatures instead of the current time. The time may be specified as a date or time in the YYYYMMDD[Z] or in YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. When generating SSHFP DNS records from public keys using the -r flag, the following options are accepted: hashalg=algorithm Selects a hash algorithm to use when printing SSHFP records using the -D flag. Valid algorithms are sha1 and sha256. The default is to print both. The -O option may be specified multiple times. -P passphrase Provides the (old) passphrase. -p Requests changing the passphrase of a private key file instead of creating a new private key. The program will prompt for the file containing the private key, for the old passphrase, and twice for the new passphrase. -Q Test whether keys have been revoked in a KRL. If the -l option is also specified then the contents of the KRL will be printed. -q Silence ssh-keygen. -R hostname | [hostname]:port Removes all keys belonging to the specified hostname (with optional port number) from a known_hosts file. This option is useful to delete hashed hosts (see the -H option above). -r hostname Print the SSHFP fingerprint resource record named hostname for the specified public key file. -s ca_key Certify (sign) a public key using the specified CA key. See the CERTIFICATES section for details. When generating a KRL, -s specifies a path to a CA public key file used to revoke certificates directly by key ID or serial number. See the KEY REVOCATION LISTS section for details. -t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa Specifies the type of key to create. The possible values are dsa, ecdsa, ecdsa-sk, ed25519, ed25519-sk, or rsa. This flag may also be used to specify the desired signature type when signing certificates using an RSA CA key. The available RSA signature variants are ssh-rsa (SHA1 signatures, not recommended), rsa-sha2-256, and rsa-sha2-512 (the default). -U When used in combination with -s or -Y sign, this option indicates that a CA key resides in a ssh-agent(1). See the CERTIFICATES section for more information. -u Update a KRL. When specified with -k, keys listed via the command line are added to the existing KRL rather than a new KRL being created. -V validity_interval Specify a validity interval when signing a certificate. A validity interval may consist of a single time, indicating that the certificate is valid beginning now and expiring at that time, or may consist of two times separated by a colon to indicate an explicit time interval. The start time may be specified as: The string always to indicate the certificate has no specified start time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time before the current system time consisting of a minus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. The end time may be specified similarly to the start time: The string forever to indicate the certificate has no specified end time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time after the current system time consisting of a plus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. For example: +52w1d Valid from now to 52 weeks and one day from now. -4w:+4w Valid from four weeks ago to four weeks from now. 20100101123000:20110101123000 Valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011. 20100101123000Z:20110101123000Z Similar, but interpreted in the UTC time zone rather than the system time zone. -1d:20110101 Valid from yesterday to midnight, January 1st, 2011. 0x1:0x2000000000 Valid from roughly early 1970 to May 2033. -1m:forever Valid from one minute ago and never expiring. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful for debugging moduli generation. Multiple -v options increase the verbosity. The maximum is 3. -w provider Specifies a path to a library that will be used when creating FIDO authenticator-hosted keys, overriding the default of using the internal USB HID support. -Y find-principals Find the principal(s) associated with the public key of a signature, provided using the -s flag in an authorized signers file provided using the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. If one or more matching principals are found, they are returned on standard output. -Y match-principals Find principal matching the principal name provided using the -I flag in the authorized signers file specified using the -f flag. If one or more matching principals are found, they are returned on standard output. -Y check-novalidate Checks that a signature generated using -Y sign has a valid structure. This does not validate if a signature comes from an authorized signer. When testing a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag. Successful testing of the signature is signalled by returning a zero exit status. -Y sign Cryptographically sign a file or some data using an SSH key. When signing, accepts zero or more files to sign on the command-line - if no files are specified then will sign data presented on standard input. Signatures are written to the path of the input file with .sig appended, or to standard output if the message to be signed was read from standard input. The key used for signing is specified using the -f option and may refer to either a private key, or a public key with the private half available via ssh-agent(1). An additional signature namespace, used to prevent signature confusion across different domains of use (e.g. file signing vs email signing) must be provided via the -n flag. Namespaces are arbitrary strings, and may include: file for file signing, email for email signing. For custom uses, it is recommended to use names following a NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces. -Y verify Request to verify a signature generated using -Y sign as described above. When verifying a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag, along with the identity of the signer using -I and a list of allowed signers via the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. A file containing revoked keys can be passed using the -r flag. The revocation file may be a KRL or a one-per-line list of public keys. Successful verification by an authorized signer is signalled by returning a zero exit status. -y This option will read a private OpenSSH format file and print an OpenSSH public key to stdout. -Z cipher Specifies the cipher to use for encryption when writing an OpenSSH-format private key file. The list of available ciphers may be obtained using "ssh -Q cipher". The default is aes256-ctr. -z serial_number Specifies a serial number to be embedded in the certificate to distinguish this certificate from others from the same CA. If the serial_number is prefixed with a + character, then the serial number will be incremented for each certificate signed on a single command-line. The default serial number is zero. When generating a KRL, the -z flag is used to specify a KRL version number. MODULI GENERATION top may be used to generate groups for the Diffie-Hellman Group Exchange (DH-GEX) protocol. Generating these groups is a two- step process: first, candidate primes are generated using a fast, but memory intensive process. These candidate primes are then tested for suitability (a CPU-intensive process). Generation of primes is performed using the -M generate option. The desired length of the primes may be specified by the -O bits option. For example: # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates By default, the search for primes begins at a random point in the desired length range. This may be overridden using the -O start option, which specifies a different start point (in hex). Once a set of candidates have been generated, they must be screened for suitability. This may be performed using the -M screen option. In this mode will read candidates from standard input (or a file specified using the -f option). For example: # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048 By default, each candidate will be subjected to 100 primality tests. This may be overridden using the -O prime-tests option. The DH generator value will be chosen automatically for the prime under consideration. If a specific generator is desired, it may be requested using the -O generator option. Valid generator values are 2, 3, and 5. Screened DH groups may be installed in /etc/moduli. It is important that this file contains moduli of a range of bit lengths. A number of options are available for moduli generation and screening via the -O flag: lines=number Exit after screening the specified number of lines while performing DH candidate screening. start-line=line-number Start screening at the specified line number while performing DH candidate screening. checkpoint=filename Write the last line processed to the specified file while performing DH candidate screening. This will be used to skip lines in the input file that have already been processed if the job is restarted. memory=mbytes Specify the amount of memory to use (in megabytes) when generating candidate moduli for DH-GEX. start=hex-value Specify start point (in hex) when generating candidate moduli for DH-GEX. generator=value Specify desired generator (in decimal) when testing candidate moduli for DH-GEX. CERTIFICATES top supports signing of keys to produce certificates that may be used for user or host authentication. Certificates consist of a public key, some identity information, zero or more principal (user or host) names and a set of options that are signed by a Certification Authority (CA) key. Clients or servers may then trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys. Note that OpenSSH certificates are a different, and much simpler, format to the X.509 certificates used in ssl(8). supports two types of certificates: user and host. User certificates authenticate users to servers, whereas host certificates authenticate server hosts to users. To generate a user certificate: $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub The resultant certificate will be placed in /path/to/user_key-cert.pub. A host certificate requires the -h option: $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub The host certificate will be output to /path/to/host_key-cert.pub. It is possible to sign using a CA key stored in a PKCS#11 token by providing the token library using -D and identifying the CA key by providing its public half as an argument to -s: $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub Similarly, it is possible for the CA key to be hosted in a ssh-agent(1). This is indicated by the -U flag and, again, the CA key must be identified by its public half. $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub In all cases, key_id is a "key identifier" that is logged by the server when the certificate is used for authentication. Certificates may be limited to be valid for a set of principal (user/host) names. By default, generated certificates are valid for all users or hosts. To generate a certificate for a specified set of principals: $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub $ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub Additional limitations on the validity and use of user certificates may be specified through certificate options. A certificate option may disable features of the SSH session, may be valid only when presented from particular source addresses or may force the use of a specific command. The options that are valid for user certificates are: clear Clear all enabled permissions. This is useful for clearing the default set of permissions so permissions may be added individually. critical:name[=contents] extension:name[=contents] Includes an arbitrary certificate critical option or extension. The specified name should include a domain suffix, e.g. name@example.com. If contents is specified then it is included as the contents of the extension/option encoded as a string, otherwise the extension/option is created with no contents (usually indicating a flag). Extensions may be ignored by a client or server that does not recognise them, whereas unknown critical options will cause the certificate to be refused. force-command=command Forces the execution of command instead of any shell or command specified by the user when the certificate is used for authentication. no-agent-forwarding Disable ssh-agent(1) forwarding (permitted by default). no-port-forwarding Disable port forwarding (permitted by default). no-pty Disable PTY allocation (permitted by default). no-user-rc Disable execution of ~/.ssh/rc by sshd(8) (permitted by default). no-x11-forwarding Disable X11 forwarding (permitted by default). permit-agent-forwarding Allows ssh-agent(1) forwarding. permit-port-forwarding Allows port forwarding. permit-pty Allows PTY allocation. permit-user-rc Allows execution of ~/.ssh/rc by sshd(8). permit-X11-forwarding Allows X11 forwarding. no-touch-required Do not require signatures made using this key include demonstration of user presence (e.g. by having the user touch the authenticator). This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. source-address=address_list Restrict the source addresses from which the certificate is considered valid. The address_list is a comma- separated list of one or more address/netmask pairs in CIDR format. verify-required Require signatures made using this key indicate that the user was first verified. This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. At present, no standard options are valid for host keys. Finally, certificates may be defined with a validity lifetime. The -V option allows specification of certificate start and end times. A certificate that is presented at a time outside this range will not be considered valid. By default, certificates are valid from the Unix Epoch to the distant future. For certificates to be used for user or host authentication, the CA public key must be trusted by sshd(8) or ssh(1). Refer to those manual pages for details. FIDO AUTHENTICATOR top is able to generate FIDO authenticator-backed keys, after which they may be used much like any other key type supported by OpenSSH, so long as the hardware authenticator is attached when the keys are used. FIDO authenticators generally require the user to explicitly authorise operations by touching or tapping them. FIDO keys consist of two parts: a key handle part stored in the private key file on disk, and a per-device private key that is unique to each FIDO authenticator and that cannot be exported from the authenticator hardware. These are combined by the hardware at authentication time to derive the real key that is used to sign authentication challenges. Supported key types are ecdsa-sk and ed25519-sk. The options that are valid for FIDO keys are: application Override the default FIDO application/origin string of ssh:. This may be useful when generating host or domain-specific resident keys. The specified application string must begin with ssh:. challenge=path Specifies a path to a challenge string that will be passed to the FIDO authenticator during key generation. The challenge string may be used as part of an out-of- band protocol for key enrollment (a random challenge is used by default). device Explicitly specify a fido(4) device to use, rather than letting the authenticator middleware select one. no-touch-required Indicate that the generated private key should not require touch events (user presence) when making signatures. Note that sshd(8) will refuse such signatures by default, unless overridden via an authorized_keys option. resident Indicate that the key handle should be stored on the FIDO authenticator itself. This makes it easier to use the authenticator on multiple computers. Resident keys may be supported on FIDO2 authenticators and typically require that a PIN be set on the authenticator prior to generation. Resident keys may be loaded off the authenticator using ssh-add(1). Storing both parts of a key on a FIDO authenticator increases the likelihood of an attacker being able to use a stolen authenticator device. user A username to be associated with a resident key, overriding the empty default username. Specifying a username may be useful when generating multiple resident keys for the same application name. verify-required Indicate that this private key should require user verification for each signature. Not all FIDO authenticators support this option. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. write-attestation=path May be used at key generation time to record the attestation data returned from FIDO authenticators during key generation. This information is potentially sensitive. By default, this information is discarded. KEY REVOCATION LISTS top is able to manage OpenSSH format Key Revocation Lists (KRLs). These binary files specify keys or certificates to be revoked using a compact format, taking as little as one bit per certificate if they are being revoked by serial number. KRLs may be generated using the -k flag. This option reads one or more files from the command line and generates a new KRL. The files may either contain a KRL specification (see below) or public keys, listed one per line. Plain public keys are revoked by listing their hash or contents in the KRL and certificates revoked by serial number or key ID (if the serial is zero or not available). Revoking keys using a KRL specification offers explicit control over the types of record used to revoke keys and may be used to directly revoke certificates by serial number or key ID without having the complete original certificate on hand. A KRL specification consists of lines containing one of the following directives followed by a colon and some directive-specific information. serial: serial_number[-serial_number] Revokes a certificate with the specified serial number. Serial numbers are 64-bit values, not including zero and may be expressed in decimal, hex or octal. If two serial numbers are specified separated by a hyphen, then the range of serial numbers including and between each is revoked. The CA key must have been specified on the command line using the -s option. id: key_id Revokes a certificate with the specified key ID string. The CA key must have been specified on the command line using the -s option. key: public_key Revokes the specified key. If a certificate is listed, then it is revoked as a plain public key. sha1: public_key Revokes the specified key by including its SHA1 hash in the KRL. sha256: public_key Revokes the specified key by including its SHA256 hash in the KRL. KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions prior to 7.9. hash: fingerprint Revokes a key using a fingerprint hash, as obtained from a sshd(8) authentication log message or the -l flag. Only SHA256 fingerprints are supported here and resultant KRLs are not supported by OpenSSH versions prior to 7.9. KRLs may be updated using the -u flag in addition to -k. When this option is specified, keys listed via the command line are merged into the KRL, adding to those already there. It is also possible, given a KRL, to test whether it revokes a particular key (or keys). The -Q flag will query an existing KRL, testing each key specified on the command line. If any key listed on the command line has been revoked (or an error encountered) then will exit with a non-zero exit status. A zero exit status will only be returned if no key was revoked. ALLOWED SIGNERS top When verifying signatures, uses a simple list of identities and keys to determine whether a signature comes from an authorized source. This "allowed signers" file uses a format patterned after the AUTHORIZED_KEYS FILE FORMAT described in sshd(8). Each line of the file contains the following space-separated fields: principals, options, keytype, base64-encoded key. Empty lines and lines starting with a # are ignored as comments. The principals field is a pattern-list (see PATTERNS in ssh_config(5)) consisting of one or more comma-separated USER@DOMAIN identity patterns that are accepted for signing. When verifying, the identity presented via the -I option must match a principals pattern in order for the corresponding key to be considered acceptable for verification. The options (if present) consist of comma-separated option specifications. No spaces are permitted, except within double quotes. The following option specifications are supported (note that option keywords are case-insensitive): cert-authority Indicates that this key is accepted as a certificate authority (CA) and that certificates signed by this CA may be accepted for verification. namespaces=namespace-list Specifies a pattern-list of namespaces that are accepted for this key. If this option is present, the signature namespace embedded in the signature object and presented on the verification command-line must match the specified list before the key will be considered acceptable. valid-after=timestamp Indicates that the key is valid for use at or after the specified timestamp, which may be a date or time in the YYYYMMDD[Z] or YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. valid-before=timestamp Indicates that the key is valid for use at or before the specified timestamp. When verifying signatures made by certificates, the expected principal name must match both the principals pattern in the allowed signers file and the principals embedded in the certificate itself. An example allowed signers file: # Comments allowed at start of line user1@example.com,user2@example.com ssh-rsa AAAAX1... # A certificate authority, trusted for all principals in a domain. *@example.com cert-authority ssh-ed25519 AAAB4... # A key that is accepted only for file signing. user2@example.com namespaces="file" ssh-ed25519 AAA41... ENVIRONMENT top SSH_SK_PROVIDER Specifies a path to a library that will be used when loading any FIDO authenticator-hosted keys, overriding the default of using the built-in USB HID support. FILES top ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specify a passphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 128-bit AES. This file is not automatically accessed by but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machines where the user wishes to log in using public key authentication. There is no need to keep the contents of this file secret. /etc/moduli Contains Diffie-Hellman groups used for DH-GEX. The file format is described in moduli(5). SEE ALSO top ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU September 4, 2023 SSH-KEYGEN(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a ssh key and store it in the file ~/.ssh/apache-rsync Bash Command:<START>ssh-keygen -f ~/.ssh/apache-rsync<END> |
Create a ssh key of RSA type, and prompt for a filename to store it, presenting the default for this type of key as $HOME/.ssh/id_rsa | ssh-keygen -t rsa | ['ssh-keygen'] | Output a Bash command to accomplish the following task. Task: Create a ssh key of RSA type, and prompt for a filename to store it, presenting the default for this type of key as $HOME/.ssh/id_rsa Bash Command:<START>ssh-keygen -t rsa<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh-keygen\n\n> Generate SSH keys used for authentication, password-less logins, and other things.\n> More information: <https://man.openbsd.org/ssh-keygen>.\n\n- Generate a key interactively:\n\n`ssh-keygen`\n\n- Generate an ed25519 key with 32 key derivation function rounds and save the key to a specific file:\n\n`ssh-keygen -t {{ed25519}} -a {{32}} -f {{~/.ssh/filename}}`\n\n- Generate an RSA 4096-bit key with email as a comment:\n\n`ssh-keygen -t {{rsa}} -b {{4096}} -C "{{comment|email}}"`\n\n- Remove the keys of a host from the known_hosts file (useful when a known host has a new key):\n\n`ssh-keygen -R {{remote_host}}`\n\n- Retrieve the fingerprint of a key in MD5 Hex:\n\n`ssh-keygen -l -E {{md5}} -f {{~/.ssh/filename}}`\n\n- Change the password of a key:\n\n`ssh-keygen -p -f {{~/.ssh/filename}}`\n\n- Change the type of the key format (for example from OPENSSH format to PEM), the file will be rewritten in-place:\n\n`ssh-keygen -p -N "" -m {{PEM}} -f {{~/.ssh/OpenSSH_private_key}}`\n\n- Retrieve public key from secret key:\n\n`ssh-keygen -y -f {{~/.ssh/OpenSSH_private_key}}`\n Task: Create a ssh key of RSA type, and prompt for a filename to store it, presenting the default for this type of key as $HOME/.ssh/id_rsa Bash Command:<START>ssh-keygen -t rsa<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh-keygen(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh-keygen(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | MODULI GENERATION | CERTIFICATES | FIDO AUTHENTICATOR | KEY REVOCATION LISTS | ALLOWED SIGNERS | ENVIRONMENT | FILES | SEE ALSO | AUTHORS | COLOPHON SSH-KEYGEN(1) General Commands Manual SSH-KEYGEN(1) NAME top ssh-keygen OpenSSH authentication key utility SYNOPSIS top ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile] [-m format] [-N new_passphrase] [-O option] [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa] [-w provider] [-Z cipher] ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase] [-P old_passphrase] [-Z cipher] ssh-keygen -i [-f input_keyfile] [-m key_format] ssh-keygen -e [-f input_keyfile] [-m key_format] ssh-keygen -y [-f input_keyfile] ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase] ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile] ssh-keygen -B [-f input_keyfile] ssh-keygen -D pkcs11 ssh-keygen -F hostname [-lv] [-f known_hosts_file] ssh-keygen -H [-f known_hosts_file] ssh-keygen -K [-a rounds] [-w provider] ssh-keygen -R hostname [-f known_hosts_file] ssh-keygen -r hostname [-g] [-f input_keyfile] ssh-keygen -M generate [-O option] output_file ssh-keygen -M screen [-f input_file] [-O option] output_file ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider] [-n principals] [-O option] [-V validity_interval] [-z serial_number] file ... ssh-keygen -L [-f input_keyfile] ssh-keygen -A [-a rounds] [-f prefix_path] ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number] file ... ssh-keygen -Q [-l] -f krl_file file ... ssh-keygen -Y find-principals [-O option] -s signature_file -f allowed_signers_file ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file ssh-keygen -Y check-novalidate [-O option] -n namespace -s signature_file ssh-keygen -Y sign [-O option] -f key_file -n namespace file ... ssh-keygen -Y verify [-O option] -f allowed_signers_file -I signer_identity -n namespace -s signature_file [-r revocation_file] DESCRIPTION top generates, manages and converts authentication keys for ssh(1). can create keys for use by SSH protocol version 2. The type of key to be generated is specified with the -t option. If invoked without any arguments, will generate an Ed25519 key. is also used to generate groups for use in Diffie-Hellman group exchange (DH-GEX). See the MODULI GENERATION section for details. Finally, can be used to generate and update Key Revocation Lists, and to test whether given keys have been revoked by one. See the KEY REVOCATION LISTS section for details. Normally each user wishing to use SSH with public key authentication runs this once to create the authentication key in ~/.ssh/id_dsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk or ~/.ssh/id_rsa. Additionally, the system administrator may use this to generate host keys, as seen in /etc/rc. Normally this program generates the key and asks for a file in which to store the private key. The public key is stored in a file with the same name but .pub appended. The program also asks for a passphrase. The passphrase may be empty to indicate no passphrase (host keys must have an empty passphrase), or it may be a string of arbitrary length. A passphrase is similar to a password, except it can be a phrase with a series of words, punctuation, numbers, whitespace, or any string of characters you want. Good passphrases are 10-30 characters long, are not simple sentences or otherwise easily guessable (English prose has only 1-2 bits of entropy per character, and provides very bad passphrases), and contain a mix of upper and lowercase letters, numbers, and non-alphanumeric characters. The passphrase can be changed later by using the -p option. There is no way to recover a lost passphrase. If the passphrase is lost or forgotten, a new key must be generated and the corresponding public key copied to other machines. will by default write keys in an OpenSSH-specific format. This format is preferred as it offers better protection for keys at rest as well as allowing storage of key comments within the private key file itself. The key comment may be useful to help identify the key. The comment is initialized to user@host when the key is created, but can be changed using the -c option. It is still possible for to write the previously-used PEM format private keys using the -m flag. This may be used when generating new keys, and existing new-format keys may be converted using this option in conjunction with the -p (change passphrase) flag. After a key is generated, will ask where the keys should be placed to be activated. The options are as follows: -A Generate host keys of all default key types (rsa, ecdsa, and ed25519) if they do not already exist. The host keys are generated with the default key file path, an empty passphrase, default bits for the key type, and default comment. If -f has also been specified, its argument is used as a prefix to the default path for the resulting host key files. This is used by /etc/rc to generate new host keys. -a rounds When saving a private key, this option specifies the number of KDF (key derivation function, currently bcrypt_pbkdf(3)) rounds used. Higher numbers result in slower passphrase verification and increased resistance to brute-force password cracking (should the keys be stolen). The default is 16 rounds. -B Show the bubblebabble digest of specified private or public key file. -b bits Specifies the number of bits in the key to create. For RSA keys, the minimum size is 1024 bits and the default is 3072 bits. Generally, 3072 bits is considered sufficient. DSA keys must be exactly 1024 bits as specified by FIPS 186-2. For ECDSA keys, the -b flag determines the key length by selecting from one of three elliptic curve sizes: 256, 384 or 521 bits. Attempting to use bit lengths other than these three values for ECDSA keys will fail. ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the -b flag will be ignored. -C comment Provides a new comment. -c Requests changing the comment in the private and public key files. The program will prompt for the file containing the private keys, for the passphrase if the key has one, and for the new comment. -D pkcs11 Download the public keys provided by the PKCS#11 shared library pkcs11. When used in combination with -s, this option indicates that a CA key resides in a PKCS#11 token (see the CERTIFICATES section for details). -E fingerprint_hash Specifies the hash algorithm used when displaying key fingerprints. Valid options are: md5 and sha256. The default is sha256. -e This option will read a private or public OpenSSH key file and print to stdout a public key in one of the formats specified by the -m option. The default export format is RFC4716. This option allows exporting OpenSSH keys for use by other programs, including several commercial SSH implementations. -F hostname | [hostname]:port Search for the specified hostname (with optional port number) in a known_hosts file, listing any occurrences found. This option is useful to find hashed host names or addresses and may also be used in conjunction with the -H option to print found keys in a hashed format. -f filename Specifies the filename of the key file. -g Use generic DNS format when printing fingerprint resource records using the -r command. -H Hash a known_hosts file. This replaces all hostnames and addresses with hashed representations within the specified file; the original content is moved to a file with a .old suffix. These hashes may be used normally by ssh and sshd, but they do not reveal identifying information should the file's contents be disclosed. This option will not modify existing hashed hostnames and is therefore safe to use on files that mix hashed and non-hashed names. -h When signing a key, create a host certificate instead of a user certificate. See the CERTIFICATES section for details. -I certificate_identity Specify the key identity when signing a public key. See the CERTIFICATES section for details. -i This option will read an unencrypted private (or public) key file in the format specified by the -m option and print an OpenSSH compatible private (or public) key to stdout. This option allows importing keys from other software, including several commercial SSH implementations. The default import format is RFC4716. -K Download resident keys from a FIDO authenticator. Public and private key files will be written to the current directory for each downloaded key. If multiple FIDO authenticators are attached, keys will be downloaded from the first touched authenticator. See the FIDO AUTHENTICATOR section for more information. -k Generate a KRL file. In this mode, will generate a KRL file at the location specified via the -f flag that revokes every key or certificate presented on the command line. Keys/certificates to be revoked may be specified by public key file or using the format described in the KEY REVOCATION LISTS section. -L Prints the contents of one or more certificates. -l Show fingerprint of specified public key file. For RSA and DSA keys tries to find the matching public key file and prints its fingerprint. If combined with -v, a visual ASCII art representation of the key is supplied with the fingerprint. -M generate Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for eventual use by the diffie-hellman-group-exchange-* key exchange methods. The numbers generated by this operation must be further screened before use. See the MODULI GENERATION section for more information. -M screen Screen candidate parameters for Diffie-Hellman Group Exchange. This will accept a list of candidate numbers and test that they are safe (Sophie Germain) primes with acceptable group generators. The results of this operation may be added to the /etc/moduli file. See the MODULI GENERATION section for more information. -m key_format Specify a key format for key generation, the -i (import), -e (export) conversion options, and the -p change passphrase operation. The latter may be used to convert between OpenSSH private key and PEM private key formats. The supported key formats are: RFC4716 (RFC 4716/SSH2 public or private key), PKCS8 (PKCS8 public or private key) or PEM (PEM public key). By default OpenSSH will write newly-generated private keys in its own format, but when converting public keys for export the default format is RFC4716. Setting a format of PEM when generating or updating a supported private key type will cause the key to be stored in the legacy PEM private key format. -N new_passphrase Provides the new passphrase. -n principals Specify one or more principals (user or host names) to be included in a certificate when signing a key. Multiple principals may be specified, separated by commas. See the CERTIFICATES section for details. -O option Specify a key/value option. These are specific to the operation that has been requested to perform. When signing certificates, one of the options listed in the CERTIFICATES section may be specified here. When performing moduli generation or screening, one of the options listed in the MODULI GENERATION section may be specified. When generating FIDO authenticator-backed keys, the options listed in the FIDO AUTHENTICATOR section may be specified. When performing signature-related options using the -Y flag, the following options are accepted: hashalg=algorithm Selects the hash algorithm to use for hashing the message to be signed. Valid algorithms are sha256 and sha512. The default is sha512. print-pubkey Print the full public key to standard output after signature verification. verify-time=timestamp Specifies a time to use when validating signatures instead of the current time. The time may be specified as a date or time in the YYYYMMDD[Z] or in YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. When generating SSHFP DNS records from public keys using the -r flag, the following options are accepted: hashalg=algorithm Selects a hash algorithm to use when printing SSHFP records using the -D flag. Valid algorithms are sha1 and sha256. The default is to print both. The -O option may be specified multiple times. -P passphrase Provides the (old) passphrase. -p Requests changing the passphrase of a private key file instead of creating a new private key. The program will prompt for the file containing the private key, for the old passphrase, and twice for the new passphrase. -Q Test whether keys have been revoked in a KRL. If the -l option is also specified then the contents of the KRL will be printed. -q Silence ssh-keygen. -R hostname | [hostname]:port Removes all keys belonging to the specified hostname (with optional port number) from a known_hosts file. This option is useful to delete hashed hosts (see the -H option above). -r hostname Print the SSHFP fingerprint resource record named hostname for the specified public key file. -s ca_key Certify (sign) a public key using the specified CA key. See the CERTIFICATES section for details. When generating a KRL, -s specifies a path to a CA public key file used to revoke certificates directly by key ID or serial number. See the KEY REVOCATION LISTS section for details. -t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa Specifies the type of key to create. The possible values are dsa, ecdsa, ecdsa-sk, ed25519, ed25519-sk, or rsa. This flag may also be used to specify the desired signature type when signing certificates using an RSA CA key. The available RSA signature variants are ssh-rsa (SHA1 signatures, not recommended), rsa-sha2-256, and rsa-sha2-512 (the default). -U When used in combination with -s or -Y sign, this option indicates that a CA key resides in a ssh-agent(1). See the CERTIFICATES section for more information. -u Update a KRL. When specified with -k, keys listed via the command line are added to the existing KRL rather than a new KRL being created. -V validity_interval Specify a validity interval when signing a certificate. A validity interval may consist of a single time, indicating that the certificate is valid beginning now and expiring at that time, or may consist of two times separated by a colon to indicate an explicit time interval. The start time may be specified as: The string always to indicate the certificate has no specified start time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time before the current system time consisting of a minus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. The end time may be specified similarly to the start time: The string forever to indicate the certificate has no specified end time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time after the current system time consisting of a plus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. For example: +52w1d Valid from now to 52 weeks and one day from now. -4w:+4w Valid from four weeks ago to four weeks from now. 20100101123000:20110101123000 Valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011. 20100101123000Z:20110101123000Z Similar, but interpreted in the UTC time zone rather than the system time zone. -1d:20110101 Valid from yesterday to midnight, January 1st, 2011. 0x1:0x2000000000 Valid from roughly early 1970 to May 2033. -1m:forever Valid from one minute ago and never expiring. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful for debugging moduli generation. Multiple -v options increase the verbosity. The maximum is 3. -w provider Specifies a path to a library that will be used when creating FIDO authenticator-hosted keys, overriding the default of using the internal USB HID support. -Y find-principals Find the principal(s) associated with the public key of a signature, provided using the -s flag in an authorized signers file provided using the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. If one or more matching principals are found, they are returned on standard output. -Y match-principals Find principal matching the principal name provided using the -I flag in the authorized signers file specified using the -f flag. If one or more matching principals are found, they are returned on standard output. -Y check-novalidate Checks that a signature generated using -Y sign has a valid structure. This does not validate if a signature comes from an authorized signer. When testing a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag. Successful testing of the signature is signalled by returning a zero exit status. -Y sign Cryptographically sign a file or some data using an SSH key. When signing, accepts zero or more files to sign on the command-line - if no files are specified then will sign data presented on standard input. Signatures are written to the path of the input file with .sig appended, or to standard output if the message to be signed was read from standard input. The key used for signing is specified using the -f option and may refer to either a private key, or a public key with the private half available via ssh-agent(1). An additional signature namespace, used to prevent signature confusion across different domains of use (e.g. file signing vs email signing) must be provided via the -n flag. Namespaces are arbitrary strings, and may include: file for file signing, email for email signing. For custom uses, it is recommended to use names following a NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces. -Y verify Request to verify a signature generated using -Y sign as described above. When verifying a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag, along with the identity of the signer using -I and a list of allowed signers via the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. A file containing revoked keys can be passed using the -r flag. The revocation file may be a KRL or a one-per-line list of public keys. Successful verification by an authorized signer is signalled by returning a zero exit status. -y This option will read a private OpenSSH format file and print an OpenSSH public key to stdout. -Z cipher Specifies the cipher to use for encryption when writing an OpenSSH-format private key file. The list of available ciphers may be obtained using "ssh -Q cipher". The default is aes256-ctr. -z serial_number Specifies a serial number to be embedded in the certificate to distinguish this certificate from others from the same CA. If the serial_number is prefixed with a + character, then the serial number will be incremented for each certificate signed on a single command-line. The default serial number is zero. When generating a KRL, the -z flag is used to specify a KRL version number. MODULI GENERATION top may be used to generate groups for the Diffie-Hellman Group Exchange (DH-GEX) protocol. Generating these groups is a two- step process: first, candidate primes are generated using a fast, but memory intensive process. These candidate primes are then tested for suitability (a CPU-intensive process). Generation of primes is performed using the -M generate option. The desired length of the primes may be specified by the -O bits option. For example: # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates By default, the search for primes begins at a random point in the desired length range. This may be overridden using the -O start option, which specifies a different start point (in hex). Once a set of candidates have been generated, they must be screened for suitability. This may be performed using the -M screen option. In this mode will read candidates from standard input (or a file specified using the -f option). For example: # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048 By default, each candidate will be subjected to 100 primality tests. This may be overridden using the -O prime-tests option. The DH generator value will be chosen automatically for the prime under consideration. If a specific generator is desired, it may be requested using the -O generator option. Valid generator values are 2, 3, and 5. Screened DH groups may be installed in /etc/moduli. It is important that this file contains moduli of a range of bit lengths. A number of options are available for moduli generation and screening via the -O flag: lines=number Exit after screening the specified number of lines while performing DH candidate screening. start-line=line-number Start screening at the specified line number while performing DH candidate screening. checkpoint=filename Write the last line processed to the specified file while performing DH candidate screening. This will be used to skip lines in the input file that have already been processed if the job is restarted. memory=mbytes Specify the amount of memory to use (in megabytes) when generating candidate moduli for DH-GEX. start=hex-value Specify start point (in hex) when generating candidate moduli for DH-GEX. generator=value Specify desired generator (in decimal) when testing candidate moduli for DH-GEX. CERTIFICATES top supports signing of keys to produce certificates that may be used for user or host authentication. Certificates consist of a public key, some identity information, zero or more principal (user or host) names and a set of options that are signed by a Certification Authority (CA) key. Clients or servers may then trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys. Note that OpenSSH certificates are a different, and much simpler, format to the X.509 certificates used in ssl(8). supports two types of certificates: user and host. User certificates authenticate users to servers, whereas host certificates authenticate server hosts to users. To generate a user certificate: $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub The resultant certificate will be placed in /path/to/user_key-cert.pub. A host certificate requires the -h option: $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub The host certificate will be output to /path/to/host_key-cert.pub. It is possible to sign using a CA key stored in a PKCS#11 token by providing the token library using -D and identifying the CA key by providing its public half as an argument to -s: $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub Similarly, it is possible for the CA key to be hosted in a ssh-agent(1). This is indicated by the -U flag and, again, the CA key must be identified by its public half. $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub In all cases, key_id is a "key identifier" that is logged by the server when the certificate is used for authentication. Certificates may be limited to be valid for a set of principal (user/host) names. By default, generated certificates are valid for all users or hosts. To generate a certificate for a specified set of principals: $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub $ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub Additional limitations on the validity and use of user certificates may be specified through certificate options. A certificate option may disable features of the SSH session, may be valid only when presented from particular source addresses or may force the use of a specific command. The options that are valid for user certificates are: clear Clear all enabled permissions. This is useful for clearing the default set of permissions so permissions may be added individually. critical:name[=contents] extension:name[=contents] Includes an arbitrary certificate critical option or extension. The specified name should include a domain suffix, e.g. name@example.com. If contents is specified then it is included as the contents of the extension/option encoded as a string, otherwise the extension/option is created with no contents (usually indicating a flag). Extensions may be ignored by a client or server that does not recognise them, whereas unknown critical options will cause the certificate to be refused. force-command=command Forces the execution of command instead of any shell or command specified by the user when the certificate is used for authentication. no-agent-forwarding Disable ssh-agent(1) forwarding (permitted by default). no-port-forwarding Disable port forwarding (permitted by default). no-pty Disable PTY allocation (permitted by default). no-user-rc Disable execution of ~/.ssh/rc by sshd(8) (permitted by default). no-x11-forwarding Disable X11 forwarding (permitted by default). permit-agent-forwarding Allows ssh-agent(1) forwarding. permit-port-forwarding Allows port forwarding. permit-pty Allows PTY allocation. permit-user-rc Allows execution of ~/.ssh/rc by sshd(8). permit-X11-forwarding Allows X11 forwarding. no-touch-required Do not require signatures made using this key include demonstration of user presence (e.g. by having the user touch the authenticator). This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. source-address=address_list Restrict the source addresses from which the certificate is considered valid. The address_list is a comma- separated list of one or more address/netmask pairs in CIDR format. verify-required Require signatures made using this key indicate that the user was first verified. This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. At present, no standard options are valid for host keys. Finally, certificates may be defined with a validity lifetime. The -V option allows specification of certificate start and end times. A certificate that is presented at a time outside this range will not be considered valid. By default, certificates are valid from the Unix Epoch to the distant future. For certificates to be used for user or host authentication, the CA public key must be trusted by sshd(8) or ssh(1). Refer to those manual pages for details. FIDO AUTHENTICATOR top is able to generate FIDO authenticator-backed keys, after which they may be used much like any other key type supported by OpenSSH, so long as the hardware authenticator is attached when the keys are used. FIDO authenticators generally require the user to explicitly authorise operations by touching or tapping them. FIDO keys consist of two parts: a key handle part stored in the private key file on disk, and a per-device private key that is unique to each FIDO authenticator and that cannot be exported from the authenticator hardware. These are combined by the hardware at authentication time to derive the real key that is used to sign authentication challenges. Supported key types are ecdsa-sk and ed25519-sk. The options that are valid for FIDO keys are: application Override the default FIDO application/origin string of ssh:. This may be useful when generating host or domain-specific resident keys. The specified application string must begin with ssh:. challenge=path Specifies a path to a challenge string that will be passed to the FIDO authenticator during key generation. The challenge string may be used as part of an out-of- band protocol for key enrollment (a random challenge is used by default). device Explicitly specify a fido(4) device to use, rather than letting the authenticator middleware select one. no-touch-required Indicate that the generated private key should not require touch events (user presence) when making signatures. Note that sshd(8) will refuse such signatures by default, unless overridden via an authorized_keys option. resident Indicate that the key handle should be stored on the FIDO authenticator itself. This makes it easier to use the authenticator on multiple computers. Resident keys may be supported on FIDO2 authenticators and typically require that a PIN be set on the authenticator prior to generation. Resident keys may be loaded off the authenticator using ssh-add(1). Storing both parts of a key on a FIDO authenticator increases the likelihood of an attacker being able to use a stolen authenticator device. user A username to be associated with a resident key, overriding the empty default username. Specifying a username may be useful when generating multiple resident keys for the same application name. verify-required Indicate that this private key should require user verification for each signature. Not all FIDO authenticators support this option. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. write-attestation=path May be used at key generation time to record the attestation data returned from FIDO authenticators during key generation. This information is potentially sensitive. By default, this information is discarded. KEY REVOCATION LISTS top is able to manage OpenSSH format Key Revocation Lists (KRLs). These binary files specify keys or certificates to be revoked using a compact format, taking as little as one bit per certificate if they are being revoked by serial number. KRLs may be generated using the -k flag. This option reads one or more files from the command line and generates a new KRL. The files may either contain a KRL specification (see below) or public keys, listed one per line. Plain public keys are revoked by listing their hash or contents in the KRL and certificates revoked by serial number or key ID (if the serial is zero or not available). Revoking keys using a KRL specification offers explicit control over the types of record used to revoke keys and may be used to directly revoke certificates by serial number or key ID without having the complete original certificate on hand. A KRL specification consists of lines containing one of the following directives followed by a colon and some directive-specific information. serial: serial_number[-serial_number] Revokes a certificate with the specified serial number. Serial numbers are 64-bit values, not including zero and may be expressed in decimal, hex or octal. If two serial numbers are specified separated by a hyphen, then the range of serial numbers including and between each is revoked. The CA key must have been specified on the command line using the -s option. id: key_id Revokes a certificate with the specified key ID string. The CA key must have been specified on the command line using the -s option. key: public_key Revokes the specified key. If a certificate is listed, then it is revoked as a plain public key. sha1: public_key Revokes the specified key by including its SHA1 hash in the KRL. sha256: public_key Revokes the specified key by including its SHA256 hash in the KRL. KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions prior to 7.9. hash: fingerprint Revokes a key using a fingerprint hash, as obtained from a sshd(8) authentication log message or the -l flag. Only SHA256 fingerprints are supported here and resultant KRLs are not supported by OpenSSH versions prior to 7.9. KRLs may be updated using the -u flag in addition to -k. When this option is specified, keys listed via the command line are merged into the KRL, adding to those already there. It is also possible, given a KRL, to test whether it revokes a particular key (or keys). The -Q flag will query an existing KRL, testing each key specified on the command line. If any key listed on the command line has been revoked (or an error encountered) then will exit with a non-zero exit status. A zero exit status will only be returned if no key was revoked. ALLOWED SIGNERS top When verifying signatures, uses a simple list of identities and keys to determine whether a signature comes from an authorized source. This "allowed signers" file uses a format patterned after the AUTHORIZED_KEYS FILE FORMAT described in sshd(8). Each line of the file contains the following space-separated fields: principals, options, keytype, base64-encoded key. Empty lines and lines starting with a # are ignored as comments. The principals field is a pattern-list (see PATTERNS in ssh_config(5)) consisting of one or more comma-separated USER@DOMAIN identity patterns that are accepted for signing. When verifying, the identity presented via the -I option must match a principals pattern in order for the corresponding key to be considered acceptable for verification. The options (if present) consist of comma-separated option specifications. No spaces are permitted, except within double quotes. The following option specifications are supported (note that option keywords are case-insensitive): cert-authority Indicates that this key is accepted as a certificate authority (CA) and that certificates signed by this CA may be accepted for verification. namespaces=namespace-list Specifies a pattern-list of namespaces that are accepted for this key. If this option is present, the signature namespace embedded in the signature object and presented on the verification command-line must match the specified list before the key will be considered acceptable. valid-after=timestamp Indicates that the key is valid for use at or after the specified timestamp, which may be a date or time in the YYYYMMDD[Z] or YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. valid-before=timestamp Indicates that the key is valid for use at or before the specified timestamp. When verifying signatures made by certificates, the expected principal name must match both the principals pattern in the allowed signers file and the principals embedded in the certificate itself. An example allowed signers file: # Comments allowed at start of line user1@example.com,user2@example.com ssh-rsa AAAAX1... # A certificate authority, trusted for all principals in a domain. *@example.com cert-authority ssh-ed25519 AAAB4... # A key that is accepted only for file signing. user2@example.com namespaces="file" ssh-ed25519 AAA41... ENVIRONMENT top SSH_SK_PROVIDER Specifies a path to a library that will be used when loading any FIDO authenticator-hosted keys, overriding the default of using the built-in USB HID support. FILES top ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specify a passphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 128-bit AES. This file is not automatically accessed by but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machines where the user wishes to log in using public key authentication. There is no need to keep the contents of this file secret. /etc/moduli Contains Diffie-Hellman groups used for DH-GEX. The file format is described in moduli(5). SEE ALSO top ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU September 4, 2023 SSH-KEYGEN(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a ssh key of RSA type, and prompt for a filename to store it, presenting the default for this type of key as $HOME/.ssh/id_rsa Bash Command:<START>ssh-keygen -t rsa<END> |
Create a ssh key with no passphrase and store it in "outfile". | ssh-keygen -f outfile -N '' | ['ssh-keygen'] | Output a Bash command to accomplish the following task. Task: Create a ssh key with no passphrase and store it in "outfile". Bash Command:<START>ssh-keygen -f outfile -N ''<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh-keygen\n\n> Generate SSH keys used for authentication, password-less logins, and other things.\n> More information: <https://man.openbsd.org/ssh-keygen>.\n\n- Generate a key interactively:\n\n`ssh-keygen`\n\n- Generate an ed25519 key with 32 key derivation function rounds and save the key to a specific file:\n\n`ssh-keygen -t {{ed25519}} -a {{32}} -f {{~/.ssh/filename}}`\n\n- Generate an RSA 4096-bit key with email as a comment:\n\n`ssh-keygen -t {{rsa}} -b {{4096}} -C "{{comment|email}}"`\n\n- Remove the keys of a host from the known_hosts file (useful when a known host has a new key):\n\n`ssh-keygen -R {{remote_host}}`\n\n- Retrieve the fingerprint of a key in MD5 Hex:\n\n`ssh-keygen -l -E {{md5}} -f {{~/.ssh/filename}}`\n\n- Change the password of a key:\n\n`ssh-keygen -p -f {{~/.ssh/filename}}`\n\n- Change the type of the key format (for example from OPENSSH format to PEM), the file will be rewritten in-place:\n\n`ssh-keygen -p -N "" -m {{PEM}} -f {{~/.ssh/OpenSSH_private_key}}`\n\n- Retrieve public key from secret key:\n\n`ssh-keygen -y -f {{~/.ssh/OpenSSH_private_key}}`\n Task: Create a ssh key with no passphrase and store it in "outfile". Bash Command:<START>ssh-keygen -f outfile -N ''<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh-keygen(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh-keygen(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | MODULI GENERATION | CERTIFICATES | FIDO AUTHENTICATOR | KEY REVOCATION LISTS | ALLOWED SIGNERS | ENVIRONMENT | FILES | SEE ALSO | AUTHORS | COLOPHON SSH-KEYGEN(1) General Commands Manual SSH-KEYGEN(1) NAME top ssh-keygen OpenSSH authentication key utility SYNOPSIS top ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile] [-m format] [-N new_passphrase] [-O option] [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa] [-w provider] [-Z cipher] ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase] [-P old_passphrase] [-Z cipher] ssh-keygen -i [-f input_keyfile] [-m key_format] ssh-keygen -e [-f input_keyfile] [-m key_format] ssh-keygen -y [-f input_keyfile] ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase] ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile] ssh-keygen -B [-f input_keyfile] ssh-keygen -D pkcs11 ssh-keygen -F hostname [-lv] [-f known_hosts_file] ssh-keygen -H [-f known_hosts_file] ssh-keygen -K [-a rounds] [-w provider] ssh-keygen -R hostname [-f known_hosts_file] ssh-keygen -r hostname [-g] [-f input_keyfile] ssh-keygen -M generate [-O option] output_file ssh-keygen -M screen [-f input_file] [-O option] output_file ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider] [-n principals] [-O option] [-V validity_interval] [-z serial_number] file ... ssh-keygen -L [-f input_keyfile] ssh-keygen -A [-a rounds] [-f prefix_path] ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number] file ... ssh-keygen -Q [-l] -f krl_file file ... ssh-keygen -Y find-principals [-O option] -s signature_file -f allowed_signers_file ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file ssh-keygen -Y check-novalidate [-O option] -n namespace -s signature_file ssh-keygen -Y sign [-O option] -f key_file -n namespace file ... ssh-keygen -Y verify [-O option] -f allowed_signers_file -I signer_identity -n namespace -s signature_file [-r revocation_file] DESCRIPTION top generates, manages and converts authentication keys for ssh(1). can create keys for use by SSH protocol version 2. The type of key to be generated is specified with the -t option. If invoked without any arguments, will generate an Ed25519 key. is also used to generate groups for use in Diffie-Hellman group exchange (DH-GEX). See the MODULI GENERATION section for details. Finally, can be used to generate and update Key Revocation Lists, and to test whether given keys have been revoked by one. See the KEY REVOCATION LISTS section for details. Normally each user wishing to use SSH with public key authentication runs this once to create the authentication key in ~/.ssh/id_dsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk or ~/.ssh/id_rsa. Additionally, the system administrator may use this to generate host keys, as seen in /etc/rc. Normally this program generates the key and asks for a file in which to store the private key. The public key is stored in a file with the same name but .pub appended. The program also asks for a passphrase. The passphrase may be empty to indicate no passphrase (host keys must have an empty passphrase), or it may be a string of arbitrary length. A passphrase is similar to a password, except it can be a phrase with a series of words, punctuation, numbers, whitespace, or any string of characters you want. Good passphrases are 10-30 characters long, are not simple sentences or otherwise easily guessable (English prose has only 1-2 bits of entropy per character, and provides very bad passphrases), and contain a mix of upper and lowercase letters, numbers, and non-alphanumeric characters. The passphrase can be changed later by using the -p option. There is no way to recover a lost passphrase. If the passphrase is lost or forgotten, a new key must be generated and the corresponding public key copied to other machines. will by default write keys in an OpenSSH-specific format. This format is preferred as it offers better protection for keys at rest as well as allowing storage of key comments within the private key file itself. The key comment may be useful to help identify the key. The comment is initialized to user@host when the key is created, but can be changed using the -c option. It is still possible for to write the previously-used PEM format private keys using the -m flag. This may be used when generating new keys, and existing new-format keys may be converted using this option in conjunction with the -p (change passphrase) flag. After a key is generated, will ask where the keys should be placed to be activated. The options are as follows: -A Generate host keys of all default key types (rsa, ecdsa, and ed25519) if they do not already exist. The host keys are generated with the default key file path, an empty passphrase, default bits for the key type, and default comment. If -f has also been specified, its argument is used as a prefix to the default path for the resulting host key files. This is used by /etc/rc to generate new host keys. -a rounds When saving a private key, this option specifies the number of KDF (key derivation function, currently bcrypt_pbkdf(3)) rounds used. Higher numbers result in slower passphrase verification and increased resistance to brute-force password cracking (should the keys be stolen). The default is 16 rounds. -B Show the bubblebabble digest of specified private or public key file. -b bits Specifies the number of bits in the key to create. For RSA keys, the minimum size is 1024 bits and the default is 3072 bits. Generally, 3072 bits is considered sufficient. DSA keys must be exactly 1024 bits as specified by FIPS 186-2. For ECDSA keys, the -b flag determines the key length by selecting from one of three elliptic curve sizes: 256, 384 or 521 bits. Attempting to use bit lengths other than these three values for ECDSA keys will fail. ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the -b flag will be ignored. -C comment Provides a new comment. -c Requests changing the comment in the private and public key files. The program will prompt for the file containing the private keys, for the passphrase if the key has one, and for the new comment. -D pkcs11 Download the public keys provided by the PKCS#11 shared library pkcs11. When used in combination with -s, this option indicates that a CA key resides in a PKCS#11 token (see the CERTIFICATES section for details). -E fingerprint_hash Specifies the hash algorithm used when displaying key fingerprints. Valid options are: md5 and sha256. The default is sha256. -e This option will read a private or public OpenSSH key file and print to stdout a public key in one of the formats specified by the -m option. The default export format is RFC4716. This option allows exporting OpenSSH keys for use by other programs, including several commercial SSH implementations. -F hostname | [hostname]:port Search for the specified hostname (with optional port number) in a known_hosts file, listing any occurrences found. This option is useful to find hashed host names or addresses and may also be used in conjunction with the -H option to print found keys in a hashed format. -f filename Specifies the filename of the key file. -g Use generic DNS format when printing fingerprint resource records using the -r command. -H Hash a known_hosts file. This replaces all hostnames and addresses with hashed representations within the specified file; the original content is moved to a file with a .old suffix. These hashes may be used normally by ssh and sshd, but they do not reveal identifying information should the file's contents be disclosed. This option will not modify existing hashed hostnames and is therefore safe to use on files that mix hashed and non-hashed names. -h When signing a key, create a host certificate instead of a user certificate. See the CERTIFICATES section for details. -I certificate_identity Specify the key identity when signing a public key. See the CERTIFICATES section for details. -i This option will read an unencrypted private (or public) key file in the format specified by the -m option and print an OpenSSH compatible private (or public) key to stdout. This option allows importing keys from other software, including several commercial SSH implementations. The default import format is RFC4716. -K Download resident keys from a FIDO authenticator. Public and private key files will be written to the current directory for each downloaded key. If multiple FIDO authenticators are attached, keys will be downloaded from the first touched authenticator. See the FIDO AUTHENTICATOR section for more information. -k Generate a KRL file. In this mode, will generate a KRL file at the location specified via the -f flag that revokes every key or certificate presented on the command line. Keys/certificates to be revoked may be specified by public key file or using the format described in the KEY REVOCATION LISTS section. -L Prints the contents of one or more certificates. -l Show fingerprint of specified public key file. For RSA and DSA keys tries to find the matching public key file and prints its fingerprint. If combined with -v, a visual ASCII art representation of the key is supplied with the fingerprint. -M generate Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for eventual use by the diffie-hellman-group-exchange-* key exchange methods. The numbers generated by this operation must be further screened before use. See the MODULI GENERATION section for more information. -M screen Screen candidate parameters for Diffie-Hellman Group Exchange. This will accept a list of candidate numbers and test that they are safe (Sophie Germain) primes with acceptable group generators. The results of this operation may be added to the /etc/moduli file. See the MODULI GENERATION section for more information. -m key_format Specify a key format for key generation, the -i (import), -e (export) conversion options, and the -p change passphrase operation. The latter may be used to convert between OpenSSH private key and PEM private key formats. The supported key formats are: RFC4716 (RFC 4716/SSH2 public or private key), PKCS8 (PKCS8 public or private key) or PEM (PEM public key). By default OpenSSH will write newly-generated private keys in its own format, but when converting public keys for export the default format is RFC4716. Setting a format of PEM when generating or updating a supported private key type will cause the key to be stored in the legacy PEM private key format. -N new_passphrase Provides the new passphrase. -n principals Specify one or more principals (user or host names) to be included in a certificate when signing a key. Multiple principals may be specified, separated by commas. See the CERTIFICATES section for details. -O option Specify a key/value option. These are specific to the operation that has been requested to perform. When signing certificates, one of the options listed in the CERTIFICATES section may be specified here. When performing moduli generation or screening, one of the options listed in the MODULI GENERATION section may be specified. When generating FIDO authenticator-backed keys, the options listed in the FIDO AUTHENTICATOR section may be specified. When performing signature-related options using the -Y flag, the following options are accepted: hashalg=algorithm Selects the hash algorithm to use for hashing the message to be signed. Valid algorithms are sha256 and sha512. The default is sha512. print-pubkey Print the full public key to standard output after signature verification. verify-time=timestamp Specifies a time to use when validating signatures instead of the current time. The time may be specified as a date or time in the YYYYMMDD[Z] or in YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. When generating SSHFP DNS records from public keys using the -r flag, the following options are accepted: hashalg=algorithm Selects a hash algorithm to use when printing SSHFP records using the -D flag. Valid algorithms are sha1 and sha256. The default is to print both. The -O option may be specified multiple times. -P passphrase Provides the (old) passphrase. -p Requests changing the passphrase of a private key file instead of creating a new private key. The program will prompt for the file containing the private key, for the old passphrase, and twice for the new passphrase. -Q Test whether keys have been revoked in a KRL. If the -l option is also specified then the contents of the KRL will be printed. -q Silence ssh-keygen. -R hostname | [hostname]:port Removes all keys belonging to the specified hostname (with optional port number) from a known_hosts file. This option is useful to delete hashed hosts (see the -H option above). -r hostname Print the SSHFP fingerprint resource record named hostname for the specified public key file. -s ca_key Certify (sign) a public key using the specified CA key. See the CERTIFICATES section for details. When generating a KRL, -s specifies a path to a CA public key file used to revoke certificates directly by key ID or serial number. See the KEY REVOCATION LISTS section for details. -t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa Specifies the type of key to create. The possible values are dsa, ecdsa, ecdsa-sk, ed25519, ed25519-sk, or rsa. This flag may also be used to specify the desired signature type when signing certificates using an RSA CA key. The available RSA signature variants are ssh-rsa (SHA1 signatures, not recommended), rsa-sha2-256, and rsa-sha2-512 (the default). -U When used in combination with -s or -Y sign, this option indicates that a CA key resides in a ssh-agent(1). See the CERTIFICATES section for more information. -u Update a KRL. When specified with -k, keys listed via the command line are added to the existing KRL rather than a new KRL being created. -V validity_interval Specify a validity interval when signing a certificate. A validity interval may consist of a single time, indicating that the certificate is valid beginning now and expiring at that time, or may consist of two times separated by a colon to indicate an explicit time interval. The start time may be specified as: The string always to indicate the certificate has no specified start time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time before the current system time consisting of a minus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. The end time may be specified similarly to the start time: The string forever to indicate the certificate has no specified end time. A date or time in the system time zone formatted as YYYYMMDD or YYYYMMDDHHMM[SS]. A date or time in the UTC time zone as YYYYMMDDZ or YYYYMMDDHHMM[SS]Z. A relative time after the current system time consisting of a plus sign followed by an interval in the format described in the TIME FORMATS section of sshd_config(5). A raw seconds since epoch (Jan 1 1970 00:00:00 UTC) as a hexadecimal number beginning with 0x. For example: +52w1d Valid from now to 52 weeks and one day from now. -4w:+4w Valid from four weeks ago to four weeks from now. 20100101123000:20110101123000 Valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011. 20100101123000Z:20110101123000Z Similar, but interpreted in the UTC time zone rather than the system time zone. -1d:20110101 Valid from yesterday to midnight, January 1st, 2011. 0x1:0x2000000000 Valid from roughly early 1970 to May 2033. -1m:forever Valid from one minute ago and never expiring. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful for debugging moduli generation. Multiple -v options increase the verbosity. The maximum is 3. -w provider Specifies a path to a library that will be used when creating FIDO authenticator-hosted keys, overriding the default of using the internal USB HID support. -Y find-principals Find the principal(s) associated with the public key of a signature, provided using the -s flag in an authorized signers file provided using the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. If one or more matching principals are found, they are returned on standard output. -Y match-principals Find principal matching the principal name provided using the -I flag in the authorized signers file specified using the -f flag. If one or more matching principals are found, they are returned on standard output. -Y check-novalidate Checks that a signature generated using -Y sign has a valid structure. This does not validate if a signature comes from an authorized signer. When testing a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag. Successful testing of the signature is signalled by returning a zero exit status. -Y sign Cryptographically sign a file or some data using an SSH key. When signing, accepts zero or more files to sign on the command-line - if no files are specified then will sign data presented on standard input. Signatures are written to the path of the input file with .sig appended, or to standard output if the message to be signed was read from standard input. The key used for signing is specified using the -f option and may refer to either a private key, or a public key with the private half available via ssh-agent(1). An additional signature namespace, used to prevent signature confusion across different domains of use (e.g. file signing vs email signing) must be provided via the -n flag. Namespaces are arbitrary strings, and may include: file for file signing, email for email signing. For custom uses, it is recommended to use names following a NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces. -Y verify Request to verify a signature generated using -Y sign as described above. When verifying a signature, accepts a message on standard input and a signature namespace using -n. A file containing the corresponding signature must also be supplied using the -s flag, along with the identity of the signer using -I and a list of allowed signers via the -f flag. The format of the allowed signers file is documented in the ALLOWED SIGNERS section below. A file containing revoked keys can be passed using the -r flag. The revocation file may be a KRL or a one-per-line list of public keys. Successful verification by an authorized signer is signalled by returning a zero exit status. -y This option will read a private OpenSSH format file and print an OpenSSH public key to stdout. -Z cipher Specifies the cipher to use for encryption when writing an OpenSSH-format private key file. The list of available ciphers may be obtained using "ssh -Q cipher". The default is aes256-ctr. -z serial_number Specifies a serial number to be embedded in the certificate to distinguish this certificate from others from the same CA. If the serial_number is prefixed with a + character, then the serial number will be incremented for each certificate signed on a single command-line. The default serial number is zero. When generating a KRL, the -z flag is used to specify a KRL version number. MODULI GENERATION top may be used to generate groups for the Diffie-Hellman Group Exchange (DH-GEX) protocol. Generating these groups is a two- step process: first, candidate primes are generated using a fast, but memory intensive process. These candidate primes are then tested for suitability (a CPU-intensive process). Generation of primes is performed using the -M generate option. The desired length of the primes may be specified by the -O bits option. For example: # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates By default, the search for primes begins at a random point in the desired length range. This may be overridden using the -O start option, which specifies a different start point (in hex). Once a set of candidates have been generated, they must be screened for suitability. This may be performed using the -M screen option. In this mode will read candidates from standard input (or a file specified using the -f option). For example: # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048 By default, each candidate will be subjected to 100 primality tests. This may be overridden using the -O prime-tests option. The DH generator value will be chosen automatically for the prime under consideration. If a specific generator is desired, it may be requested using the -O generator option. Valid generator values are 2, 3, and 5. Screened DH groups may be installed in /etc/moduli. It is important that this file contains moduli of a range of bit lengths. A number of options are available for moduli generation and screening via the -O flag: lines=number Exit after screening the specified number of lines while performing DH candidate screening. start-line=line-number Start screening at the specified line number while performing DH candidate screening. checkpoint=filename Write the last line processed to the specified file while performing DH candidate screening. This will be used to skip lines in the input file that have already been processed if the job is restarted. memory=mbytes Specify the amount of memory to use (in megabytes) when generating candidate moduli for DH-GEX. start=hex-value Specify start point (in hex) when generating candidate moduli for DH-GEX. generator=value Specify desired generator (in decimal) when testing candidate moduli for DH-GEX. CERTIFICATES top supports signing of keys to produce certificates that may be used for user or host authentication. Certificates consist of a public key, some identity information, zero or more principal (user or host) names and a set of options that are signed by a Certification Authority (CA) key. Clients or servers may then trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys. Note that OpenSSH certificates are a different, and much simpler, format to the X.509 certificates used in ssl(8). supports two types of certificates: user and host. User certificates authenticate users to servers, whereas host certificates authenticate server hosts to users. To generate a user certificate: $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub The resultant certificate will be placed in /path/to/user_key-cert.pub. A host certificate requires the -h option: $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub The host certificate will be output to /path/to/host_key-cert.pub. It is possible to sign using a CA key stored in a PKCS#11 token by providing the token library using -D and identifying the CA key by providing its public half as an argument to -s: $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub Similarly, it is possible for the CA key to be hosted in a ssh-agent(1). This is indicated by the -U flag and, again, the CA key must be identified by its public half. $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub In all cases, key_id is a "key identifier" that is logged by the server when the certificate is used for authentication. Certificates may be limited to be valid for a set of principal (user/host) names. By default, generated certificates are valid for all users or hosts. To generate a certificate for a specified set of principals: $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub $ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub Additional limitations on the validity and use of user certificates may be specified through certificate options. A certificate option may disable features of the SSH session, may be valid only when presented from particular source addresses or may force the use of a specific command. The options that are valid for user certificates are: clear Clear all enabled permissions. This is useful for clearing the default set of permissions so permissions may be added individually. critical:name[=contents] extension:name[=contents] Includes an arbitrary certificate critical option or extension. The specified name should include a domain suffix, e.g. name@example.com. If contents is specified then it is included as the contents of the extension/option encoded as a string, otherwise the extension/option is created with no contents (usually indicating a flag). Extensions may be ignored by a client or server that does not recognise them, whereas unknown critical options will cause the certificate to be refused. force-command=command Forces the execution of command instead of any shell or command specified by the user when the certificate is used for authentication. no-agent-forwarding Disable ssh-agent(1) forwarding (permitted by default). no-port-forwarding Disable port forwarding (permitted by default). no-pty Disable PTY allocation (permitted by default). no-user-rc Disable execution of ~/.ssh/rc by sshd(8) (permitted by default). no-x11-forwarding Disable X11 forwarding (permitted by default). permit-agent-forwarding Allows ssh-agent(1) forwarding. permit-port-forwarding Allows port forwarding. permit-pty Allows PTY allocation. permit-user-rc Allows execution of ~/.ssh/rc by sshd(8). permit-X11-forwarding Allows X11 forwarding. no-touch-required Do not require signatures made using this key include demonstration of user presence (e.g. by having the user touch the authenticator). This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. source-address=address_list Restrict the source addresses from which the certificate is considered valid. The address_list is a comma- separated list of one or more address/netmask pairs in CIDR format. verify-required Require signatures made using this key indicate that the user was first verified. This option only makes sense for the FIDO authenticator algorithms ecdsa-sk and ed25519-sk. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. At present, no standard options are valid for host keys. Finally, certificates may be defined with a validity lifetime. The -V option allows specification of certificate start and end times. A certificate that is presented at a time outside this range will not be considered valid. By default, certificates are valid from the Unix Epoch to the distant future. For certificates to be used for user or host authentication, the CA public key must be trusted by sshd(8) or ssh(1). Refer to those manual pages for details. FIDO AUTHENTICATOR top is able to generate FIDO authenticator-backed keys, after which they may be used much like any other key type supported by OpenSSH, so long as the hardware authenticator is attached when the keys are used. FIDO authenticators generally require the user to explicitly authorise operations by touching or tapping them. FIDO keys consist of two parts: a key handle part stored in the private key file on disk, and a per-device private key that is unique to each FIDO authenticator and that cannot be exported from the authenticator hardware. These are combined by the hardware at authentication time to derive the real key that is used to sign authentication challenges. Supported key types are ecdsa-sk and ed25519-sk. The options that are valid for FIDO keys are: application Override the default FIDO application/origin string of ssh:. This may be useful when generating host or domain-specific resident keys. The specified application string must begin with ssh:. challenge=path Specifies a path to a challenge string that will be passed to the FIDO authenticator during key generation. The challenge string may be used as part of an out-of- band protocol for key enrollment (a random challenge is used by default). device Explicitly specify a fido(4) device to use, rather than letting the authenticator middleware select one. no-touch-required Indicate that the generated private key should not require touch events (user presence) when making signatures. Note that sshd(8) will refuse such signatures by default, unless overridden via an authorized_keys option. resident Indicate that the key handle should be stored on the FIDO authenticator itself. This makes it easier to use the authenticator on multiple computers. Resident keys may be supported on FIDO2 authenticators and typically require that a PIN be set on the authenticator prior to generation. Resident keys may be loaded off the authenticator using ssh-add(1). Storing both parts of a key on a FIDO authenticator increases the likelihood of an attacker being able to use a stolen authenticator device. user A username to be associated with a resident key, overriding the empty default username. Specifying a username may be useful when generating multiple resident keys for the same application name. verify-required Indicate that this private key should require user verification for each signature. Not all FIDO authenticators support this option. Currently PIN authentication is the only supported verification method, but other methods may be supported in the future. write-attestation=path May be used at key generation time to record the attestation data returned from FIDO authenticators during key generation. This information is potentially sensitive. By default, this information is discarded. KEY REVOCATION LISTS top is able to manage OpenSSH format Key Revocation Lists (KRLs). These binary files specify keys or certificates to be revoked using a compact format, taking as little as one bit per certificate if they are being revoked by serial number. KRLs may be generated using the -k flag. This option reads one or more files from the command line and generates a new KRL. The files may either contain a KRL specification (see below) or public keys, listed one per line. Plain public keys are revoked by listing their hash or contents in the KRL and certificates revoked by serial number or key ID (if the serial is zero or not available). Revoking keys using a KRL specification offers explicit control over the types of record used to revoke keys and may be used to directly revoke certificates by serial number or key ID without having the complete original certificate on hand. A KRL specification consists of lines containing one of the following directives followed by a colon and some directive-specific information. serial: serial_number[-serial_number] Revokes a certificate with the specified serial number. Serial numbers are 64-bit values, not including zero and may be expressed in decimal, hex or octal. If two serial numbers are specified separated by a hyphen, then the range of serial numbers including and between each is revoked. The CA key must have been specified on the command line using the -s option. id: key_id Revokes a certificate with the specified key ID string. The CA key must have been specified on the command line using the -s option. key: public_key Revokes the specified key. If a certificate is listed, then it is revoked as a plain public key. sha1: public_key Revokes the specified key by including its SHA1 hash in the KRL. sha256: public_key Revokes the specified key by including its SHA256 hash in the KRL. KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions prior to 7.9. hash: fingerprint Revokes a key using a fingerprint hash, as obtained from a sshd(8) authentication log message or the -l flag. Only SHA256 fingerprints are supported here and resultant KRLs are not supported by OpenSSH versions prior to 7.9. KRLs may be updated using the -u flag in addition to -k. When this option is specified, keys listed via the command line are merged into the KRL, adding to those already there. It is also possible, given a KRL, to test whether it revokes a particular key (or keys). The -Q flag will query an existing KRL, testing each key specified on the command line. If any key listed on the command line has been revoked (or an error encountered) then will exit with a non-zero exit status. A zero exit status will only be returned if no key was revoked. ALLOWED SIGNERS top When verifying signatures, uses a simple list of identities and keys to determine whether a signature comes from an authorized source. This "allowed signers" file uses a format patterned after the AUTHORIZED_KEYS FILE FORMAT described in sshd(8). Each line of the file contains the following space-separated fields: principals, options, keytype, base64-encoded key. Empty lines and lines starting with a # are ignored as comments. The principals field is a pattern-list (see PATTERNS in ssh_config(5)) consisting of one or more comma-separated USER@DOMAIN identity patterns that are accepted for signing. When verifying, the identity presented via the -I option must match a principals pattern in order for the corresponding key to be considered acceptable for verification. The options (if present) consist of comma-separated option specifications. No spaces are permitted, except within double quotes. The following option specifications are supported (note that option keywords are case-insensitive): cert-authority Indicates that this key is accepted as a certificate authority (CA) and that certificates signed by this CA may be accepted for verification. namespaces=namespace-list Specifies a pattern-list of namespaces that are accepted for this key. If this option is present, the signature namespace embedded in the signature object and presented on the verification command-line must match the specified list before the key will be considered acceptable. valid-after=timestamp Indicates that the key is valid for use at or after the specified timestamp, which may be a date or time in the YYYYMMDD[Z] or YYYYMMDDHHMM[SS][Z] formats. Dates and times will be interpreted in the current system time zone unless suffixed with a Z character, which causes them to be interpreted in the UTC time zone. valid-before=timestamp Indicates that the key is valid for use at or before the specified timestamp. When verifying signatures made by certificates, the expected principal name must match both the principals pattern in the allowed signers file and the principals embedded in the certificate itself. An example allowed signers file: # Comments allowed at start of line user1@example.com,user2@example.com ssh-rsa AAAAX1... # A certificate authority, trusted for all principals in a domain. *@example.com cert-authority ssh-ed25519 AAAB4... # A key that is accepted only for file signing. user2@example.com namespaces="file" ssh-ed25519 AAA41... ENVIRONMENT top SSH_SK_PROVIDER Specifies a path to a library that will be used when loading any FIDO authenticator-hosted keys, overriding the default of using the built-in USB HID support. FILES top ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specify a passphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 128-bit AES. This file is not automatically accessed by but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519, authenticator-hosted Ed25519 or RSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machines where the user wishes to log in using public key authentication. There is no need to keep the contents of this file secret. /etc/moduli Contains Diffie-Hellman groups used for DH-GEX. The file format is described in moduli(5). SEE ALSO top ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU September 4, 2023 SSH-KEYGEN(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a ssh key with no passphrase and store it in "outfile". Bash Command:<START>ssh-keygen -f outfile -N ''<END> |
Create a ssh tunnel on local port 2222 through "bridge.example.com" to "remote.example.com" port 22 without executing any commands and run in the background | ssh -N -L 2222:remote.example.com:22 bridge.example.com& | ['ssh'] | Output a Bash command to accomplish the following task. Task: Create a ssh tunnel on local port 2222 through "bridge.example.com" to "remote.example.com" port 22 without executing any commands and run in the background Bash Command:<START>ssh -N -L 2222:remote.example.com:22 bridge.example.com&<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh\n\n> Secure Shell is a protocol used to securely log onto remote systems.\n> It can be used for logging or executing commands on a remote server.\n> More information: <https://man.openbsd.org/ssh>.\n\n- Connect to a remote server:\n\n`ssh {{username}}@{{remote_host}}`\n\n- Connect to a remote server with a specific identity (private key):\n\n`ssh -i {{path/to/key_file}} {{username}}@{{remote_host}}`\n\n- Connect to a remote server using a specific [p]ort:\n\n`ssh {{username}}@{{remote_host}} -p {{2222}}`\n\n- Run a command on a remote server with a [t]ty allocation allowing interaction with the remote command:\n\n`ssh {{username}}@{{remote_host}} -t {{command}} {{command_arguments}}`\n\n- SSH tunneling: [D]ynamic port forwarding (SOCKS proxy on `localhost:1080`):\n\n`ssh -D {{1080}} {{username}}@{{remote_host}}`\n\n- SSH tunneling: Forward a specific port (`localhost:9999` to `example.org:80`) along with disabling pseudo-[T]ty allocation and executio[N] of remote commands:\n\n`ssh -L {{9999}}:{{example.org}}:{{80}} -N -T {{username}}@{{remote_host}}`\n\n- SSH [J]umping: Connect through a jumphost to a remote server (Multiple jump hops may be specified separated by comma characters):\n\n`ssh -J {{username}}@{{jump_host}} {{username}}@{{remote_host}}`\n\n- Agent forwarding: Forward the authentication information to the remote machine (see `man ssh_config` for available options):\n\n`ssh -A {{username}}@{{remote_host}}`\n Task: Create a ssh tunnel on local port 2222 through "bridge.example.com" to "remote.example.com" port 22 without executing any commands and run in the background Bash Command:<START>ssh -N -L 2222:remote.example.com:22 bridge.example.com&<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHENTICATION | ESCAPE CHARACTERS | TCP FORWARDING | X11 FORWARDING | VERIFYING HOST KEYS | SSH-BASED VIRTUAL PRIVATE NETWORKS | ENVIRONMENT | FILES | EXIT STATUS | SEE ALSO | STANDARDS | AUTHORS | COLOPHON SSH(1) General Commands Manual SSH(1) NAME top ssh OpenSSH remote login client SYNOPSIS top ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface] [-b bind_address] [-c cipher_spec] [-D [bind_address:]port] [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11] [-i identity_file] [-J destination] [-L address] [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-P tag] [-p port] [-R address] [-S ctl_path] [-W host:port] [-w local_tun[:remote_tun]] destination [command [argument ...]] [-Q query_option] DESCRIPTION top (SSH client) is a program for logging into a remote machine and for executing commands on a remote machine. It is intended to provide secure encrypted communications between two untrusted hosts over an insecure network. X11 connections, arbitrary TCP ports and Unix-domain sockets can also be forwarded over the secure channel. connects and logs into the specified destination, which may be specified as either [user@]hostname or a URI of the form ssh://[user@]hostname[:port]. The user must prove their identity to the remote machine using one of several methods (see below). If a command is specified, it will be executed on the remote host instead of a login shell. A complete command line may be specified as command, or it may have additional arguments. If supplied, the arguments will be appended to the command, separated by spaces, before it is sent to the server to be executed. The options are as follows: -4 Forces to use IPv4 addresses only. -6 Forces to use IPv6 addresses only. -A Enables forwarding of connections from an authentication agent such as ssh-agent(1). This can also be specified on a per-host basis in a configuration file. Agent forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the agent's Unix-domain socket) can access the local agent through the forwarded connection. An attacker cannot obtain key material from the agent, however they can perform operations on the keys that enable them to authenticate using the identities loaded into the agent. A safer alternative may be to use a jump host (see -J). -a Disables forwarding of the authentication agent connection. -B bind_interface Bind to the address of bind_interface before attempting to connect to the destination host. This is only useful on systems with more than one address. -b bind_address Use bind_address on the local machine as the source address of the connection. Only useful on systems with more than one address. -C Requests compression of all data (including stdin, stdout, stderr, and data for forwarded X11, TCP and Unix-domain connections). The compression algorithm is the same used by gzip(1). Compression is desirable on modem lines and other slow connections, but will only slow down things on fast networks. The default value can be set on a host-by-host basis in the configuration files; see the Compression option in ssh_config(5). -c cipher_spec Selects the cipher specification for encrypting the session. cipher_spec is a comma-separated list of ciphers listed in order of preference. See the Ciphers keyword in ssh_config(5) for more information. -D [bind_address:]port Specifies a local dynamic application-level port forwarding. This works by allocating a socket to listen to port on the local side, optionally bound to the specified bind_address. Whenever a connection is made to this port, the connection is forwarded over the secure channel, and the application protocol is then used to determine where to connect to from the remote machine. Currently the SOCKS4 and SOCKS5 protocols are supported, and will act as a SOCKS server. Only root can forward privileged ports. Dynamic port forwardings can also be specified in the configuration file. IPv6 addresses can be specified by enclosing the address in square brackets. Only the superuser can forward privileged ports. By default, the local port is bound in accordance with the GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a specific address. The bind_address of localhost indicates that the listening port be bound for local use only, while an empty address or * indicates that the port should be available from all interfaces. -E log_file Append debug logs to log_file instead of standard error. -e escape_char Sets the escape character for sessions with a pty (default: ~). The escape character is only recognized at the beginning of a line. The escape character followed by a dot (.) closes the connection; followed by control-Z suspends the connection; and followed by itself sends the escape character once. Setting the character to none disables any escapes and makes the session fully transparent. -F configfile Specifies an alternative per-user configuration file. If a configuration file is given on the command line, the system-wide configuration file (/etc/ssh/ssh_config) will be ignored. The default for the per-user configuration file is ~/.ssh/config. If set to none, no configuration files will be read. -f Requests to go to background just before command execution. This is useful if is going to ask for passwords or passphrases, but the user wants it in the background. This implies -n. The recommended way to start X11 programs at a remote site is with something like ssh -f host xterm. If the ExitOnForwardFailure configuration option is set to yes, then a client started with -f will wait for all remote port forwards to be successfully established before placing itself in the background. Refer to the description of ForkAfterAuthentication in ssh_config(5) for details. -G Causes to print its configuration after evaluating Host and Match blocks and exit. -g Allows remote hosts to connect to local forwarded ports. If used on a multiplexed connection, then this option must be specified on the master process. -I pkcs11 Specify the PKCS#11 shared library should use to communicate with a PKCS#11 token providing keys for user authentication. -i identity_file Selects a file from which the identity (private key) for public key authentication is read. You can also specify a public key file to use the corresponding private key that is loaded in ssh-agent(1) when the private key file is not present locally. The default is ~/.ssh/id_rsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk and ~/.ssh/id_dsa. Identity files may also be specified on a per-host basis in the configuration file. It is possible to have multiple -i options (and multiple identities specified in configuration files). If no certificates have been explicitly specified by the CertificateFile directive, will also try to load certificate information from the filename obtained by appending -cert.pub to identity filenames. -J destination Connect to the target host by first making an connection to the jump host described by destination and then establishing a TCP forwarding to the ultimate destination from there. Multiple jump hops may be specified separated by comma characters. This is a shortcut to specify a ProxyJump configuration directive. Note that configuration directives supplied on the command-line generally apply to the destination host and not any specified jump hosts. Use ~/.ssh/config to specify configuration for jump hosts. -K Enables GSSAPI-based authentication and forwarding (delegation) of GSSAPI credentials to the server. -k Disables forwarding (delegation) of GSSAPI credentials to the server. -L [bind_address:]port:host:hostport -L [bind_address:]port:remote_socket -L local_socket:host:hostport -L local_socket:remote_socket Specifies that connections to the given TCP port or Unix socket on the local (client) host are to be forwarded to the given host and port, or Unix socket, on the remote side. This works by allocating a socket to listen to either a TCP port on the local side, optionally bound to the specified bind_address, or to a Unix socket. Whenever a connection is made to the local port or socket, the connection is forwarded over the secure channel, and a connection is made to either host port hostport, or the Unix socket remote_socket, from the remote machine. Port forwardings can also be specified in the configuration file. Only the superuser can forward privileged ports. IPv6 addresses can be specified by enclosing the address in square brackets. By default, the local port is bound in accordance with the GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a specific address. The bind_address of localhost indicates that the listening port be bound for local use only, while an empty address or * indicates that the port should be available from all interfaces. -l login_name Specifies the user to log in as on the remote machine. This also may be specified on a per-host basis in the configuration file. -M Places the client into master mode for connection sharing. Multiple -M options places into master mode but with confirmation required using ssh-askpass(1) before each operation that changes the multiplexing state (e.g. opening a new session). Refer to the description of ControlMaster in ssh_config(5) for details. -m mac_spec A comma-separated list of MAC (message authentication code) algorithms, specified in order of preference. See the MACs keyword in ssh_config(5) for more information. -N Do not execute a remote command. This is useful for just forwarding ports. Refer to the description of SessionType in ssh_config(5) for details. -n Redirects stdin from /dev/null (actually, prevents reading from stdin). This must be used when is run in the background. A common trick is to use this to run X11 programs on a remote machine. For example, ssh -n shadows.cs.hut.fi emacs & will start an emacs on shadows.cs.hut.fi, and the X11 connection will be automatically forwarded over an encrypted channel. The program will be put in the background. (This does not work if needs to ask for a password or passphrase; see also the -f option.) Refer to the description of StdinNull in ssh_config(5) for details. -O ctl_cmd Control an active connection multiplexing master process. When the -O option is specified, the ctl_cmd argument is interpreted and passed to the master process. Valid commands are: check (check that the master process is running), forward (request forwardings without command execution), cancel (cancel forwardings), exit (request the master to exit), and stop (request the master to stop accepting further multiplexing requests). -o option Can be used to give options in the format used in the configuration file. This is useful for specifying options for which there is no separate command-line flag. For full details of the options listed below, and their possible values, see ssh_config(5). AddKeysToAgent AddressFamily BatchMode BindAddress CanonicalDomains CanonicalizeFallbackLocal CanonicalizeHostname CanonicalizeMaxDots CanonicalizePermittedCNAMEs CASignatureAlgorithms CertificateFile CheckHostIP Ciphers ClearAllForwardings Compression ConnectionAttempts ConnectTimeout ControlMaster ControlPath ControlPersist DynamicForward EnableEscapeCommandline EscapeChar ExitOnForwardFailure FingerprintHash ForkAfterAuthentication ForwardAgent ForwardX11 ForwardX11Timeout ForwardX11Trusted GatewayPorts GlobalKnownHostsFile GSSAPIAuthentication GSSAPIDelegateCredentials HashKnownHosts Host HostbasedAcceptedAlgorithms HostbasedAuthentication HostKeyAlgorithms HostKeyAlias Hostname IdentitiesOnly IdentityAgent IdentityFile IPQoS KbdInteractiveAuthentication KbdInteractiveDevices KexAlgorithms KnownHostsCommand LocalCommand LocalForward LogLevel MACs Match NoHostAuthenticationForLocalhost NumberOfPasswordPrompts PasswordAuthentication PermitLocalCommand PermitRemoteOpen PKCS11Provider Port PreferredAuthentications ProxyCommand ProxyJump ProxyUseFdpass PubkeyAcceptedAlgorithms PubkeyAuthentication RekeyLimit RemoteCommand RemoteForward RequestTTY RequiredRSASize SendEnv ServerAliveInterval ServerAliveCountMax SessionType SetEnv StdinNull StreamLocalBindMask StreamLocalBindUnlink StrictHostKeyChecking TCPKeepAlive Tunnel TunnelDevice UpdateHostKeys User UserKnownHostsFile VerifyHostKeyDNS VisualHostKey XAuthLocation -P tag Specify a tag name that may be used to select configuration in ssh_config(5). Refer to the Tag and Match keywords in ssh_config(5) for more information. -p port Port to connect to on the remote host. This can be specified on a per-host basis in the configuration file. -Q query_option Queries for the algorithms supported by one of the following features: cipher (supported symmetric ciphers), cipher-auth (supported symmetric ciphers that support authenticated encryption), help (supported query terms for use with the -Q flag), mac (supported message integrity codes), kex (key exchange algorithms), key (key types), key-ca-sign (valid CA signature algorithms for certificates), key-cert (certificate key types), key-plain (non-certificate key types), key-sig (all key types and signature algorithms), protocol-version (supported SSH protocol versions), and sig (supported signature algorithms). Alternatively, any keyword from ssh_config(5) or sshd_config(5) that takes an algorithm list may be used as an alias for the corresponding query_option. -q Quiet mode. Causes most warning and diagnostic messages to be suppressed. -R [bind_address:]port:host:hostport -R [bind_address:]port:local_socket -R remote_socket:host:hostport -R remote_socket:local_socket -R [bind_address:]port Specifies that connections to the given TCP port or Unix socket on the remote (server) host are to be forwarded to the local side. This works by allocating a socket to listen to either a TCP port or to a Unix socket on the remote side. Whenever a connection is made to this port or Unix socket, the connection is forwarded over the secure channel, and a connection is made from the local machine to either an explicit destination specified by host port hostport, or local_socket, or, if no explicit destination was specified, will act as a SOCKS 4/5 proxy and forward connections to the destinations requested by the remote SOCKS client. Port forwardings can also be specified in the configuration file. Privileged ports can be forwarded only when logging in as root on the remote machine. IPv6 addresses can be specified by enclosing the address in square brackets. By default, TCP listening sockets on the server will be bound to the loopback interface only. This may be overridden by specifying a bind_address. An empty bind_address, or the address *, indicates that the remote socket should listen on all interfaces. Specifying a remote bind_address will only succeed if the server's GatewayPorts option is enabled (see sshd_config(5)). If the port argument is 0, the listen port will be dynamically allocated on the server and reported to the client at run time. When used together with -O forward, the allocated port will be printed to the standard output. -S ctl_path Specifies the location of a control socket for connection sharing, or the string none to disable connection sharing. Refer to the description of ControlPath and ControlMaster in ssh_config(5) for details. -s May be used to request invocation of a subsystem on the remote system. Subsystems facilitate the use of SSH as a secure transport for other applications (e.g. sftp(1)). The subsystem is specified as the remote command. Refer to the description of SessionType in ssh_config(5) for details. -T Disable pseudo-terminal allocation. -t Force pseudo-terminal allocation. This can be used to execute arbitrary screen-based programs on a remote machine, which can be very useful, e.g. when implementing menu services. Multiple -t options force tty allocation, even if has no local tty. -V Display the version number and exit. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful in debugging connection, authentication, and configuration problems. Multiple -v options increase the verbosity. The maximum is 3. -W host:port Requests that standard input and output on the client be forwarded to host on port over the secure channel. Implies -N, -T, ExitOnForwardFailure and ClearAllForwardings, though these can be overridden in the configuration file or using -o command line options. -w local_tun[:remote_tun] Requests tunnel device forwarding with the specified tun(4) devices between the client (local_tun) and the server (remote_tun). The devices may be specified by numerical ID or the keyword any, which uses the next available tunnel device. If remote_tun is not specified, it defaults to any. See also the Tunnel and TunnelDevice directives in ssh_config(5). If the Tunnel directive is unset, it will be set to the default tunnel mode, which is point-to-point. If a different Tunnel forwarding mode it desired, then it should be specified before -w. -X Enables X11 forwarding. This can also be specified on a per-host basis in a configuration file. X11 forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the user's X authorization database) can access the local X11 display through the forwarded connection. An attacker may then be able to perform activities such as keystroke monitoring. For this reason, X11 forwarding is subjected to X11 SECURITY extension restrictions by default. Refer to the -Y option and the ForwardX11Trusted directive in ssh_config(5) for more information. -x Disables X11 forwarding. -Y Enables trusted X11 forwarding. Trusted X11 forwardings are not subjected to the X11 SECURITY extension controls. -y Send log information using the syslog(3) system module. By default this information is sent to stderr. may additionally obtain configuration data from a per-user configuration file and a system-wide configuration file. The file format and configuration options are described in ssh_config(5). AUTHENTICATION top The OpenSSH SSH client supports SSH protocol 2. The methods available for authentication are: GSSAPI-based authentication, host-based authentication, public key authentication, keyboard-interactive authentication, and password authentication. Authentication methods are tried in the order specified above, though PreferredAuthentications can be used to change the default order. Host-based authentication works as follows: If the machine the user logs in from is listed in /etc/hosts.equiv or /etc/shosts.equiv on the remote machine, the user is non-root and the user names are the same on both sides, or if the files ~/.rhosts or ~/.shosts exist in the user's home directory on the remote machine and contain a line containing the name of the client machine and the name of the user on that machine, the user is considered for login. Additionally, the server must be able to verify the client's host key (see the description of /etc/ssh/ssh_known_hosts and ~/.ssh/known_hosts, below) for login to be permitted. This authentication method closes security holes due to IP spoofing, DNS spoofing, and routing spoofing. [Note to the administrator: /etc/hosts.equiv, ~/.rhosts, and the rlogin/rsh protocol in general, are inherently insecure and should be disabled if security is desired.] Public key authentication works as follows: The scheme is based on public-key cryptography, using cryptosystems where encryption and decryption are done using separate keys, and it is unfeasible to derive the decryption key from the encryption key. The idea is that each user creates a public/private key pair for authentication purposes. The server knows the public key, and only the user knows the private key. implements public key authentication protocol automatically, using one of the DSA, ECDSA, Ed25519 or RSA algorithms. The HISTORY section of ssl(8) contains a brief discussion of the DSA and RSA algorithms. The file ~/.ssh/authorized_keys lists the public keys that are permitted for logging in. When the user logs in, the program tells the server which key pair it would like to use for authentication. The client proves that it has access to the private key and the server checks that the corresponding public key is authorized to accept the account. The server may inform the client of errors that prevented public key authentication from succeeding after authentication completes using a different method. These may be viewed by increasing the LogLevel to DEBUG or higher (e.g. by using the -v flag). The user creates their key pair by running ssh-keygen(1). This stores the private key in ~/.ssh/id_dsa (DSA), ~/.ssh/id_ecdsa (ECDSA), ~/.ssh/id_ecdsa_sk (authenticator-hosted ECDSA), ~/.ssh/id_ed25519 (Ed25519), ~/.ssh/id_ed25519_sk (authenticator- hosted Ed25519), or ~/.ssh/id_rsa (RSA) and stores the public key in ~/.ssh/id_dsa.pub (DSA), ~/.ssh/id_ecdsa.pub (ECDSA), ~/.ssh/id_ecdsa_sk.pub (authenticator-hosted ECDSA), ~/.ssh/id_ed25519.pub (Ed25519), ~/.ssh/id_ed25519_sk.pub (authenticator-hosted Ed25519), or ~/.ssh/id_rsa.pub (RSA) in the user's home directory. The user should then copy the public key to ~/.ssh/authorized_keys in their home directory on the remote machine. The authorized_keys file corresponds to the conventional ~/.rhosts file, and has one key per line, though the lines can be very long. After this, the user can log in without giving the password. A variation on public key authentication is available in the form of certificate authentication: instead of a set of public/private keys, signed certificates are used. This has the advantage that a single trusted certification authority can be used in place of many public/private keys. See the CERTIFICATES section of ssh-keygen(1) for more information. The most convenient way to use public key or certificate authentication may be with an authentication agent. See ssh-agent(1) and (optionally) the AddKeysToAgent directive in ssh_config(5) for more information. Keyboard-interactive authentication works as follows: The server sends an arbitrary "challenge" text and prompts for a response, possibly multiple times. Examples of keyboard-interactive authentication include BSD Authentication (see login.conf(5)) and PAM (some non-OpenBSD systems). Finally, if other authentication methods fail, prompts the user for a password. The password is sent to the remote host for checking; however, since all communications are encrypted, the password cannot be seen by someone listening on the network. automatically maintains and checks a database containing identification for all hosts it has ever been used with. Host keys are stored in ~/.ssh/known_hosts in the user's home directory. Additionally, the file /etc/ssh/ssh_known_hosts is automatically checked for known hosts. Any new hosts are automatically added to the user's file. If a host's identification ever changes, warns about this and disables password authentication to prevent server spoofing or man-in-the- middle attacks, which could otherwise be used to circumvent the encryption. The StrictHostKeyChecking option can be used to control logins to machines whose host key is not known or has changed. When the user's identity has been accepted by the server, the server either executes the given command in a non-interactive session or, if no command has been specified, logs into the machine and gives the user a normal shell as an interactive session. All communication with the remote command or shell will be automatically encrypted. If an interactive session is requested, by default will only request a pseudo-terminal (pty) for interactive sessions when the client has one. The flags -T and -t can be used to override this behaviour. If a pseudo-terminal has been allocated, the user may use the escape characters noted below. If no pseudo-terminal has been allocated, the session is transparent and can be used to reliably transfer binary data. On most systems, setting the escape character to none will also make the session transparent even if a tty is used. The session terminates when the command or shell on the remote machine exits and all X11 and TCP connections have been closed. ESCAPE CHARACTERS top When a pseudo-terminal has been requested, supports a number of functions through the use of an escape character. A single tilde character can be sent as ~~ or by following the tilde by a character other than those described below. The escape character must always follow a newline to be interpreted as special. The escape character can be changed in configuration files using the EscapeChar configuration directive or on the command line by the -e option. The supported escapes (assuming the default ~) are: ~. Disconnect. ~^Z Background . ~# List forwarded connections. ~& Background at logout when waiting for forwarded connection / X11 sessions to terminate. ~? Display a list of escape characters. ~B Send a BREAK to the remote system (only useful if the peer supports it). ~C Open command line. Currently this allows the addition of port forwardings using the -L, -R and -D options (see above). It also allows the cancellation of existing port-forwardings with -KL[bind_address:]port for local, -KR[bind_address:]port for remote and -KD[bind_address:]port for dynamic port-forwardings. !command allows the user to execute a local command if the PermitLocalCommand option is enabled in ssh_config(5). Basic help is available, using the -h option. ~R Request rekeying of the connection (only useful if the peer supports it). ~V Decrease the verbosity (LogLevel) when errors are being written to stderr. ~v Increase the verbosity (LogLevel) when errors are being written to stderr. TCP FORWARDING top Forwarding of arbitrary TCP connections over a secure channel can be specified either on the command line or in a configuration file. One possible application of TCP forwarding is a secure connection to a mail server; another is going through firewalls. In the example below, we look at encrypting communication for an IRC client, even though the IRC server it connects to does not directly support encrypted communication. This works as follows: the user connects to the remote host using , specifying the ports to be used to forward the connection. After that it is possible to start the program locally, and will encrypt and forward the connection to the remote server. The following example tunnels an IRC session from the client to an IRC server at server.example.com, joining channel #users, nickname pinky, using the standard IRC port, 6667: $ ssh -f -L 6667:localhost:6667 server.example.com sleep 10 $ irc -c '#users' pinky IRC/127.0.0.1 The -f option backgrounds and the remote command sleep 10 is specified to allow an amount of time (10 seconds, in the example) to start the program which is going to use the tunnel. If no connections are made within the time specified, will exit. X11 FORWARDING top If the ForwardX11 variable is set to yes (or see the description of the -X, -x, and -Y options above) and the user is using X11 (the DISPLAY environment variable is set), the connection to the X11 display is automatically forwarded to the remote side in such a way that any X11 programs started from the shell (or command) will go through the encrypted channel, and the connection to the real X server will be made from the local machine. The user should not manually set DISPLAY. Forwarding of X11 connections can be configured on the command line or in configuration files. The DISPLAY value set by will point to the server machine, but with a display number greater than zero. This is normal, and happens because creates a proxy X server on the server machine for forwarding the connections over the encrypted channel. will also automatically set up Xauthority data on the server machine. For this purpose, it will generate a random authorization cookie, store it in Xauthority on the server, and verify that any forwarded connections carry this cookie and replace it by the real cookie when the connection is opened. The real authentication cookie is never sent to the server machine (and no cookies are sent in the plain). If the ForwardAgent variable is set to yes (or see the description of the -A and -a options above) and the user is using an authentication agent, the connection to the agent is automatically forwarded to the remote side. VERIFYING HOST KEYS top When connecting to a server for the first time, a fingerprint of the server's public key is presented to the user (unless the option StrictHostKeyChecking has been disabled). Fingerprints can be determined using ssh-keygen(1): $ ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key If the fingerprint is already known, it can be matched and the key can be accepted or rejected. If only legacy (MD5) fingerprints for the server are available, the ssh-keygen(1) -E option may be used to downgrade the fingerprint algorithm to match. Because of the difficulty of comparing host keys just by looking at fingerprint strings, there is also support to compare host keys visually, using random art. By setting the VisualHostKey option to yes, a small ASCII graphic gets displayed on every login to a server, no matter if the session itself is interactive or not. By learning the pattern a known server produces, a user can easily find out that the host key has changed when a completely different pattern is displayed. Because these patterns are not unambiguous however, a pattern that looks similar to the pattern remembered only gives a good probability that the host key is the same, not guaranteed proof. To get a listing of the fingerprints along with their random art for all known hosts, the following command line can be used: $ ssh-keygen -lv -f ~/.ssh/known_hosts If the fingerprint is unknown, an alternative method of verification is available: SSH fingerprints verified by DNS. An additional resource record (RR), SSHFP, is added to a zonefile and the connecting client is able to match the fingerprint with that of the key presented. In this example, we are connecting a client to a server, host.example.com. The SSHFP resource records should first be added to the zonefile for host.example.com: $ ssh-keygen -r host.example.com. The output lines will have to be added to the zonefile. To check that the zone is answering fingerprint queries: $ dig -t SSHFP host.example.com Finally the client connects: $ ssh -o "VerifyHostKeyDNS ask" host.example.com [...] Matching host key fingerprint found in DNS. Are you sure you want to continue connecting (yes/no)? See the VerifyHostKeyDNS option in ssh_config(5) for more information. SSH-BASED VIRTUAL PRIVATE NETWORKS top contains support for Virtual Private Network (VPN) tunnelling using the tun(4) network pseudo-device, allowing two networks to be joined securely. The sshd_config(5) configuration option PermitTunnel controls whether the server supports this, and at what level (layer 2 or 3 traffic). The following example would connect client network 10.0.50.0/24 with remote network 10.0.99.0/24 using a point-to-point connection from 10.1.1.1 to 10.1.1.2, provided that the SSH server running on the gateway to the remote network, at 192.168.1.15, allows it. On the client: # ssh -f -w 0:1 192.168.1.15 true # ifconfig tun0 10.1.1.1 10.1.1.2 netmask 255.255.255.252 # route add 10.0.99.0/24 10.1.1.2 On the server: # ifconfig tun1 10.1.1.2 10.1.1.1 netmask 255.255.255.252 # route add 10.0.50.0/24 10.1.1.1 Client access may be more finely tuned via the /root/.ssh/authorized_keys file (see below) and the PermitRootLogin server option. The following entry would permit connections on tun(4) device 1 from user jane and on tun device 2 from user john, if PermitRootLogin is set to forced-commands-only: tunnel="1",command="sh /etc/netstart tun1" ssh-rsa ... jane tunnel="2",command="sh /etc/netstart tun2" ssh-rsa ... john Since an SSH-based setup entails a fair amount of overhead, it may be more suited to temporary setups, such as for wireless VPNs. More permanent VPNs are better provided by tools such as ipsecctl(8) and isakmpd(8). ENVIRONMENT top will normally set the following environment variables: DISPLAY The DISPLAY variable indicates the location of the X11 server. It is automatically set by to point to a value of the form hostname:n, where hostname indicates the host where the shell runs, and n is an integer 1. uses this special value to forward X11 connections over the secure channel. The user should normally not set DISPLAY explicitly, as that will render the X11 connection insecure (and will require the user to manually copy any required authorization cookies). HOME Set to the path of the user's home directory. LOGNAME Synonym for USER; set for compatibility with systems that use this variable. MAIL Set to the path of the user's mailbox. PATH Set to the default PATH, as specified when compiling . SSH_ASKPASS If needs a passphrase, it will read the passphrase from the current terminal if it was run from a terminal. If does not have a terminal associated with it but DISPLAY and SSH_ASKPASS are set, it will execute the program specified by SSH_ASKPASS and open an X11 window to read the passphrase. This is particularly useful when calling from a .xsession or related script. (Note that on some machines it may be necessary to redirect the input from /dev/null to make this work.) SSH_ASKPASS_REQUIRE Allows further control over the use of an askpass program. If this variable is set to never then will never attempt to use one. If it is set to prefer, then will prefer to use the askpass program instead of the TTY when requesting passwords. Finally, if the variable is set to force, then the askpass program will be used for all passphrase input regardless of whether DISPLAY is set. SSH_AUTH_SOCK Identifies the path of a Unix-domain socket used to communicate with the agent. SSH_CONNECTION Identifies the client and server ends of the connection. The variable contains four space-separated values: client IP address, client port number, server IP address, and server port number. SSH_ORIGINAL_COMMAND This variable contains the original command line if a forced command is executed. It can be used to extract the original arguments. SSH_TTY This is set to the name of the tty (path to the device) associated with the current shell or command. If the current session has no tty, this variable is not set. SSH_TUNNEL Optionally set by sshd(8) to contain the interface names assigned if tunnel forwarding was requested by the client. SSH_USER_AUTH Optionally set by sshd(8), this variable may contain a pathname to a file that lists the authentication methods successfully used when the session was established, including any public keys that were used. TZ This variable is set to indicate the present time zone if it was set when the daemon was started (i.e. the daemon passes the value on to new connections). USER Set to the name of the user logging in. Additionally, reads ~/.ssh/environment, and adds lines of the format VARNAME=value to the environment if the file exists and users are allowed to change their environment. For more information, see the PermitUserEnvironment option in sshd_config(5). FILES top ~/.rhosts This file is used for host-based authentication (see above). On some machines this file may need to be world- readable if the user's home directory is on an NFS partition, because sshd(8) reads it as root. Additionally, this file must be owned by the user, and must not have write permissions for anyone else. The recommended permission for most machines is read/write for the user, and not accessible by others. ~/.shosts This file is used in exactly the same way as .rhosts, but allows host-based authentication without permitting login with rlogin/rsh. ~/.ssh/ This directory is the default location for all user- specific configuration and authentication information. There is no general requirement to keep the entire contents of this directory secret, but the recommended permissions are read/write/execute for the user, and not accessible by others. ~/.ssh/authorized_keys Lists the public keys (DSA, ECDSA, Ed25519, RSA) that can be used for logging in as this user. The format of this file is described in the sshd(8) manual page. This file is not highly sensitive, but the recommended permissions are read/write for the user, and not accessible by others. ~/.ssh/config This is the per-user configuration file. The file format and configuration options are described in ssh_config(5). Because of the potential for abuse, this file must have strict permissions: read/write for the user, and not writable by others. ~/.ssh/environment Contains additional definitions for environment variables; see ENVIRONMENT, above. ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the private key for authentication. These files contain sensitive data and should be readable by the user but not accessible by others (read/write/execute). will simply ignore a private key file if it is accessible by others. It is possible to specify a passphrase when generating the key which will be used to encrypt the sensitive part of this file using AES-128. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the public key for authentication. These files are not sensitive and can (but need not) be readable by anyone. ~/.ssh/known_hosts Contains a list of host keys for all hosts the user has logged into that are not already in the systemwide list of known host keys. See sshd(8) for further details of the format of this file. ~/.ssh/rc Commands in this file are executed by when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information. /etc/hosts.equiv This file is for host-based authentication (see above). It should only be writable by root. /etc/shosts.equiv This file is used in exactly the same way as hosts.equiv, but allows host-based authentication without permitting login with rlogin/rsh. /etc/ssh/ssh_config Systemwide configuration file. The file format and configuration options are described in ssh_config(5). /etc/ssh/ssh_host_key /etc/ssh/ssh_host_dsa_key /etc/ssh/ssh_host_ecdsa_key /etc/ssh/ssh_host_ed25519_key /etc/ssh/ssh_host_rsa_key These files contain the private parts of the host keys and are used for host-based authentication. /etc/ssh/ssh_known_hosts Systemwide list of known host keys. This file should be prepared by the system administrator to contain the public host keys of all machines in the organization. It should be world-readable. See sshd(8) for further details of the format of this file. /etc/ssh/sshrc Commands in this file are executed by when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information. EXIT STATUS top exits with the exit status of the remote command or with 255 if an error occurred. SEE ALSO top scp(1), sftp(1), ssh-add(1), ssh-agent(1), ssh-keygen(1), ssh-keyscan(1), tun(4), ssh_config(5), ssh-keysign(8), sshd(8) STANDARDS top S. Lehtinen and C. Lonvick, The Secure Shell (SSH) Protocol Assigned Numbers, RFC 4250, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Protocol Architecture, RFC 4251, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Authentication Protocol, RFC 4252, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Transport Layer Protocol, RFC 4253, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Connection Protocol, RFC 4254, January 2006. J. Schlyter and W. Griffin, Using DNS to Securely Publish Secure Shell (SSH) Key Fingerprints, RFC 4255, January 2006. F. Cusack and M. Forssen, Generic Message Exchange Authentication for the Secure Shell Protocol (SSH), RFC 4256, January 2006. J. Galbraith and P. Remaker, The Secure Shell (SSH) Session Channel Break Extension, RFC 4335, January 2006. M. Bellare, T. Kohno, and C. Namprempre, The Secure Shell (SSH) Transport Layer Encryption Modes, RFC 4344, January 2006. B. Harris, Improved Arcfour Modes for the Secure Shell (SSH) Transport Layer Protocol, RFC 4345, January 2006. M. Friedl, N. Provos, and W. Simpson, Diffie-Hellman Group Exchange for the Secure Shell (SSH) Transport Layer Protocol, RFC 4419, March 2006. J. Galbraith and R. Thayer, The Secure Shell (SSH) Public Key File Format, RFC 4716, November 2006. D. Stebila and J. Green, Elliptic Curve Algorithm Integration in the Secure Shell Transport Layer, RFC 5656, December 2009. A. Perrig and D. Song, Hash Visualization: a New Technique to improve Real-World Security, 1999, International Workshop on Cryptographic Techniques and E-Commerce (CrypTEC '99). AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU October 11, 2023 SSH(1) Pages that refer to this page: stap-jupyter(1), systemd-stdio-bridge(1), tar(1), sd_bus_default(3), environment.d(5), proc(5), user@.service(5), pty(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a ssh tunnel on local port 2222 through "bridge.example.com" to "remote.example.com" port 22 without executing any commands and run in the background Bash Command:<START>ssh -N -L 2222:remote.example.com:22 bridge.example.com&<END> |
Create a symbolc link in the current directory to "target" | ln -s target | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolc link in the current directory to "target" Bash Command:<START>ln -s target<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolc link in the current directory to "target" Bash Command:<START>ln -s target<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolc link in the current directory to "target" Bash Command:<START>ln -s target<END> |
Create a symbolc link named "latest" to the last modified file or directory in "target-directory" | ln -s target-directory/`ls -rt target-directory | tail -n1` latest | ['ls', 'tail', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolc link named "latest" to the last modified file or directory in "target-directory" Bash Command:<START>ln -s target-directory/`ls -rt target-directory | tail -n1` latest<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ls\n\n> List directory contents.\n> More information: <https://www.gnu.org/software/coreutils/ls>.\n\n- List files one per line:\n\n`ls -1`\n\n- List all files, including hidden files:\n\n`ls -a`\n\n- List all files, with trailing `/` added to directory names:\n\n`ls -F`\n\n- Long format list (permissions, ownership, size, and modification date) of all files:\n\n`ls -la`\n\n- Long format list with size displayed using human-readable units (KiB, MiB, GiB):\n\n`ls -lh`\n\n- Long format list sorted by size (descending) recursively:\n\n`ls -lSR`\n\n- Long format list of all files, sorted by modification date (oldest first):\n\n`ls -ltr`\n\n- Only list directories:\n\n`ls -d */`\n # tail\n\n> Display the last part of a file.\n> See also: `head`.\n> More information: <https://www.gnu.org/software/coreutils/tail>.\n\n- Show last 'count' lines in file:\n\n`tail --lines {{count}} {{path/to/file}}`\n\n- Print a file from a specific line number:\n\n`tail --lines +{{count}} {{path/to/file}}`\n\n- Print a specific count of bytes from the end of a given file:\n\n`tail --bytes {{count}} {{path/to/file}}`\n\n- Print the last lines of a given file and keep reading it until `Ctrl + C`:\n\n`tail --follow {{path/to/file}}`\n\n- Keep reading file until `Ctrl + C`, even if the file is inaccessible:\n\n`tail --retry --follow {{path/to/file}}`\n\n- Show last 'num' lines in 'file' and refresh every 'n' seconds:\n\n`tail --lines {{count}} --sleep-interval {{seconds}} --follow {{path/to/file}}`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolc link named "latest" to the last modified file or directory in "target-directory" Bash Command:<START>ln -s target-directory/`ls -rt target-directory | tail -n1` latest<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ls(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ls(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LS(1) User Commands LS(1) NAME top ls - list directory contents SYNOPSIS top ls [OPTION]... [FILE]... DESCRIPTION top List information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuvSUX nor --sort is specified. Mandatory arguments to long options are mandatory for short options too. -a, --all do not ignore entries starting with . -A, --almost-all do not list implied . and .. --author with -l, print the author of each file -b, --escape print C-style escapes for nongraphic characters --block-size=SIZE with -l, scale sizes by SIZE when printing them; e.g., '--block-size=M'; see SIZE format below -B, --ignore-backups do not list implied entries ending with ~ -c with -lt: sort by, and show, ctime (time of last change of file status information); with -l: show ctime and sort by name; otherwise: sort by ctime, newest first -C list entries by columns --color[=WHEN] color the output WHEN; more info below -d, --directory list directories themselves, not their contents -D, --dired generate output designed for Emacs' dired mode -f list all entries in directory order -F, --classify[=WHEN] append indicator (one of */=>@|) to entries WHEN --file-type likewise, except do not append '*' --format=WORD across -x, commas -m, horizontal -x, long -l, single-column -1, verbose -l, vertical -C --full-time like -l --time-style=full-iso -g like -l, but do not list owner --group-directories-first group directories before files; can be augmented with a --sort option, but any use of --sort=none (-U) disables grouping -G, --no-group in a long listing, don't print group names -h, --human-readable with -l and -s, print sizes like 1K 234M 2G etc. --si likewise, but use powers of 1000 not 1024 -H, --dereference-command-line follow symbolic links listed on the command line --dereference-command-line-symlink-to-dir follow each command line symbolic link that points to a directory --hide=PATTERN do not list implied entries matching shell PATTERN (overridden by -a or -A) --hyperlink[=WHEN] hyperlink file names WHEN --indicator-style=WORD append indicator with style WORD to entry names: none (default), slash (-p), file-type (--file-type), classify (-F) -i, --inode print the index number of each file -I, --ignore=PATTERN do not list implied entries matching shell PATTERN -k, --kibibytes default to 1024-byte blocks for file system usage; used only with -s and per directory totals -l use a long listing format -L, --dereference when showing file information for a symbolic link, show information for the file the link references rather than for the link itself -m fill width with a comma separated list of entries -n, --numeric-uid-gid like -l, but list numeric user and group IDs -N, --literal print entry names without quoting -o like -l, but do not list group information -p, --indicator-style=slash append / indicator to directories -q, --hide-control-chars print ? instead of nongraphic characters --show-control-chars show nongraphic characters as-is (the default, unless program is 'ls' and output is a terminal) -Q, --quote-name enclose entry names in double quotes --quoting-style=WORD use quoting style WORD for entry names: literal, locale, shell, shell-always, shell-escape, shell-escape-always, c, escape (overrides QUOTING_STYLE environment variable) -r, --reverse reverse order while sorting -R, --recursive list subdirectories recursively -s, --size print the allocated size of each file, in blocks -S sort by file size, largest first --sort=WORD sort by WORD instead of name: none (-U), size (-S), time (-t), version (-v), extension (-X), width --time=WORD select which timestamp used to display or sort; access time (-u): atime, access, use; metadata change time (-c): ctime, status; modified time (default): mtime, modification; birth time: birth, creation; with -l, WORD determines which time to show; with --sort=time, sort by WORD (newest first) --time-style=TIME_STYLE time/date format with -l; see TIME_STYLE below -t sort by time, newest first; see --time -T, --tabsize=COLS assume tab stops at each COLS instead of 8 -u with -lt: sort by, and show, access time; with -l: show access time and sort by name; otherwise: sort by access time, newest first -U do not sort; list entries in directory order -v natural sort of (version) numbers within text -w, --width=COLS set output width to COLS. 0 means no limit -x list entries by lines instead of by columns -X sort alphabetically by entry extension -Z, --context print any security context of each file --zero end each output line with NUL, not newline -1 list one file per line --help display this help and exit --version output version information and exit The SIZE argument is an integer and optional unit (example: 10K is 10*1024). Units are K,M,G,T,P,E,Z,Y,R,Q (powers of 1024) or KB,MB,... (powers of 1000). Binary prefixes can be used, too: KiB=K, MiB=M, and so on. The TIME_STYLE argument can be full-iso, long-iso, iso, locale, or +FORMAT. FORMAT is interpreted like in date(1). If FORMAT is FORMAT1<newline>FORMAT2, then FORMAT1 applies to non-recent files and FORMAT2 to recent files. TIME_STYLE prefixed with 'posix-' takes effect only outside the POSIX locale. Also the TIME_STYLE environment variable sets the default style to use. The WHEN argument defaults to 'always' and can also be 'auto' or 'never'. Using color to distinguish file types is disabled both by default and with --color=never. With --color=auto, ls emits color codes only when standard output is connected to a terminal. The LS_COLORS environment variable can change the settings. Use the dircolors(1) command to set it. Exit status: 0 if OK, 1 if minor problems (e.g., cannot access subdirectory), 2 if serious trouble (e.g., cannot access command-line argument). AUTHOR top Written by Richard M. Stallman and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top dircolors(1) Full documentation <https://www.gnu.org/software/coreutils/ls> or available locally via: info '(coreutils) ls invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LS(1) Pages that refer to this page: column(1), find(1), namei(1), stat(2), statx(2), glob(3), strverscmp(3), core(5), dir_colors(5), passwd(5), proc(5), mq_overview(7), symlink(7), lsblk(8), lsof(8), setfiles(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. tail(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training tail(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TAIL(1) User Commands TAIL(1) NAME top tail - output the last part of files SYNOPSIS top tail [OPTION]... [FILE]... DESCRIPTION top Print the last 10 lines of each FILE to standard output. With more than one FILE, precede each with a header giving the file name. With no FILE, or when FILE is -, read standard input. Mandatory arguments to long options are mandatory for short options too. -c, --bytes=[+]NUM output the last NUM bytes; or use -c +NUM to output starting with byte NUM of each file -f, --follow[={name|descriptor}] output appended data as the file grows; an absent option argument means 'descriptor' -F same as --follow=name --retry -n, --lines=[+]NUM output the last NUM lines, instead of the last 10; or use -n +NUM to skip NUM-1 lines at the start --max-unchanged-stats=N with --follow=name, reopen a FILE which has not changed size after N (default 5) iterations to see if it has been unlinked or renamed (this is the usual case of rotated log files); with inotify, this option is rarely useful --pid=PID with -f, terminate after process ID, PID dies -q, --quiet, --silent never output headers giving file names --retry keep trying to open a file if it is inaccessible -s, --sleep-interval=N with -f, sleep for approximately N seconds (default 1.0) between iterations; with inotify and --pid=P, check process P at least once every N seconds -v, --verbose always output headers giving file names -z, --zero-terminated line delimiter is NUL, not newline --help display this help and exit --version output version information and exit NUM may have a multiplier suffix: b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024, GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y, R, Q. Binary prefixes can be used, too: KiB=K, MiB=M, and so on. With --follow (-f), tail defaults to following the file descriptor, which means that even if a tail'ed file is renamed, tail will continue to track its end. This default behavior is not desirable when you really want to track the actual name of the file, not the file descriptor (e.g., log rotation). Use --follow=name in that case. That causes tail to track the named file in a way that accommodates renaming, removal and creation. AUTHOR top Written by Paul Rubin, David MacKenzie, Ian Lance Taylor, and Jim Meyering. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top head(1) Full documentation <https://www.gnu.org/software/coreutils/tail> or available locally via: info '(coreutils) tail invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TAIL(1) Pages that refer to this page: head(1), pmcd(1), pmdalogger(1), pmdasystemd(1), pmdaweblog(1), pon(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolc link named "latest" to the last modified file or directory in "target-directory" Bash Command:<START>ln -s target-directory/`ls -rt target-directory | tail -n1` latest<END> |
Create a symbolc link named "public_html" to "current/app/webroot" under the current working directory | ln -s `pwd`/current/app/webroot public_html | ['pwd', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolc link named "public_html" to "current/app/webroot" under the current working directory Bash Command:<START>ln -s `pwd`/current/app/webroot public_html<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # pwd\n\n> Print name of current/working directory.\n> More information: <https://www.gnu.org/software/coreutils/pwd>.\n\n- Print the current directory:\n\n`pwd`\n\n- Print the current directory, and resolve all symlinks (i.e. show the "physical" path):\n\n`pwd --physical`\n\n- Print the current logical directory:\n\n`pwd --logical`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolc link named "public_html" to "current/app/webroot" under the current working directory Bash Command:<START>ln -s `pwd`/current/app/webroot public_html<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: pwd(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training pwd(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON PWD(1) User Commands PWD(1) NAME top pwd - print name of current/working directory SYNOPSIS top pwd [OPTION]... DESCRIPTION top Print the full filename of the current working directory. -L, --logical use PWD from environment, even if it contains symlinks -P, --physical avoid all symlinks --help display this help and exit --version output version information and exit If no option is specified, -P is assumed. NOTE: your shell may have its own version of pwd, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. AUTHOR top Written by Jim Meyering. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top getcwd(3) Full documentation <https://www.gnu.org/software/coreutils/pwd> or available locally via: info '(coreutils) pwd invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 PWD(1) Pages that refer to this page: getcwd(3) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolc link named "public_html" to "current/app/webroot" under the current working directory Bash Command:<START>ln -s `pwd`/current/app/webroot public_html<END> |
Create a symbolic link in "/bar/tmp/" for each file in directory "/foo" that does not start with "runscript" | find /foo -maxdepth 1 -type f ! -name 'runscript*' -exec ln -s {} /bar/tmp/ \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in "/bar/tmp/" for each file in directory "/foo" that does not start with "runscript" Bash Command:<START>find /foo -maxdepth 1 -type f ! -name 'runscript*' -exec ln -s {} /bar/tmp/ \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in "/bar/tmp/" for each file in directory "/foo" that does not start with "runscript" Bash Command:<START>find /foo -maxdepth 1 -type f ! -name 'runscript*' -exec ln -s {} /bar/tmp/ \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in "/bar/tmp/" for each file in directory "/foo" that does not start with "runscript" Bash Command:<START>find /foo -maxdepth 1 -type f ! -name 'runscript*' -exec ln -s {} /bar/tmp/ \;<END> |
Create a symbolic link in directory "/path/to/dir" for each file and directory under the current directory starting with "." | find $PWD -name '.[^.]*' -exec ln -s '{}' /path/to/dir \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in directory "/path/to/dir" for each file and directory under the current directory starting with "." Bash Command:<START>find $PWD -name '.[^.]*' -exec ln -s '{}' /path/to/dir \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in directory "/path/to/dir" for each file and directory under the current directory starting with "." Bash Command:<START>find $PWD -name '.[^.]*' -exec ln -s '{}' /path/to/dir \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in directory "/path/to/dir" for each file and directory under the current directory starting with "." Bash Command:<START>find $PWD -name '.[^.]*' -exec ln -s '{}' /path/to/dir \;<END> |
Create a symbolic link in directory "new" for each file in "original" directory tree | find original -type f -exec ln -s {} new/{} \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in directory "new" for each file in "original" directory tree Bash Command:<START>find original -type f -exec ln -s {} new/{} \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in directory "new" for each file in "original" directory tree Bash Command:<START>find original -type f -exec ln -s {} new/{} \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in directory "new" for each file in "original" directory tree Bash Command:<START>find original -type f -exec ln -s {} new/{} \;<END> |
Create a symbolic link in target directory "$tmpdir" for each file under the current directory | find $PWD -type f -exec ln -st $tmpdir {} + | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in target directory "$tmpdir" for each file under the current directory Bash Command:<START>find $PWD -type f -exec ln -st $tmpdir {} +<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in target directory "$tmpdir" for each file under the current directory Bash Command:<START>find $PWD -type f -exec ln -st $tmpdir {} +<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in target directory "$tmpdir" for each file under the current directory Bash Command:<START>find $PWD -type f -exec ln -st $tmpdir {} +<END> |
Create a symbolic link in target directory "~/newlinks" to "$source" | ln -s "$source" -t ~/newlinks | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in target directory "~/newlinks" to "$source" Bash Command:<START>ln -s "$source" -t ~/newlinks<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in target directory "~/newlinks" to "$source" Bash Command:<START>ln -s "$source" -t ~/newlinks<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in target directory "~/newlinks" to "$source" Bash Command:<START>ln -s "$source" -t ~/newlinks<END> |
Create a symbolic link in the current directory for each .jpg file under "dir" | ln -s "$(find dir -name '*.jpg')" . | ['find', 'dir', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in the current directory for each .jpg file under "dir" Bash Command:<START>ln -s "$(find dir -name '*.jpg')" .<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # dir\n\n> List directory contents using one line per file, special characters are represented by backslash escape sequences.\n> Works as `ls -C --escape`.\n> More information: <https://manned.org/dir>.\n\n- List all files, including hidden files:\n\n`dir -all`\n\n- List files including their author (`-l` is required):\n\n`dir -l --author`\n\n- List files excluding those that match a specified blob pattern:\n\n`dir --hide={{pattern}}`\n\n- List subdirectories recursively:\n\n`dir --recursive`\n\n- Display help:\n\n`dir --help`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in the current directory for each .jpg file under "dir" Bash Command:<START>ln -s "$(find dir -name '*.jpg')" .<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. dir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training dir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON DIR(1) User Commands DIR(1) NAME top dir - list directory contents SYNOPSIS top dir [OPTION]... [FILE]... DESCRIPTION top List information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuvSUX nor --sort is specified. Mandatory arguments to long options are mandatory for short options too. -a, --all do not ignore entries starting with . -A, --almost-all do not list implied . and .. --author with -l, print the author of each file -b, --escape print C-style escapes for nongraphic characters --block-size=SIZE with -l, scale sizes by SIZE when printing them; e.g., '--block-size=M'; see SIZE format below -B, --ignore-backups do not list implied entries ending with ~ -c with -lt: sort by, and show, ctime (time of last change of file status information); with -l: show ctime and sort by name; otherwise: sort by ctime, newest first -C list entries by columns --color[=WHEN] color the output WHEN; more info below -d, --directory list directories themselves, not their contents -D, --dired generate output designed for Emacs' dired mode -f list all entries in directory order -F, --classify[=WHEN] append indicator (one of */=>@|) to entries WHEN --file-type likewise, except do not append '*' --format=WORD across -x, commas -m, horizontal -x, long -l, single-column -1, verbose -l, vertical -C --full-time like -l --time-style=full-iso -g like -l, but do not list owner --group-directories-first group directories before files; can be augmented with a --sort option, but any use of --sort=none (-U) disables grouping -G, --no-group in a long listing, don't print group names -h, --human-readable with -l and -s, print sizes like 1K 234M 2G etc. --si likewise, but use powers of 1000 not 1024 -H, --dereference-command-line follow symbolic links listed on the command line --dereference-command-line-symlink-to-dir follow each command line symbolic link that points to a directory --hide=PATTERN do not list implied entries matching shell PATTERN (overridden by -a or -A) --hyperlink[=WHEN] hyperlink file names WHEN --indicator-style=WORD append indicator with style WORD to entry names: none (default), slash (-p), file-type (--file-type), classify (-F) -i, --inode print the index number of each file -I, --ignore=PATTERN do not list implied entries matching shell PATTERN -k, --kibibytes default to 1024-byte blocks for file system usage; used only with -s and per directory totals -l use a long listing format -L, --dereference when showing file information for a symbolic link, show information for the file the link references rather than for the link itself -m fill width with a comma separated list of entries -n, --numeric-uid-gid like -l, but list numeric user and group IDs -N, --literal print entry names without quoting -o like -l, but do not list group information -p, --indicator-style=slash append / indicator to directories -q, --hide-control-chars print ? instead of nongraphic characters --show-control-chars show nongraphic characters as-is (the default, unless program is 'ls' and output is a terminal) -Q, --quote-name enclose entry names in double quotes --quoting-style=WORD use quoting style WORD for entry names: literal, locale, shell, shell-always, shell-escape, shell-escape-always, c, escape (overrides QUOTING_STYLE environment variable) -r, --reverse reverse order while sorting -R, --recursive list subdirectories recursively -s, --size print the allocated size of each file, in blocks -S sort by file size, largest first --sort=WORD sort by WORD instead of name: none (-U), size (-S), time (-t), version (-v), extension (-X), width --time=WORD select which timestamp used to display or sort; access time (-u): atime, access, use; metadata change time (-c): ctime, status; modified time (default): mtime, modification; birth time: birth, creation; with -l, WORD determines which time to show; with --sort=time, sort by WORD (newest first) --time-style=TIME_STYLE time/date format with -l; see TIME_STYLE below -t sort by time, newest first; see --time -T, --tabsize=COLS assume tab stops at each COLS instead of 8 -u with -lt: sort by, and show, access time; with -l: show access time and sort by name; otherwise: sort by access time, newest first -U do not sort; list entries in directory order -v natural sort of (version) numbers within text -w, --width=COLS set output width to COLS. 0 means no limit -x list entries by lines instead of by columns -X sort alphabetically by entry extension -Z, --context print any security context of each file --zero end each output line with NUL, not newline -1 list one file per line --help display this help and exit --version output version information and exit The SIZE argument is an integer and optional unit (example: 10K is 10*1024). Units are K,M,G,T,P,E,Z,Y,R,Q (powers of 1024) or KB,MB,... (powers of 1000). Binary prefixes can be used, too: KiB=K, MiB=M, and so on. The TIME_STYLE argument can be full-iso, long-iso, iso, locale, or +FORMAT. FORMAT is interpreted like in date(1). If FORMAT is FORMAT1<newline>FORMAT2, then FORMAT1 applies to non-recent files and FORMAT2 to recent files. TIME_STYLE prefixed with 'posix-' takes effect only outside the POSIX locale. Also the TIME_STYLE environment variable sets the default style to use. The WHEN argument defaults to 'always' and can also be 'auto' or 'never'. Using color to distinguish file types is disabled both by default and with --color=never. With --color=auto, ls emits color codes only when standard output is connected to a terminal. The LS_COLORS environment variable can change the settings. Use the dircolors(1) command to set it. Exit status: 0 if OK, 1 if minor problems (e.g., cannot access subdirectory), 2 if serious trouble (e.g., cannot access command-line argument). AUTHOR top Written by Richard M. Stallman and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/dir> or available locally via: info '(coreutils) dir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 DIR(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in the current directory for each .jpg file under "dir" Bash Command:<START>ln -s "$(find dir -name '*.jpg')" .<END> |
Create a symbolic link in the current directory for each file .dbf under the directories matching "/home/michael/foxpro/mount/A[1FV]/[12][0-9][0-9][0-9]" | find /home/michael/foxpro/mount/A[1FV]/[12][0-9][0-9][0-9] -name '*.dbf' -type f -exec ln -s {} \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in the current directory for each file .dbf under the directories matching "/home/michael/foxpro/mount/A[1FV]/[12][0-9][0-9][0-9]" Bash Command:<START>find /home/michael/foxpro/mount/A[1FV]/[12][0-9][0-9][0-9] -name '*.dbf' -type f -exec ln -s {} \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in the current directory for each file .dbf under the directories matching "/home/michael/foxpro/mount/A[1FV]/[12][0-9][0-9][0-9]" Bash Command:<START>find /home/michael/foxpro/mount/A[1FV]/[12][0-9][0-9][0-9] -name '*.dbf' -type f -exec ln -s {} \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in the current directory for each file .dbf under the directories matching "/home/michael/foxpro/mount/A[1FV]/[12][0-9][0-9][0-9]" Bash Command:<START>find /home/michael/foxpro/mount/A[1FV]/[12][0-9][0-9][0-9] -name '*.dbf' -type f -exec ln -s {} \;<END> |
Create a symbolic link in the current directory for each file under the directories matching "../[12][0-9][0-9]" | find ../[12][0-9][0-9][0-9] -type f -exec ln -s {} \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in the current directory for each file under the directories matching "../[12][0-9][0-9]" Bash Command:<START>find ../[12][0-9][0-9][0-9] -type f -exec ln -s {} \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in the current directory for each file under the directories matching "../[12][0-9][0-9]" Bash Command:<START>find ../[12][0-9][0-9][0-9] -type f -exec ln -s {} \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in the current directory for each file under the directories matching "../[12][0-9][0-9]" Bash Command:<START>find ../[12][0-9][0-9][0-9] -type f -exec ln -s {} \;<END> |
Create a symbolic link in the current directory for each hidden file or directory in "git-stuff/home/" excluding "." and ".." | ln -s git-stuff/home/.[!.]* . | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in the current directory for each hidden file or directory in "git-stuff/home/" excluding "." and ".." Bash Command:<START>ln -s git-stuff/home/.[!.]* .<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in the current directory for each hidden file or directory in "git-stuff/home/" excluding "." and ".." Bash Command:<START>ln -s git-stuff/home/.[!.]* .<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in the current directory for each hidden file or directory in "git-stuff/home/" excluding "." and ".." Bash Command:<START>ln -s git-stuff/home/.[!.]* .<END> |
Create a symbolic link in the current directory to "$file" | ln -s "$file" | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in the current directory to "$file" Bash Command:<START>ln -s "$file"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in the current directory to "$file" Bash Command:<START>ln -s "$file"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in the current directory to "$file" Bash Command:<START>ln -s "$file"<END> |
Create a symbolic link in the current directory to "../config/init" | ln -s "../config/init" | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link in the current directory to "../config/init" Bash Command:<START>ln -s "../config/init"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link in the current directory to "../config/init" Bash Command:<START>ln -s "../config/init"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link in the current directory to "../config/init" Bash Command:<START>ln -s "../config/init"<END> |
Create a symbolic link named "$1/link" to the current working directory | ln -s "`pwd`" $1/link | ['pwd', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "$1/link" to the current working directory Bash Command:<START>ln -s "`pwd`" $1/link<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # pwd\n\n> Print name of current/working directory.\n> More information: <https://www.gnu.org/software/coreutils/pwd>.\n\n- Print the current directory:\n\n`pwd`\n\n- Print the current directory, and resolve all symlinks (i.e. show the "physical" path):\n\n`pwd --physical`\n\n- Print the current logical directory:\n\n`pwd --logical`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "$1/link" to the current working directory Bash Command:<START>ln -s "`pwd`" $1/link<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: pwd(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training pwd(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON PWD(1) User Commands PWD(1) NAME top pwd - print name of current/working directory SYNOPSIS top pwd [OPTION]... DESCRIPTION top Print the full filename of the current working directory. -L, --logical use PWD from environment, even if it contains symlinks -P, --physical avoid all symlinks --help display this help and exit --version output version information and exit If no option is specified, -P is assumed. NOTE: your shell may have its own version of pwd, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. AUTHOR top Written by Jim Meyering. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top getcwd(3) Full documentation <https://www.gnu.org/software/coreutils/pwd> or available locally via: info '(coreutils) pwd invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 PWD(1) Pages that refer to this page: getcwd(3) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "$1/link" to the current working directory Bash Command:<START>ln -s "`pwd`" $1/link<END> |
Create a symbolic link named "$1/link" to the existing full and real path of "$2" | ln -s "$(readlink -e "$2")" "$1/link" | ['readlink', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "$1/link" to the existing full and real path of "$2" Bash Command:<START>ln -s "$(readlink -e "$2")" "$1/link"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # readlink\n\n> Follow symlinks and get symlink information.\n> More information: <https://www.gnu.org/software/coreutils/readlink>.\n\n- Get the actual file to which the symlink points:\n\n`readlink {{path/to/file}}`\n\n- Get the absolute path to a file:\n\n`readlink -f {{path/to/file}}`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "$1/link" to the existing full and real path of "$2" Bash Command:<START>ln -s "$(readlink -e "$2")" "$1/link"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: readlink(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training readlink(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON READLINK(1) User Commands READLINK(1) NAME top readlink - print resolved symbolic links or canonical file names SYNOPSIS top readlink [OPTION]... FILE... DESCRIPTION top Note realpath(1) is the preferred command to use for canonicalization functionality. Print value of a symbolic link or canonical file name -f, --canonicalize canonicalize by following every symlink in every component of the given name recursively; all but the last component must exist -e, --canonicalize-existing canonicalize by following every symlink in every component of the given name recursively, all components must exist -m, --canonicalize-missing canonicalize by following every symlink in every component of the given name recursively, without requirements on components existence -n, --no-newline do not output the trailing delimiter -q, --quiet -s, --silent suppress most error messages (on by default) -v, --verbose report error messages -z, --zero end each output line with NUL, not newline --help display this help and exit --version output version information and exit AUTHOR top Written by Dmitry V. Levin. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top readlink(2), realpath(1), realpath(3) Full documentation <https://www.gnu.org/software/coreutils/readlink> or available locally via: info '(coreutils) readlink invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 READLINK(1) Pages that refer to this page: basename(1), dirname(1), dpkg-realpath(1), realpath(1), unshare(1), mount(2), readlink(2), unshare(2), namespaces(7), mount(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "$1/link" to the existing full and real path of "$2" Bash Command:<START>ln -s "$(readlink -e "$2")" "$1/link"<END> |
Create a symbolic link named "$HOME/bin/" to "$HOME/downloads/fnord" | ln -s $HOME/downloads/fnord $HOME/bin/ | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "$HOME/bin/" to "$HOME/downloads/fnord" Bash Command:<START>ln -s $HOME/downloads/fnord $HOME/bin/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "$HOME/bin/" to "$HOME/downloads/fnord" Bash Command:<START>ln -s $HOME/downloads/fnord $HOME/bin/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "$HOME/bin/" to "$HOME/downloads/fnord" Bash Command:<START>ln -s $HOME/downloads/fnord $HOME/bin/<END> |
Create a symbolic link named "$SYMLINK" to "$ACTUAL_DIR" | ln -s "$ACTUAL_DIR" "$SYMLINK" | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "$SYMLINK" to "$ACTUAL_DIR" Bash Command:<START>ln -s "$ACTUAL_DIR" "$SYMLINK"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "$SYMLINK" to "$ACTUAL_DIR" Bash Command:<START>ln -s "$ACTUAL_DIR" "$SYMLINK"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "$SYMLINK" to "$ACTUAL_DIR" Bash Command:<START>ln -s "$ACTUAL_DIR" "$SYMLINK"<END> |
Create a symbolic link named "$tmpdir/bam" to the full path of command "bam2" found in "$PATH" | ln -s "$(which bam2)" "$tmpdir"/bam | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "$tmpdir/bam" to the full path of command "bam2" found in "$PATH" Bash Command:<START>ln -s "$(which bam2)" "$tmpdir"/bam<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "$tmpdir/bam" to the full path of command "bam2" found in "$PATH" Bash Command:<START>ln -s "$(which bam2)" "$tmpdir"/bam<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "$tmpdir/bam" to the full path of command "bam2" found in "$PATH" Bash Command:<START>ln -s "$(which bam2)" "$tmpdir"/bam<END> |
Create a symbolic link named "${DESTINATION}${file}" to "${TARGET}${file}" | ln -s "${TARGET}${file}" "${DESTINATION}${file}" | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "${DESTINATION}${file}" to "${TARGET}${file}" Bash Command:<START>ln -s "${TARGET}${file}" "${DESTINATION}${file}"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "${DESTINATION}${file}" to "${TARGET}${file}" Bash Command:<START>ln -s "${TARGET}${file}" "${DESTINATION}${file}"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "${DESTINATION}${file}" to "${TARGET}${file}" Bash Command:<START>ln -s "${TARGET}${file}" "${DESTINATION}${file}"<END> |
Create a symbolic link named ".bash_profile" to ".bashrc" | ln -s .bashrc .bash_profile | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named ".bash_profile" to ".bashrc" Bash Command:<START>ln -s .bashrc .bash_profile<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named ".bash_profile" to ".bashrc" Bash Command:<START>ln -s .bashrc .bash_profile<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named ".bash_profile" to ".bashrc" Bash Command:<START>ln -s .bashrc .bash_profile<END> |
Create a symbolic link named ".profile" to "git-stuff/home/profile" without dereferencing ".profile" | ln -sn git-stuff/home/profile .profile | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named ".profile" to "git-stuff/home/profile" without dereferencing ".profile" Bash Command:<START>ln -sn git-stuff/home/profile .profile<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named ".profile" to "git-stuff/home/profile" without dereferencing ".profile" Bash Command:<START>ln -sn git-stuff/home/profile .profile<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named ".profile" to "git-stuff/home/profile" without dereferencing ".profile" Bash Command:<START>ln -sn git-stuff/home/profile .profile<END> |
Create a symbolic link named "/lib/libc.so.0" to "/lib/libc.so.6" | ln -s /lib/libc.so.6 /lib/libc.so.0 | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "/lib/libc.so.0" to "/lib/libc.so.6" Bash Command:<START>ln -s /lib/libc.so.6 /lib/libc.so.0<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "/lib/libc.so.0" to "/lib/libc.so.6" Bash Command:<START>ln -s /lib/libc.so.6 /lib/libc.so.0<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "/lib/libc.so.0" to "/lib/libc.so.6" Bash Command:<START>ln -s /lib/libc.so.6 /lib/libc.so.0<END> |
Create a symbolic link named "/usr/bin/my-editor" to "/usr/share/my-editor/my-editor-executable" and attemp to hard link directories | ln -sF /usr/share/my-editor/my-editor-executable /usr/bin/my-editor | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "/usr/bin/my-editor" to "/usr/share/my-editor/my-editor-executable" and attemp to hard link directories Bash Command:<START>ln -sF /usr/share/my-editor/my-editor-executable /usr/bin/my-editor<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "/usr/bin/my-editor" to "/usr/share/my-editor/my-editor-executable" and attemp to hard link directories Bash Command:<START>ln -sF /usr/share/my-editor/my-editor-executable /usr/bin/my-editor<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "/usr/bin/my-editor" to "/usr/share/my-editor/my-editor-executable" and attemp to hard link directories Bash Command:<START>ln -sF /usr/share/my-editor/my-editor-executable /usr/bin/my-editor<END> |
Create a symbolic link named "/usr/local/bin/subl" to "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" | sudo ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" /usr/local/bin/subl | ['sudo', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "/usr/local/bin/subl" to "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>sudo ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" /usr/local/bin/subl<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # sudo\n\n> Executes a single command as the superuser or another user.\n> More information: <https://www.sudo.ws/sudo.html>.\n\n- Run a command as the superuser:\n\n`sudo {{less /var/log/syslog}}`\n\n- Edit a file as the superuser with your default editor:\n\n`sudo --edit {{/etc/fstab}}`\n\n- Run a command as another user and/or group:\n\n`sudo --user={{user}} --group={{group}} {{id -a}}`\n\n- Repeat the last command prefixed with `sudo` (only in Bash, Zsh, etc.):\n\n`sudo !!`\n\n- Launch the default shell with superuser privileges and run login-specific files (`.profile`, `.bash_profile`, etc.):\n\n`sudo --login`\n\n- Launch the default shell with superuser privileges without changing the environment:\n\n`sudo --shell`\n\n- Launch the default shell as the specified user, loading the user's environment and reading login-specific files (`.profile`, `.bash_profile`, etc.):\n\n`sudo --login --user={{user}}`\n\n- List the allowed (and forbidden) commands for the invoking user:\n\n`sudo --list`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "/usr/local/bin/subl" to "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>sudo ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" /usr/local/bin/subl<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: sudo(8) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training sudo(8) Linux manual page NAME | SYNOPSIS | DESCRIPTION | COMMAND EXECUTION | EXIT VALUE | SECURITY NOTES | ENVIRONMENT | FILES | EXAMPLES | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHORS | CAVEATS | BUGS | SUPPORT | DISCLAIMER | COLOPHON SUDO(8) System Manager's Manual SUDO(8) NAME top sudo, sudoedit execute a command as another user SYNOPSIS top sudo -h | -K | -k | -V sudo -v [-ABkNnS] [-g group] [-h host] [-p prompt] [-u user] sudo -l [-ABkNnS] [-g group] [-h host] [-p prompt] [-U user] [-u user] [command [arg ...]] sudo [-ABbEHnPS] [-C num] [-D directory] [-g group] [-h host] [-p prompt] [-R directory] [-T timeout] [-u user] [VAR=value] [-i | -s] [command [arg ...]] sudoedit [-ABkNnS] [-C num] [-D directory] [-g group] [-h host] [-p prompt] [-R directory] [-T timeout] [-u user] file ... DESCRIPTION top allows a permitted user to execute a command as the superuser or another user, as specified by the security policy. The invoking user's real (not effective) user-ID is used to determine the user name with which to query the security policy. supports a plugin architecture for security policies, auditing, and input/output logging. Third parties can develop and distribute their own plugins to work seamlessly with the front- end. The default security policy is sudoers, which is configured via the file /etc/sudoers, or via LDAP. See the Plugins section for more information. The security policy determines what privileges, if any, a user has to run . The policy may require that users authenticate themselves with a password or another authentication mechanism. If authentication is required, will exit if the user's password is not entered within a configurable time limit. This limit is policy-specific; the default password prompt timeout for the sudoers security policy is 5 minutes. Security policies may support credential caching to allow the user to run again for a period of time without requiring authentication. By default, the sudoers policy caches credentials on a per-terminal basis for 5 minutes. See the timestamp_type and timestamp_timeout options in sudoers(5) for more information. By running with the -v option, a user can update the cached credentials without running a command. On systems where is the primary method of gaining superuser privileges, it is imperative to avoid syntax errors in the security policy configuration files. For the default security policy, sudoers(5), changes to the configuration files should be made using the visudo(8) utility which will ensure that no syntax errors are introduced. When invoked as sudoedit, the -e option (described below), is implied. Security policies and audit plugins may log successful and failed attempts to run . If an I/O plugin is configured, the running command's input and output may be logged as well. The options are as follows: -A, --askpass Normally, if requires a password, it will read it from the user's terminal. If the -A (askpass) option is specified, a (possibly graphical) helper program is executed to read the user's password and output the password to the standard output. If the SUDO_ASKPASS environment variable is set, it specifies the path to the helper program. Otherwise, if sudo.conf(5) contains a line specifying the askpass program, that value will be used. For example: # Path to askpass helper program Path askpass /usr/X11R6/bin/ssh-askpass If no askpass program is available, will exit with an error. -B, --bell Ring the bell as part of the password prompt when a terminal is present. This option has no effect if an askpass program is used. -b, --background Run the given command in the background. It is not possible to use shell job control to manipulate background processes started by . Most interactive commands will fail to work properly in background mode. -C num, --close-from=num Close all file descriptors greater than or equal to num before executing a command. Values less than three are not permitted. By default, will close all open file descriptors other than standard input, standard output, and standard error when executing a command. The security policy may restrict the user's ability to use this option. The sudoers policy only permits use of the -C option when the administrator has enabled the closefrom_override option. -D directory, --chdir=directory Run the command in the specified directory instead of the current working directory. The security policy may return an error if the user does not have permission to specify the working directory. -E, --preserve-env Indicates to the security policy that the user wishes to preserve their existing environment variables. The security policy may return an error if the user does not have permission to preserve the environment. --preserve-env=list Indicates to the security policy that the user wishes to add the comma-separated list of environment variables to those preserved from the user's environment. The security policy may return an error if the user does not have permission to preserve the environment. This option may be specified multiple times. -e, --edit Edit one or more files instead of running a command. In lieu of a path name, the string "sudoedit" is used when consulting the security policy. If the user is authorized by the policy, the following steps are taken: 1. Temporary copies are made of the files to be edited with the owner set to the invoking user. 2. The editor specified by the policy is run to edit the temporary files. The sudoers policy uses the SUDO_EDITOR, VISUAL and EDITOR environment variables (in that order). If none of SUDO_EDITOR, VISUAL or EDITOR are set, the first program listed in the editor sudoers(5) option is used. 3. If they have been modified, the temporary files are copied back to their original location and the temporary versions are removed. To help prevent the editing of unauthorized files, the following restrictions are enforced unless explicitly allowed by the security policy: Symbolic links may not be edited (version 1.8.15 and higher). Symbolic links along the path to be edited are not followed when the parent directory is writable by the invoking user unless that user is root (version 1.8.16 and higher). Files located in a directory that is writable by the invoking user may not be edited unless that user is root (version 1.8.16 and higher). Users are never allowed to edit device special files. If the specified file does not exist, it will be created. Unlike most commands run by sudo, the editor is run with the invoking user's environment unmodified. If the temporary file becomes empty after editing, the user will be prompted before it is installed. If, for some reason, is unable to update a file with its edited version, the user will receive a warning and the edited copy will remain in a temporary file. -g group, --group=group Run the command with the primary group set to group instead of the primary group specified by the target user's password database entry. The group may be either a group name or a numeric group-ID (GID) prefixed with the # character (e.g., #0 for GID 0). When running a command as a GID, many shells require that the # be escaped with a backslash (\). If no -u option is specified, the command will be run as the invoking user. In either case, the primary group will be set to group. The sudoers policy permits any of the target user's groups to be specified via the -g option as long as the -P option is not in use. -H, --set-home Request that the security policy set the HOME environment variable to the home directory specified by the target user's password database entry. Depending on the policy, this may be the default behavior. -h, --help Display a short help message to the standard output and exit. -h host, --host=host Run the command on the specified host if the security policy plugin supports remote commands. The sudoers plugin does not currently support running remote commands. This may also be used in conjunction with the -l option to list a user's privileges for the remote host. -i, --login Run the shell specified by the target user's password database entry as a login shell. This means that login- specific resource files such as .profile, .bash_profile, or .login will be read by the shell. If a command is specified, it is passed to the shell as a simple command using the -c option. The command and any args are concatenated, separated by spaces, after escaping each character (including white space) with a backslash (\) except for alphanumerics, underscores, hyphens, and dollar signs. If no command is specified, an interactive shell is executed. attempts to change to that user's home directory before running the shell. The command is run with an environment similar to the one a user would receive at log in. Most shells behave differently when a command is specified as compared to an interactive session; consult the shell's manual for details. The Command environment section in the sudoers(5) manual documents how the -i option affects the environment in which a command is run when the sudoers policy is in use. -K, --remove-timestamp Similar to the -k option, except that it removes every cached credential for the user, regardless of the terminal or parent process ID. The next time is run, a password must be entered if the security policy requires authentication. It is not possible to use the -K option in conjunction with a command or other option. This option does not require a password. Not all security policies support credential caching. -k, --reset-timestamp When used without a command, invalidates the user's cached credentials for the current session. The next time is run in the session, a password must be entered if the security policy requires authentication. By default, the sudoers policy uses a separate record in the credential cache for each terminal (or parent process ID if no terminal is present). This prevents the -k option from interfering with commands run in a different terminal session. See the timestamp_type option in sudoers(5) for more information. This option does not require a password, and was added to allow a user to revoke permissions from a .logout file. When used in conjunction with a command or an option that may require a password, this option will cause to ignore the user's cached credentials. As a result, will prompt for a password (if one is required by the security policy) and will not update the user's cached credentials. Not all security policies support credential caching. -l, --list If no command is specified, list the privileges for the invoking user (or the user specified by the -U option) on the current host. A longer list format is used if this option is specified multiple times and the security policy supports a verbose output format. If a command is specified and is permitted by the security policy for the invoking user (or the, user specified by the -U option) on the current host, the fully-qualified path to the command is displayed along with any args. If -l is specified more than once (and the security policy supports it), the matching rule is displayed in a verbose format along with the command. If a command is specified but not allowed by the policy, will exit with a status value of 1. -N, --no-update Do not update the user's cached credentials, even if the user successfully authenticates. Unlike the -k flag, existing cached credentials are used if they are valid. To detect when the user's cached credentials are valid (or when no authentication is required), the following can be used: sudo -Nnv Not all security policies support credential caching. -n, --non-interactive Avoid prompting the user for input of any kind. If a password is required for the command to run, will display an error message and exit. -P, --preserve-groups Preserve the invoking user's group vector unaltered. By default, the sudoers policy will initialize the group vector to the list of groups the target user is a member of. The real and effective group-IDs, however, are still set to match the target user. -p prompt, --prompt=prompt Use a custom password prompt with optional escape sequences. The following percent (%) escape sequences are supported by the sudoers policy: %H expanded to the host name including the domain name (only if the machine's host name is fully qualified or the fqdn option is set in sudoers(5)) %h expanded to the local host name without the domain name %p expanded to the name of the user whose password is being requested (respects the rootpw, targetpw, and runaspw flags in sudoers(5)) %U expanded to the login name of the user the command will be run as (defaults to root unless the -u option is also specified) %u expanded to the invoking user's login name %% two consecutive % characters are collapsed into a single % character The custom prompt will override the default prompt specified by either the security policy or the SUDO_PROMPT environment variable. On systems that use PAM, the custom prompt will also override the prompt specified by a PAM module unless the passprompt_override flag is disabled in sudoers. -R directory, --chroot=directory Change to the specified root directory (see chroot(8)) before running the command. The security policy may return an error if the user does not have permission to specify the root directory. -S, --stdin Write the prompt to the standard error and read the password from the standard input instead of using the terminal device. -s, --shell Run the shell specified by the SHELL environment variable if it is set or the shell specified by the invoking user's password database entry. If a command is specified, it is passed to the shell as a simple command using the -c option. The command and any args are concatenated, separated by spaces, after escaping each character (including white space) with a backslash (\) except for alphanumerics, underscores, hyphens, and dollar signs. If no command is specified, an interactive shell is executed. Most shells behave differently when a command is specified as compared to an interactive session; consult the shell's manual for details. -U user, --other-user=user Used in conjunction with the -l option to list the privileges for user instead of for the invoking user. The security policy may restrict listing other users' privileges. When using the sudoers policy, the -U option is restricted to the root user and users with either the list priviege for the specified user or the ability to run any command as root or user on the current host. -T timeout, --command-timeout=timeout Used to set a timeout for the command. If the timeout expires before the command has exited, the command will be terminated. The security policy may restrict the user's ability to set timeouts. The sudoers policy requires that user-specified timeouts be explicitly enabled. -u user, --user=user Run the command as a user other than the default target user (usually root). The user may be either a user name or a numeric user-ID (UID) prefixed with the # character (e.g., #0 for UID 0). When running commands as a UID, many shells require that the # be escaped with a backslash (\). Some security policies may restrict UIDs to those listed in the password database. The sudoers policy allows UIDs that are not in the password database as long as the targetpw option is not set. Other security policies may not support this. -V, --version Print the version string as well as the version string of any configured plugins. If the invoking user is already root, the -V option will display the options passed to configure when was built; plugins may display additional information such as default options. -v, --validate Update the user's cached credentials, authenticating the user if necessary. For the sudoers plugin, this extends the timeout for another 5 minutes by default, but does not run a command. Not all security policies support cached credentials. -- The -- is used to delimit the end of the options. Subsequent options are passed to the command. Options that take a value may only be specified once unless otherwise indicated in the description. This is to help guard against problems caused by poorly written scripts that invoke sudo with user-controlled input. Environment variables to be set for the command may also be passed as options to in the form VAR=value, for example LD_LIBRARY_PATH=/usr/local/pkg/lib. Environment variables may be subject to restrictions imposed by the security policy plugin. The sudoers policy subjects environment variables passed as options to the same restrictions as existing environment variables with one important difference. If the setenv option is set in sudoers, the command to be run has the SETENV tag set or the command matched is ALL, the user may set variables that would otherwise be forbidden. See sudoers(5) for more information. COMMAND EXECUTION top When executes a command, the security policy specifies the execution environment for the command. Typically, the real and effective user and group and IDs are set to match those of the target user, as specified in the password database, and the group vector is initialized based on the group database (unless the -P option was specified). The following parameters may be specified by security policy: real and effective user-ID real and effective group-ID supplementary group-IDs the environment list current working directory file creation mode mask (umask) scheduling priority (aka nice value) Process model There are two distinct ways can run a command. If an I/O logging plugin is configured to log terminal I/O, or if the security policy explicitly requests it, a new pseudo-terminal (pty) is allocated and fork(2) is used to create a second process, referred to as the monitor. The monitor creates a new terminal session with itself as the leader and the pty as its controlling terminal, calls fork(2) again, sets up the execution environment as described above, and then uses the execve(2) system call to run the command in the child process. The monitor exists to relay job control signals between the user's terminal and the pty the command is being run in. This makes it possible to suspend and resume the command normally. Without the monitor, the command would be in what POSIX terms an orphaned process group and it would not receive any job control signals from the kernel. When the command exits or is terminated by a signal, the monitor passes the command's exit status to the main process and exits. After receiving the command's exit status, the main process passes the command's exit status to the security policy's close function, as well as the close function of any configured audit plugin, and exits. This mode is the default for sudo versions 1.9.14 and above when using the sudoers policy. If no pty is used, calls fork(2), sets up the execution environment as described above, and uses the execve(2) system call to run the command in the child process. The main process waits until the command has completed, then passes the command's exit status to the security policy's close function, as well as the close function of any configured audit plugins, and exits. As a special case, if the policy plugin does not define a close function, will execute the command directly instead of calling fork(2) first. The sudoers policy plugin will only define a close function when I/O logging is enabled, a pty is required, an SELinux role is specified, the command has an associated timeout, or the pam_session or pam_setcred options are enabled. Both pam_session and pam_setcred are enabled by default on systems using PAM. This mode is the default for sudo versions prior to 1.9.14 when using the sudoers policy. On systems that use PAM, the security policy's close function is responsible for closing the PAM session. It may also log the command's exit status. Signal handling When the command is run as a child of the process, will relay signals it receives to the command. The SIGINT and SIGQUIT signals are only relayed when the command is being run in a new pty or when the signal was sent by a user process, not the kernel. This prevents the command from receiving SIGINT twice each time the user enters control-C. Some signals, such as SIGSTOP and SIGKILL, cannot be caught and thus will not be relayed to the command. As a general rule, SIGTSTP should be used instead of SIGSTOP when you wish to suspend a command being run by . As a special case, will not relay signals that were sent by the command it is running. This prevents the command from accidentally killing itself. On some systems, the reboot(8) utility sends SIGTERM to all non-system processes other than itself before rebooting the system. This prevents from relaying the SIGTERM signal it received back to reboot(8), which might then exit before the system was actually rebooted, leaving it in a half-dead state similar to single user mode. Note, however, that this check only applies to the command run by and not any other processes that the command may create. As a result, running a script that calls reboot(8) or shutdown(8) via may cause the system to end up in this undefined state unless the reboot(8) or shutdown(8) are run using the exec() family of functions instead of system() (which interposes a shell between the command and the calling process). Plugins Plugins may be specified via Plugin directives in the sudo.conf(5) file. They may be loaded as dynamic shared objects (on systems that support them), or compiled directly into the binary. If no sudo.conf(5) file is present, or if it doesn't contain any Plugin lines, will use sudoers(5) for the policy, auditing, and I/O logging plugins. See the sudo.conf(5) manual for details of the /etc/sudo.conf file and the sudo_plugin(5) manual for more information about the plugin architecture. EXIT VALUE top Upon successful execution of a command, the exit status from will be the exit status of the program that was executed. If the command terminated due to receipt of a signal, will send itself the same signal that terminated the command. If the -l option was specified without a command, will exit with a value of 0 if the user is allowed to run and they authenticated successfully (as required by the security policy). If a command is specified with the -l option, the exit value will only be 0 if the command is permitted by the security policy, otherwise it will be 1. If there is an authentication failure, a configuration/permission problem, or if the given command cannot be executed, exits with a value of 1. In the latter case, the error string is printed to the standard error. If cannot stat(2) one or more entries in the user's PATH, an error is printed to the standard error. (If the directory does not exist or if it is not really a directory, the entry is ignored and no error is printed.) This should not happen under normal circumstances. The most common reason for stat(2) to return permission denied is if you are running an automounter and one of the directories in your PATH is on a machine that is currently unreachable. SECURITY NOTES top tries to be safe when executing external commands. To prevent command spoofing, checks "." and "" (both denoting current directory) last when searching for a command in the user's PATH (if one or both are in the PATH). Depending on the security policy, the user's PATH environment variable may be modified, replaced, or passed unchanged to the program that executes. Users should never be granted privileges to execute files that are writable by the user or that reside in a directory that is writable by the user. If the user can modify or replace the command there is no way to limit what additional commands they can run. By default, will only log the command it explicitly runs. If a user runs a command such as sudo su or sudo sh, subsequent commands run from that shell are not subject to sudo's security policy. The same is true for commands that offer shell escapes (including most editors). If I/O logging is enabled, subsequent commands will have their input and/or output logged, but there will not be traditional logs for those commands. Because of this, care must be taken when giving users access to commands via to verify that the command does not inadvertently give the user an effective root shell. For information on ways to address this, see the Preventing shell escapes section in sudoers(5). To prevent the disclosure of potentially sensitive information, disables core dumps by default while it is executing (they are re-enabled for the command that is run). This historical practice dates from a time when most operating systems allowed set-user-ID processes to dump core by default. To aid in debugging crashes, you may wish to re-enable core dumps by setting disable_coredump to false in the sudo.conf(5) file as follows: Set disable_coredump false See the sudo.conf(5) manual for more information. ENVIRONMENT top utilizes the following environment variables. The security policy has control over the actual content of the command's environment. EDITOR Default editor to use in -e (sudoedit) mode if neither SUDO_EDITOR nor VISUAL is set. MAIL Set to the mail spool of the target user when the -i option is specified, or when env_reset is enabled in sudoers (unless MAIL is present in the env_keep list). HOME Set to the home directory of the target user when the -i or -H options are specified, when the -s option is specified and set_home is set in sudoers, when always_set_home is enabled in sudoers, or when env_reset is enabled in sudoers and HOME is not present in the env_keep list. LOGNAME Set to the login name of the target user when the -i option is specified, when the set_logname option is enabled in sudoers, or when the env_reset option is enabled in sudoers (unless LOGNAME is present in the env_keep list). PATH May be overridden by the security policy. SHELL Used to determine shell to run with -s option. SUDO_ASKPASS Specifies the path to a helper program used to read the password if no terminal is available or if the -A option is specified. SUDO_COMMAND Set to the command run by sudo, including any args. The args are truncated at 4096 characters to prevent a potential execution error. SUDO_EDITOR Default editor to use in -e (sudoedit) mode. SUDO_GID Set to the group-ID of the user who invoked sudo. SUDO_PROMPT Used as the default password prompt unless the -p option was specified. SUDO_PS1 If set, PS1 will be set to its value for the program being run. SUDO_UID Set to the user-ID of the user who invoked sudo. SUDO_USER Set to the login name of the user who invoked sudo. USER Set to the same value as LOGNAME, described above. VISUAL Default editor to use in -e (sudoedit) mode if SUDO_EDITOR is not set. FILES top /etc/sudo.conf front-end configuration EXAMPLES top The following examples assume a properly configured security policy. To get a file listing of an unreadable directory: $ sudo ls /usr/local/protected To list the home directory of user yaz on a machine where the file system holding ~yaz is not exported as root: $ sudo -u yaz ls ~yaz To edit the index.html file as user www: $ sudoedit -u www ~www/htdocs/index.html To view system logs only accessible to root and users in the adm group: $ sudo -g adm more /var/log/syslog To run an editor as jim with a different primary group: $ sudoedit -u jim -g audio ~jim/sound.txt To shut down a machine: $ sudo shutdown -r +15 "quick reboot" To make a usage listing of the directories in the /home partition. The commands are run in a sub-shell to allow the cd command and file redirection to work. $ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE" DIAGNOSTICS top Error messages produced by include: editing files in a writable directory is not permitted By default, sudoedit does not permit editing a file when any of the parent directories are writable by the invoking user. This avoids a race condition that could allow the user to overwrite an arbitrary file. See the sudoedit_checkdir option in sudoers(5) for more information. editing symbolic links is not permitted By default, sudoedit does not follow symbolic links when opening files. See the sudoedit_follow option in sudoers(5) for more information. effective uid is not 0, is sudo installed setuid root? was not run with root privileges. The binary must be owned by the root user and have the set-user-ID bit set. Also, it must not be located on a file system mounted with the nosuid option or on an NFS file system that maps uid 0 to an unprivileged uid. effective uid is not 0, is sudo on a file system with the 'nosuid' option set or an NFS file system without root privileges? was not run with root privileges. The binary has the proper owner and permissions but it still did not run with root privileges. The most common reason for this is that the file system the binary is located on is mounted with the nosuid option or it is an NFS file system that maps uid 0 to an unprivileged uid. fatal error, unable to load plugins An error occurred while loading or initializing the plugins specified in sudo.conf(5). invalid environment variable name One or more environment variable names specified via the -E option contained an equal sign (=). The arguments to the -E option should be environment variable names without an associated value. no password was provided When tried to read the password, it did not receive any characters. This may happen if no terminal is available (or the -S option is specified) and the standard input has been redirected from /dev/null. a terminal is required to read the password needs to read the password but there is no mechanism available for it to do so. A terminal is not present to read the password from, has not been configured to read from the standard input, the -S option was not used, and no askpass helper has been specified either via the sudo.conf(5) file or the SUDO_ASKPASS environment variable. no writable temporary directory found sudoedit was unable to find a usable temporary directory in which to store its intermediate files. The no new privileges flag is set, which prevents sudo from running as root. was run by a process that has the Linux no new privileges flag is set. This causes the set-user-ID bit to be ignored when running an executable, which will prevent from functioning. The most likely cause for this is running within a container that sets this flag. Check the documentation to see if it is possible to configure the container such that the flag is not set. sudo must be owned by uid 0 and have the setuid bit set was not run with root privileges. The binary does not have the correct owner or permissions. It must be owned by the root user and have the set-user-ID bit set. sudoedit is not supported on this platform It is only possible to run sudoedit on systems that support setting the effective user-ID. timed out reading password The user did not enter a password before the password timeout (5 minutes by default) expired. you do not exist in the passwd database Your user-ID does not appear in the system passwd database. you may not specify environment variables in edit mode It is only possible to specify environment variables when running a command. When editing a file, the editor is run with the user's environment unmodified. SEE ALSO top su(1), stat(2), login_cap(3), passwd(5), sudo.conf(5), sudo_plugin(5), sudoers(5), sudoers_timestamp(5), sudoreplay(8), visudo(8) HISTORY top See the HISTORY.md file in the distribution (https://www.sudo.ws/about/history/) for a brief history of sudo. AUTHORS top Many people have worked on over the years; this version consists of code written primarily by: Todd C. Miller See the CONTRIBUTORS.md file in the distribution (https://www.sudo.ws/about/contributors/) for an exhaustive list of people who have contributed to . CAVEATS top There is no easy way to prevent a user from gaining a root shell if that user is allowed to run arbitrary commands via . Also, many programs (such as editors) allow the user to run commands via shell escapes, thus avoiding sudo's checks. However, on most systems it is possible to prevent shell escapes with the sudoers(5) plugin's noexec functionality. It is not meaningful to run the cd command directly via sudo, e.g., $ sudo cd /usr/local/protected since when the command exits the parent process (your shell) will still be the same. The -D option can be used to run a command in a specific directory. Running shell scripts via can expose the same kernel bugs that make set-user-ID shell scripts unsafe on some operating systems (if your OS has a /dev/fd/ directory, set-user-ID shell scripts are generally safe). BUGS top If you believe you have found a bug in , you can submit a bug report at https://bugzilla.sudo.ws/ SUPPORT top Limited free support is available via the sudo-users mailing list, see https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives. DISCLAIMER top is provided AS IS and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. See the LICENSE.md file distributed with or https://www.sudo.ws/about/license/ for complete details. COLOPHON top This page is part of the sudo (execute a command as another user) project. Information about the project can be found at https://www.sudo.ws/. If you have a bug report for this manual page, see https://bugzilla.sudo.ws/. This page was obtained from the project's upstream Git repository https://github.com/sudo-project/sudo on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-12-21.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org Sudo 1.9.15p4 August 9, 2023 SUDO(8) Pages that refer to this page: homectl(1), journalctl(1), localectl(1), loginctl(1), machinectl(1), portablectl(1), setpriv(1), systemctl(1), systemd(1), systemd-analyze(1), systemd-ask-password(1), systemd-inhibit(1), systemd-nspawn(1), systemd-vmspawn(1), timedatectl(1), uid0(1), userdbctl(1), nsswitch.conf(5), credentials(7), systemd-tmpfiles(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "/usr/local/bin/subl" to "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>sudo ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" /usr/local/bin/subl<END> |
Create a symbolic link named "foo" to "/var/cache/apt/archives/bash_4.3-14ubuntu1_amd64.deb" | ln -s /var/cache/apt/archives/bash_4.3-14ubuntu1_amd64.deb foo | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "foo" to "/var/cache/apt/archives/bash_4.3-14ubuntu1_amd64.deb" Bash Command:<START>ln -s /var/cache/apt/archives/bash_4.3-14ubuntu1_amd64.deb foo<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "foo" to "/var/cache/apt/archives/bash_4.3-14ubuntu1_amd64.deb" Bash Command:<START>ln -s /var/cache/apt/archives/bash_4.3-14ubuntu1_amd64.deb foo<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "foo" to "/var/cache/apt/archives/bash_4.3-14ubuntu1_amd64.deb" Bash Command:<START>ln -s /var/cache/apt/archives/bash_4.3-14ubuntu1_amd64.deb foo<END> |
Create a symbolic link named "temp" to "newtarget" | ln -s newtarget temp | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "temp" to "newtarget" Bash Command:<START>ln -s newtarget temp<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "temp" to "newtarget" Bash Command:<START>ln -s newtarget temp<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "temp" to "newtarget" Bash Command:<START>ln -s newtarget temp<END> |
Create a symbolic link named "wh" to "$wh" | ln -s "$wh" wh | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "wh" to "$wh" Bash Command:<START>ln -s "$wh" wh<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "wh" to "$wh" Bash Command:<START>ln -s "$wh" wh<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "wh" to "$wh" Bash Command:<START>ln -s "$wh" wh<END> |
Create a symbolic link named "~/bin/subl" to "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" | ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" ~/bin/subl | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "~/bin/subl" to "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" ~/bin/subl<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "~/bin/subl" to "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" ~/bin/subl<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "~/bin/subl" to "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" ~/bin/subl<END> |
Create a symbolic link named "~/bin/subl" to "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" | ln -s "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" ~/bin/subl | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named "~/bin/subl" to "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" ~/bin/subl<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named "~/bin/subl" to "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" ~/bin/subl<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named "~/bin/subl" to "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" ~/bin/subl<END> |
Create a symbolic link named the basename of "$file" to "$file" | ln -s $file `basename $file` | ['basename', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link named the basename of "$file" to "$file" Bash Command:<START>ln -s $file `basename $file`<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # basename\n\n> Remove leading directory portions from a path.\n> More information: <https://www.gnu.org/software/coreutils/basename>.\n\n- Show only the file name from a path:\n\n`basename {{path/to/file}}`\n\n- Show only the rightmost directory name from a path:\n\n`basename {{path/to/directory/}}`\n\n- Show only the file name from a path, with a suffix removed:\n\n`basename {{path/to/file}} {{suffix}}`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link named the basename of "$file" to "$file" Bash Command:<START>ln -s $file `basename $file`<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: basename(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training basename(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON BASENAME(1) User Commands BASENAME(1) NAME top basename - strip directory and suffix from filenames SYNOPSIS top basename NAME [SUFFIX] basename OPTION... NAME... DESCRIPTION top Print NAME with any leading directory components removed. If specified, also remove a trailing SUFFIX. Mandatory arguments to long options are mandatory for short options too. -a, --multiple support multiple arguments and treat each as a NAME -s, --suffix=SUFFIX remove a trailing SUFFIX; implies -a -z, --zero end each output line with NUL, not newline --help display this help and exit --version output version information and exit EXAMPLES top basename /usr/bin/sort -> "sort" basename include/stdio.h .h -> "stdio" basename -s .h include/stdio.h -> "stdio" basename -a any/str1 any/str2 -> "str1" followed by "str2" AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top dirname(1), readlink(1) Full documentation <https://www.gnu.org/software/coreutils/basename> or available locally via: info '(coreutils) basename invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 BASENAME(1) Pages that refer to this page: dirname(1), pmsignal(1), basename(3) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link named the basename of "$file" to "$file" Bash Command:<START>ln -s $file `basename $file`<END> |
Create a symbolic link relative to link location named "$dest_dir/$orig_name" to "$orig_dest" | ln -r -s "$orig_dest" "$dest_dir/$orig_name" | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link relative to link location named "$dest_dir/$orig_name" to "$orig_dest" Bash Command:<START>ln -r -s "$orig_dest" "$dest_dir/$orig_name"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link relative to link location named "$dest_dir/$orig_name" to "$orig_dest" Bash Command:<START>ln -r -s "$orig_dest" "$dest_dir/$orig_name"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link relative to link location named "$dest_dir/$orig_name" to "$orig_dest" Bash Command:<START>ln -r -s "$orig_dest" "$dest_dir/$orig_name"<END> |
Create a symbolic link to "$file" named "/tmp/allfiles" | ln $file /tmp/allfiles | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link to "$file" named "/tmp/allfiles" Bash Command:<START>ln $file /tmp/allfiles<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link to "$file" named "/tmp/allfiles" Bash Command:<START>ln $file /tmp/allfiles<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link to "$file" named "/tmp/allfiles" Bash Command:<START>ln $file /tmp/allfiles<END> |
Create a symbolic link to file "/usr/bin/perl" named with escaped characters "/usr/local/bin/perl\r\n" | sudo ln -s /usr/bin/perl /usr/local/bin/perl`echo -e '\r'` | ['echo', 'sudo', 'ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic link to file "/usr/bin/perl" named with escaped characters "/usr/local/bin/perl\r\n" Bash Command:<START>sudo ln -s /usr/bin/perl /usr/local/bin/perl`echo -e '\r'`<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # echo\n\n> Print given arguments.\n> More information: <https://www.gnu.org/software/coreutils/echo>.\n\n- Print a text message. Note: quotes are optional:\n\n`echo "{{Hello World}}"`\n\n- Print a message with environment variables:\n\n`echo "{{My path is $PATH}}"`\n\n- Print a message without the trailing newline:\n\n`echo -n "{{Hello World}}"`\n\n- Append a message to the file:\n\n`echo "{{Hello World}}" >> {{file.txt}}`\n\n- Enable interpretation of backslash escapes (special characters):\n\n`echo -e "{{Column 1\tColumn 2}}"`\n\n- Print the exit status of the last executed command (Note: In Windows Command Prompt and PowerShell the equivalent commands are `echo %errorlevel%` and `$lastexitcode` respectively):\n\n`echo $?`\n # sudo\n\n> Executes a single command as the superuser or another user.\n> More information: <https://www.sudo.ws/sudo.html>.\n\n- Run a command as the superuser:\n\n`sudo {{less /var/log/syslog}}`\n\n- Edit a file as the superuser with your default editor:\n\n`sudo --edit {{/etc/fstab}}`\n\n- Run a command as another user and/or group:\n\n`sudo --user={{user}} --group={{group}} {{id -a}}`\n\n- Repeat the last command prefixed with `sudo` (only in Bash, Zsh, etc.):\n\n`sudo !!`\n\n- Launch the default shell with superuser privileges and run login-specific files (`.profile`, `.bash_profile`, etc.):\n\n`sudo --login`\n\n- Launch the default shell with superuser privileges without changing the environment:\n\n`sudo --shell`\n\n- Launch the default shell as the specified user, loading the user's environment and reading login-specific files (`.profile`, `.bash_profile`, etc.):\n\n`sudo --login --user={{user}}`\n\n- List the allowed (and forbidden) commands for the invoking user:\n\n`sudo --list`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic link to file "/usr/bin/perl" named with escaped characters "/usr/local/bin/perl\r\n" Bash Command:<START>sudo ln -s /usr/bin/perl /usr/local/bin/perl`echo -e '\r'`<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: echo(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training echo(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON ECHO(1) User Commands ECHO(1) NAME top echo - display a line of text SYNOPSIS top echo [SHORT-OPTION]... [STRING]... echo LONG-OPTION DESCRIPTION top Echo the STRING(s) to standard output. -n do not output the trailing newline -e enable interpretation of backslash escapes -E disable interpretation of backslash escapes (default) --help display this help and exit --version output version information and exit If -e is in effect, the following sequences are recognized: \\ backslash \a alert (BEL) \b backspace \c produce no further output \e escape \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \0NNN byte with octal value NNN (1 to 3 digits) \xHH byte with hexadecimal value HH (1 to 2 digits) NOTE: your shell may have its own version of echo, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. NOTE: printf(1) is a preferred alternative, which does not have issues outputting option-like strings. AUTHOR top Written by Brian Fox and Chet Ramey. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top printf(1) Full documentation <https://www.gnu.org/software/coreutils/echo> or available locally via: info '(coreutils) echo invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 ECHO(1) Pages that refer to this page: ldapcompare(1), systemd-ask-password(1), systemd-run(1), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. sudo(8) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training sudo(8) Linux manual page NAME | SYNOPSIS | DESCRIPTION | COMMAND EXECUTION | EXIT VALUE | SECURITY NOTES | ENVIRONMENT | FILES | EXAMPLES | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHORS | CAVEATS | BUGS | SUPPORT | DISCLAIMER | COLOPHON SUDO(8) System Manager's Manual SUDO(8) NAME top sudo, sudoedit execute a command as another user SYNOPSIS top sudo -h | -K | -k | -V sudo -v [-ABkNnS] [-g group] [-h host] [-p prompt] [-u user] sudo -l [-ABkNnS] [-g group] [-h host] [-p prompt] [-U user] [-u user] [command [arg ...]] sudo [-ABbEHnPS] [-C num] [-D directory] [-g group] [-h host] [-p prompt] [-R directory] [-T timeout] [-u user] [VAR=value] [-i | -s] [command [arg ...]] sudoedit [-ABkNnS] [-C num] [-D directory] [-g group] [-h host] [-p prompt] [-R directory] [-T timeout] [-u user] file ... DESCRIPTION top allows a permitted user to execute a command as the superuser or another user, as specified by the security policy. The invoking user's real (not effective) user-ID is used to determine the user name with which to query the security policy. supports a plugin architecture for security policies, auditing, and input/output logging. Third parties can develop and distribute their own plugins to work seamlessly with the front- end. The default security policy is sudoers, which is configured via the file /etc/sudoers, or via LDAP. See the Plugins section for more information. The security policy determines what privileges, if any, a user has to run . The policy may require that users authenticate themselves with a password or another authentication mechanism. If authentication is required, will exit if the user's password is not entered within a configurable time limit. This limit is policy-specific; the default password prompt timeout for the sudoers security policy is 5 minutes. Security policies may support credential caching to allow the user to run again for a period of time without requiring authentication. By default, the sudoers policy caches credentials on a per-terminal basis for 5 minutes. See the timestamp_type and timestamp_timeout options in sudoers(5) for more information. By running with the -v option, a user can update the cached credentials without running a command. On systems where is the primary method of gaining superuser privileges, it is imperative to avoid syntax errors in the security policy configuration files. For the default security policy, sudoers(5), changes to the configuration files should be made using the visudo(8) utility which will ensure that no syntax errors are introduced. When invoked as sudoedit, the -e option (described below), is implied. Security policies and audit plugins may log successful and failed attempts to run . If an I/O plugin is configured, the running command's input and output may be logged as well. The options are as follows: -A, --askpass Normally, if requires a password, it will read it from the user's terminal. If the -A (askpass) option is specified, a (possibly graphical) helper program is executed to read the user's password and output the password to the standard output. If the SUDO_ASKPASS environment variable is set, it specifies the path to the helper program. Otherwise, if sudo.conf(5) contains a line specifying the askpass program, that value will be used. For example: # Path to askpass helper program Path askpass /usr/X11R6/bin/ssh-askpass If no askpass program is available, will exit with an error. -B, --bell Ring the bell as part of the password prompt when a terminal is present. This option has no effect if an askpass program is used. -b, --background Run the given command in the background. It is not possible to use shell job control to manipulate background processes started by . Most interactive commands will fail to work properly in background mode. -C num, --close-from=num Close all file descriptors greater than or equal to num before executing a command. Values less than three are not permitted. By default, will close all open file descriptors other than standard input, standard output, and standard error when executing a command. The security policy may restrict the user's ability to use this option. The sudoers policy only permits use of the -C option when the administrator has enabled the closefrom_override option. -D directory, --chdir=directory Run the command in the specified directory instead of the current working directory. The security policy may return an error if the user does not have permission to specify the working directory. -E, --preserve-env Indicates to the security policy that the user wishes to preserve their existing environment variables. The security policy may return an error if the user does not have permission to preserve the environment. --preserve-env=list Indicates to the security policy that the user wishes to add the comma-separated list of environment variables to those preserved from the user's environment. The security policy may return an error if the user does not have permission to preserve the environment. This option may be specified multiple times. -e, --edit Edit one or more files instead of running a command. In lieu of a path name, the string "sudoedit" is used when consulting the security policy. If the user is authorized by the policy, the following steps are taken: 1. Temporary copies are made of the files to be edited with the owner set to the invoking user. 2. The editor specified by the policy is run to edit the temporary files. The sudoers policy uses the SUDO_EDITOR, VISUAL and EDITOR environment variables (in that order). If none of SUDO_EDITOR, VISUAL or EDITOR are set, the first program listed in the editor sudoers(5) option is used. 3. If they have been modified, the temporary files are copied back to their original location and the temporary versions are removed. To help prevent the editing of unauthorized files, the following restrictions are enforced unless explicitly allowed by the security policy: Symbolic links may not be edited (version 1.8.15 and higher). Symbolic links along the path to be edited are not followed when the parent directory is writable by the invoking user unless that user is root (version 1.8.16 and higher). Files located in a directory that is writable by the invoking user may not be edited unless that user is root (version 1.8.16 and higher). Users are never allowed to edit device special files. If the specified file does not exist, it will be created. Unlike most commands run by sudo, the editor is run with the invoking user's environment unmodified. If the temporary file becomes empty after editing, the user will be prompted before it is installed. If, for some reason, is unable to update a file with its edited version, the user will receive a warning and the edited copy will remain in a temporary file. -g group, --group=group Run the command with the primary group set to group instead of the primary group specified by the target user's password database entry. The group may be either a group name or a numeric group-ID (GID) prefixed with the # character (e.g., #0 for GID 0). When running a command as a GID, many shells require that the # be escaped with a backslash (\). If no -u option is specified, the command will be run as the invoking user. In either case, the primary group will be set to group. The sudoers policy permits any of the target user's groups to be specified via the -g option as long as the -P option is not in use. -H, --set-home Request that the security policy set the HOME environment variable to the home directory specified by the target user's password database entry. Depending on the policy, this may be the default behavior. -h, --help Display a short help message to the standard output and exit. -h host, --host=host Run the command on the specified host if the security policy plugin supports remote commands. The sudoers plugin does not currently support running remote commands. This may also be used in conjunction with the -l option to list a user's privileges for the remote host. -i, --login Run the shell specified by the target user's password database entry as a login shell. This means that login- specific resource files such as .profile, .bash_profile, or .login will be read by the shell. If a command is specified, it is passed to the shell as a simple command using the -c option. The command and any args are concatenated, separated by spaces, after escaping each character (including white space) with a backslash (\) except for alphanumerics, underscores, hyphens, and dollar signs. If no command is specified, an interactive shell is executed. attempts to change to that user's home directory before running the shell. The command is run with an environment similar to the one a user would receive at log in. Most shells behave differently when a command is specified as compared to an interactive session; consult the shell's manual for details. The Command environment section in the sudoers(5) manual documents how the -i option affects the environment in which a command is run when the sudoers policy is in use. -K, --remove-timestamp Similar to the -k option, except that it removes every cached credential for the user, regardless of the terminal or parent process ID. The next time is run, a password must be entered if the security policy requires authentication. It is not possible to use the -K option in conjunction with a command or other option. This option does not require a password. Not all security policies support credential caching. -k, --reset-timestamp When used without a command, invalidates the user's cached credentials for the current session. The next time is run in the session, a password must be entered if the security policy requires authentication. By default, the sudoers policy uses a separate record in the credential cache for each terminal (or parent process ID if no terminal is present). This prevents the -k option from interfering with commands run in a different terminal session. See the timestamp_type option in sudoers(5) for more information. This option does not require a password, and was added to allow a user to revoke permissions from a .logout file. When used in conjunction with a command or an option that may require a password, this option will cause to ignore the user's cached credentials. As a result, will prompt for a password (if one is required by the security policy) and will not update the user's cached credentials. Not all security policies support credential caching. -l, --list If no command is specified, list the privileges for the invoking user (or the user specified by the -U option) on the current host. A longer list format is used if this option is specified multiple times and the security policy supports a verbose output format. If a command is specified and is permitted by the security policy for the invoking user (or the, user specified by the -U option) on the current host, the fully-qualified path to the command is displayed along with any args. If -l is specified more than once (and the security policy supports it), the matching rule is displayed in a verbose format along with the command. If a command is specified but not allowed by the policy, will exit with a status value of 1. -N, --no-update Do not update the user's cached credentials, even if the user successfully authenticates. Unlike the -k flag, existing cached credentials are used if they are valid. To detect when the user's cached credentials are valid (or when no authentication is required), the following can be used: sudo -Nnv Not all security policies support credential caching. -n, --non-interactive Avoid prompting the user for input of any kind. If a password is required for the command to run, will display an error message and exit. -P, --preserve-groups Preserve the invoking user's group vector unaltered. By default, the sudoers policy will initialize the group vector to the list of groups the target user is a member of. The real and effective group-IDs, however, are still set to match the target user. -p prompt, --prompt=prompt Use a custom password prompt with optional escape sequences. The following percent (%) escape sequences are supported by the sudoers policy: %H expanded to the host name including the domain name (only if the machine's host name is fully qualified or the fqdn option is set in sudoers(5)) %h expanded to the local host name without the domain name %p expanded to the name of the user whose password is being requested (respects the rootpw, targetpw, and runaspw flags in sudoers(5)) %U expanded to the login name of the user the command will be run as (defaults to root unless the -u option is also specified) %u expanded to the invoking user's login name %% two consecutive % characters are collapsed into a single % character The custom prompt will override the default prompt specified by either the security policy or the SUDO_PROMPT environment variable. On systems that use PAM, the custom prompt will also override the prompt specified by a PAM module unless the passprompt_override flag is disabled in sudoers. -R directory, --chroot=directory Change to the specified root directory (see chroot(8)) before running the command. The security policy may return an error if the user does not have permission to specify the root directory. -S, --stdin Write the prompt to the standard error and read the password from the standard input instead of using the terminal device. -s, --shell Run the shell specified by the SHELL environment variable if it is set or the shell specified by the invoking user's password database entry. If a command is specified, it is passed to the shell as a simple command using the -c option. The command and any args are concatenated, separated by spaces, after escaping each character (including white space) with a backslash (\) except for alphanumerics, underscores, hyphens, and dollar signs. If no command is specified, an interactive shell is executed. Most shells behave differently when a command is specified as compared to an interactive session; consult the shell's manual for details. -U user, --other-user=user Used in conjunction with the -l option to list the privileges for user instead of for the invoking user. The security policy may restrict listing other users' privileges. When using the sudoers policy, the -U option is restricted to the root user and users with either the list priviege for the specified user or the ability to run any command as root or user on the current host. -T timeout, --command-timeout=timeout Used to set a timeout for the command. If the timeout expires before the command has exited, the command will be terminated. The security policy may restrict the user's ability to set timeouts. The sudoers policy requires that user-specified timeouts be explicitly enabled. -u user, --user=user Run the command as a user other than the default target user (usually root). The user may be either a user name or a numeric user-ID (UID) prefixed with the # character (e.g., #0 for UID 0). When running commands as a UID, many shells require that the # be escaped with a backslash (\). Some security policies may restrict UIDs to those listed in the password database. The sudoers policy allows UIDs that are not in the password database as long as the targetpw option is not set. Other security policies may not support this. -V, --version Print the version string as well as the version string of any configured plugins. If the invoking user is already root, the -V option will display the options passed to configure when was built; plugins may display additional information such as default options. -v, --validate Update the user's cached credentials, authenticating the user if necessary. For the sudoers plugin, this extends the timeout for another 5 minutes by default, but does not run a command. Not all security policies support cached credentials. -- The -- is used to delimit the end of the options. Subsequent options are passed to the command. Options that take a value may only be specified once unless otherwise indicated in the description. This is to help guard against problems caused by poorly written scripts that invoke sudo with user-controlled input. Environment variables to be set for the command may also be passed as options to in the form VAR=value, for example LD_LIBRARY_PATH=/usr/local/pkg/lib. Environment variables may be subject to restrictions imposed by the security policy plugin. The sudoers policy subjects environment variables passed as options to the same restrictions as existing environment variables with one important difference. If the setenv option is set in sudoers, the command to be run has the SETENV tag set or the command matched is ALL, the user may set variables that would otherwise be forbidden. See sudoers(5) for more information. COMMAND EXECUTION top When executes a command, the security policy specifies the execution environment for the command. Typically, the real and effective user and group and IDs are set to match those of the target user, as specified in the password database, and the group vector is initialized based on the group database (unless the -P option was specified). The following parameters may be specified by security policy: real and effective user-ID real and effective group-ID supplementary group-IDs the environment list current working directory file creation mode mask (umask) scheduling priority (aka nice value) Process model There are two distinct ways can run a command. If an I/O logging plugin is configured to log terminal I/O, or if the security policy explicitly requests it, a new pseudo-terminal (pty) is allocated and fork(2) is used to create a second process, referred to as the monitor. The monitor creates a new terminal session with itself as the leader and the pty as its controlling terminal, calls fork(2) again, sets up the execution environment as described above, and then uses the execve(2) system call to run the command in the child process. The monitor exists to relay job control signals between the user's terminal and the pty the command is being run in. This makes it possible to suspend and resume the command normally. Without the monitor, the command would be in what POSIX terms an orphaned process group and it would not receive any job control signals from the kernel. When the command exits or is terminated by a signal, the monitor passes the command's exit status to the main process and exits. After receiving the command's exit status, the main process passes the command's exit status to the security policy's close function, as well as the close function of any configured audit plugin, and exits. This mode is the default for sudo versions 1.9.14 and above when using the sudoers policy. If no pty is used, calls fork(2), sets up the execution environment as described above, and uses the execve(2) system call to run the command in the child process. The main process waits until the command has completed, then passes the command's exit status to the security policy's close function, as well as the close function of any configured audit plugins, and exits. As a special case, if the policy plugin does not define a close function, will execute the command directly instead of calling fork(2) first. The sudoers policy plugin will only define a close function when I/O logging is enabled, a pty is required, an SELinux role is specified, the command has an associated timeout, or the pam_session or pam_setcred options are enabled. Both pam_session and pam_setcred are enabled by default on systems using PAM. This mode is the default for sudo versions prior to 1.9.14 when using the sudoers policy. On systems that use PAM, the security policy's close function is responsible for closing the PAM session. It may also log the command's exit status. Signal handling When the command is run as a child of the process, will relay signals it receives to the command. The SIGINT and SIGQUIT signals are only relayed when the command is being run in a new pty or when the signal was sent by a user process, not the kernel. This prevents the command from receiving SIGINT twice each time the user enters control-C. Some signals, such as SIGSTOP and SIGKILL, cannot be caught and thus will not be relayed to the command. As a general rule, SIGTSTP should be used instead of SIGSTOP when you wish to suspend a command being run by . As a special case, will not relay signals that were sent by the command it is running. This prevents the command from accidentally killing itself. On some systems, the reboot(8) utility sends SIGTERM to all non-system processes other than itself before rebooting the system. This prevents from relaying the SIGTERM signal it received back to reboot(8), which might then exit before the system was actually rebooted, leaving it in a half-dead state similar to single user mode. Note, however, that this check only applies to the command run by and not any other processes that the command may create. As a result, running a script that calls reboot(8) or shutdown(8) via may cause the system to end up in this undefined state unless the reboot(8) or shutdown(8) are run using the exec() family of functions instead of system() (which interposes a shell between the command and the calling process). Plugins Plugins may be specified via Plugin directives in the sudo.conf(5) file. They may be loaded as dynamic shared objects (on systems that support them), or compiled directly into the binary. If no sudo.conf(5) file is present, or if it doesn't contain any Plugin lines, will use sudoers(5) for the policy, auditing, and I/O logging plugins. See the sudo.conf(5) manual for details of the /etc/sudo.conf file and the sudo_plugin(5) manual for more information about the plugin architecture. EXIT VALUE top Upon successful execution of a command, the exit status from will be the exit status of the program that was executed. If the command terminated due to receipt of a signal, will send itself the same signal that terminated the command. If the -l option was specified without a command, will exit with a value of 0 if the user is allowed to run and they authenticated successfully (as required by the security policy). If a command is specified with the -l option, the exit value will only be 0 if the command is permitted by the security policy, otherwise it will be 1. If there is an authentication failure, a configuration/permission problem, or if the given command cannot be executed, exits with a value of 1. In the latter case, the error string is printed to the standard error. If cannot stat(2) one or more entries in the user's PATH, an error is printed to the standard error. (If the directory does not exist or if it is not really a directory, the entry is ignored and no error is printed.) This should not happen under normal circumstances. The most common reason for stat(2) to return permission denied is if you are running an automounter and one of the directories in your PATH is on a machine that is currently unreachable. SECURITY NOTES top tries to be safe when executing external commands. To prevent command spoofing, checks "." and "" (both denoting current directory) last when searching for a command in the user's PATH (if one or both are in the PATH). Depending on the security policy, the user's PATH environment variable may be modified, replaced, or passed unchanged to the program that executes. Users should never be granted privileges to execute files that are writable by the user or that reside in a directory that is writable by the user. If the user can modify or replace the command there is no way to limit what additional commands they can run. By default, will only log the command it explicitly runs. If a user runs a command such as sudo su or sudo sh, subsequent commands run from that shell are not subject to sudo's security policy. The same is true for commands that offer shell escapes (including most editors). If I/O logging is enabled, subsequent commands will have their input and/or output logged, but there will not be traditional logs for those commands. Because of this, care must be taken when giving users access to commands via to verify that the command does not inadvertently give the user an effective root shell. For information on ways to address this, see the Preventing shell escapes section in sudoers(5). To prevent the disclosure of potentially sensitive information, disables core dumps by default while it is executing (they are re-enabled for the command that is run). This historical practice dates from a time when most operating systems allowed set-user-ID processes to dump core by default. To aid in debugging crashes, you may wish to re-enable core dumps by setting disable_coredump to false in the sudo.conf(5) file as follows: Set disable_coredump false See the sudo.conf(5) manual for more information. ENVIRONMENT top utilizes the following environment variables. The security policy has control over the actual content of the command's environment. EDITOR Default editor to use in -e (sudoedit) mode if neither SUDO_EDITOR nor VISUAL is set. MAIL Set to the mail spool of the target user when the -i option is specified, or when env_reset is enabled in sudoers (unless MAIL is present in the env_keep list). HOME Set to the home directory of the target user when the -i or -H options are specified, when the -s option is specified and set_home is set in sudoers, when always_set_home is enabled in sudoers, or when env_reset is enabled in sudoers and HOME is not present in the env_keep list. LOGNAME Set to the login name of the target user when the -i option is specified, when the set_logname option is enabled in sudoers, or when the env_reset option is enabled in sudoers (unless LOGNAME is present in the env_keep list). PATH May be overridden by the security policy. SHELL Used to determine shell to run with -s option. SUDO_ASKPASS Specifies the path to a helper program used to read the password if no terminal is available or if the -A option is specified. SUDO_COMMAND Set to the command run by sudo, including any args. The args are truncated at 4096 characters to prevent a potential execution error. SUDO_EDITOR Default editor to use in -e (sudoedit) mode. SUDO_GID Set to the group-ID of the user who invoked sudo. SUDO_PROMPT Used as the default password prompt unless the -p option was specified. SUDO_PS1 If set, PS1 will be set to its value for the program being run. SUDO_UID Set to the user-ID of the user who invoked sudo. SUDO_USER Set to the login name of the user who invoked sudo. USER Set to the same value as LOGNAME, described above. VISUAL Default editor to use in -e (sudoedit) mode if SUDO_EDITOR is not set. FILES top /etc/sudo.conf front-end configuration EXAMPLES top The following examples assume a properly configured security policy. To get a file listing of an unreadable directory: $ sudo ls /usr/local/protected To list the home directory of user yaz on a machine where the file system holding ~yaz is not exported as root: $ sudo -u yaz ls ~yaz To edit the index.html file as user www: $ sudoedit -u www ~www/htdocs/index.html To view system logs only accessible to root and users in the adm group: $ sudo -g adm more /var/log/syslog To run an editor as jim with a different primary group: $ sudoedit -u jim -g audio ~jim/sound.txt To shut down a machine: $ sudo shutdown -r +15 "quick reboot" To make a usage listing of the directories in the /home partition. The commands are run in a sub-shell to allow the cd command and file redirection to work. $ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE" DIAGNOSTICS top Error messages produced by include: editing files in a writable directory is not permitted By default, sudoedit does not permit editing a file when any of the parent directories are writable by the invoking user. This avoids a race condition that could allow the user to overwrite an arbitrary file. See the sudoedit_checkdir option in sudoers(5) for more information. editing symbolic links is not permitted By default, sudoedit does not follow symbolic links when opening files. See the sudoedit_follow option in sudoers(5) for more information. effective uid is not 0, is sudo installed setuid root? was not run with root privileges. The binary must be owned by the root user and have the set-user-ID bit set. Also, it must not be located on a file system mounted with the nosuid option or on an NFS file system that maps uid 0 to an unprivileged uid. effective uid is not 0, is sudo on a file system with the 'nosuid' option set or an NFS file system without root privileges? was not run with root privileges. The binary has the proper owner and permissions but it still did not run with root privileges. The most common reason for this is that the file system the binary is located on is mounted with the nosuid option or it is an NFS file system that maps uid 0 to an unprivileged uid. fatal error, unable to load plugins An error occurred while loading or initializing the plugins specified in sudo.conf(5). invalid environment variable name One or more environment variable names specified via the -E option contained an equal sign (=). The arguments to the -E option should be environment variable names without an associated value. no password was provided When tried to read the password, it did not receive any characters. This may happen if no terminal is available (or the -S option is specified) and the standard input has been redirected from /dev/null. a terminal is required to read the password needs to read the password but there is no mechanism available for it to do so. A terminal is not present to read the password from, has not been configured to read from the standard input, the -S option was not used, and no askpass helper has been specified either via the sudo.conf(5) file or the SUDO_ASKPASS environment variable. no writable temporary directory found sudoedit was unable to find a usable temporary directory in which to store its intermediate files. The no new privileges flag is set, which prevents sudo from running as root. was run by a process that has the Linux no new privileges flag is set. This causes the set-user-ID bit to be ignored when running an executable, which will prevent from functioning. The most likely cause for this is running within a container that sets this flag. Check the documentation to see if it is possible to configure the container such that the flag is not set. sudo must be owned by uid 0 and have the setuid bit set was not run with root privileges. The binary does not have the correct owner or permissions. It must be owned by the root user and have the set-user-ID bit set. sudoedit is not supported on this platform It is only possible to run sudoedit on systems that support setting the effective user-ID. timed out reading password The user did not enter a password before the password timeout (5 minutes by default) expired. you do not exist in the passwd database Your user-ID does not appear in the system passwd database. you may not specify environment variables in edit mode It is only possible to specify environment variables when running a command. When editing a file, the editor is run with the user's environment unmodified. SEE ALSO top su(1), stat(2), login_cap(3), passwd(5), sudo.conf(5), sudo_plugin(5), sudoers(5), sudoers_timestamp(5), sudoreplay(8), visudo(8) HISTORY top See the HISTORY.md file in the distribution (https://www.sudo.ws/about/history/) for a brief history of sudo. AUTHORS top Many people have worked on over the years; this version consists of code written primarily by: Todd C. Miller See the CONTRIBUTORS.md file in the distribution (https://www.sudo.ws/about/contributors/) for an exhaustive list of people who have contributed to . CAVEATS top There is no easy way to prevent a user from gaining a root shell if that user is allowed to run arbitrary commands via . Also, many programs (such as editors) allow the user to run commands via shell escapes, thus avoiding sudo's checks. However, on most systems it is possible to prevent shell escapes with the sudoers(5) plugin's noexec functionality. It is not meaningful to run the cd command directly via sudo, e.g., $ sudo cd /usr/local/protected since when the command exits the parent process (your shell) will still be the same. The -D option can be used to run a command in a specific directory. Running shell scripts via can expose the same kernel bugs that make set-user-ID shell scripts unsafe on some operating systems (if your OS has a /dev/fd/ directory, set-user-ID shell scripts are generally safe). BUGS top If you believe you have found a bug in , you can submit a bug report at https://bugzilla.sudo.ws/ SUPPORT top Limited free support is available via the sudo-users mailing list, see https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives. DISCLAIMER top is provided AS IS and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. See the LICENSE.md file distributed with or https://www.sudo.ws/about/license/ for complete details. COLOPHON top This page is part of the sudo (execute a command as another user) project. Information about the project can be found at https://www.sudo.ws/. If you have a bug report for this manual page, see https://bugzilla.sudo.ws/. This page was obtained from the project's upstream Git repository https://github.com/sudo-project/sudo on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-12-21.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org Sudo 1.9.15p4 August 9, 2023 SUDO(8) Pages that refer to this page: homectl(1), journalctl(1), localectl(1), loginctl(1), machinectl(1), portablectl(1), setpriv(1), systemctl(1), systemd(1), systemd-analyze(1), systemd-ask-password(1), systemd-inhibit(1), systemd-nspawn(1), systemd-vmspawn(1), timedatectl(1), uid0(1), userdbctl(1), nsswitch.conf(5), credentials(7), systemd-tmpfiles(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic link to file "/usr/bin/perl" named with escaped characters "/usr/local/bin/perl\r\n" Bash Command:<START>sudo ln -s /usr/bin/perl /usr/local/bin/perl`echo -e '\r'`<END> |
Create a symbolic lnk named "$1/link" to "$dir" | ln -s "$dir" "$1/link" | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symbolic lnk named "$1/link" to "$dir" Bash Command:<START>ln -s "$dir" "$1/link"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symbolic lnk named "$1/link" to "$dir" Bash Command:<START>ln -s "$dir" "$1/link"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symbolic lnk named "$1/link" to "$dir" Bash Command:<START>ln -s "$dir" "$1/link"<END> |
Create a symolic link in "/usr/local/" to "/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl" | ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/ | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symolic link in "/usr/local/" to "/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symolic link in "/usr/local/" to "/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symolic link in "/usr/local/" to "/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/<END> |
Create a symolic link in "/usr/local/bin/" to "/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl" | ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/bin/ | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symolic link in "/usr/local/bin/" to "/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/bin/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symolic link in "/usr/local/bin/" to "/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/bin/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symolic link in "/usr/local/bin/" to "/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/bin/<END> |
Create a symolic link in "/usr/local/bin/" to "/Applications/Sublime\ Text\ 2.app/Contents/SharedSupport/bin/subl" | ln -s /Applications/Sublime\ Text\ 2.app/Contents/SharedSupport/bin/subl /usr/local/bin/ | ['ln'] | Output a Bash command to accomplish the following task. Task: Create a symolic link in "/usr/local/bin/" to "/Applications/Sublime\ Text\ 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text\ 2.app/Contents/SharedSupport/bin/subl /usr/local/bin/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create a symolic link in "/usr/local/bin/" to "/Applications/Sublime\ Text\ 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text\ 2.app/Contents/SharedSupport/bin/subl /usr/local/bin/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a symolic link in "/usr/local/bin/" to "/Applications/Sublime\ Text\ 2.app/Contents/SharedSupport/bin/subl" Bash Command:<START>ln -s /Applications/Sublime\ Text\ 2.app/Contents/SharedSupport/bin/subl /usr/local/bin/<END> |
Create a tar archive with all *.java files under the current directory | find . -type f -name "*.java" | xargs tar cvf myfile.tar | ['find', 'tar', 'xargs'] | Output a Bash command to accomplish the following task. Task: Create a tar archive with all *.java files under the current directory Bash Command:<START>find . -type f -name "*.java" | xargs tar cvf myfile.tar<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # tar\n\n> Archiving utility.\n> Often combined with a compression method, such as `gzip` or `bzip2`.\n> More information: <https://www.gnu.org/software/tar>.\n\n- [c]reate an archive and write it to a [f]ile:\n\n`tar cf {{path/to/target.tar}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive and write it to a [f]ile:\n\n`tar czf {{path/to/target.tar.gz}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive from a directory using relative paths:\n\n`tar czf {{path/to/target.tar.gz}} --directory={{path/to/directory}} .`\n\n- E[x]tract a (compressed) archive [f]ile into the current directory [v]erbosely:\n\n`tar xvf {{path/to/source.tar[.gz|.bz2|.xz]}}`\n\n- E[x]tract a (compressed) archive [f]ile into the target directory:\n\n`tar xf {{path/to/source.tar[.gz|.bz2|.xz]}} --directory={{path/to/directory}}`\n\n- [c]reate a compressed archive and write it to a [f]ile, using the file extension to [a]utomatically determine the compression program:\n\n`tar caf {{path/to/target.tar.xz}} {{path/to/file1 path/to/file2 ...}}`\n\n- Lis[t] the contents of a tar [f]ile [v]erbosely:\n\n`tar tvf {{path/to/source.tar}}`\n\n- E[x]tract files matching a pattern from an archive [f]ile:\n\n`tar xf {{path/to/source.tar}} --wildcards "{{*.html}}"`\n # xargs\n\n> Execute a command with piped arguments coming from another command, a file, etc.\n> The input is treated as a single block of text and split into separate pieces on spaces, tabs, newlines and end-of-file.\n> More information: <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/xargs.html>.\n\n- Run a command using the input data as arguments:\n\n`{{arguments_source}} | xargs {{command}}`\n\n- Run multiple chained commands on the input data:\n\n`{{arguments_source}} | xargs sh -c "{{command1}} && {{command2}} | {{command3}}"`\n\n- Delete all files with a `.backup` extension (`-print0` uses a null character to split file names, and `-0` uses it as delimiter):\n\n`find . -name {{'*.backup'}} -print0 | xargs -0 rm -v`\n\n- Execute the command once for each input line, replacing any occurrences of the placeholder (here marked as `_`) with the input line:\n\n`{{arguments_source}} | xargs -I _ {{command}} _ {{optional_extra_arguments}}`\n\n- Parallel runs of up to `max-procs` processes at a time; the default is 1. If `max-procs` is 0, xargs will run as many processes as possible at a time:\n\n`{{arguments_source}} | xargs -P {{max-procs}} {{command}}`\n Task: Create a tar archive with all *.java files under the current directory Bash Command:<START>find . -type f -name "*.java" | xargs tar cvf myfile.tar<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. tar(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training tar(1) Linux manual page NAME | SYNOPSIS | NOTE | DESCRIPTION | OPTIONS | RETURN VALUE | SEE ALSO | BUG REPORTS | COPYRIGHT | COLOPHON TAR(1) GNU TAR Manual TAR(1) NAME top tar - an archiving utility SYNOPSIS top Traditional usage tar {A|c|d|r|t|u|x}[GnSkUWOmpsMBiajJzZhPlRvwo] [ARG...] UNIX-style usage tar -A [OPTIONS] -f ARCHIVE ARCHIVE... tar -c [-f ARCHIVE] [OPTIONS] [FILE...] tar -d [-f ARCHIVE] [OPTIONS] [FILE...] tar -r [-f ARCHIVE] [OPTIONS] [FILE...] tar -t [-f ARCHIVE] [OPTIONS] [MEMBER...] tar -u [-f ARCHIVE] [OPTIONS] [FILE...] tar -x [-f ARCHIVE] [OPTIONS] [MEMBER...] GNU-style usage tar {--catenate|--concatenate} [OPTIONS] --file ARCHIVE ARCHIVE... tar --create [--file ARCHIVE] [OPTIONS] [FILE...] tar {--diff|--compare} [--file ARCHIVE] [OPTIONS] [FILE...] tar --delete [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --append [--file ARCHIVE] [OPTIONS] [FILE...] tar --list [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --test-label [--file ARCHIVE] [OPTIONS] [LABEL...] tar --update [--file ARCHIVE] [OPTIONS] [FILE...] tar {--extract|--get} [--file ARCHIVE] [OPTIONS] [MEMBER...] NOTE top This manpage is a short description of GNU tar. For a detailed discussion, including examples and usage recommendations, refer to the GNU Tar Manual available in texinfo format. If the info reader and the tar documentation are properly installed on your system, the command info tar should give you access to the complete manual. You can also view the manual using the info mode in emacs(1), or find it in various formats online at https://www.gnu.org/software/tar/manual If any discrepancies occur between this manpage and the GNU Tar Manual, the later shall be considered the authoritative source. DESCRIPTION top GNU tar is an archiving program designed to store multiple files in a single file (an archive), and to manipulate such archives. The archive can be either a regular file or a device (e.g. a tape drive, hence the name of the program, which stands for tape archiver), which can be located either on the local or on a remote machine. Option styles Options to GNU tar can be given in three different styles. In traditional style, the first argument is a cluster of option letters and all subsequent arguments supply arguments to those options that require them. The arguments are read in the same order as the option letters. Any command line words that remain after all options have been processed are treated as non-option arguments: file or archive member names. For example, the c option requires creating the archive, the v option requests the verbose operation, and the f option takes an argument that sets the name of the archive to operate upon. The following command, written in the traditional style, instructs tar to store all files from the directory /etc into the archive file etc.tar, verbosely listing the files being archived: tar cfv etc.tar /etc In UNIX or short-option style, each option letter is prefixed with a single dash, as in other command line utilities. If an option takes an argument, the argument follows it, either as a separate command line word, or immediately following the option. However, if the option takes an optional argument, the argument must follow the option letter without any intervening whitespace, as in -g/tmp/snar.db. Any number of options not taking arguments can be clustered together after a single dash, e.g. -vkp. An option that takes an argument (whether mandatory or optional) can appear at the end of such a cluster, e.g. -vkpf a.tar. The example command above written in the short-option style could look like: tar -cvf etc.tar /etc or tar -c -v -f etc.tar /etc In GNU or long-option style, each option begins with two dashes and has a meaningful name, consisting of lower-case letters and dashes. When used, the long option can be abbreviated to its initial letters, provided that this does not create ambiguity. Arguments to long options are supplied either as a separate command line word, immediately following the option, or separated from the option by an equals sign with no intervening whitespace. Optional arguments must always use the latter method. Here are several ways of writing the example command in this style: tar --create --file etc.tar --verbose /etc or (abbreviating some options): tar --cre --file=etc.tar --verb /etc The options in all three styles can be intermixed, although doing so with old options is not encouraged. Operation mode The options listed in the table below tell GNU tar what operation it is to perform. Exactly one of them must be given. The meaning of non-option arguments depends on the operation mode requested. -A, --catenate, --concatenate Append archives to the end of another archive. The arguments are treated as the names of archives to append. All archives must be of the same format as the archive they are appended to, otherwise the resulting archive might be unusable with non-GNU implementations of tar. Notice also that when more than one archive is given, the members from archives other than the first one will be accessible in the resulting archive only when using the -i (--ignore-zeros) option. Compressed archives cannot be concatenated. -c, --create Create a new archive. Arguments supply the names of the files to be archived. Directories are archived recursively, unless the --no-recursion option is given. -d, --diff, --compare Find differences between archive and file system. The arguments are optional and specify archive members to compare. If not given, the current working directory is assumed. --delete Delete from the archive. The arguments supply names of the archive members to be removed. At least one argument must be given. This option does not operate on compressed archives. There is no short option equivalent. -r, --append Append files to the end of an archive. Arguments have the same meaning as for -c (--create). -t, --list List the contents of an archive. Arguments are optional. When given, they specify the names of the members to list. --test-label Test the archive volume label and exit. When used without arguments, it prints the volume label (if any) and exits with status 0. When one or more command line arguments are given. tar compares the volume label with each argument. It exits with code 0 if a match is found, and with code 1 otherwise. No output is displayed, unless used together with the -v (--verbose) option. There is no short option equivalent for this option. -u, --update Append files which are newer than the corresponding copy in the archive. Arguments have the same meaning as with the -c and -r options. Notice, that newer files don't replace their old archive copies, but instead are appended to the end of archive. The resulting archive can thus contain several members of the same name, corresponding to various versions of the same file. -x, --extract, --get Extract files from an archive. Arguments are optional. When given, they specify names of the archive members to be extracted. --show-defaults Show built-in defaults for various tar options and exit. -?, --help Display a short option summary and exit. --usage Display a list of available options and exit. --version Print program version and copyright information and exit. OPTIONS top Operation modifiers --check-device Check device numbers when creating incremental archives (default). -g, --listed-incremental=FILE Handle new GNU-format incremental backups. FILE is the name of a snapshot file, where tar stores additional information which is used to decide which files changed since the previous incremental dump and, consequently, must be dumped again. If FILE does not exist when creating an archive, it will be created and all files will be added to the resulting archive (the level 0 dump). To create incremental archives of non-zero level N, you need a copy of the snapshot file created for level N-1, and use it as FILE. When listing or extracting, the actual content of FILE is not inspected, it is needed only due to syntactical requirements. It is therefore common practice to use /dev/null in its place. --hole-detection=METHOD Use METHOD to detect holes in sparse files. This option implies --sparse. Valid values for METHOD are seek and raw. Default is seek with fallback to raw when not applicable. -G, --incremental Handle old GNU-format incremental backups. --ignore-failed-read Do not exit with nonzero on unreadable files. --level=NUMBER Set dump level for a created listed-incremental archive. Currently only --level=0 is meaningful: it instructs tar to truncate the snapshot file before dumping, thereby forcing a level 0 dump. -n, --seek Assume the archive is seekable. Normally tar determines automatically whether the archive can be seeked or not. This option is intended for use in cases when such recognition fails. It takes effect only if the archive is open for reading (e.g. with --list or --extract options). --no-check-device Do not check device numbers when creating incremental archives. --no-seek Assume the archive is not seekable. --occurrence[=N] Process only the Nth occurrence of each file in the archive. This option is valid only when used with one of the following subcommands: --delete, --diff, --extract or --list and when a list of files is given either on the command line or via the -T option. The default N is 1. --restrict Disable the use of some potentially harmful options. --sparse-version=MAJOR[.MINOR] Set which version of the sparse format to use. This option implies --sparse. Valid argument values are 0.0, 0.1, and 1.0. For a detailed discussion of sparse formats, refer to the GNU Tar Manual, appendix D, "Sparse Formats". Using the info reader, it can be accessed running the following command: info tar 'Sparse Formats'. -S, --sparse Handle sparse files efficiently. Some files in the file system may have segments which were actually never written (quite often these are database files created by such systems as DBM). When given this option, tar attempts to determine if the file is sparse prior to archiving it, and if so, to reduce the resulting archive size by not dumping empty parts of the file. Overwrite control These options control tar actions when extracting a file over an existing copy on disk. -k, --keep-old-files Don't replace existing files when extracting. --keep-newer-files Don't replace existing files that are newer than their archive copies. --keep-directory-symlink Don't replace existing symlinks to directories when extracting. --no-overwrite-dir Preserve metadata of existing directories. --one-top-level[=DIR] Extract all files into DIR, or, if used without argument, into a subdirectory named by the base name of the archive (minus standard compression suffixes recognizable by --auto-compress). --overwrite Overwrite existing files when extracting. --overwrite-dir Overwrite metadata of existing directories when extracting (default). --recursive-unlink Recursively remove all files in the directory prior to extracting it. --remove-files Remove files from disk after adding them to the archive. --skip-old-files Don't replace existing files when extracting, silently skip over them. -U, --unlink-first Remove each file prior to extracting over it. -W, --verify Verify the archive after writing it. Output stream selection --ignore-command-error Ignore subprocess exit codes. --no-ignore-command-error Treat non-zero exit codes of children as error (default). -O, --to-stdout Extract files to standard output. --to-command=COMMAND Pipe extracted files to COMMAND. The argument is the pathname of an external program, optionally with command line arguments. The program will be invoked and the contents of the file being extracted supplied to it on its standard input. Additional data will be supplied via the following environment variables: TAR_FILETYPE Type of the file. It is a single letter with the following meaning: f Regular file d Directory l Symbolic link h Hard link b Block device c Character device Currently only regular files are supported. TAR_MODE File mode, an octal number. TAR_FILENAME The name of the file. TAR_REALNAME Name of the file as stored in the archive. TAR_UNAME Name of the file owner. TAR_GNAME Name of the file owner group. TAR_ATIME Time of last access. It is a decimal number, representing seconds since the Epoch. If the archive provides times with nanosecond precision, the nanoseconds are appended to the timestamp after a decimal point. TAR_MTIME Time of last modification. TAR_CTIME Time of last status change. TAR_SIZE Size of the file. TAR_UID UID of the file owner. TAR_GID GID of the file owner. Additionally, the following variables contain information about tar operation mode and the archive being processed: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. Handling of file attributes --atime-preserve[=METHOD] Preserve access times on dumped files, either by restoring the times after reading (METHOD=replace, this is the default) or by not setting the times in the first place (METHOD=system). --delay-directory-restore Delay setting modification times and permissions of extracted directories until the end of extraction. Use this option when extracting from an archive which has unusual member ordering. --group=NAME[:GID] Force NAME as group for added files. If GID is not supplied, NAME can be either a user name or numeric GID. In this case the missing part (GID or name) will be inferred from the current host's group database. When used with --group-map=FILE, affects only those files whose owner group is not listed in FILE. --group-map=FILE Read group translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single group. It must consist of two fields, delimited by any amount of whitespace: OLDGRP NEWGRP[:NEWGID] OLDGRP is either a valid group name or a GID prefixed with +. Unless NEWGID is supplied, NEWGRP must also be either a valid group name or a +GID. Otherwise, both NEWGRP and NEWGID need not be listed in the system group database. As a result, each input file with owner group OLDGRP will be stored in archive with owner group NEWGRP and GID NEWGID. --mode=CHANGES Force symbolic mode CHANGES for added files. --mtime=DATE-OR-FILE Set mtime for added files. DATE-OR-FILE is either a date/time in almost arbitrary format, or the name of an existing file. In the latter case the mtime of that file will be used. -m, --touch Don't extract file modified time. --no-delay-directory-restore Cancel the effect of the prior --delay-directory-restore option. --no-same-owner Extract files as yourself (default for ordinary users). --no-same-permissions Apply the user's umask when extracting permissions from the archive (default for ordinary users). --numeric-owner Always use numbers for user/group names. --owner=NAME[:UID] Force NAME as owner for added files. If UID is not supplied, NAME can be either a user name or numeric UID. In this case the missing part (UID or name) will be inferred from the current host's user database. When used with --owner-map=FILE, affects only those files whose owner is not listed in FILE. --owner-map=FILE Read owner translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single UID. It must consist of two fields, delimited by any amount of whitespace: OLDUSR NEWUSR[:NEWUID] OLDUSR is either a valid user name or a UID prefixed with +. Unless NEWUID is supplied, NEWUSR must also be either a valid user name or a +UID. Otherwise, both NEWUSR and NEWUID need not be listed in the system user database. As a result, each input file owned by OLDUSR will be stored in archive with owner name NEWUSR and UID NEWUID. -p, --preserve-permissions, --same-permissions Set permissions of extracted files to those recorded in the archive (default for superuser). --same-owner Try extracting files with the same ownership as exists in the archive (default for superuser). -s, --preserve-order, --same-order Tell tar that the list of file names to process is sorted in the same order as the files in the archive. --sort=ORDER When creating an archive, sort directory entries according to ORDER, which is one of none, name, or inode. The default is --sort=none, which stores archive members in the same order as returned by the operating system. Using --sort=name ensures the member ordering in the created archive is uniform and reproducible. Using --sort=inode reduces the number of disk seeks made when creating the archive and thus can considerably speed up archivation. This sorting order is supported only if the underlying system provides the necessary information. Extended file attributes --acls Enable POSIX ACLs support. --no-acls Disable POSIX ACLs support. --selinux Enable SELinux context support. --no-selinux Disable SELinux context support. --xattrs Enable extended attributes support. --no-xattrs Disable extended attributes support. --xattrs-exclude=PATTERN Specify the exclude pattern for xattr keys. PATTERN is a globbing pattern, e.g. --xattrs-exclude='user.*' to include only attributes from the user namespace. --xattrs-include=PATTERN Specify the include pattern for xattr keys. PATTERN is a globbing pattern. Device selection and switching -f, --file=ARCHIVE Use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable `TAPE'. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default. The default value can be inspected either using the --show-defaults option, or at the end of the tar --help output. An archive name that has a colon in it specifies a file or device on a remote machine. The part before the colon is taken as the machine name or IP address, and the part after it as the file or device pathname, e.g.: --file=remotehost:/dev/sr0 An optional username can be prefixed to the hostname, placing a @ sign between them. By default, the remote host is accessed via the rsh(1) command. Nowadays it is common to use ssh(1) instead. You can do so by giving the following command line option: --rsh-command=/usr/bin/ssh The remote machine should have the rmt(8) command installed. If its pathname does not match tar's default, you can inform tar about the correct pathname using the --rmt-command option. --force-local Archive file is local even if it has a colon. -F, --info-script=COMMAND, --new-volume-script=COMMAND Run COMMAND at the end of each tape (implies -M). The command can include arguments. When started, it will inherit tar's environment plus the following variables: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. TAR_FD File descriptor which can be used to communicate the new volume name to tar. If the info script fails, tar exits; otherwise, it begins writing the next volume. -L, --tape-length=N Change tape after writing Nx1024 bytes. If N is followed by a size suffix (see the subsection Size suffixes below), the suffix specifies the multiplicative factor to be used instead of 1024. This option implies -M. -M, --multi-volume Create/list/extract multi-volume archive. --rmt-command=COMMAND Use COMMAND instead of rmt when accessing remote archives. See the description of the -f option, above. --rsh-command=COMMAND Use COMMAND instead of rsh when accessing remote archives. See the description of the -f option, above. --volno-file=FILE When this option is used in conjunction with --multi-volume, tar will keep track of which volume of a multi-volume archive it is working in FILE. Device blocking -b, --blocking-factor=BLOCKS Set record size to BLOCKSx512 bytes. -B, --read-full-records When listing or extracting, accept incomplete input records after end-of-file marker. -i, --ignore-zeros Ignore zeroed blocks in archive. Normally two consecutive 512-blocks filled with zeroes mean EOF and tar stops reading after encountering them. This option instructs it to read further and is useful when reading archives created with the -A option. --record-size=NUMBER Set record size. NUMBER is the number of bytes per record. It must be multiple of 512. It can can be suffixed with a size suffix, e.g. --record-size=10K, for 10 Kilobytes. See the subsection Size suffixes, for a list of valid suffixes. Archive format selection -H, --format=FORMAT Create archive of the given format. Valid formats are: gnu GNU tar 1.13.x format oldgnu GNU format as per tar <= 1.12. pax, posix POSIX 1003.1-2001 (pax) format. ustar POSIX 1003.1-1988 (ustar) format. v7 Old V7 tar format. --old-archive, --portability Same as --format=v7. --pax-option=keyword[[:]=value][,keyword[[:]=value]]... Control pax keywords when creating PAX archives (-H pax). This option is equivalent to the -o option of the pax(1) utility. --posix Same as --format=posix. -V, --label=TEXT Create archive with volume name TEXT. If listing or extracting, use TEXT as a globbing pattern for volume name. Compression options -a, --auto-compress Use archive suffix to determine the compression program. -I, --use-compress-program=COMMAND Filter data through COMMAND. It must accept the -d option, for decompression. The argument can contain command line options. -j, --bzip2 Filter the archive through bzip2(1). -J, --xz Filter the archive through xz(1). --lzip Filter the archive through lzip(1). --lzma Filter the archive through lzma(1). --lzop Filter the archive through lzop(1). --no-auto-compress Do not use archive suffix to determine the compression program. -z, --gzip, --gunzip, --ungzip Filter the archive through gzip(1). -Z, --compress, --uncompress Filter the archive through compress(1). --zstd Filter the archive through zstd(1). Local file selection --add-file=FILE Add FILE to the archive (useful if its name starts with a dash). --backup[=CONTROL] Backup before removal. The CONTROL argument, if supplied, controls the backup policy. Its valid values are: none, off Never make backups. t, numbered Make numbered backups. nil, existing Make numbered backups if numbered backups exist, simple backups otherwise. never, simple Always make simple backups If CONTROL is not given, the value is taken from the VERSION_CONTROL environment variable. If it is not set, existing is assumed. -C, --directory=DIR Change to DIR before performing any operations. This option is order-sensitive, i.e. it affects all options that follow. --exclude=PATTERN Exclude files matching PATTERN, a glob(3)-style wildcard pattern. --exclude-backups Exclude backup and lock files. --exclude-caches Exclude contents of directories containing file CACHEDIR.TAG, except for the tag file itself. --exclude-caches-all Exclude directories containing file CACHEDIR.TAG and the file itself. --exclude-caches-under Exclude everything under directories containing CACHEDIR.TAG --exclude-ignore=FILE Before dumping a directory, see if it contains FILE. If so, read exclusion patterns from this file. The patterns affect only the directory itself. --exclude-ignore-recursive=FILE Same as --exclude-ignore, except that patterns from FILE affect both the directory and all its subdirectories. --exclude-tag=FILE Exclude contents of directories containing FILE, except for FILE itself. --exclude-tag-all=FILE Exclude directories containing FILE. --exclude-tag-under=FILE Exclude everything under directories containing FILE. --exclude-vcs Exclude version control system directories. --exclude-vcs-ignores Exclude files that match patterns read from VCS-specific ignore files. Supported files are: .cvsignore, .gitignore, .bzrignore, and .hgignore. -h, --dereference Follow symlinks; archive and dump the files they point to. --hard-dereference Follow hard links; archive and dump the files they refer to. -K, --starting-file=MEMBER Begin at the given member in the archive. --newer-mtime=DATE Work on files whose data changed after the DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --no-null Disable the effect of the previous --null option. --no-recursion Avoid descending automatically in directories. --no-unquote Do not unquote input file or member names. --no-verbatim-files-from Treat each line read from a file list as if it were supplied in the command line. I.e., leading and trailing whitespace is removed and, if the resulting string begins with a dash, it is treated as tar command line option. This is the default behavior. The --no-verbatim-files-from option is provided as a way to restore it after --verbatim-files-from option. This option is positional: it affects all --files-from options that occur after it in, until --verbatim-files-from option or end of line, whichever occurs first. It is implied by the --no-null option. --null Instruct subsequent -T options to read null-terminated names verbatim (disables special handling of names that start with a dash). See also --verbatim-files-from. -N, --newer=DATE, --after-date=DATE Only store files newer than DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --one-file-system Stay in local file system when creating archive. -P, --absolute-names Don't strip leading slashes from file names when creating archives. --recursion Recurse into directories (default). --suffix=STRING Backup before removal, override usual suffix. Default suffix is ~, unless overridden by environment variable SIMPLE_BACKUP_SUFFIX. -T, --files-from=FILE Get names to extract or create from FILE. Unless specified otherwise, the FILE must contain a list of names separated by ASCII LF (i.e. one name per line). The names read are handled the same way as command line arguments. They undergo quote removal and word splitting, and any string that starts with a - is handled as tar command line option. If this behavior is undesirable, it can be turned off using the --verbatim-files-from option. The --null option instructs tar that the names in FILE are separated by ASCII NUL character, instead of LF. It is useful if the list is generated by find(1) -print0 predicate. --unquote Unquote file or member names (default). --verbatim-files-from Treat each line obtained from a file list as a file name, even if it starts with a dash. File lists are supplied with the --files-from (-T) option. The default behavior is to handle names supplied in file lists as if they were typed in the command line, i.e. any names starting with a dash are treated as tar options. The --verbatim-files-from option disables this behavior. This option affects all --files-from options that occur after it in the command line. Its effect is reverted by the --no-verbatim-files-from option. This option is implied by the --null option. See also --add-file. -X, --exclude-from=FILE Exclude files matching patterns listed in FILE. File name transformations --strip-components=NUMBER Strip NUMBER leading components from file names on extraction. --transform=EXPRESSION, --xform=EXPRESSION Use sed replace EXPRESSION to transform file names. File name matching options These options affect both exclude and include patterns. --anchored Patterns match file name start. --ignore-case Ignore case. --no-anchored Patterns match after any / (default for exclusion). --no-ignore-case Case sensitive matching (default). --no-wildcards Verbatim string matching. --no-wildcards-match-slash Wildcards do not match /. --wildcards Use wildcards (default for exclusion). --wildcards-match-slash Wildcards match / (default for exclusion). Informative output --checkpoint[=N] Display progress messages every Nth record (default 10). --checkpoint-action=ACTION Run ACTION on each checkpoint. --clamp-mtime Only set time when the file is more recent than what was given with --mtime. --full-time Print file time to its full resolution. --index-file=FILE Send verbose output to FILE. -l, --check-links Print a message if not all links are dumped. --no-quote-chars=STRING Disable quoting for characters from STRING. --quote-chars=STRING Additionally quote characters from STRING. --quoting-style=STYLE Set quoting style for file and member names. Valid values for STYLE are literal, shell, shell-always, c, c-maybe, escape, locale, clocale. -R, --block-number Show block number within archive with each message. --show-omitted-dirs When listing or extracting, list each directory that does not match search criteria. --show-transformed-names, --show-stored-names Show file or archive names after transformation by --strip and --transform options. --totals[=SIGNAL] Print total bytes after processing the archive. If SIGNAL is given, print total bytes when this signal is delivered. Allowed signals are: SIGHUP, SIGQUIT, SIGINT, SIGUSR1, and SIGUSR2. The SIG prefix can be omitted. --utc Print file modification times in UTC. -v, --verbose Verbosely list files processed. Each instance of this option on the command line increases the verbosity level by one. The maximum verbosity level is 3. For a detailed discussion of how various verbosity levels affect tar's output, please refer to GNU Tar Manual, subsection 2.5.2 "The '--verbose' Option". --warning=KEYWORD Enable or disable warning messages identified by KEYWORD. The messages are suppressed if KEYWORD is prefixed with no- and enabled otherwise. Multiple --warning options accumulate. Keywords controlling general tar operation: all Enable all warning messages. This is the default. none Disable all warning messages. filename-with-nuls "%s: file name read contains nul character" alone-zero-block "A lone zero block at %s" Keywords applicable for tar --create: cachedir "%s: contains a cache directory tag %s; %s" file-shrank "%s: File shrank by %s bytes; padding with zeros" xdev "%s: file is on a different filesystem; not dumped" file-ignored "%s: Unknown file type; file ignored" "%s: socket ignored" "%s: door ignored" file-unchanged "%s: file is unchanged; not dumped" ignore-archive "%s: archive cannot contain itself; not dumped" file-removed "%s: File removed before we read it" file-changed "%s: file changed as we read it" failed-read Suppresses warnings about unreadable files or directories. This keyword applies only if used together with the --ignore-failed-read option. Keywords applicable for tar --extract: existing-file "%s: skipping existing file" timestamp "%s: implausibly old time stamp %s" "%s: time stamp %s is %s s in the future" contiguous-cast "Extracting contiguous files as regular files" symlink-cast "Attempting extraction of symbolic links as hard links" unknown-cast "%s: Unknown file type '%c', extracted as normal file" ignore-newer "Current %s is newer or same age" unknown-keyword "Ignoring unknown extended header keyword '%s'" decompress-program Controls verbose description of failures occurring when trying to run alternative decompressor programs. This warning is disabled by default (unless --verbose is used). A common example of what you can get when using this warning is: $ tar --warning=decompress-program -x -f archive.Z tar (child): cannot run compress: No such file or directory tar (child): trying gzip This means that tar first tried to decompress archive.Z using compress, and, when that failed, switched to gzip. record-size "Record size = %lu blocks" Keywords controlling incremental extraction: rename-directory "%s: Directory has been renamed from %s" "%s: Directory has been renamed" new-directory "%s: Directory is new" xdev "%s: directory is on a different device: not purging" bad-dumpdir "Malformed dumpdir: 'X' never used" -w, --interactive, --confirmation Ask for confirmation for every action. Compatibility options -o When creating, same as --old-archive. When extracting, same as --no-same-owner. Size suffixes Suffix Units Byte Equivalent b Blocks SIZE x 512 B Kilobytes SIZE x 1024 c Bytes SIZE G Gigabytes SIZE x 1024^3 K Kilobytes SIZE x 1024 k Kilobytes SIZE x 1024 M Megabytes SIZE x 1024^2 P Petabytes SIZE x 1024^5 T Terabytes SIZE x 1024^4 w Words SIZE x 2 RETURN VALUE top Tar's exit code indicates whether it was able to successfully perform the requested operation, and if not, what kind of error occurred. 0 Successful termination. 1 Some files differ. If tar was invoked with the --compare (--diff, -d) command line option, this means that some files in the archive differ from their disk counterparts. If tar was given one of the --create, --append or --update options, this exit code means that some files were changed while being archived and so the resulting archive does not contain the exact copy of the file set. 2 Fatal error. This means that some fatal, unrecoverable error occurred. If a subprocess that had been invoked by tar exited with a nonzero exit code, tar itself exits with that code as well. This can happen, for example, if a compression option (e.g. -z) was used and the external compressor program failed. Another example is rmt failure during backup to a remote device. SEE ALSO top bzip2(1), compress(1), gzip(1), lzma(1), lzop(1), rmt(8), symlink(7), xz(1), zstd(1). Complete tar manual: run info tar or use emacs(1) info mode to read it. Online copies of GNU tar documentation in various formats can be found at: https://www.gnu.org/software/tar/manual BUG REPORTS top Report bugs to <bug-tar@gnu.org>. COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. COLOPHON top This page is part of the tar (an archiver program) project. Information about the project can be found at http://savannah.gnu.org/projects/tar/. If you have a bug report for this manual page, see http://savannah.gnu.org/bugs/?group=tar. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/tar.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-09-12.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org TAR July 11, 2022 TAR(1) Pages that refer to this page: attr(1), dpkg-deb(1), dpkg-source(1), machinectl(1), rsync(1), st(4), suffixes(7), symlink(7), cupsd-helper(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. xargs(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training xargs(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | EXIT STATUS | STANDARDS CONFORMANCE | HISTORY | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON XARGS(1) General Commands Manual XARGS(1) NAME top xargs - build and execute command lines from standard input SYNOPSIS top xargs [options] [command [initial-arguments]] DESCRIPTION top This manual page documents the GNU version of xargs. xargs reads items from the standard input, delimited by blanks (which can be protected with double or single quotes or a backslash) or newlines, and executes the command (default is echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored. The command line for command is built up until it reaches a system-defined limit (unless the -n and -L options are used). The specified command will be invoked as many times as necessary to use up the list of input items. In general, there will be many fewer invocations of command than there were items in the input. This will normally have significant performance benefits. Some commands can usefully be executed in parallel too; see the -P option. Because Unix filenames can contain blanks and newlines, this default behaviour is often problematic; filenames containing blanks and/or newlines are incorrectly processed by xargs. In these situations it is better to use the -0 option, which prevents such problems. When using this option you will need to ensure that the program which produces the input for xargs also uses a null character as a separator. If that program is GNU find for example, the -print0 option does this for you. If any invocation of the command exits with a status of 255, xargs will stop immediately without reading any further input. An error message is issued on stderr when this happens. OPTIONS top -0, --null Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally). Disables the end-of-file string, which is treated like any other argument. Useful when input items might contain white space, quote marks, or backslashes. The GNU find -print0 option produces input suitable for this mode. -a file, --arg-file=file Read items from file instead of standard input. If you use this option, stdin remains unchanged when commands are run. Otherwise, stdin is redirected from /dev/null. --delimiter=delim, -d delim Input items are terminated by the specified character. The specified delimiter may be a single character, a C- style character escape such as \n, or an octal or hexadecimal escape code. Octal and hexadecimal escape codes are understood as for the printf command. Multibyte characters are not supported. When processing the input, quotes and backslash are not special; every character in the input is taken literally. The -d option disables any end-of-file string, which is treated like any other argument. You can use this option when the input consists of simply newline-separated items, although it is almost always better to design your program to use --null where this is possible. -E eof-str Set the end-of-file string to eof-str. If the end-of-file string occurs as a line of input, the rest of the input is ignored. If neither -E nor -e is used, no end-of-file string is used. -e[eof-str], --eof[=eof-str] This option is a synonym for the -E option. Use -E instead, because it is POSIX compliant while this option is not. If eof-str is omitted, there is no end-of-file string. If neither -E nor -e is used, no end-of-file string is used. -I replace-str Replace occurrences of replace-str in the initial- arguments with names read from standard input. Also, unquoted blanks do not terminate input items; instead the separator is the newline character. Implies -x and -L 1. -i[replace-str], --replace[=replace-str] This option is a synonym for -Ireplace-str if replace-str is specified. If the replace-str argument is missing, the effect is the same as -I{}. The -i option is deprecated; use -I instead. -L max-lines Use at most max-lines nonblank input lines per command line. Trailing blanks cause an input line to be logically continued on the next input line. Implies -x. -l[max-lines], --max-lines[=max-lines] Synonym for the -L option. Unlike -L, the max-lines argument is optional. If max-lines is not specified, it defaults to one. The -l option is deprecated since the POSIX standard specifies -L instead. -n max-args, --max-args=max-args Use at most max-args arguments per command line. Fewer than max-args arguments will be used if the size (see the -s option) is exceeded, unless the -x option is given, in which case xargs will exit. -P max-procs, --max-procs=max-procs Run up to max-procs processes at a time; the default is 1. If max-procs is 0, xargs will run as many processes as possible at a time. Use the -n option or the -L option with -P; otherwise chances are that only one exec will be done. While xargs is running, you can send its process a SIGUSR1 signal to increase the number of commands to run simultaneously, or a SIGUSR2 to decrease the number. You cannot increase it above an implementation-defined limit (which is shown with --show-limits). You cannot decrease it below 1. xargs never terminates its commands; when asked to decrease, it merely waits for more than one existing command to terminate before starting another. Please note that it is up to the called processes to properly manage parallel access to shared resources. For example, if more than one of them tries to print to stdout, the output will be produced in an indeterminate order (and very likely mixed up) unless the processes collaborate in some way to prevent this. Using some kind of locking scheme is one way to prevent such problems. In general, using a locking scheme will help ensure correct output but reduce performance. If you don't want to tolerate the performance difference, simply arrange for each process to produce a separate output file (or otherwise use separate resources). -o, --open-tty Reopen stdin as /dev/tty in the child process before executing the command. This is useful if you want xargs to run an interactive application. -p, --interactive Prompt the user about whether to run each command line and read a line from the terminal. Only run the command line if the response starts with `y' or `Y'. Implies -t. --process-slot-var=name Set the environment variable name to a unique value in each running child process. Values are reused once child processes exit. This can be used in a rudimentary load distribution scheme, for example. -r, --no-run-if-empty If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there is no input. This option is a GNU extension. -s max-chars, --max-chars=max-chars Use at most max-chars characters per command line, including the command and initial-arguments and the terminating nulls at the ends of the argument strings. The largest allowed value is system-dependent, and is calculated as the argument length limit for exec, less the size of your environment, less 2048 bytes of headroom. If this value is more than 128 KiB, 128 KiB is used as the default value; otherwise, the default value is the maximum. 1 KiB is 1024 bytes. xargs automatically adapts to tighter constraints. --show-limits Display the limits on the command-line length which are imposed by the operating system, xargs' choice of buffer size and the -s option. Pipe the input from /dev/null (and perhaps specify --no-run-if-empty) if you don't want xargs to do anything. -t, --verbose Print the command line on the standard error output before executing it. -x, --exit Exit if the size (see the -s option) is exceeded. -- Delimit the option list. Later arguments, if any, are treated as operands even if they begin with -. For example, xargs -- --help runs the command --help (found in PATH) instead of printing the usage text, and xargs -- --mycommand runs the command --mycommand instead of rejecting this as unrecognized option. --help Print a summary of the options to xargs and exit. --version Print the version number of xargs and exit. The options --max-lines (-L, -l), --replace (-I, -i) and --max- args (-n) are mutually exclusive. If some of them are specified at the same time, then xargs will generally use the option specified last on the command line, i.e., it will reset the value of the offending option (given before) to its default value. Additionally, xargs will issue a warning diagnostic on stderr. The exception to this rule is that the special max-args value 1 ('-n1') is ignored after the --replace option and its aliases -I and -i, because it would not actually conflict. EXAMPLES top find /tmp -name core -type f -print | xargs /bin/rm -f Find files named core in or below the directory /tmp and delete them. Note that this will work incorrectly if there are any filenames containing newlines or spaces. find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing spaces or newlines are correctly handled. find /tmp -depth -name core -type f -delete Find files named core in or below the directory /tmp and delete them, but more efficiently than in the previous example (because we avoid the need to use fork(2) and exec(2) to launch rm and we don't need the extra xargs process). cut -d: -f1 < /etc/passwd | sort | xargs echo Generates a compact listing of all the users on the system. EXIT STATUS top xargs exits with the following status: 0 if it succeeds 123 if any invocation of the command exited with status 1125 124 if the command exited with status 255 125 if the command is killed by a signal 126 if the command cannot be run 127 if the command is not found 1 if some other error occurred. Exit codes greater than 128 are used by the shell to indicate that a program died due to a fatal signal. STANDARDS CONFORMANCE top As of GNU xargs version 4.2.9, the default behaviour of xargs is not to have a logical end-of-file marker. POSIX (IEEE Std 1003.1, 2004 Edition) allows this. The -l and -i options appear in the 1997 version of the POSIX standard, but do not appear in the 2004 version of the standard. Therefore you should use -L and -I instead, respectively. The -o option is an extension to the POSIX standard for better compatibility with BSD. The POSIX standard allows implementations to have a limit on the size of arguments to the exec functions. This limit could be as low as 4096 bytes including the size of the environment. For scripts to be portable, they must not rely on a larger value. However, I know of no implementation whose actual limit is that small. The --show-limits option can be used to discover the actual limits in force on the current system. HISTORY top The xargs program was invented by Herb Gellis at Bell Labs. See the Texinfo manual for findutils, Finding Files, for more information. BUGS top It is not possible for xargs to be used securely, since there will always be a time gap between the production of the list of input files and their use in the commands that xargs issues. If other users have access to the system, they can manipulate the filesystem during this time window to force the action of the commands xargs runs to apply to files that you didn't intend. For a more detailed discussion of this and related problems, please refer to the ``Security Considerations'' chapter in the findutils Texinfo documentation. The -execdir option of find can often be used as a more secure alternative. When you use the -I option, each line read from the input is buffered internally. This means that there is an upper limit on the length of input line that xargs will accept when used with the -I option. To work around this limitation, you can use the -s option to increase the amount of buffer space that xargs uses, and you can also use an extra invocation of xargs to ensure that very long lines do not occur. For example: somecommand | xargs -s 50000 echo | xargs -I '{}' -s 100000 rm '{}' Here, the first invocation of xargs has no input line length limit because it doesn't use the -i option. The second invocation of xargs does have such a limit, but we have ensured that it never encounters a line which is longer than it can handle. This is not an ideal solution. Instead, the -i option should not impose a line length limit, which is why this discussion appears in the BUGS section. The problem doesn't occur with the output of find(1) because it emits just one filename per line. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 19902023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top find(1), kill(1), locate(1), updatedb(1), fork(2), execvp(3), locatedb(5), signal(7) Full documentation <https://www.gnu.org/software/findutils/xargs> or available locally via: info xargs COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org XARGS(1) Pages that refer to this page: dpkg-name(1), find(1), grep(1), locate(1), updatedb(1), lsof(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a tar archive with all *.java files under the current directory Bash Command:<START>find . -type f -name "*.java" | xargs tar cvf myfile.tar<END> |
Create a tar file containing all the files in ~/Library folder that contain spaces in their names | find ~/Library -name '* *' -print0 | xargs -0 tar rf blah.tar | ['find', 'tar', 'xargs'] | Output a Bash command to accomplish the following task. Task: Create a tar file containing all the files in ~/Library folder that contain spaces in their names Bash Command:<START>find ~/Library -name '* *' -print0 | xargs -0 tar rf blah.tar<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # tar\n\n> Archiving utility.\n> Often combined with a compression method, such as `gzip` or `bzip2`.\n> More information: <https://www.gnu.org/software/tar>.\n\n- [c]reate an archive and write it to a [f]ile:\n\n`tar cf {{path/to/target.tar}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive and write it to a [f]ile:\n\n`tar czf {{path/to/target.tar.gz}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive from a directory using relative paths:\n\n`tar czf {{path/to/target.tar.gz}} --directory={{path/to/directory}} .`\n\n- E[x]tract a (compressed) archive [f]ile into the current directory [v]erbosely:\n\n`tar xvf {{path/to/source.tar[.gz|.bz2|.xz]}}`\n\n- E[x]tract a (compressed) archive [f]ile into the target directory:\n\n`tar xf {{path/to/source.tar[.gz|.bz2|.xz]}} --directory={{path/to/directory}}`\n\n- [c]reate a compressed archive and write it to a [f]ile, using the file extension to [a]utomatically determine the compression program:\n\n`tar caf {{path/to/target.tar.xz}} {{path/to/file1 path/to/file2 ...}}`\n\n- Lis[t] the contents of a tar [f]ile [v]erbosely:\n\n`tar tvf {{path/to/source.tar}}`\n\n- E[x]tract files matching a pattern from an archive [f]ile:\n\n`tar xf {{path/to/source.tar}} --wildcards "{{*.html}}"`\n # xargs\n\n> Execute a command with piped arguments coming from another command, a file, etc.\n> The input is treated as a single block of text and split into separate pieces on spaces, tabs, newlines and end-of-file.\n> More information: <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/xargs.html>.\n\n- Run a command using the input data as arguments:\n\n`{{arguments_source}} | xargs {{command}}`\n\n- Run multiple chained commands on the input data:\n\n`{{arguments_source}} | xargs sh -c "{{command1}} && {{command2}} | {{command3}}"`\n\n- Delete all files with a `.backup` extension (`-print0` uses a null character to split file names, and `-0` uses it as delimiter):\n\n`find . -name {{'*.backup'}} -print0 | xargs -0 rm -v`\n\n- Execute the command once for each input line, replacing any occurrences of the placeholder (here marked as `_`) with the input line:\n\n`{{arguments_source}} | xargs -I _ {{command}} _ {{optional_extra_arguments}}`\n\n- Parallel runs of up to `max-procs` processes at a time; the default is 1. If `max-procs` is 0, xargs will run as many processes as possible at a time:\n\n`{{arguments_source}} | xargs -P {{max-procs}} {{command}}`\n Task: Create a tar file containing all the files in ~/Library folder that contain spaces in their names Bash Command:<START>find ~/Library -name '* *' -print0 | xargs -0 tar rf blah.tar<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. tar(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training tar(1) Linux manual page NAME | SYNOPSIS | NOTE | DESCRIPTION | OPTIONS | RETURN VALUE | SEE ALSO | BUG REPORTS | COPYRIGHT | COLOPHON TAR(1) GNU TAR Manual TAR(1) NAME top tar - an archiving utility SYNOPSIS top Traditional usage tar {A|c|d|r|t|u|x}[GnSkUWOmpsMBiajJzZhPlRvwo] [ARG...] UNIX-style usage tar -A [OPTIONS] -f ARCHIVE ARCHIVE... tar -c [-f ARCHIVE] [OPTIONS] [FILE...] tar -d [-f ARCHIVE] [OPTIONS] [FILE...] tar -r [-f ARCHIVE] [OPTIONS] [FILE...] tar -t [-f ARCHIVE] [OPTIONS] [MEMBER...] tar -u [-f ARCHIVE] [OPTIONS] [FILE...] tar -x [-f ARCHIVE] [OPTIONS] [MEMBER...] GNU-style usage tar {--catenate|--concatenate} [OPTIONS] --file ARCHIVE ARCHIVE... tar --create [--file ARCHIVE] [OPTIONS] [FILE...] tar {--diff|--compare} [--file ARCHIVE] [OPTIONS] [FILE...] tar --delete [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --append [--file ARCHIVE] [OPTIONS] [FILE...] tar --list [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --test-label [--file ARCHIVE] [OPTIONS] [LABEL...] tar --update [--file ARCHIVE] [OPTIONS] [FILE...] tar {--extract|--get} [--file ARCHIVE] [OPTIONS] [MEMBER...] NOTE top This manpage is a short description of GNU tar. For a detailed discussion, including examples and usage recommendations, refer to the GNU Tar Manual available in texinfo format. If the info reader and the tar documentation are properly installed on your system, the command info tar should give you access to the complete manual. You can also view the manual using the info mode in emacs(1), or find it in various formats online at https://www.gnu.org/software/tar/manual If any discrepancies occur between this manpage and the GNU Tar Manual, the later shall be considered the authoritative source. DESCRIPTION top GNU tar is an archiving program designed to store multiple files in a single file (an archive), and to manipulate such archives. The archive can be either a regular file or a device (e.g. a tape drive, hence the name of the program, which stands for tape archiver), which can be located either on the local or on a remote machine. Option styles Options to GNU tar can be given in three different styles. In traditional style, the first argument is a cluster of option letters and all subsequent arguments supply arguments to those options that require them. The arguments are read in the same order as the option letters. Any command line words that remain after all options have been processed are treated as non-option arguments: file or archive member names. For example, the c option requires creating the archive, the v option requests the verbose operation, and the f option takes an argument that sets the name of the archive to operate upon. The following command, written in the traditional style, instructs tar to store all files from the directory /etc into the archive file etc.tar, verbosely listing the files being archived: tar cfv etc.tar /etc In UNIX or short-option style, each option letter is prefixed with a single dash, as in other command line utilities. If an option takes an argument, the argument follows it, either as a separate command line word, or immediately following the option. However, if the option takes an optional argument, the argument must follow the option letter without any intervening whitespace, as in -g/tmp/snar.db. Any number of options not taking arguments can be clustered together after a single dash, e.g. -vkp. An option that takes an argument (whether mandatory or optional) can appear at the end of such a cluster, e.g. -vkpf a.tar. The example command above written in the short-option style could look like: tar -cvf etc.tar /etc or tar -c -v -f etc.tar /etc In GNU or long-option style, each option begins with two dashes and has a meaningful name, consisting of lower-case letters and dashes. When used, the long option can be abbreviated to its initial letters, provided that this does not create ambiguity. Arguments to long options are supplied either as a separate command line word, immediately following the option, or separated from the option by an equals sign with no intervening whitespace. Optional arguments must always use the latter method. Here are several ways of writing the example command in this style: tar --create --file etc.tar --verbose /etc or (abbreviating some options): tar --cre --file=etc.tar --verb /etc The options in all three styles can be intermixed, although doing so with old options is not encouraged. Operation mode The options listed in the table below tell GNU tar what operation it is to perform. Exactly one of them must be given. The meaning of non-option arguments depends on the operation mode requested. -A, --catenate, --concatenate Append archives to the end of another archive. The arguments are treated as the names of archives to append. All archives must be of the same format as the archive they are appended to, otherwise the resulting archive might be unusable with non-GNU implementations of tar. Notice also that when more than one archive is given, the members from archives other than the first one will be accessible in the resulting archive only when using the -i (--ignore-zeros) option. Compressed archives cannot be concatenated. -c, --create Create a new archive. Arguments supply the names of the files to be archived. Directories are archived recursively, unless the --no-recursion option is given. -d, --diff, --compare Find differences between archive and file system. The arguments are optional and specify archive members to compare. If not given, the current working directory is assumed. --delete Delete from the archive. The arguments supply names of the archive members to be removed. At least one argument must be given. This option does not operate on compressed archives. There is no short option equivalent. -r, --append Append files to the end of an archive. Arguments have the same meaning as for -c (--create). -t, --list List the contents of an archive. Arguments are optional. When given, they specify the names of the members to list. --test-label Test the archive volume label and exit. When used without arguments, it prints the volume label (if any) and exits with status 0. When one or more command line arguments are given. tar compares the volume label with each argument. It exits with code 0 if a match is found, and with code 1 otherwise. No output is displayed, unless used together with the -v (--verbose) option. There is no short option equivalent for this option. -u, --update Append files which are newer than the corresponding copy in the archive. Arguments have the same meaning as with the -c and -r options. Notice, that newer files don't replace their old archive copies, but instead are appended to the end of archive. The resulting archive can thus contain several members of the same name, corresponding to various versions of the same file. -x, --extract, --get Extract files from an archive. Arguments are optional. When given, they specify names of the archive members to be extracted. --show-defaults Show built-in defaults for various tar options and exit. -?, --help Display a short option summary and exit. --usage Display a list of available options and exit. --version Print program version and copyright information and exit. OPTIONS top Operation modifiers --check-device Check device numbers when creating incremental archives (default). -g, --listed-incremental=FILE Handle new GNU-format incremental backups. FILE is the name of a snapshot file, where tar stores additional information which is used to decide which files changed since the previous incremental dump and, consequently, must be dumped again. If FILE does not exist when creating an archive, it will be created and all files will be added to the resulting archive (the level 0 dump). To create incremental archives of non-zero level N, you need a copy of the snapshot file created for level N-1, and use it as FILE. When listing or extracting, the actual content of FILE is not inspected, it is needed only due to syntactical requirements. It is therefore common practice to use /dev/null in its place. --hole-detection=METHOD Use METHOD to detect holes in sparse files. This option implies --sparse. Valid values for METHOD are seek and raw. Default is seek with fallback to raw when not applicable. -G, --incremental Handle old GNU-format incremental backups. --ignore-failed-read Do not exit with nonzero on unreadable files. --level=NUMBER Set dump level for a created listed-incremental archive. Currently only --level=0 is meaningful: it instructs tar to truncate the snapshot file before dumping, thereby forcing a level 0 dump. -n, --seek Assume the archive is seekable. Normally tar determines automatically whether the archive can be seeked or not. This option is intended for use in cases when such recognition fails. It takes effect only if the archive is open for reading (e.g. with --list or --extract options). --no-check-device Do not check device numbers when creating incremental archives. --no-seek Assume the archive is not seekable. --occurrence[=N] Process only the Nth occurrence of each file in the archive. This option is valid only when used with one of the following subcommands: --delete, --diff, --extract or --list and when a list of files is given either on the command line or via the -T option. The default N is 1. --restrict Disable the use of some potentially harmful options. --sparse-version=MAJOR[.MINOR] Set which version of the sparse format to use. This option implies --sparse. Valid argument values are 0.0, 0.1, and 1.0. For a detailed discussion of sparse formats, refer to the GNU Tar Manual, appendix D, "Sparse Formats". Using the info reader, it can be accessed running the following command: info tar 'Sparse Formats'. -S, --sparse Handle sparse files efficiently. Some files in the file system may have segments which were actually never written (quite often these are database files created by such systems as DBM). When given this option, tar attempts to determine if the file is sparse prior to archiving it, and if so, to reduce the resulting archive size by not dumping empty parts of the file. Overwrite control These options control tar actions when extracting a file over an existing copy on disk. -k, --keep-old-files Don't replace existing files when extracting. --keep-newer-files Don't replace existing files that are newer than their archive copies. --keep-directory-symlink Don't replace existing symlinks to directories when extracting. --no-overwrite-dir Preserve metadata of existing directories. --one-top-level[=DIR] Extract all files into DIR, or, if used without argument, into a subdirectory named by the base name of the archive (minus standard compression suffixes recognizable by --auto-compress). --overwrite Overwrite existing files when extracting. --overwrite-dir Overwrite metadata of existing directories when extracting (default). --recursive-unlink Recursively remove all files in the directory prior to extracting it. --remove-files Remove files from disk after adding them to the archive. --skip-old-files Don't replace existing files when extracting, silently skip over them. -U, --unlink-first Remove each file prior to extracting over it. -W, --verify Verify the archive after writing it. Output stream selection --ignore-command-error Ignore subprocess exit codes. --no-ignore-command-error Treat non-zero exit codes of children as error (default). -O, --to-stdout Extract files to standard output. --to-command=COMMAND Pipe extracted files to COMMAND. The argument is the pathname of an external program, optionally with command line arguments. The program will be invoked and the contents of the file being extracted supplied to it on its standard input. Additional data will be supplied via the following environment variables: TAR_FILETYPE Type of the file. It is a single letter with the following meaning: f Regular file d Directory l Symbolic link h Hard link b Block device c Character device Currently only regular files are supported. TAR_MODE File mode, an octal number. TAR_FILENAME The name of the file. TAR_REALNAME Name of the file as stored in the archive. TAR_UNAME Name of the file owner. TAR_GNAME Name of the file owner group. TAR_ATIME Time of last access. It is a decimal number, representing seconds since the Epoch. If the archive provides times with nanosecond precision, the nanoseconds are appended to the timestamp after a decimal point. TAR_MTIME Time of last modification. TAR_CTIME Time of last status change. TAR_SIZE Size of the file. TAR_UID UID of the file owner. TAR_GID GID of the file owner. Additionally, the following variables contain information about tar operation mode and the archive being processed: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. Handling of file attributes --atime-preserve[=METHOD] Preserve access times on dumped files, either by restoring the times after reading (METHOD=replace, this is the default) or by not setting the times in the first place (METHOD=system). --delay-directory-restore Delay setting modification times and permissions of extracted directories until the end of extraction. Use this option when extracting from an archive which has unusual member ordering. --group=NAME[:GID] Force NAME as group for added files. If GID is not supplied, NAME can be either a user name or numeric GID. In this case the missing part (GID or name) will be inferred from the current host's group database. When used with --group-map=FILE, affects only those files whose owner group is not listed in FILE. --group-map=FILE Read group translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single group. It must consist of two fields, delimited by any amount of whitespace: OLDGRP NEWGRP[:NEWGID] OLDGRP is either a valid group name or a GID prefixed with +. Unless NEWGID is supplied, NEWGRP must also be either a valid group name or a +GID. Otherwise, both NEWGRP and NEWGID need not be listed in the system group database. As a result, each input file with owner group OLDGRP will be stored in archive with owner group NEWGRP and GID NEWGID. --mode=CHANGES Force symbolic mode CHANGES for added files. --mtime=DATE-OR-FILE Set mtime for added files. DATE-OR-FILE is either a date/time in almost arbitrary format, or the name of an existing file. In the latter case the mtime of that file will be used. -m, --touch Don't extract file modified time. --no-delay-directory-restore Cancel the effect of the prior --delay-directory-restore option. --no-same-owner Extract files as yourself (default for ordinary users). --no-same-permissions Apply the user's umask when extracting permissions from the archive (default for ordinary users). --numeric-owner Always use numbers for user/group names. --owner=NAME[:UID] Force NAME as owner for added files. If UID is not supplied, NAME can be either a user name or numeric UID. In this case the missing part (UID or name) will be inferred from the current host's user database. When used with --owner-map=FILE, affects only those files whose owner is not listed in FILE. --owner-map=FILE Read owner translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single UID. It must consist of two fields, delimited by any amount of whitespace: OLDUSR NEWUSR[:NEWUID] OLDUSR is either a valid user name or a UID prefixed with +. Unless NEWUID is supplied, NEWUSR must also be either a valid user name or a +UID. Otherwise, both NEWUSR and NEWUID need not be listed in the system user database. As a result, each input file owned by OLDUSR will be stored in archive with owner name NEWUSR and UID NEWUID. -p, --preserve-permissions, --same-permissions Set permissions of extracted files to those recorded in the archive (default for superuser). --same-owner Try extracting files with the same ownership as exists in the archive (default for superuser). -s, --preserve-order, --same-order Tell tar that the list of file names to process is sorted in the same order as the files in the archive. --sort=ORDER When creating an archive, sort directory entries according to ORDER, which is one of none, name, or inode. The default is --sort=none, which stores archive members in the same order as returned by the operating system. Using --sort=name ensures the member ordering in the created archive is uniform and reproducible. Using --sort=inode reduces the number of disk seeks made when creating the archive and thus can considerably speed up archivation. This sorting order is supported only if the underlying system provides the necessary information. Extended file attributes --acls Enable POSIX ACLs support. --no-acls Disable POSIX ACLs support. --selinux Enable SELinux context support. --no-selinux Disable SELinux context support. --xattrs Enable extended attributes support. --no-xattrs Disable extended attributes support. --xattrs-exclude=PATTERN Specify the exclude pattern for xattr keys. PATTERN is a globbing pattern, e.g. --xattrs-exclude='user.*' to include only attributes from the user namespace. --xattrs-include=PATTERN Specify the include pattern for xattr keys. PATTERN is a globbing pattern. Device selection and switching -f, --file=ARCHIVE Use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable `TAPE'. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default. The default value can be inspected either using the --show-defaults option, or at the end of the tar --help output. An archive name that has a colon in it specifies a file or device on a remote machine. The part before the colon is taken as the machine name or IP address, and the part after it as the file or device pathname, e.g.: --file=remotehost:/dev/sr0 An optional username can be prefixed to the hostname, placing a @ sign between them. By default, the remote host is accessed via the rsh(1) command. Nowadays it is common to use ssh(1) instead. You can do so by giving the following command line option: --rsh-command=/usr/bin/ssh The remote machine should have the rmt(8) command installed. If its pathname does not match tar's default, you can inform tar about the correct pathname using the --rmt-command option. --force-local Archive file is local even if it has a colon. -F, --info-script=COMMAND, --new-volume-script=COMMAND Run COMMAND at the end of each tape (implies -M). The command can include arguments. When started, it will inherit tar's environment plus the following variables: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. TAR_FD File descriptor which can be used to communicate the new volume name to tar. If the info script fails, tar exits; otherwise, it begins writing the next volume. -L, --tape-length=N Change tape after writing Nx1024 bytes. If N is followed by a size suffix (see the subsection Size suffixes below), the suffix specifies the multiplicative factor to be used instead of 1024. This option implies -M. -M, --multi-volume Create/list/extract multi-volume archive. --rmt-command=COMMAND Use COMMAND instead of rmt when accessing remote archives. See the description of the -f option, above. --rsh-command=COMMAND Use COMMAND instead of rsh when accessing remote archives. See the description of the -f option, above. --volno-file=FILE When this option is used in conjunction with --multi-volume, tar will keep track of which volume of a multi-volume archive it is working in FILE. Device blocking -b, --blocking-factor=BLOCKS Set record size to BLOCKSx512 bytes. -B, --read-full-records When listing or extracting, accept incomplete input records after end-of-file marker. -i, --ignore-zeros Ignore zeroed blocks in archive. Normally two consecutive 512-blocks filled with zeroes mean EOF and tar stops reading after encountering them. This option instructs it to read further and is useful when reading archives created with the -A option. --record-size=NUMBER Set record size. NUMBER is the number of bytes per record. It must be multiple of 512. It can can be suffixed with a size suffix, e.g. --record-size=10K, for 10 Kilobytes. See the subsection Size suffixes, for a list of valid suffixes. Archive format selection -H, --format=FORMAT Create archive of the given format. Valid formats are: gnu GNU tar 1.13.x format oldgnu GNU format as per tar <= 1.12. pax, posix POSIX 1003.1-2001 (pax) format. ustar POSIX 1003.1-1988 (ustar) format. v7 Old V7 tar format. --old-archive, --portability Same as --format=v7. --pax-option=keyword[[:]=value][,keyword[[:]=value]]... Control pax keywords when creating PAX archives (-H pax). This option is equivalent to the -o option of the pax(1) utility. --posix Same as --format=posix. -V, --label=TEXT Create archive with volume name TEXT. If listing or extracting, use TEXT as a globbing pattern for volume name. Compression options -a, --auto-compress Use archive suffix to determine the compression program. -I, --use-compress-program=COMMAND Filter data through COMMAND. It must accept the -d option, for decompression. The argument can contain command line options. -j, --bzip2 Filter the archive through bzip2(1). -J, --xz Filter the archive through xz(1). --lzip Filter the archive through lzip(1). --lzma Filter the archive through lzma(1). --lzop Filter the archive through lzop(1). --no-auto-compress Do not use archive suffix to determine the compression program. -z, --gzip, --gunzip, --ungzip Filter the archive through gzip(1). -Z, --compress, --uncompress Filter the archive through compress(1). --zstd Filter the archive through zstd(1). Local file selection --add-file=FILE Add FILE to the archive (useful if its name starts with a dash). --backup[=CONTROL] Backup before removal. The CONTROL argument, if supplied, controls the backup policy. Its valid values are: none, off Never make backups. t, numbered Make numbered backups. nil, existing Make numbered backups if numbered backups exist, simple backups otherwise. never, simple Always make simple backups If CONTROL is not given, the value is taken from the VERSION_CONTROL environment variable. If it is not set, existing is assumed. -C, --directory=DIR Change to DIR before performing any operations. This option is order-sensitive, i.e. it affects all options that follow. --exclude=PATTERN Exclude files matching PATTERN, a glob(3)-style wildcard pattern. --exclude-backups Exclude backup and lock files. --exclude-caches Exclude contents of directories containing file CACHEDIR.TAG, except for the tag file itself. --exclude-caches-all Exclude directories containing file CACHEDIR.TAG and the file itself. --exclude-caches-under Exclude everything under directories containing CACHEDIR.TAG --exclude-ignore=FILE Before dumping a directory, see if it contains FILE. If so, read exclusion patterns from this file. The patterns affect only the directory itself. --exclude-ignore-recursive=FILE Same as --exclude-ignore, except that patterns from FILE affect both the directory and all its subdirectories. --exclude-tag=FILE Exclude contents of directories containing FILE, except for FILE itself. --exclude-tag-all=FILE Exclude directories containing FILE. --exclude-tag-under=FILE Exclude everything under directories containing FILE. --exclude-vcs Exclude version control system directories. --exclude-vcs-ignores Exclude files that match patterns read from VCS-specific ignore files. Supported files are: .cvsignore, .gitignore, .bzrignore, and .hgignore. -h, --dereference Follow symlinks; archive and dump the files they point to. --hard-dereference Follow hard links; archive and dump the files they refer to. -K, --starting-file=MEMBER Begin at the given member in the archive. --newer-mtime=DATE Work on files whose data changed after the DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --no-null Disable the effect of the previous --null option. --no-recursion Avoid descending automatically in directories. --no-unquote Do not unquote input file or member names. --no-verbatim-files-from Treat each line read from a file list as if it were supplied in the command line. I.e., leading and trailing whitespace is removed and, if the resulting string begins with a dash, it is treated as tar command line option. This is the default behavior. The --no-verbatim-files-from option is provided as a way to restore it after --verbatim-files-from option. This option is positional: it affects all --files-from options that occur after it in, until --verbatim-files-from option or end of line, whichever occurs first. It is implied by the --no-null option. --null Instruct subsequent -T options to read null-terminated names verbatim (disables special handling of names that start with a dash). See also --verbatim-files-from. -N, --newer=DATE, --after-date=DATE Only store files newer than DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --one-file-system Stay in local file system when creating archive. -P, --absolute-names Don't strip leading slashes from file names when creating archives. --recursion Recurse into directories (default). --suffix=STRING Backup before removal, override usual suffix. Default suffix is ~, unless overridden by environment variable SIMPLE_BACKUP_SUFFIX. -T, --files-from=FILE Get names to extract or create from FILE. Unless specified otherwise, the FILE must contain a list of names separated by ASCII LF (i.e. one name per line). The names read are handled the same way as command line arguments. They undergo quote removal and word splitting, and any string that starts with a - is handled as tar command line option. If this behavior is undesirable, it can be turned off using the --verbatim-files-from option. The --null option instructs tar that the names in FILE are separated by ASCII NUL character, instead of LF. It is useful if the list is generated by find(1) -print0 predicate. --unquote Unquote file or member names (default). --verbatim-files-from Treat each line obtained from a file list as a file name, even if it starts with a dash. File lists are supplied with the --files-from (-T) option. The default behavior is to handle names supplied in file lists as if they were typed in the command line, i.e. any names starting with a dash are treated as tar options. The --verbatim-files-from option disables this behavior. This option affects all --files-from options that occur after it in the command line. Its effect is reverted by the --no-verbatim-files-from option. This option is implied by the --null option. See also --add-file. -X, --exclude-from=FILE Exclude files matching patterns listed in FILE. File name transformations --strip-components=NUMBER Strip NUMBER leading components from file names on extraction. --transform=EXPRESSION, --xform=EXPRESSION Use sed replace EXPRESSION to transform file names. File name matching options These options affect both exclude and include patterns. --anchored Patterns match file name start. --ignore-case Ignore case. --no-anchored Patterns match after any / (default for exclusion). --no-ignore-case Case sensitive matching (default). --no-wildcards Verbatim string matching. --no-wildcards-match-slash Wildcards do not match /. --wildcards Use wildcards (default for exclusion). --wildcards-match-slash Wildcards match / (default for exclusion). Informative output --checkpoint[=N] Display progress messages every Nth record (default 10). --checkpoint-action=ACTION Run ACTION on each checkpoint. --clamp-mtime Only set time when the file is more recent than what was given with --mtime. --full-time Print file time to its full resolution. --index-file=FILE Send verbose output to FILE. -l, --check-links Print a message if not all links are dumped. --no-quote-chars=STRING Disable quoting for characters from STRING. --quote-chars=STRING Additionally quote characters from STRING. --quoting-style=STYLE Set quoting style for file and member names. Valid values for STYLE are literal, shell, shell-always, c, c-maybe, escape, locale, clocale. -R, --block-number Show block number within archive with each message. --show-omitted-dirs When listing or extracting, list each directory that does not match search criteria. --show-transformed-names, --show-stored-names Show file or archive names after transformation by --strip and --transform options. --totals[=SIGNAL] Print total bytes after processing the archive. If SIGNAL is given, print total bytes when this signal is delivered. Allowed signals are: SIGHUP, SIGQUIT, SIGINT, SIGUSR1, and SIGUSR2. The SIG prefix can be omitted. --utc Print file modification times in UTC. -v, --verbose Verbosely list files processed. Each instance of this option on the command line increases the verbosity level by one. The maximum verbosity level is 3. For a detailed discussion of how various verbosity levels affect tar's output, please refer to GNU Tar Manual, subsection 2.5.2 "The '--verbose' Option". --warning=KEYWORD Enable or disable warning messages identified by KEYWORD. The messages are suppressed if KEYWORD is prefixed with no- and enabled otherwise. Multiple --warning options accumulate. Keywords controlling general tar operation: all Enable all warning messages. This is the default. none Disable all warning messages. filename-with-nuls "%s: file name read contains nul character" alone-zero-block "A lone zero block at %s" Keywords applicable for tar --create: cachedir "%s: contains a cache directory tag %s; %s" file-shrank "%s: File shrank by %s bytes; padding with zeros" xdev "%s: file is on a different filesystem; not dumped" file-ignored "%s: Unknown file type; file ignored" "%s: socket ignored" "%s: door ignored" file-unchanged "%s: file is unchanged; not dumped" ignore-archive "%s: archive cannot contain itself; not dumped" file-removed "%s: File removed before we read it" file-changed "%s: file changed as we read it" failed-read Suppresses warnings about unreadable files or directories. This keyword applies only if used together with the --ignore-failed-read option. Keywords applicable for tar --extract: existing-file "%s: skipping existing file" timestamp "%s: implausibly old time stamp %s" "%s: time stamp %s is %s s in the future" contiguous-cast "Extracting contiguous files as regular files" symlink-cast "Attempting extraction of symbolic links as hard links" unknown-cast "%s: Unknown file type '%c', extracted as normal file" ignore-newer "Current %s is newer or same age" unknown-keyword "Ignoring unknown extended header keyword '%s'" decompress-program Controls verbose description of failures occurring when trying to run alternative decompressor programs. This warning is disabled by default (unless --verbose is used). A common example of what you can get when using this warning is: $ tar --warning=decompress-program -x -f archive.Z tar (child): cannot run compress: No such file or directory tar (child): trying gzip This means that tar first tried to decompress archive.Z using compress, and, when that failed, switched to gzip. record-size "Record size = %lu blocks" Keywords controlling incremental extraction: rename-directory "%s: Directory has been renamed from %s" "%s: Directory has been renamed" new-directory "%s: Directory is new" xdev "%s: directory is on a different device: not purging" bad-dumpdir "Malformed dumpdir: 'X' never used" -w, --interactive, --confirmation Ask for confirmation for every action. Compatibility options -o When creating, same as --old-archive. When extracting, same as --no-same-owner. Size suffixes Suffix Units Byte Equivalent b Blocks SIZE x 512 B Kilobytes SIZE x 1024 c Bytes SIZE G Gigabytes SIZE x 1024^3 K Kilobytes SIZE x 1024 k Kilobytes SIZE x 1024 M Megabytes SIZE x 1024^2 P Petabytes SIZE x 1024^5 T Terabytes SIZE x 1024^4 w Words SIZE x 2 RETURN VALUE top Tar's exit code indicates whether it was able to successfully perform the requested operation, and if not, what kind of error occurred. 0 Successful termination. 1 Some files differ. If tar was invoked with the --compare (--diff, -d) command line option, this means that some files in the archive differ from their disk counterparts. If tar was given one of the --create, --append or --update options, this exit code means that some files were changed while being archived and so the resulting archive does not contain the exact copy of the file set. 2 Fatal error. This means that some fatal, unrecoverable error occurred. If a subprocess that had been invoked by tar exited with a nonzero exit code, tar itself exits with that code as well. This can happen, for example, if a compression option (e.g. -z) was used and the external compressor program failed. Another example is rmt failure during backup to a remote device. SEE ALSO top bzip2(1), compress(1), gzip(1), lzma(1), lzop(1), rmt(8), symlink(7), xz(1), zstd(1). Complete tar manual: run info tar or use emacs(1) info mode to read it. Online copies of GNU tar documentation in various formats can be found at: https://www.gnu.org/software/tar/manual BUG REPORTS top Report bugs to <bug-tar@gnu.org>. COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. COLOPHON top This page is part of the tar (an archiver program) project. Information about the project can be found at http://savannah.gnu.org/projects/tar/. If you have a bug report for this manual page, see http://savannah.gnu.org/bugs/?group=tar. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/tar.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-09-12.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org TAR July 11, 2022 TAR(1) Pages that refer to this page: attr(1), dpkg-deb(1), dpkg-source(1), machinectl(1), rsync(1), st(4), suffixes(7), symlink(7), cupsd-helper(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. xargs(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training xargs(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | EXIT STATUS | STANDARDS CONFORMANCE | HISTORY | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON XARGS(1) General Commands Manual XARGS(1) NAME top xargs - build and execute command lines from standard input SYNOPSIS top xargs [options] [command [initial-arguments]] DESCRIPTION top This manual page documents the GNU version of xargs. xargs reads items from the standard input, delimited by blanks (which can be protected with double or single quotes or a backslash) or newlines, and executes the command (default is echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored. The command line for command is built up until it reaches a system-defined limit (unless the -n and -L options are used). The specified command will be invoked as many times as necessary to use up the list of input items. In general, there will be many fewer invocations of command than there were items in the input. This will normally have significant performance benefits. Some commands can usefully be executed in parallel too; see the -P option. Because Unix filenames can contain blanks and newlines, this default behaviour is often problematic; filenames containing blanks and/or newlines are incorrectly processed by xargs. In these situations it is better to use the -0 option, which prevents such problems. When using this option you will need to ensure that the program which produces the input for xargs also uses a null character as a separator. If that program is GNU find for example, the -print0 option does this for you. If any invocation of the command exits with a status of 255, xargs will stop immediately without reading any further input. An error message is issued on stderr when this happens. OPTIONS top -0, --null Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally). Disables the end-of-file string, which is treated like any other argument. Useful when input items might contain white space, quote marks, or backslashes. The GNU find -print0 option produces input suitable for this mode. -a file, --arg-file=file Read items from file instead of standard input. If you use this option, stdin remains unchanged when commands are run. Otherwise, stdin is redirected from /dev/null. --delimiter=delim, -d delim Input items are terminated by the specified character. The specified delimiter may be a single character, a C- style character escape such as \n, or an octal or hexadecimal escape code. Octal and hexadecimal escape codes are understood as for the printf command. Multibyte characters are not supported. When processing the input, quotes and backslash are not special; every character in the input is taken literally. The -d option disables any end-of-file string, which is treated like any other argument. You can use this option when the input consists of simply newline-separated items, although it is almost always better to design your program to use --null where this is possible. -E eof-str Set the end-of-file string to eof-str. If the end-of-file string occurs as a line of input, the rest of the input is ignored. If neither -E nor -e is used, no end-of-file string is used. -e[eof-str], --eof[=eof-str] This option is a synonym for the -E option. Use -E instead, because it is POSIX compliant while this option is not. If eof-str is omitted, there is no end-of-file string. If neither -E nor -e is used, no end-of-file string is used. -I replace-str Replace occurrences of replace-str in the initial- arguments with names read from standard input. Also, unquoted blanks do not terminate input items; instead the separator is the newline character. Implies -x and -L 1. -i[replace-str], --replace[=replace-str] This option is a synonym for -Ireplace-str if replace-str is specified. If the replace-str argument is missing, the effect is the same as -I{}. The -i option is deprecated; use -I instead. -L max-lines Use at most max-lines nonblank input lines per command line. Trailing blanks cause an input line to be logically continued on the next input line. Implies -x. -l[max-lines], --max-lines[=max-lines] Synonym for the -L option. Unlike -L, the max-lines argument is optional. If max-lines is not specified, it defaults to one. The -l option is deprecated since the POSIX standard specifies -L instead. -n max-args, --max-args=max-args Use at most max-args arguments per command line. Fewer than max-args arguments will be used if the size (see the -s option) is exceeded, unless the -x option is given, in which case xargs will exit. -P max-procs, --max-procs=max-procs Run up to max-procs processes at a time; the default is 1. If max-procs is 0, xargs will run as many processes as possible at a time. Use the -n option or the -L option with -P; otherwise chances are that only one exec will be done. While xargs is running, you can send its process a SIGUSR1 signal to increase the number of commands to run simultaneously, or a SIGUSR2 to decrease the number. You cannot increase it above an implementation-defined limit (which is shown with --show-limits). You cannot decrease it below 1. xargs never terminates its commands; when asked to decrease, it merely waits for more than one existing command to terminate before starting another. Please note that it is up to the called processes to properly manage parallel access to shared resources. For example, if more than one of them tries to print to stdout, the output will be produced in an indeterminate order (and very likely mixed up) unless the processes collaborate in some way to prevent this. Using some kind of locking scheme is one way to prevent such problems. In general, using a locking scheme will help ensure correct output but reduce performance. If you don't want to tolerate the performance difference, simply arrange for each process to produce a separate output file (or otherwise use separate resources). -o, --open-tty Reopen stdin as /dev/tty in the child process before executing the command. This is useful if you want xargs to run an interactive application. -p, --interactive Prompt the user about whether to run each command line and read a line from the terminal. Only run the command line if the response starts with `y' or `Y'. Implies -t. --process-slot-var=name Set the environment variable name to a unique value in each running child process. Values are reused once child processes exit. This can be used in a rudimentary load distribution scheme, for example. -r, --no-run-if-empty If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there is no input. This option is a GNU extension. -s max-chars, --max-chars=max-chars Use at most max-chars characters per command line, including the command and initial-arguments and the terminating nulls at the ends of the argument strings. The largest allowed value is system-dependent, and is calculated as the argument length limit for exec, less the size of your environment, less 2048 bytes of headroom. If this value is more than 128 KiB, 128 KiB is used as the default value; otherwise, the default value is the maximum. 1 KiB is 1024 bytes. xargs automatically adapts to tighter constraints. --show-limits Display the limits on the command-line length which are imposed by the operating system, xargs' choice of buffer size and the -s option. Pipe the input from /dev/null (and perhaps specify --no-run-if-empty) if you don't want xargs to do anything. -t, --verbose Print the command line on the standard error output before executing it. -x, --exit Exit if the size (see the -s option) is exceeded. -- Delimit the option list. Later arguments, if any, are treated as operands even if they begin with -. For example, xargs -- --help runs the command --help (found in PATH) instead of printing the usage text, and xargs -- --mycommand runs the command --mycommand instead of rejecting this as unrecognized option. --help Print a summary of the options to xargs and exit. --version Print the version number of xargs and exit. The options --max-lines (-L, -l), --replace (-I, -i) and --max- args (-n) are mutually exclusive. If some of them are specified at the same time, then xargs will generally use the option specified last on the command line, i.e., it will reset the value of the offending option (given before) to its default value. Additionally, xargs will issue a warning diagnostic on stderr. The exception to this rule is that the special max-args value 1 ('-n1') is ignored after the --replace option and its aliases -I and -i, because it would not actually conflict. EXAMPLES top find /tmp -name core -type f -print | xargs /bin/rm -f Find files named core in or below the directory /tmp and delete them. Note that this will work incorrectly if there are any filenames containing newlines or spaces. find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing spaces or newlines are correctly handled. find /tmp -depth -name core -type f -delete Find files named core in or below the directory /tmp and delete them, but more efficiently than in the previous example (because we avoid the need to use fork(2) and exec(2) to launch rm and we don't need the extra xargs process). cut -d: -f1 < /etc/passwd | sort | xargs echo Generates a compact listing of all the users on the system. EXIT STATUS top xargs exits with the following status: 0 if it succeeds 123 if any invocation of the command exited with status 1125 124 if the command exited with status 255 125 if the command is killed by a signal 126 if the command cannot be run 127 if the command is not found 1 if some other error occurred. Exit codes greater than 128 are used by the shell to indicate that a program died due to a fatal signal. STANDARDS CONFORMANCE top As of GNU xargs version 4.2.9, the default behaviour of xargs is not to have a logical end-of-file marker. POSIX (IEEE Std 1003.1, 2004 Edition) allows this. The -l and -i options appear in the 1997 version of the POSIX standard, but do not appear in the 2004 version of the standard. Therefore you should use -L and -I instead, respectively. The -o option is an extension to the POSIX standard for better compatibility with BSD. The POSIX standard allows implementations to have a limit on the size of arguments to the exec functions. This limit could be as low as 4096 bytes including the size of the environment. For scripts to be portable, they must not rely on a larger value. However, I know of no implementation whose actual limit is that small. The --show-limits option can be used to discover the actual limits in force on the current system. HISTORY top The xargs program was invented by Herb Gellis at Bell Labs. See the Texinfo manual for findutils, Finding Files, for more information. BUGS top It is not possible for xargs to be used securely, since there will always be a time gap between the production of the list of input files and their use in the commands that xargs issues. If other users have access to the system, they can manipulate the filesystem during this time window to force the action of the commands xargs runs to apply to files that you didn't intend. For a more detailed discussion of this and related problems, please refer to the ``Security Considerations'' chapter in the findutils Texinfo documentation. The -execdir option of find can often be used as a more secure alternative. When you use the -I option, each line read from the input is buffered internally. This means that there is an upper limit on the length of input line that xargs will accept when used with the -I option. To work around this limitation, you can use the -s option to increase the amount of buffer space that xargs uses, and you can also use an extra invocation of xargs to ensure that very long lines do not occur. For example: somecommand | xargs -s 50000 echo | xargs -I '{}' -s 100000 rm '{}' Here, the first invocation of xargs has no input line length limit because it doesn't use the -i option. The second invocation of xargs does have such a limit, but we have ensured that it never encounters a line which is longer than it can handle. This is not an ideal solution. Instead, the -i option should not impose a line length limit, which is why this discussion appears in the BUGS section. The problem doesn't occur with the output of find(1) because it emits just one filename per line. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 19902023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top find(1), kill(1), locate(1), updatedb(1), fork(2), execvp(3), locatedb(5), signal(7) Full documentation <https://www.gnu.org/software/findutils/xargs> or available locally via: info xargs COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org XARGS(1) Pages that refer to this page: dpkg-name(1), find(1), grep(1), locate(1), updatedb(1), lsof(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a tar file containing all the files in ~/Library folder that contain spaces in their names Bash Command:<START>find ~/Library -name '* *' -print0 | xargs -0 tar rf blah.tar<END> |
Create a variable CDATE in the current shell that contains the date in '%Y-%m-%d %H:%M:%S' format , and a variable EPOCH that contains the seconds since epoch | source <(date +"CDATE='%Y-%m-%d %H:%M:%S' EPOCH='%s'") | ['date'] | Output a Bash command to accomplish the following task. Task: Create a variable CDATE in the current shell that contains the date in '%Y-%m-%d %H:%M:%S' format , and a variable EPOCH that contains the seconds since epoch Bash Command:<START>source <(date +"CDATE='%Y-%m-%d %H:%M:%S' EPOCH='%s'")<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # date\n\n> Set or display the system date.\n> More information: <https://www.gnu.org/software/coreutils/date>.\n\n- Display the current date using the default locale's format:\n\n`date +%c`\n\n- Display the current date in UTC, using the ISO 8601 format:\n\n`date -u +%Y-%m-%dT%H:%M:%S%Z`\n\n- Display the current date as a Unix timestamp (seconds since the Unix epoch):\n\n`date +%s`\n\n- Convert a date specified as a Unix timestamp to the default format:\n\n`date -d @{{1473305798}}`\n\n- Convert a given date to the Unix timestamp format:\n\n`date -d "{{2018-09-01 00:00}}" +%s --utc`\n\n- Display the current date using the RFC-3339 format (`YYYY-MM-DD hh:mm:ss TZ`):\n\n`date --rfc-3339=s`\n\n- Set the current date using the format `MMDDhhmmYYYY.ss` (`YYYY` and `.ss` are optional):\n\n`date {{093023592021.59}}`\n\n- Display the current ISO week number:\n\n`date +%V`\n Task: Create a variable CDATE in the current shell that contains the date in '%Y-%m-%d %H:%M:%S' format , and a variable EPOCH that contains the seconds since epoch Bash Command:<START>source <(date +"CDATE='%Y-%m-%d %H:%M:%S' EPOCH='%s'")<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: date(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training date(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON DATE(1) User Commands DATE(1) NAME top date - print or set the system date and time SYNOPSIS top date [OPTION]... [+FORMAT] date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]] DESCRIPTION top Display date and time in the given FORMAT. With -s, or with [MMDDhhmm[[CC]YY][.ss]], set the date and time. Mandatory arguments to long options are mandatory for short options too. -d, --date=STRING display time described by STRING, not 'now' --debug annotate the parsed date, and warn about questionable usage to stderr -f, --file=DATEFILE like --date; once for each line of DATEFILE -I[FMT], --iso-8601[=FMT] output date/time in ISO 8601 format. FMT='date' for date only (the default), 'hours', 'minutes', 'seconds', or 'ns' for date and time to the indicated precision. Example: 2006-08-14T02:34:56-06:00 --resolution output the available resolution of timestamps Example: 0.000000001 -R, --rfc-email output date and time in RFC 5322 format. Example: Mon, 14 Aug 2006 02:34:56 -0600 --rfc-3339=FMT output date/time in RFC 3339 format. FMT='date', 'seconds', or 'ns' for date and time to the indicated precision. Example: 2006-08-14 02:34:56-06:00 -r, --reference=FILE display the last modification time of FILE -s, --set=STRING set time described by STRING -u, --utc, --universal print or set Coordinated Universal Time (UTC) --help display this help and exit --version output version information and exit All options that specify the date to display are mutually exclusive. I.e.: --date, --file, --reference, --resolution. FORMAT controls the output. Interpreted sequences are: %% a literal % %a locale's abbreviated weekday name (e.g., Sun) %A locale's full weekday name (e.g., Sunday) %b locale's abbreviated month name (e.g., Jan) %B locale's full month name (e.g., January) %c locale's date and time (e.g., Thu Mar 3 23:05:25 2005) %C century; like %Y, except omit last two digits (e.g., 20) %d day of month (e.g., 01) %D date; same as %m/%d/%y %e day of month, space padded; same as %_d %F full date; like %+4Y-%m-%d %g last two digits of year of ISO week number (see %G) %G year of ISO week number (see %V); normally useful only with %V %h same as %b %H hour (00..23) %I hour (01..12) %j day of year (001..366) %k hour, space padded ( 0..23); same as %_H %l hour, space padded ( 1..12); same as %_I %m month (01..12) %M minute (00..59) %n a newline %N nanoseconds (000000000..999999999) %p locale's equivalent of either AM or PM; blank if not known %P like %p, but lower case %q quarter of year (1..4) %r locale's 12-hour clock time (e.g., 11:11:04 PM) %R 24-hour hour and minute; same as %H:%M %s seconds since the Epoch (1970-01-01 00:00 UTC) %S second (00..60) %t a tab %T time; same as %H:%M:%S %u day of week (1..7); 1 is Monday %U week number of year, with Sunday as first day of week (00..53) %V ISO week number, with Monday as first day of week (01..53) %w day of week (0..6); 0 is Sunday %W week number of year, with Monday as first day of week (00..53) %x locale's date representation (e.g., 12/31/99) %X locale's time representation (e.g., 23:13:48) %y last two digits of year (00..99) %Y year %z +hhmm numeric time zone (e.g., -0400) %:z +hh:mm numeric time zone (e.g., -04:00) %::z +hh:mm:ss numeric time zone (e.g., -04:00:00) %:::z numeric time zone with : to necessary precision (e.g., -04, +05:30) %Z alphabetic time zone abbreviation (e.g., EDT) By default, date pads numeric fields with zeroes. The following optional flags may follow '%': - (hyphen) do not pad the field _ (underscore) pad with spaces 0 (zero) pad with zeros + pad with zeros, and put '+' before future years with >4 digits ^ use upper case if possible # use opposite case if possible After any flags comes an optional field width, as a decimal number; then an optional modifier, which is either E to use the locale's alternate representations if available, or O to use the locale's alternate numeric symbols if available. EXAMPLES top Convert seconds since the Epoch (1970-01-01 UTC) to a date $ date --date='@2147483647' Show the time on the west coast of the US (use tzselect(1) to find TZ) $ TZ='America/Los_Angeles' date Show the local time for 9AM next Friday on the west coast of the US $ date --date='TZ="America/Los_Angeles" 09:00 next Fri' DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/date> or available locally via: info '(coreutils) date invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 DATE(1) Pages that refer to this page: cronnext(1), dir(1), gawk(1), locale(1), ls(1), pmdashping(1), pmdate(1), timedatectl(1), vdir(1), clock_getres(2), gettimeofday(2), stime(2), time(2), ctime(3), difftime(3), posix_spawn(3), strftime(3), tzset(3), rtc(4), crontab(5), locale(5), utmp(5), lvmreport(7), time(7), hwclock(8), rtcwake(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create a variable CDATE in the current shell that contains the date in '%Y-%m-%d %H:%M:%S' format , and a variable EPOCH that contains the seconds since epoch Bash Command:<START>source <(date +"CDATE='%Y-%m-%d %H:%M:%S' EPOCH='%s'")<END> |
Create all directories in the path specified by variable $javaUsrLib as super user | sudo mkdir -p $javaUsrLib | ['mkdir', 'sudo'] | Output a Bash command to accomplish the following task. Task: Create all directories in the path specified by variable $javaUsrLib as super user Bash Command:<START>sudo mkdir -p $javaUsrLib<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n # sudo\n\n> Executes a single command as the superuser or another user.\n> More information: <https://www.sudo.ws/sudo.html>.\n\n- Run a command as the superuser:\n\n`sudo {{less /var/log/syslog}}`\n\n- Edit a file as the superuser with your default editor:\n\n`sudo --edit {{/etc/fstab}}`\n\n- Run a command as another user and/or group:\n\n`sudo --user={{user}} --group={{group}} {{id -a}}`\n\n- Repeat the last command prefixed with `sudo` (only in Bash, Zsh, etc.):\n\n`sudo !!`\n\n- Launch the default shell with superuser privileges and run login-specific files (`.profile`, `.bash_profile`, etc.):\n\n`sudo --login`\n\n- Launch the default shell with superuser privileges without changing the environment:\n\n`sudo --shell`\n\n- Launch the default shell as the specified user, loading the user's environment and reading login-specific files (`.profile`, `.bash_profile`, etc.):\n\n`sudo --login --user={{user}}`\n\n- List the allowed (and forbidden) commands for the invoking user:\n\n`sudo --list`\n Task: Create all directories in the path specified by variable $javaUsrLib as super user Bash Command:<START>sudo mkdir -p $javaUsrLib<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. sudo(8) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training sudo(8) Linux manual page NAME | SYNOPSIS | DESCRIPTION | COMMAND EXECUTION | EXIT VALUE | SECURITY NOTES | ENVIRONMENT | FILES | EXAMPLES | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHORS | CAVEATS | BUGS | SUPPORT | DISCLAIMER | COLOPHON SUDO(8) System Manager's Manual SUDO(8) NAME top sudo, sudoedit execute a command as another user SYNOPSIS top sudo -h | -K | -k | -V sudo -v [-ABkNnS] [-g group] [-h host] [-p prompt] [-u user] sudo -l [-ABkNnS] [-g group] [-h host] [-p prompt] [-U user] [-u user] [command [arg ...]] sudo [-ABbEHnPS] [-C num] [-D directory] [-g group] [-h host] [-p prompt] [-R directory] [-T timeout] [-u user] [VAR=value] [-i | -s] [command [arg ...]] sudoedit [-ABkNnS] [-C num] [-D directory] [-g group] [-h host] [-p prompt] [-R directory] [-T timeout] [-u user] file ... DESCRIPTION top allows a permitted user to execute a command as the superuser or another user, as specified by the security policy. The invoking user's real (not effective) user-ID is used to determine the user name with which to query the security policy. supports a plugin architecture for security policies, auditing, and input/output logging. Third parties can develop and distribute their own plugins to work seamlessly with the front- end. The default security policy is sudoers, which is configured via the file /etc/sudoers, or via LDAP. See the Plugins section for more information. The security policy determines what privileges, if any, a user has to run . The policy may require that users authenticate themselves with a password or another authentication mechanism. If authentication is required, will exit if the user's password is not entered within a configurable time limit. This limit is policy-specific; the default password prompt timeout for the sudoers security policy is 5 minutes. Security policies may support credential caching to allow the user to run again for a period of time without requiring authentication. By default, the sudoers policy caches credentials on a per-terminal basis for 5 minutes. See the timestamp_type and timestamp_timeout options in sudoers(5) for more information. By running with the -v option, a user can update the cached credentials without running a command. On systems where is the primary method of gaining superuser privileges, it is imperative to avoid syntax errors in the security policy configuration files. For the default security policy, sudoers(5), changes to the configuration files should be made using the visudo(8) utility which will ensure that no syntax errors are introduced. When invoked as sudoedit, the -e option (described below), is implied. Security policies and audit plugins may log successful and failed attempts to run . If an I/O plugin is configured, the running command's input and output may be logged as well. The options are as follows: -A, --askpass Normally, if requires a password, it will read it from the user's terminal. If the -A (askpass) option is specified, a (possibly graphical) helper program is executed to read the user's password and output the password to the standard output. If the SUDO_ASKPASS environment variable is set, it specifies the path to the helper program. Otherwise, if sudo.conf(5) contains a line specifying the askpass program, that value will be used. For example: # Path to askpass helper program Path askpass /usr/X11R6/bin/ssh-askpass If no askpass program is available, will exit with an error. -B, --bell Ring the bell as part of the password prompt when a terminal is present. This option has no effect if an askpass program is used. -b, --background Run the given command in the background. It is not possible to use shell job control to manipulate background processes started by . Most interactive commands will fail to work properly in background mode. -C num, --close-from=num Close all file descriptors greater than or equal to num before executing a command. Values less than three are not permitted. By default, will close all open file descriptors other than standard input, standard output, and standard error when executing a command. The security policy may restrict the user's ability to use this option. The sudoers policy only permits use of the -C option when the administrator has enabled the closefrom_override option. -D directory, --chdir=directory Run the command in the specified directory instead of the current working directory. The security policy may return an error if the user does not have permission to specify the working directory. -E, --preserve-env Indicates to the security policy that the user wishes to preserve their existing environment variables. The security policy may return an error if the user does not have permission to preserve the environment. --preserve-env=list Indicates to the security policy that the user wishes to add the comma-separated list of environment variables to those preserved from the user's environment. The security policy may return an error if the user does not have permission to preserve the environment. This option may be specified multiple times. -e, --edit Edit one or more files instead of running a command. In lieu of a path name, the string "sudoedit" is used when consulting the security policy. If the user is authorized by the policy, the following steps are taken: 1. Temporary copies are made of the files to be edited with the owner set to the invoking user. 2. The editor specified by the policy is run to edit the temporary files. The sudoers policy uses the SUDO_EDITOR, VISUAL and EDITOR environment variables (in that order). If none of SUDO_EDITOR, VISUAL or EDITOR are set, the first program listed in the editor sudoers(5) option is used. 3. If they have been modified, the temporary files are copied back to their original location and the temporary versions are removed. To help prevent the editing of unauthorized files, the following restrictions are enforced unless explicitly allowed by the security policy: Symbolic links may not be edited (version 1.8.15 and higher). Symbolic links along the path to be edited are not followed when the parent directory is writable by the invoking user unless that user is root (version 1.8.16 and higher). Files located in a directory that is writable by the invoking user may not be edited unless that user is root (version 1.8.16 and higher). Users are never allowed to edit device special files. If the specified file does not exist, it will be created. Unlike most commands run by sudo, the editor is run with the invoking user's environment unmodified. If the temporary file becomes empty after editing, the user will be prompted before it is installed. If, for some reason, is unable to update a file with its edited version, the user will receive a warning and the edited copy will remain in a temporary file. -g group, --group=group Run the command with the primary group set to group instead of the primary group specified by the target user's password database entry. The group may be either a group name or a numeric group-ID (GID) prefixed with the # character (e.g., #0 for GID 0). When running a command as a GID, many shells require that the # be escaped with a backslash (\). If no -u option is specified, the command will be run as the invoking user. In either case, the primary group will be set to group. The sudoers policy permits any of the target user's groups to be specified via the -g option as long as the -P option is not in use. -H, --set-home Request that the security policy set the HOME environment variable to the home directory specified by the target user's password database entry. Depending on the policy, this may be the default behavior. -h, --help Display a short help message to the standard output and exit. -h host, --host=host Run the command on the specified host if the security policy plugin supports remote commands. The sudoers plugin does not currently support running remote commands. This may also be used in conjunction with the -l option to list a user's privileges for the remote host. -i, --login Run the shell specified by the target user's password database entry as a login shell. This means that login- specific resource files such as .profile, .bash_profile, or .login will be read by the shell. If a command is specified, it is passed to the shell as a simple command using the -c option. The command and any args are concatenated, separated by spaces, after escaping each character (including white space) with a backslash (\) except for alphanumerics, underscores, hyphens, and dollar signs. If no command is specified, an interactive shell is executed. attempts to change to that user's home directory before running the shell. The command is run with an environment similar to the one a user would receive at log in. Most shells behave differently when a command is specified as compared to an interactive session; consult the shell's manual for details. The Command environment section in the sudoers(5) manual documents how the -i option affects the environment in which a command is run when the sudoers policy is in use. -K, --remove-timestamp Similar to the -k option, except that it removes every cached credential for the user, regardless of the terminal or parent process ID. The next time is run, a password must be entered if the security policy requires authentication. It is not possible to use the -K option in conjunction with a command or other option. This option does not require a password. Not all security policies support credential caching. -k, --reset-timestamp When used without a command, invalidates the user's cached credentials for the current session. The next time is run in the session, a password must be entered if the security policy requires authentication. By default, the sudoers policy uses a separate record in the credential cache for each terminal (or parent process ID if no terminal is present). This prevents the -k option from interfering with commands run in a different terminal session. See the timestamp_type option in sudoers(5) for more information. This option does not require a password, and was added to allow a user to revoke permissions from a .logout file. When used in conjunction with a command or an option that may require a password, this option will cause to ignore the user's cached credentials. As a result, will prompt for a password (if one is required by the security policy) and will not update the user's cached credentials. Not all security policies support credential caching. -l, --list If no command is specified, list the privileges for the invoking user (or the user specified by the -U option) on the current host. A longer list format is used if this option is specified multiple times and the security policy supports a verbose output format. If a command is specified and is permitted by the security policy for the invoking user (or the, user specified by the -U option) on the current host, the fully-qualified path to the command is displayed along with any args. If -l is specified more than once (and the security policy supports it), the matching rule is displayed in a verbose format along with the command. If a command is specified but not allowed by the policy, will exit with a status value of 1. -N, --no-update Do not update the user's cached credentials, even if the user successfully authenticates. Unlike the -k flag, existing cached credentials are used if they are valid. To detect when the user's cached credentials are valid (or when no authentication is required), the following can be used: sudo -Nnv Not all security policies support credential caching. -n, --non-interactive Avoid prompting the user for input of any kind. If a password is required for the command to run, will display an error message and exit. -P, --preserve-groups Preserve the invoking user's group vector unaltered. By default, the sudoers policy will initialize the group vector to the list of groups the target user is a member of. The real and effective group-IDs, however, are still set to match the target user. -p prompt, --prompt=prompt Use a custom password prompt with optional escape sequences. The following percent (%) escape sequences are supported by the sudoers policy: %H expanded to the host name including the domain name (only if the machine's host name is fully qualified or the fqdn option is set in sudoers(5)) %h expanded to the local host name without the domain name %p expanded to the name of the user whose password is being requested (respects the rootpw, targetpw, and runaspw flags in sudoers(5)) %U expanded to the login name of the user the command will be run as (defaults to root unless the -u option is also specified) %u expanded to the invoking user's login name %% two consecutive % characters are collapsed into a single % character The custom prompt will override the default prompt specified by either the security policy or the SUDO_PROMPT environment variable. On systems that use PAM, the custom prompt will also override the prompt specified by a PAM module unless the passprompt_override flag is disabled in sudoers. -R directory, --chroot=directory Change to the specified root directory (see chroot(8)) before running the command. The security policy may return an error if the user does not have permission to specify the root directory. -S, --stdin Write the prompt to the standard error and read the password from the standard input instead of using the terminal device. -s, --shell Run the shell specified by the SHELL environment variable if it is set or the shell specified by the invoking user's password database entry. If a command is specified, it is passed to the shell as a simple command using the -c option. The command and any args are concatenated, separated by spaces, after escaping each character (including white space) with a backslash (\) except for alphanumerics, underscores, hyphens, and dollar signs. If no command is specified, an interactive shell is executed. Most shells behave differently when a command is specified as compared to an interactive session; consult the shell's manual for details. -U user, --other-user=user Used in conjunction with the -l option to list the privileges for user instead of for the invoking user. The security policy may restrict listing other users' privileges. When using the sudoers policy, the -U option is restricted to the root user and users with either the list priviege for the specified user or the ability to run any command as root or user on the current host. -T timeout, --command-timeout=timeout Used to set a timeout for the command. If the timeout expires before the command has exited, the command will be terminated. The security policy may restrict the user's ability to set timeouts. The sudoers policy requires that user-specified timeouts be explicitly enabled. -u user, --user=user Run the command as a user other than the default target user (usually root). The user may be either a user name or a numeric user-ID (UID) prefixed with the # character (e.g., #0 for UID 0). When running commands as a UID, many shells require that the # be escaped with a backslash (\). Some security policies may restrict UIDs to those listed in the password database. The sudoers policy allows UIDs that are not in the password database as long as the targetpw option is not set. Other security policies may not support this. -V, --version Print the version string as well as the version string of any configured plugins. If the invoking user is already root, the -V option will display the options passed to configure when was built; plugins may display additional information such as default options. -v, --validate Update the user's cached credentials, authenticating the user if necessary. For the sudoers plugin, this extends the timeout for another 5 minutes by default, but does not run a command. Not all security policies support cached credentials. -- The -- is used to delimit the end of the options. Subsequent options are passed to the command. Options that take a value may only be specified once unless otherwise indicated in the description. This is to help guard against problems caused by poorly written scripts that invoke sudo with user-controlled input. Environment variables to be set for the command may also be passed as options to in the form VAR=value, for example LD_LIBRARY_PATH=/usr/local/pkg/lib. Environment variables may be subject to restrictions imposed by the security policy plugin. The sudoers policy subjects environment variables passed as options to the same restrictions as existing environment variables with one important difference. If the setenv option is set in sudoers, the command to be run has the SETENV tag set or the command matched is ALL, the user may set variables that would otherwise be forbidden. See sudoers(5) for more information. COMMAND EXECUTION top When executes a command, the security policy specifies the execution environment for the command. Typically, the real and effective user and group and IDs are set to match those of the target user, as specified in the password database, and the group vector is initialized based on the group database (unless the -P option was specified). The following parameters may be specified by security policy: real and effective user-ID real and effective group-ID supplementary group-IDs the environment list current working directory file creation mode mask (umask) scheduling priority (aka nice value) Process model There are two distinct ways can run a command. If an I/O logging plugin is configured to log terminal I/O, or if the security policy explicitly requests it, a new pseudo-terminal (pty) is allocated and fork(2) is used to create a second process, referred to as the monitor. The monitor creates a new terminal session with itself as the leader and the pty as its controlling terminal, calls fork(2) again, sets up the execution environment as described above, and then uses the execve(2) system call to run the command in the child process. The monitor exists to relay job control signals between the user's terminal and the pty the command is being run in. This makes it possible to suspend and resume the command normally. Without the monitor, the command would be in what POSIX terms an orphaned process group and it would not receive any job control signals from the kernel. When the command exits or is terminated by a signal, the monitor passes the command's exit status to the main process and exits. After receiving the command's exit status, the main process passes the command's exit status to the security policy's close function, as well as the close function of any configured audit plugin, and exits. This mode is the default for sudo versions 1.9.14 and above when using the sudoers policy. If no pty is used, calls fork(2), sets up the execution environment as described above, and uses the execve(2) system call to run the command in the child process. The main process waits until the command has completed, then passes the command's exit status to the security policy's close function, as well as the close function of any configured audit plugins, and exits. As a special case, if the policy plugin does not define a close function, will execute the command directly instead of calling fork(2) first. The sudoers policy plugin will only define a close function when I/O logging is enabled, a pty is required, an SELinux role is specified, the command has an associated timeout, or the pam_session or pam_setcred options are enabled. Both pam_session and pam_setcred are enabled by default on systems using PAM. This mode is the default for sudo versions prior to 1.9.14 when using the sudoers policy. On systems that use PAM, the security policy's close function is responsible for closing the PAM session. It may also log the command's exit status. Signal handling When the command is run as a child of the process, will relay signals it receives to the command. The SIGINT and SIGQUIT signals are only relayed when the command is being run in a new pty or when the signal was sent by a user process, not the kernel. This prevents the command from receiving SIGINT twice each time the user enters control-C. Some signals, such as SIGSTOP and SIGKILL, cannot be caught and thus will not be relayed to the command. As a general rule, SIGTSTP should be used instead of SIGSTOP when you wish to suspend a command being run by . As a special case, will not relay signals that were sent by the command it is running. This prevents the command from accidentally killing itself. On some systems, the reboot(8) utility sends SIGTERM to all non-system processes other than itself before rebooting the system. This prevents from relaying the SIGTERM signal it received back to reboot(8), which might then exit before the system was actually rebooted, leaving it in a half-dead state similar to single user mode. Note, however, that this check only applies to the command run by and not any other processes that the command may create. As a result, running a script that calls reboot(8) or shutdown(8) via may cause the system to end up in this undefined state unless the reboot(8) or shutdown(8) are run using the exec() family of functions instead of system() (which interposes a shell between the command and the calling process). Plugins Plugins may be specified via Plugin directives in the sudo.conf(5) file. They may be loaded as dynamic shared objects (on systems that support them), or compiled directly into the binary. If no sudo.conf(5) file is present, or if it doesn't contain any Plugin lines, will use sudoers(5) for the policy, auditing, and I/O logging plugins. See the sudo.conf(5) manual for details of the /etc/sudo.conf file and the sudo_plugin(5) manual for more information about the plugin architecture. EXIT VALUE top Upon successful execution of a command, the exit status from will be the exit status of the program that was executed. If the command terminated due to receipt of a signal, will send itself the same signal that terminated the command. If the -l option was specified without a command, will exit with a value of 0 if the user is allowed to run and they authenticated successfully (as required by the security policy). If a command is specified with the -l option, the exit value will only be 0 if the command is permitted by the security policy, otherwise it will be 1. If there is an authentication failure, a configuration/permission problem, or if the given command cannot be executed, exits with a value of 1. In the latter case, the error string is printed to the standard error. If cannot stat(2) one or more entries in the user's PATH, an error is printed to the standard error. (If the directory does not exist or if it is not really a directory, the entry is ignored and no error is printed.) This should not happen under normal circumstances. The most common reason for stat(2) to return permission denied is if you are running an automounter and one of the directories in your PATH is on a machine that is currently unreachable. SECURITY NOTES top tries to be safe when executing external commands. To prevent command spoofing, checks "." and "" (both denoting current directory) last when searching for a command in the user's PATH (if one or both are in the PATH). Depending on the security policy, the user's PATH environment variable may be modified, replaced, or passed unchanged to the program that executes. Users should never be granted privileges to execute files that are writable by the user or that reside in a directory that is writable by the user. If the user can modify or replace the command there is no way to limit what additional commands they can run. By default, will only log the command it explicitly runs. If a user runs a command such as sudo su or sudo sh, subsequent commands run from that shell are not subject to sudo's security policy. The same is true for commands that offer shell escapes (including most editors). If I/O logging is enabled, subsequent commands will have their input and/or output logged, but there will not be traditional logs for those commands. Because of this, care must be taken when giving users access to commands via to verify that the command does not inadvertently give the user an effective root shell. For information on ways to address this, see the Preventing shell escapes section in sudoers(5). To prevent the disclosure of potentially sensitive information, disables core dumps by default while it is executing (they are re-enabled for the command that is run). This historical practice dates from a time when most operating systems allowed set-user-ID processes to dump core by default. To aid in debugging crashes, you may wish to re-enable core dumps by setting disable_coredump to false in the sudo.conf(5) file as follows: Set disable_coredump false See the sudo.conf(5) manual for more information. ENVIRONMENT top utilizes the following environment variables. The security policy has control over the actual content of the command's environment. EDITOR Default editor to use in -e (sudoedit) mode if neither SUDO_EDITOR nor VISUAL is set. MAIL Set to the mail spool of the target user when the -i option is specified, or when env_reset is enabled in sudoers (unless MAIL is present in the env_keep list). HOME Set to the home directory of the target user when the -i or -H options are specified, when the -s option is specified and set_home is set in sudoers, when always_set_home is enabled in sudoers, or when env_reset is enabled in sudoers and HOME is not present in the env_keep list. LOGNAME Set to the login name of the target user when the -i option is specified, when the set_logname option is enabled in sudoers, or when the env_reset option is enabled in sudoers (unless LOGNAME is present in the env_keep list). PATH May be overridden by the security policy. SHELL Used to determine shell to run with -s option. SUDO_ASKPASS Specifies the path to a helper program used to read the password if no terminal is available or if the -A option is specified. SUDO_COMMAND Set to the command run by sudo, including any args. The args are truncated at 4096 characters to prevent a potential execution error. SUDO_EDITOR Default editor to use in -e (sudoedit) mode. SUDO_GID Set to the group-ID of the user who invoked sudo. SUDO_PROMPT Used as the default password prompt unless the -p option was specified. SUDO_PS1 If set, PS1 will be set to its value for the program being run. SUDO_UID Set to the user-ID of the user who invoked sudo. SUDO_USER Set to the login name of the user who invoked sudo. USER Set to the same value as LOGNAME, described above. VISUAL Default editor to use in -e (sudoedit) mode if SUDO_EDITOR is not set. FILES top /etc/sudo.conf front-end configuration EXAMPLES top The following examples assume a properly configured security policy. To get a file listing of an unreadable directory: $ sudo ls /usr/local/protected To list the home directory of user yaz on a machine where the file system holding ~yaz is not exported as root: $ sudo -u yaz ls ~yaz To edit the index.html file as user www: $ sudoedit -u www ~www/htdocs/index.html To view system logs only accessible to root and users in the adm group: $ sudo -g adm more /var/log/syslog To run an editor as jim with a different primary group: $ sudoedit -u jim -g audio ~jim/sound.txt To shut down a machine: $ sudo shutdown -r +15 "quick reboot" To make a usage listing of the directories in the /home partition. The commands are run in a sub-shell to allow the cd command and file redirection to work. $ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE" DIAGNOSTICS top Error messages produced by include: editing files in a writable directory is not permitted By default, sudoedit does not permit editing a file when any of the parent directories are writable by the invoking user. This avoids a race condition that could allow the user to overwrite an arbitrary file. See the sudoedit_checkdir option in sudoers(5) for more information. editing symbolic links is not permitted By default, sudoedit does not follow symbolic links when opening files. See the sudoedit_follow option in sudoers(5) for more information. effective uid is not 0, is sudo installed setuid root? was not run with root privileges. The binary must be owned by the root user and have the set-user-ID bit set. Also, it must not be located on a file system mounted with the nosuid option or on an NFS file system that maps uid 0 to an unprivileged uid. effective uid is not 0, is sudo on a file system with the 'nosuid' option set or an NFS file system without root privileges? was not run with root privileges. The binary has the proper owner and permissions but it still did not run with root privileges. The most common reason for this is that the file system the binary is located on is mounted with the nosuid option or it is an NFS file system that maps uid 0 to an unprivileged uid. fatal error, unable to load plugins An error occurred while loading or initializing the plugins specified in sudo.conf(5). invalid environment variable name One or more environment variable names specified via the -E option contained an equal sign (=). The arguments to the -E option should be environment variable names without an associated value. no password was provided When tried to read the password, it did not receive any characters. This may happen if no terminal is available (or the -S option is specified) and the standard input has been redirected from /dev/null. a terminal is required to read the password needs to read the password but there is no mechanism available for it to do so. A terminal is not present to read the password from, has not been configured to read from the standard input, the -S option was not used, and no askpass helper has been specified either via the sudo.conf(5) file or the SUDO_ASKPASS environment variable. no writable temporary directory found sudoedit was unable to find a usable temporary directory in which to store its intermediate files. The no new privileges flag is set, which prevents sudo from running as root. was run by a process that has the Linux no new privileges flag is set. This causes the set-user-ID bit to be ignored when running an executable, which will prevent from functioning. The most likely cause for this is running within a container that sets this flag. Check the documentation to see if it is possible to configure the container such that the flag is not set. sudo must be owned by uid 0 and have the setuid bit set was not run with root privileges. The binary does not have the correct owner or permissions. It must be owned by the root user and have the set-user-ID bit set. sudoedit is not supported on this platform It is only possible to run sudoedit on systems that support setting the effective user-ID. timed out reading password The user did not enter a password before the password timeout (5 minutes by default) expired. you do not exist in the passwd database Your user-ID does not appear in the system passwd database. you may not specify environment variables in edit mode It is only possible to specify environment variables when running a command. When editing a file, the editor is run with the user's environment unmodified. SEE ALSO top su(1), stat(2), login_cap(3), passwd(5), sudo.conf(5), sudo_plugin(5), sudoers(5), sudoers_timestamp(5), sudoreplay(8), visudo(8) HISTORY top See the HISTORY.md file in the distribution (https://www.sudo.ws/about/history/) for a brief history of sudo. AUTHORS top Many people have worked on over the years; this version consists of code written primarily by: Todd C. Miller See the CONTRIBUTORS.md file in the distribution (https://www.sudo.ws/about/contributors/) for an exhaustive list of people who have contributed to . CAVEATS top There is no easy way to prevent a user from gaining a root shell if that user is allowed to run arbitrary commands via . Also, many programs (such as editors) allow the user to run commands via shell escapes, thus avoiding sudo's checks. However, on most systems it is possible to prevent shell escapes with the sudoers(5) plugin's noexec functionality. It is not meaningful to run the cd command directly via sudo, e.g., $ sudo cd /usr/local/protected since when the command exits the parent process (your shell) will still be the same. The -D option can be used to run a command in a specific directory. Running shell scripts via can expose the same kernel bugs that make set-user-ID shell scripts unsafe on some operating systems (if your OS has a /dev/fd/ directory, set-user-ID shell scripts are generally safe). BUGS top If you believe you have found a bug in , you can submit a bug report at https://bugzilla.sudo.ws/ SUPPORT top Limited free support is available via the sudo-users mailing list, see https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives. DISCLAIMER top is provided AS IS and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. See the LICENSE.md file distributed with or https://www.sudo.ws/about/license/ for complete details. COLOPHON top This page is part of the sudo (execute a command as another user) project. Information about the project can be found at https://www.sudo.ws/. If you have a bug report for this manual page, see https://bugzilla.sudo.ws/. This page was obtained from the project's upstream Git repository https://github.com/sudo-project/sudo on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-12-21.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org Sudo 1.9.15p4 August 9, 2023 SUDO(8) Pages that refer to this page: homectl(1), journalctl(1), localectl(1), loginctl(1), machinectl(1), portablectl(1), setpriv(1), systemctl(1), systemd(1), systemd-analyze(1), systemd-ask-password(1), systemd-inhibit(1), systemd-nspawn(1), systemd-vmspawn(1), timedatectl(1), uid0(1), userdbctl(1), nsswitch.conf(5), credentials(7), systemd-tmpfiles(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create all directories in the path specified by variable $javaUsrLib as super user Bash Command:<START>sudo mkdir -p $javaUsrLib<END> |
Create all directories in the path specified by variable $tempWork | mkdir -p $tempWork | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create all directories in the path specified by variable $tempWork Bash Command:<START>mkdir -p $tempWork<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create all directories in the path specified by variable $tempWork Bash Command:<START>mkdir -p $tempWork<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create all directories in the path specified by variable $tempWork Bash Command:<START>mkdir -p $tempWork<END> |
Create an archive named newArch from the contents of ./test directory | find ./test -printf "././%f\n"| cpio -o -F newArch | ['find'] | Output a Bash command to accomplish the following task. Task: Create an archive named newArch from the contents of ./test directory Bash Command:<START>find ./test -printf "././%f\n"| cpio -o -F newArch<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n Task: Create an archive named newArch from the contents of ./test directory Bash Command:<START>find ./test -printf "././%f\n"| cpio -o -F newArch<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an archive named newArch from the contents of ./test directory Bash Command:<START>find ./test -printf "././%f\n"| cpio -o -F newArch<END> |
Create an empty file "foo" in each directory under the current directory containing a file named "bar". | find -name "bar" -execdir touch foo \; | ['find', 'touch'] | Output a Bash command to accomplish the following task. Task: Create an empty file "foo" in each directory under the current directory containing a file named "bar". Bash Command:<START>find -name "bar" -execdir touch foo \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # touch\n\n> Create files and set access/modification times.\n> More information: <https://manned.org/man/freebsd-13.1/touch>.\n\n- Create specific files:\n\n`touch {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [a]ccess or [m]odification times to the current one and don't [c]reate file if it doesn't exist:\n\n`touch -c -{{a|m}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [t]ime to a specific value and don't [c]reate file if it doesn't exist:\n\n`touch -c -t {{YYYYMMDDHHMM.SS}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file time of a specific file to the time of anothe[r] file and don't [c]reate file if it doesn't exist:\n\n`touch -c -r {{~/.emacs}} {{path/to/file1 path/to/file2 ...}}`\n Task: Create an empty file "foo" in each directory under the current directory containing a file named "bar". Bash Command:<START>find -name "bar" -execdir touch foo \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. touch(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training touch(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TOUCH(1) User Commands TOUCH(1) NAME top touch - change file timestamps SYNOPSIS top touch [OPTION]... FILE... DESCRIPTION top Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by Paul Rubin, Arnold Robbins, Jim Kingdon, David MacKenzie, and Randy Smith. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/touch> or available locally via: info '(coreutils) touch invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TOUCH(1) Pages that refer to this page: last(1@@util-linux), utime(2), utimensat(2), systemd-update-done.service(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an empty file "foo" in each directory under the current directory containing a file named "bar". Bash Command:<START>find -name "bar" -execdir touch foo \;<END> |
Create an empty file 'last.check' in directory pointed by variable "log_dir", with specified timestamp. | touch -m 201111301200.00 $log_dir/last.check | ['touch'] | Output a Bash command to accomplish the following task. Task: Create an empty file 'last.check' in directory pointed by variable "log_dir", with specified timestamp. Bash Command:<START>touch -m 201111301200.00 $log_dir/last.check<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # touch\n\n> Create files and set access/modification times.\n> More information: <https://manned.org/man/freebsd-13.1/touch>.\n\n- Create specific files:\n\n`touch {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [a]ccess or [m]odification times to the current one and don't [c]reate file if it doesn't exist:\n\n`touch -c -{{a|m}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [t]ime to a specific value and don't [c]reate file if it doesn't exist:\n\n`touch -c -t {{YYYYMMDDHHMM.SS}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file time of a specific file to the time of anothe[r] file and don't [c]reate file if it doesn't exist:\n\n`touch -c -r {{~/.emacs}} {{path/to/file1 path/to/file2 ...}}`\n Task: Create an empty file 'last.check' in directory pointed by variable "log_dir", with specified timestamp. Bash Command:<START>touch -m 201111301200.00 $log_dir/last.check<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: touch(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training touch(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TOUCH(1) User Commands TOUCH(1) NAME top touch - change file timestamps SYNOPSIS top touch [OPTION]... FILE... DESCRIPTION top Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by Paul Rubin, Arnold Robbins, Jim Kingdon, David MacKenzie, and Randy Smith. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/touch> or available locally via: info '(coreutils) touch invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TOUCH(1) Pages that refer to this page: last(1@@util-linux), utime(2), utimensat(2), systemd-update-done.service(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an empty file 'last.check' in directory pointed by variable "log_dir", with specified timestamp. Bash Command:<START>touch -m 201111301200.00 $log_dir/last.check<END> |
Create an empty file (or update timestamp of file) specified by variable "correctFilePathAndName" | touch "$correctFilePathAndName" | ['touch'] | Output a Bash command to accomplish the following task. Task: Create an empty file (or update timestamp of file) specified by variable "correctFilePathAndName" Bash Command:<START>touch "$correctFilePathAndName"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # touch\n\n> Create files and set access/modification times.\n> More information: <https://manned.org/man/freebsd-13.1/touch>.\n\n- Create specific files:\n\n`touch {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [a]ccess or [m]odification times to the current one and don't [c]reate file if it doesn't exist:\n\n`touch -c -{{a|m}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [t]ime to a specific value and don't [c]reate file if it doesn't exist:\n\n`touch -c -t {{YYYYMMDDHHMM.SS}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file time of a specific file to the time of anothe[r] file and don't [c]reate file if it doesn't exist:\n\n`touch -c -r {{~/.emacs}} {{path/to/file1 path/to/file2 ...}}`\n Task: Create an empty file (or update timestamp of file) specified by variable "correctFilePathAndName" Bash Command:<START>touch "$correctFilePathAndName"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: touch(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training touch(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TOUCH(1) User Commands TOUCH(1) NAME top touch - change file timestamps SYNOPSIS top touch [OPTION]... FILE... DESCRIPTION top Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by Paul Rubin, Arnold Robbins, Jim Kingdon, David MacKenzie, and Randy Smith. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/touch> or available locally via: info '(coreutils) touch invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TOUCH(1) Pages that refer to this page: last(1@@util-linux), utime(2), utimensat(2), systemd-update-done.service(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an empty file (or update timestamp of file) specified by variable "correctFilePathAndName" Bash Command:<START>touch "$correctFilePathAndName"<END> |
Create an empty file called "emptyfile.c" | cp /dev/null emptyfile.c | ['cp'] | Output a Bash command to accomplish the following task. Task: Create an empty file called "emptyfile.c" Bash Command:<START>cp /dev/null emptyfile.c<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # cp\n\n> Copy files and directories.\n> More information: <https://www.gnu.org/software/coreutils/cp>.\n\n- Copy a file to another location:\n\n`cp {{path/to/source_file.ext}} {{path/to/target_file.ext}}`\n\n- Copy a file into another directory, keeping the filename:\n\n`cp {{path/to/source_file.ext}} {{path/to/target_parent_directory}}`\n\n- Recursively copy a directory's contents to another location (if the destination exists, the directory is copied inside it):\n\n`cp -r {{path/to/source_directory}} {{path/to/target_directory}}`\n\n- Copy a directory recursively, in verbose mode (shows files as they are copied):\n\n`cp -vr {{path/to/source_directory}} {{path/to/target_directory}}`\n\n- Copy multiple files at once to a directory:\n\n`cp -t {{path/to/destination_directory}} {{path/to/file1 path/to/file2 ...}}`\n\n- Copy all files with a specific extension to another location, in interactive mode (prompts user before overwriting):\n\n`cp -i {{*.ext}} {{path/to/target_directory}}`\n\n- Follow symbolic links before copying:\n\n`cp -L {{link}} {{path/to/target_directory}}`\n\n- Use the full path of source files, creating any missing intermediate directories when copying:\n\n`cp --parents {{source/path/to/file}} {{path/to/target_file}}`\n Task: Create an empty file called "emptyfile.c" Bash Command:<START>cp /dev/null emptyfile.c<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: cp(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training cp(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON CP(1) User Commands CP(1) NAME top cp - copy files and directories SYNOPSIS top cp [OPTION]... [-T] SOURCE DEST cp [OPTION]... SOURCE... DIRECTORY cp [OPTION]... -t DIRECTORY SOURCE... DESCRIPTION top Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY. Mandatory arguments to long options are mandatory for short options too. -a, --archive same as -dR --preserve=all --attributes-only don't copy the file data, just the attributes --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument --copy-contents copy contents of special files when recursive -d same as --no-dereference --preserve=links --debug explain how a file is copied. Implies -v -f, --force if an existing destination file cannot be opened, remove it and try again (this option is ignored when the -n option is also used) -i, --interactive prompt before overwrite (overrides a previous -n option) -H follow command-line symbolic links in SOURCE -l, --link hard link files instead of copying -L, --dereference always follow symbolic links in SOURCE -n, --no-clobber do not overwrite an existing file (overrides a -u or previous -i option). See also --update -P, --no-dereference never follow symbolic links in SOURCE -p same as --preserve=mode,ownership,timestamps --preserve[=ATTR_LIST] preserve the specified attributes --no-preserve=ATTR_LIST don't preserve the specified attributes --parents use full source file name under DIRECTORY -R, -r, --recursive copy directories recursively --reflink[=WHEN] control clone/CoW copies. See below --remove-destination remove each existing destination file before attempting to open it (contrast with --force) --sparse=WHEN control creation of sparse files. See below --strip-trailing-slashes remove any trailing slashes from each SOURCE argument -s, --symbolic-link make symbolic links instead of copying -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY copy all SOURCE arguments into DIRECTORY -T, --no-target-directory treat DEST as a normal file --update[=UPDATE] control which existing files are updated; UPDATE={all,none,older(default)}. See below -u equivalent to --update[=older] -v, --verbose explain what is being done -x, --one-file-system stay on this file system -Z set SELinux security context of destination file to default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit ATTR_LIST is a comma-separated list of attributes. Attributes are 'mode' for permissions (including any ACL and xattr permissions), 'ownership' for user and group, 'timestamps' for file timestamps, 'links' for hard links, 'context' for security context, 'xattr' for extended attributes, and 'all' for all attributes. By default, sparse SOURCE files are detected by a crude heuristic and the corresponding DEST file is made sparse as well. That is the behavior selected by --sparse=auto. Specify --sparse=always to create a sparse DEST file whenever the SOURCE file contains a long enough sequence of zero bytes. Use --sparse=never to inhibit creation of sparse files. UPDATE controls which existing files in the destination are replaced. 'all' is the default operation when an --update option is not specified, and results in all existing files in the destination being replaced. 'none' is similar to the --no-clobber option, in that no files in the destination are replaced, but also skipped files do not induce a failure. 'older' is the default operation when --update is specified, and results in files being replaced if they're older than the corresponding source file. When --reflink[=always] is specified, perform a lightweight copy, where the data blocks are copied only when modified. If this is not possible the copy fails, or if --reflink=auto is specified, fall back to a standard copy. Use --reflink=never to ensure a standard copy is performed. The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups As a special case, cp makes a backup of SOURCE when the force and backup options are given and SOURCE and DEST are the same name for an existing, regular file. AUTHOR top Written by Torbjorn Granlund, David MacKenzie, and Jim Meyering. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top install(1) Full documentation <https://www.gnu.org/software/coreutils/cp> or available locally via: info '(coreutils) cp invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 CP(1) Pages that refer to this page: install(1), pmlogmv(1), rsync(1), cpuset(7), symlink(7), e2image(8), readprofile(8), swapon(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an empty file called "emptyfile.c" Bash Command:<START>cp /dev/null emptyfile.c<END> |
Create an empty file in each directory named "mydir" under current directory. | find . -type d -name "mydir" -exec touch '{}/abc.txt' \; | ['find', 'touch'] | Output a Bash command to accomplish the following task. Task: Create an empty file in each directory named "mydir" under current directory. Bash Command:<START>find . -type d -name "mydir" -exec touch '{}/abc.txt' \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # touch\n\n> Create files and set access/modification times.\n> More information: <https://manned.org/man/freebsd-13.1/touch>.\n\n- Create specific files:\n\n`touch {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [a]ccess or [m]odification times to the current one and don't [c]reate file if it doesn't exist:\n\n`touch -c -{{a|m}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [t]ime to a specific value and don't [c]reate file if it doesn't exist:\n\n`touch -c -t {{YYYYMMDDHHMM.SS}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file time of a specific file to the time of anothe[r] file and don't [c]reate file if it doesn't exist:\n\n`touch -c -r {{~/.emacs}} {{path/to/file1 path/to/file2 ...}}`\n Task: Create an empty file in each directory named "mydir" under current directory. Bash Command:<START>find . -type d -name "mydir" -exec touch '{}/abc.txt' \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. touch(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training touch(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TOUCH(1) User Commands TOUCH(1) NAME top touch - change file timestamps SYNOPSIS top touch [OPTION]... FILE... DESCRIPTION top Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by Paul Rubin, Arnold Robbins, Jim Kingdon, David MacKenzie, and Randy Smith. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/touch> or available locally via: info '(coreutils) touch invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TOUCH(1) Pages that refer to this page: last(1@@util-linux), utime(2), utimensat(2), systemd-update-done.service(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an empty file in each directory named "mydir" under current directory. Bash Command:<START>find . -type d -name "mydir" -exec touch '{}/abc.txt' \;<END> |
Create an empty file with a carriage return character in its name. | touch $'Icon\r' | ['touch'] | Output a Bash command to accomplish the following task. Task: Create an empty file with a carriage return character in its name. Bash Command:<START>touch $'Icon\r'<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # touch\n\n> Create files and set access/modification times.\n> More information: <https://manned.org/man/freebsd-13.1/touch>.\n\n- Create specific files:\n\n`touch {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [a]ccess or [m]odification times to the current one and don't [c]reate file if it doesn't exist:\n\n`touch -c -{{a|m}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [t]ime to a specific value and don't [c]reate file if it doesn't exist:\n\n`touch -c -t {{YYYYMMDDHHMM.SS}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file time of a specific file to the time of anothe[r] file and don't [c]reate file if it doesn't exist:\n\n`touch -c -r {{~/.emacs}} {{path/to/file1 path/to/file2 ...}}`\n Task: Create an empty file with a carriage return character in its name. Bash Command:<START>touch $'Icon\r'<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: touch(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training touch(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TOUCH(1) User Commands TOUCH(1) NAME top touch - change file timestamps SYNOPSIS top touch [OPTION]... FILE... DESCRIPTION top Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by Paul Rubin, Arnold Robbins, Jim Kingdon, David MacKenzie, and Randy Smith. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/touch> or available locally via: info '(coreutils) touch invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TOUCH(1) Pages that refer to this page: last(1@@util-linux), utime(2), utimensat(2), systemd-update-done.service(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an empty file with a carriage return character in its name. Bash Command:<START>touch $'Icon\r'<END> |
Create an empty index.html in each directory under the current one, updating timestamps of already existing index.html files. | find . -type d -exec touch {}/index.html \; | ['find', 'touch'] | Output a Bash command to accomplish the following task. Task: Create an empty index.html in each directory under the current one, updating timestamps of already existing index.html files. Bash Command:<START>find . -type d -exec touch {}/index.html \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # touch\n\n> Create files and set access/modification times.\n> More information: <https://manned.org/man/freebsd-13.1/touch>.\n\n- Create specific files:\n\n`touch {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [a]ccess or [m]odification times to the current one and don't [c]reate file if it doesn't exist:\n\n`touch -c -{{a|m}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [t]ime to a specific value and don't [c]reate file if it doesn't exist:\n\n`touch -c -t {{YYYYMMDDHHMM.SS}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file time of a specific file to the time of anothe[r] file and don't [c]reate file if it doesn't exist:\n\n`touch -c -r {{~/.emacs}} {{path/to/file1 path/to/file2 ...}}`\n Task: Create an empty index.html in each directory under the current one, updating timestamps of already existing index.html files. Bash Command:<START>find . -type d -exec touch {}/index.html \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. touch(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training touch(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TOUCH(1) User Commands TOUCH(1) NAME top touch - change file timestamps SYNOPSIS top touch [OPTION]... FILE... DESCRIPTION top Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by Paul Rubin, Arnold Robbins, Jim Kingdon, David MacKenzie, and Randy Smith. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/touch> or available locally via: info '(coreutils) touch invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TOUCH(1) Pages that refer to this page: last(1@@util-linux), utime(2), utimensat(2), systemd-update-done.service(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an empty index.html in each directory under the current one, updating timestamps of already existing index.html files. Bash Command:<START>find . -type d -exec touch {}/index.html \;<END> |
Create an empty index.html, or update its timestamp if it already exists. | touch index.html | ['touch'] | Output a Bash command to accomplish the following task. Task: Create an empty index.html, or update its timestamp if it already exists. Bash Command:<START>touch index.html<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # touch\n\n> Create files and set access/modification times.\n> More information: <https://manned.org/man/freebsd-13.1/touch>.\n\n- Create specific files:\n\n`touch {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [a]ccess or [m]odification times to the current one and don't [c]reate file if it doesn't exist:\n\n`touch -c -{{a|m}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [t]ime to a specific value and don't [c]reate file if it doesn't exist:\n\n`touch -c -t {{YYYYMMDDHHMM.SS}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file time of a specific file to the time of anothe[r] file and don't [c]reate file if it doesn't exist:\n\n`touch -c -r {{~/.emacs}} {{path/to/file1 path/to/file2 ...}}`\n Task: Create an empty index.html, or update its timestamp if it already exists. Bash Command:<START>touch index.html<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: touch(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training touch(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TOUCH(1) User Commands TOUCH(1) NAME top touch - change file timestamps SYNOPSIS top touch [OPTION]... FILE... DESCRIPTION top Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by Paul Rubin, Arnold Robbins, Jim Kingdon, David MacKenzie, and Randy Smith. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/touch> or available locally via: info '(coreutils) touch invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TOUCH(1) Pages that refer to this page: last(1@@util-linux), utime(2), utimensat(2), systemd-update-done.service(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create an empty index.html, or update its timestamp if it already exists. Bash Command:<START>touch index.html<END> |
Create compressed archive from "my_large_file_1" and "my_large_file_2" and split into files of size 1024 MiB with prefix "myfiles_split.tgz_" | tar cz my_large_file_1 my_large_file_2 | split -b 1024MiB - myfiles_split.tgz_ | ['tar', 'split'] | Output a Bash command to accomplish the following task. Task: Create compressed archive from "my_large_file_1" and "my_large_file_2" and split into files of size 1024 MiB with prefix "myfiles_split.tgz_" Bash Command:<START>tar cz my_large_file_1 my_large_file_2 | split -b 1024MiB - myfiles_split.tgz_<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # tar\n\n> Archiving utility.\n> Often combined with a compression method, such as `gzip` or `bzip2`.\n> More information: <https://www.gnu.org/software/tar>.\n\n- [c]reate an archive and write it to a [f]ile:\n\n`tar cf {{path/to/target.tar}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive and write it to a [f]ile:\n\n`tar czf {{path/to/target.tar.gz}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive from a directory using relative paths:\n\n`tar czf {{path/to/target.tar.gz}} --directory={{path/to/directory}} .`\n\n- E[x]tract a (compressed) archive [f]ile into the current directory [v]erbosely:\n\n`tar xvf {{path/to/source.tar[.gz|.bz2|.xz]}}`\n\n- E[x]tract a (compressed) archive [f]ile into the target directory:\n\n`tar xf {{path/to/source.tar[.gz|.bz2|.xz]}} --directory={{path/to/directory}}`\n\n- [c]reate a compressed archive and write it to a [f]ile, using the file extension to [a]utomatically determine the compression program:\n\n`tar caf {{path/to/target.tar.xz}} {{path/to/file1 path/to/file2 ...}}`\n\n- Lis[t] the contents of a tar [f]ile [v]erbosely:\n\n`tar tvf {{path/to/source.tar}}`\n\n- E[x]tract files matching a pattern from an archive [f]ile:\n\n`tar xf {{path/to/source.tar}} --wildcards "{{*.html}}"`\n # split\n\n> Split a file into pieces.\n> More information: <https://www.gnu.org/software/coreutils/split>.\n\n- Split a file, each split having 10 lines (except the last split):\n\n`split -l {{10}} {{path/to/file}}`\n\n- Split a file into 5 files. File is split such that each split has same size (except the last split):\n\n`split -n {{5}} {{path/to/file}}`\n\n- Split a file with 512 bytes in each split (except the last split; use 512k for kilobytes and 512m for megabytes):\n\n`split -b {{512}} {{path/to/file}}`\n\n- Split a file with at most 512 bytes in each split without breaking lines:\n\n`split -C {{512}} {{path/to/file}}`\n Task: Create compressed archive from "my_large_file_1" and "my_large_file_2" and split into files of size 1024 MiB with prefix "myfiles_split.tgz_" Bash Command:<START>tar cz my_large_file_1 my_large_file_2 | split -b 1024MiB - myfiles_split.tgz_<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: tar(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training tar(1) Linux manual page NAME | SYNOPSIS | NOTE | DESCRIPTION | OPTIONS | RETURN VALUE | SEE ALSO | BUG REPORTS | COPYRIGHT | COLOPHON TAR(1) GNU TAR Manual TAR(1) NAME top tar - an archiving utility SYNOPSIS top Traditional usage tar {A|c|d|r|t|u|x}[GnSkUWOmpsMBiajJzZhPlRvwo] [ARG...] UNIX-style usage tar -A [OPTIONS] -f ARCHIVE ARCHIVE... tar -c [-f ARCHIVE] [OPTIONS] [FILE...] tar -d [-f ARCHIVE] [OPTIONS] [FILE...] tar -r [-f ARCHIVE] [OPTIONS] [FILE...] tar -t [-f ARCHIVE] [OPTIONS] [MEMBER...] tar -u [-f ARCHIVE] [OPTIONS] [FILE...] tar -x [-f ARCHIVE] [OPTIONS] [MEMBER...] GNU-style usage tar {--catenate|--concatenate} [OPTIONS] --file ARCHIVE ARCHIVE... tar --create [--file ARCHIVE] [OPTIONS] [FILE...] tar {--diff|--compare} [--file ARCHIVE] [OPTIONS] [FILE...] tar --delete [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --append [--file ARCHIVE] [OPTIONS] [FILE...] tar --list [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --test-label [--file ARCHIVE] [OPTIONS] [LABEL...] tar --update [--file ARCHIVE] [OPTIONS] [FILE...] tar {--extract|--get} [--file ARCHIVE] [OPTIONS] [MEMBER...] NOTE top This manpage is a short description of GNU tar. For a detailed discussion, including examples and usage recommendations, refer to the GNU Tar Manual available in texinfo format. If the info reader and the tar documentation are properly installed on your system, the command info tar should give you access to the complete manual. You can also view the manual using the info mode in emacs(1), or find it in various formats online at https://www.gnu.org/software/tar/manual If any discrepancies occur between this manpage and the GNU Tar Manual, the later shall be considered the authoritative source. DESCRIPTION top GNU tar is an archiving program designed to store multiple files in a single file (an archive), and to manipulate such archives. The archive can be either a regular file or a device (e.g. a tape drive, hence the name of the program, which stands for tape archiver), which can be located either on the local or on a remote machine. Option styles Options to GNU tar can be given in three different styles. In traditional style, the first argument is a cluster of option letters and all subsequent arguments supply arguments to those options that require them. The arguments are read in the same order as the option letters. Any command line words that remain after all options have been processed are treated as non-option arguments: file or archive member names. For example, the c option requires creating the archive, the v option requests the verbose operation, and the f option takes an argument that sets the name of the archive to operate upon. The following command, written in the traditional style, instructs tar to store all files from the directory /etc into the archive file etc.tar, verbosely listing the files being archived: tar cfv etc.tar /etc In UNIX or short-option style, each option letter is prefixed with a single dash, as in other command line utilities. If an option takes an argument, the argument follows it, either as a separate command line word, or immediately following the option. However, if the option takes an optional argument, the argument must follow the option letter without any intervening whitespace, as in -g/tmp/snar.db. Any number of options not taking arguments can be clustered together after a single dash, e.g. -vkp. An option that takes an argument (whether mandatory or optional) can appear at the end of such a cluster, e.g. -vkpf a.tar. The example command above written in the short-option style could look like: tar -cvf etc.tar /etc or tar -c -v -f etc.tar /etc In GNU or long-option style, each option begins with two dashes and has a meaningful name, consisting of lower-case letters and dashes. When used, the long option can be abbreviated to its initial letters, provided that this does not create ambiguity. Arguments to long options are supplied either as a separate command line word, immediately following the option, or separated from the option by an equals sign with no intervening whitespace. Optional arguments must always use the latter method. Here are several ways of writing the example command in this style: tar --create --file etc.tar --verbose /etc or (abbreviating some options): tar --cre --file=etc.tar --verb /etc The options in all three styles can be intermixed, although doing so with old options is not encouraged. Operation mode The options listed in the table below tell GNU tar what operation it is to perform. Exactly one of them must be given. The meaning of non-option arguments depends on the operation mode requested. -A, --catenate, --concatenate Append archives to the end of another archive. The arguments are treated as the names of archives to append. All archives must be of the same format as the archive they are appended to, otherwise the resulting archive might be unusable with non-GNU implementations of tar. Notice also that when more than one archive is given, the members from archives other than the first one will be accessible in the resulting archive only when using the -i (--ignore-zeros) option. Compressed archives cannot be concatenated. -c, --create Create a new archive. Arguments supply the names of the files to be archived. Directories are archived recursively, unless the --no-recursion option is given. -d, --diff, --compare Find differences between archive and file system. The arguments are optional and specify archive members to compare. If not given, the current working directory is assumed. --delete Delete from the archive. The arguments supply names of the archive members to be removed. At least one argument must be given. This option does not operate on compressed archives. There is no short option equivalent. -r, --append Append files to the end of an archive. Arguments have the same meaning as for -c (--create). -t, --list List the contents of an archive. Arguments are optional. When given, they specify the names of the members to list. --test-label Test the archive volume label and exit. When used without arguments, it prints the volume label (if any) and exits with status 0. When one or more command line arguments are given. tar compares the volume label with each argument. It exits with code 0 if a match is found, and with code 1 otherwise. No output is displayed, unless used together with the -v (--verbose) option. There is no short option equivalent for this option. -u, --update Append files which are newer than the corresponding copy in the archive. Arguments have the same meaning as with the -c and -r options. Notice, that newer files don't replace their old archive copies, but instead are appended to the end of archive. The resulting archive can thus contain several members of the same name, corresponding to various versions of the same file. -x, --extract, --get Extract files from an archive. Arguments are optional. When given, they specify names of the archive members to be extracted. --show-defaults Show built-in defaults for various tar options and exit. -?, --help Display a short option summary and exit. --usage Display a list of available options and exit. --version Print program version and copyright information and exit. OPTIONS top Operation modifiers --check-device Check device numbers when creating incremental archives (default). -g, --listed-incremental=FILE Handle new GNU-format incremental backups. FILE is the name of a snapshot file, where tar stores additional information which is used to decide which files changed since the previous incremental dump and, consequently, must be dumped again. If FILE does not exist when creating an archive, it will be created and all files will be added to the resulting archive (the level 0 dump). To create incremental archives of non-zero level N, you need a copy of the snapshot file created for level N-1, and use it as FILE. When listing or extracting, the actual content of FILE is not inspected, it is needed only due to syntactical requirements. It is therefore common practice to use /dev/null in its place. --hole-detection=METHOD Use METHOD to detect holes in sparse files. This option implies --sparse. Valid values for METHOD are seek and raw. Default is seek with fallback to raw when not applicable. -G, --incremental Handle old GNU-format incremental backups. --ignore-failed-read Do not exit with nonzero on unreadable files. --level=NUMBER Set dump level for a created listed-incremental archive. Currently only --level=0 is meaningful: it instructs tar to truncate the snapshot file before dumping, thereby forcing a level 0 dump. -n, --seek Assume the archive is seekable. Normally tar determines automatically whether the archive can be seeked or not. This option is intended for use in cases when such recognition fails. It takes effect only if the archive is open for reading (e.g. with --list or --extract options). --no-check-device Do not check device numbers when creating incremental archives. --no-seek Assume the archive is not seekable. --occurrence[=N] Process only the Nth occurrence of each file in the archive. This option is valid only when used with one of the following subcommands: --delete, --diff, --extract or --list and when a list of files is given either on the command line or via the -T option. The default N is 1. --restrict Disable the use of some potentially harmful options. --sparse-version=MAJOR[.MINOR] Set which version of the sparse format to use. This option implies --sparse. Valid argument values are 0.0, 0.1, and 1.0. For a detailed discussion of sparse formats, refer to the GNU Tar Manual, appendix D, "Sparse Formats". Using the info reader, it can be accessed running the following command: info tar 'Sparse Formats'. -S, --sparse Handle sparse files efficiently. Some files in the file system may have segments which were actually never written (quite often these are database files created by such systems as DBM). When given this option, tar attempts to determine if the file is sparse prior to archiving it, and if so, to reduce the resulting archive size by not dumping empty parts of the file. Overwrite control These options control tar actions when extracting a file over an existing copy on disk. -k, --keep-old-files Don't replace existing files when extracting. --keep-newer-files Don't replace existing files that are newer than their archive copies. --keep-directory-symlink Don't replace existing symlinks to directories when extracting. --no-overwrite-dir Preserve metadata of existing directories. --one-top-level[=DIR] Extract all files into DIR, or, if used without argument, into a subdirectory named by the base name of the archive (minus standard compression suffixes recognizable by --auto-compress). --overwrite Overwrite existing files when extracting. --overwrite-dir Overwrite metadata of existing directories when extracting (default). --recursive-unlink Recursively remove all files in the directory prior to extracting it. --remove-files Remove files from disk after adding them to the archive. --skip-old-files Don't replace existing files when extracting, silently skip over them. -U, --unlink-first Remove each file prior to extracting over it. -W, --verify Verify the archive after writing it. Output stream selection --ignore-command-error Ignore subprocess exit codes. --no-ignore-command-error Treat non-zero exit codes of children as error (default). -O, --to-stdout Extract files to standard output. --to-command=COMMAND Pipe extracted files to COMMAND. The argument is the pathname of an external program, optionally with command line arguments. The program will be invoked and the contents of the file being extracted supplied to it on its standard input. Additional data will be supplied via the following environment variables: TAR_FILETYPE Type of the file. It is a single letter with the following meaning: f Regular file d Directory l Symbolic link h Hard link b Block device c Character device Currently only regular files are supported. TAR_MODE File mode, an octal number. TAR_FILENAME The name of the file. TAR_REALNAME Name of the file as stored in the archive. TAR_UNAME Name of the file owner. TAR_GNAME Name of the file owner group. TAR_ATIME Time of last access. It is a decimal number, representing seconds since the Epoch. If the archive provides times with nanosecond precision, the nanoseconds are appended to the timestamp after a decimal point. TAR_MTIME Time of last modification. TAR_CTIME Time of last status change. TAR_SIZE Size of the file. TAR_UID UID of the file owner. TAR_GID GID of the file owner. Additionally, the following variables contain information about tar operation mode and the archive being processed: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. Handling of file attributes --atime-preserve[=METHOD] Preserve access times on dumped files, either by restoring the times after reading (METHOD=replace, this is the default) or by not setting the times in the first place (METHOD=system). --delay-directory-restore Delay setting modification times and permissions of extracted directories until the end of extraction. Use this option when extracting from an archive which has unusual member ordering. --group=NAME[:GID] Force NAME as group for added files. If GID is not supplied, NAME can be either a user name or numeric GID. In this case the missing part (GID or name) will be inferred from the current host's group database. When used with --group-map=FILE, affects only those files whose owner group is not listed in FILE. --group-map=FILE Read group translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single group. It must consist of two fields, delimited by any amount of whitespace: OLDGRP NEWGRP[:NEWGID] OLDGRP is either a valid group name or a GID prefixed with +. Unless NEWGID is supplied, NEWGRP must also be either a valid group name or a +GID. Otherwise, both NEWGRP and NEWGID need not be listed in the system group database. As a result, each input file with owner group OLDGRP will be stored in archive with owner group NEWGRP and GID NEWGID. --mode=CHANGES Force symbolic mode CHANGES for added files. --mtime=DATE-OR-FILE Set mtime for added files. DATE-OR-FILE is either a date/time in almost arbitrary format, or the name of an existing file. In the latter case the mtime of that file will be used. -m, --touch Don't extract file modified time. --no-delay-directory-restore Cancel the effect of the prior --delay-directory-restore option. --no-same-owner Extract files as yourself (default for ordinary users). --no-same-permissions Apply the user's umask when extracting permissions from the archive (default for ordinary users). --numeric-owner Always use numbers for user/group names. --owner=NAME[:UID] Force NAME as owner for added files. If UID is not supplied, NAME can be either a user name or numeric UID. In this case the missing part (UID or name) will be inferred from the current host's user database. When used with --owner-map=FILE, affects only those files whose owner is not listed in FILE. --owner-map=FILE Read owner translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single UID. It must consist of two fields, delimited by any amount of whitespace: OLDUSR NEWUSR[:NEWUID] OLDUSR is either a valid user name or a UID prefixed with +. Unless NEWUID is supplied, NEWUSR must also be either a valid user name or a +UID. Otherwise, both NEWUSR and NEWUID need not be listed in the system user database. As a result, each input file owned by OLDUSR will be stored in archive with owner name NEWUSR and UID NEWUID. -p, --preserve-permissions, --same-permissions Set permissions of extracted files to those recorded in the archive (default for superuser). --same-owner Try extracting files with the same ownership as exists in the archive (default for superuser). -s, --preserve-order, --same-order Tell tar that the list of file names to process is sorted in the same order as the files in the archive. --sort=ORDER When creating an archive, sort directory entries according to ORDER, which is one of none, name, or inode. The default is --sort=none, which stores archive members in the same order as returned by the operating system. Using --sort=name ensures the member ordering in the created archive is uniform and reproducible. Using --sort=inode reduces the number of disk seeks made when creating the archive and thus can considerably speed up archivation. This sorting order is supported only if the underlying system provides the necessary information. Extended file attributes --acls Enable POSIX ACLs support. --no-acls Disable POSIX ACLs support. --selinux Enable SELinux context support. --no-selinux Disable SELinux context support. --xattrs Enable extended attributes support. --no-xattrs Disable extended attributes support. --xattrs-exclude=PATTERN Specify the exclude pattern for xattr keys. PATTERN is a globbing pattern, e.g. --xattrs-exclude='user.*' to include only attributes from the user namespace. --xattrs-include=PATTERN Specify the include pattern for xattr keys. PATTERN is a globbing pattern. Device selection and switching -f, --file=ARCHIVE Use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable `TAPE'. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default. The default value can be inspected either using the --show-defaults option, or at the end of the tar --help output. An archive name that has a colon in it specifies a file or device on a remote machine. The part before the colon is taken as the machine name or IP address, and the part after it as the file or device pathname, e.g.: --file=remotehost:/dev/sr0 An optional username can be prefixed to the hostname, placing a @ sign between them. By default, the remote host is accessed via the rsh(1) command. Nowadays it is common to use ssh(1) instead. You can do so by giving the following command line option: --rsh-command=/usr/bin/ssh The remote machine should have the rmt(8) command installed. If its pathname does not match tar's default, you can inform tar about the correct pathname using the --rmt-command option. --force-local Archive file is local even if it has a colon. -F, --info-script=COMMAND, --new-volume-script=COMMAND Run COMMAND at the end of each tape (implies -M). The command can include arguments. When started, it will inherit tar's environment plus the following variables: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. TAR_FD File descriptor which can be used to communicate the new volume name to tar. If the info script fails, tar exits; otherwise, it begins writing the next volume. -L, --tape-length=N Change tape after writing Nx1024 bytes. If N is followed by a size suffix (see the subsection Size suffixes below), the suffix specifies the multiplicative factor to be used instead of 1024. This option implies -M. -M, --multi-volume Create/list/extract multi-volume archive. --rmt-command=COMMAND Use COMMAND instead of rmt when accessing remote archives. See the description of the -f option, above. --rsh-command=COMMAND Use COMMAND instead of rsh when accessing remote archives. See the description of the -f option, above. --volno-file=FILE When this option is used in conjunction with --multi-volume, tar will keep track of which volume of a multi-volume archive it is working in FILE. Device blocking -b, --blocking-factor=BLOCKS Set record size to BLOCKSx512 bytes. -B, --read-full-records When listing or extracting, accept incomplete input records after end-of-file marker. -i, --ignore-zeros Ignore zeroed blocks in archive. Normally two consecutive 512-blocks filled with zeroes mean EOF and tar stops reading after encountering them. This option instructs it to read further and is useful when reading archives created with the -A option. --record-size=NUMBER Set record size. NUMBER is the number of bytes per record. It must be multiple of 512. It can can be suffixed with a size suffix, e.g. --record-size=10K, for 10 Kilobytes. See the subsection Size suffixes, for a list of valid suffixes. Archive format selection -H, --format=FORMAT Create archive of the given format. Valid formats are: gnu GNU tar 1.13.x format oldgnu GNU format as per tar <= 1.12. pax, posix POSIX 1003.1-2001 (pax) format. ustar POSIX 1003.1-1988 (ustar) format. v7 Old V7 tar format. --old-archive, --portability Same as --format=v7. --pax-option=keyword[[:]=value][,keyword[[:]=value]]... Control pax keywords when creating PAX archives (-H pax). This option is equivalent to the -o option of the pax(1) utility. --posix Same as --format=posix. -V, --label=TEXT Create archive with volume name TEXT. If listing or extracting, use TEXT as a globbing pattern for volume name. Compression options -a, --auto-compress Use archive suffix to determine the compression program. -I, --use-compress-program=COMMAND Filter data through COMMAND. It must accept the -d option, for decompression. The argument can contain command line options. -j, --bzip2 Filter the archive through bzip2(1). -J, --xz Filter the archive through xz(1). --lzip Filter the archive through lzip(1). --lzma Filter the archive through lzma(1). --lzop Filter the archive through lzop(1). --no-auto-compress Do not use archive suffix to determine the compression program. -z, --gzip, --gunzip, --ungzip Filter the archive through gzip(1). -Z, --compress, --uncompress Filter the archive through compress(1). --zstd Filter the archive through zstd(1). Local file selection --add-file=FILE Add FILE to the archive (useful if its name starts with a dash). --backup[=CONTROL] Backup before removal. The CONTROL argument, if supplied, controls the backup policy. Its valid values are: none, off Never make backups. t, numbered Make numbered backups. nil, existing Make numbered backups if numbered backups exist, simple backups otherwise. never, simple Always make simple backups If CONTROL is not given, the value is taken from the VERSION_CONTROL environment variable. If it is not set, existing is assumed. -C, --directory=DIR Change to DIR before performing any operations. This option is order-sensitive, i.e. it affects all options that follow. --exclude=PATTERN Exclude files matching PATTERN, a glob(3)-style wildcard pattern. --exclude-backups Exclude backup and lock files. --exclude-caches Exclude contents of directories containing file CACHEDIR.TAG, except for the tag file itself. --exclude-caches-all Exclude directories containing file CACHEDIR.TAG and the file itself. --exclude-caches-under Exclude everything under directories containing CACHEDIR.TAG --exclude-ignore=FILE Before dumping a directory, see if it contains FILE. If so, read exclusion patterns from this file. The patterns affect only the directory itself. --exclude-ignore-recursive=FILE Same as --exclude-ignore, except that patterns from FILE affect both the directory and all its subdirectories. --exclude-tag=FILE Exclude contents of directories containing FILE, except for FILE itself. --exclude-tag-all=FILE Exclude directories containing FILE. --exclude-tag-under=FILE Exclude everything under directories containing FILE. --exclude-vcs Exclude version control system directories. --exclude-vcs-ignores Exclude files that match patterns read from VCS-specific ignore files. Supported files are: .cvsignore, .gitignore, .bzrignore, and .hgignore. -h, --dereference Follow symlinks; archive and dump the files they point to. --hard-dereference Follow hard links; archive and dump the files they refer to. -K, --starting-file=MEMBER Begin at the given member in the archive. --newer-mtime=DATE Work on files whose data changed after the DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --no-null Disable the effect of the previous --null option. --no-recursion Avoid descending automatically in directories. --no-unquote Do not unquote input file or member names. --no-verbatim-files-from Treat each line read from a file list as if it were supplied in the command line. I.e., leading and trailing whitespace is removed and, if the resulting string begins with a dash, it is treated as tar command line option. This is the default behavior. The --no-verbatim-files-from option is provided as a way to restore it after --verbatim-files-from option. This option is positional: it affects all --files-from options that occur after it in, until --verbatim-files-from option or end of line, whichever occurs first. It is implied by the --no-null option. --null Instruct subsequent -T options to read null-terminated names verbatim (disables special handling of names that start with a dash). See also --verbatim-files-from. -N, --newer=DATE, --after-date=DATE Only store files newer than DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --one-file-system Stay in local file system when creating archive. -P, --absolute-names Don't strip leading slashes from file names when creating archives. --recursion Recurse into directories (default). --suffix=STRING Backup before removal, override usual suffix. Default suffix is ~, unless overridden by environment variable SIMPLE_BACKUP_SUFFIX. -T, --files-from=FILE Get names to extract or create from FILE. Unless specified otherwise, the FILE must contain a list of names separated by ASCII LF (i.e. one name per line). The names read are handled the same way as command line arguments. They undergo quote removal and word splitting, and any string that starts with a - is handled as tar command line option. If this behavior is undesirable, it can be turned off using the --verbatim-files-from option. The --null option instructs tar that the names in FILE are separated by ASCII NUL character, instead of LF. It is useful if the list is generated by find(1) -print0 predicate. --unquote Unquote file or member names (default). --verbatim-files-from Treat each line obtained from a file list as a file name, even if it starts with a dash. File lists are supplied with the --files-from (-T) option. The default behavior is to handle names supplied in file lists as if they were typed in the command line, i.e. any names starting with a dash are treated as tar options. The --verbatim-files-from option disables this behavior. This option affects all --files-from options that occur after it in the command line. Its effect is reverted by the --no-verbatim-files-from option. This option is implied by the --null option. See also --add-file. -X, --exclude-from=FILE Exclude files matching patterns listed in FILE. File name transformations --strip-components=NUMBER Strip NUMBER leading components from file names on extraction. --transform=EXPRESSION, --xform=EXPRESSION Use sed replace EXPRESSION to transform file names. File name matching options These options affect both exclude and include patterns. --anchored Patterns match file name start. --ignore-case Ignore case. --no-anchored Patterns match after any / (default for exclusion). --no-ignore-case Case sensitive matching (default). --no-wildcards Verbatim string matching. --no-wildcards-match-slash Wildcards do not match /. --wildcards Use wildcards (default for exclusion). --wildcards-match-slash Wildcards match / (default for exclusion). Informative output --checkpoint[=N] Display progress messages every Nth record (default 10). --checkpoint-action=ACTION Run ACTION on each checkpoint. --clamp-mtime Only set time when the file is more recent than what was given with --mtime. --full-time Print file time to its full resolution. --index-file=FILE Send verbose output to FILE. -l, --check-links Print a message if not all links are dumped. --no-quote-chars=STRING Disable quoting for characters from STRING. --quote-chars=STRING Additionally quote characters from STRING. --quoting-style=STYLE Set quoting style for file and member names. Valid values for STYLE are literal, shell, shell-always, c, c-maybe, escape, locale, clocale. -R, --block-number Show block number within archive with each message. --show-omitted-dirs When listing or extracting, list each directory that does not match search criteria. --show-transformed-names, --show-stored-names Show file or archive names after transformation by --strip and --transform options. --totals[=SIGNAL] Print total bytes after processing the archive. If SIGNAL is given, print total bytes when this signal is delivered. Allowed signals are: SIGHUP, SIGQUIT, SIGINT, SIGUSR1, and SIGUSR2. The SIG prefix can be omitted. --utc Print file modification times in UTC. -v, --verbose Verbosely list files processed. Each instance of this option on the command line increases the verbosity level by one. The maximum verbosity level is 3. For a detailed discussion of how various verbosity levels affect tar's output, please refer to GNU Tar Manual, subsection 2.5.2 "The '--verbose' Option". --warning=KEYWORD Enable or disable warning messages identified by KEYWORD. The messages are suppressed if KEYWORD is prefixed with no- and enabled otherwise. Multiple --warning options accumulate. Keywords controlling general tar operation: all Enable all warning messages. This is the default. none Disable all warning messages. filename-with-nuls "%s: file name read contains nul character" alone-zero-block "A lone zero block at %s" Keywords applicable for tar --create: cachedir "%s: contains a cache directory tag %s; %s" file-shrank "%s: File shrank by %s bytes; padding with zeros" xdev "%s: file is on a different filesystem; not dumped" file-ignored "%s: Unknown file type; file ignored" "%s: socket ignored" "%s: door ignored" file-unchanged "%s: file is unchanged; not dumped" ignore-archive "%s: archive cannot contain itself; not dumped" file-removed "%s: File removed before we read it" file-changed "%s: file changed as we read it" failed-read Suppresses warnings about unreadable files or directories. This keyword applies only if used together with the --ignore-failed-read option. Keywords applicable for tar --extract: existing-file "%s: skipping existing file" timestamp "%s: implausibly old time stamp %s" "%s: time stamp %s is %s s in the future" contiguous-cast "Extracting contiguous files as regular files" symlink-cast "Attempting extraction of symbolic links as hard links" unknown-cast "%s: Unknown file type '%c', extracted as normal file" ignore-newer "Current %s is newer or same age" unknown-keyword "Ignoring unknown extended header keyword '%s'" decompress-program Controls verbose description of failures occurring when trying to run alternative decompressor programs. This warning is disabled by default (unless --verbose is used). A common example of what you can get when using this warning is: $ tar --warning=decompress-program -x -f archive.Z tar (child): cannot run compress: No such file or directory tar (child): trying gzip This means that tar first tried to decompress archive.Z using compress, and, when that failed, switched to gzip. record-size "Record size = %lu blocks" Keywords controlling incremental extraction: rename-directory "%s: Directory has been renamed from %s" "%s: Directory has been renamed" new-directory "%s: Directory is new" xdev "%s: directory is on a different device: not purging" bad-dumpdir "Malformed dumpdir: 'X' never used" -w, --interactive, --confirmation Ask for confirmation for every action. Compatibility options -o When creating, same as --old-archive. When extracting, same as --no-same-owner. Size suffixes Suffix Units Byte Equivalent b Blocks SIZE x 512 B Kilobytes SIZE x 1024 c Bytes SIZE G Gigabytes SIZE x 1024^3 K Kilobytes SIZE x 1024 k Kilobytes SIZE x 1024 M Megabytes SIZE x 1024^2 P Petabytes SIZE x 1024^5 T Terabytes SIZE x 1024^4 w Words SIZE x 2 RETURN VALUE top Tar's exit code indicates whether it was able to successfully perform the requested operation, and if not, what kind of error occurred. 0 Successful termination. 1 Some files differ. If tar was invoked with the --compare (--diff, -d) command line option, this means that some files in the archive differ from their disk counterparts. If tar was given one of the --create, --append or --update options, this exit code means that some files were changed while being archived and so the resulting archive does not contain the exact copy of the file set. 2 Fatal error. This means that some fatal, unrecoverable error occurred. If a subprocess that had been invoked by tar exited with a nonzero exit code, tar itself exits with that code as well. This can happen, for example, if a compression option (e.g. -z) was used and the external compressor program failed. Another example is rmt failure during backup to a remote device. SEE ALSO top bzip2(1), compress(1), gzip(1), lzma(1), lzop(1), rmt(8), symlink(7), xz(1), zstd(1). Complete tar manual: run info tar or use emacs(1) info mode to read it. Online copies of GNU tar documentation in various formats can be found at: https://www.gnu.org/software/tar/manual BUG REPORTS top Report bugs to <bug-tar@gnu.org>. COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. COLOPHON top This page is part of the tar (an archiver program) project. Information about the project can be found at http://savannah.gnu.org/projects/tar/. If you have a bug report for this manual page, see http://savannah.gnu.org/bugs/?group=tar. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/tar.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-09-12.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org TAR July 11, 2022 TAR(1) Pages that refer to this page: attr(1), dpkg-deb(1), dpkg-source(1), machinectl(1), rsync(1), st(4), suffixes(7), symlink(7), cupsd-helper(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. split(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training split(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON SPLIT(1) User Commands SPLIT(1) NAME top split - split a file into pieces SYNOPSIS top split [OPTION]... [FILE [PREFIX]] DESCRIPTION top Output pieces of FILE to PREFIXaa, PREFIXab, ...; default size is 1000 lines, and default PREFIX is 'x'. With no FILE, or when FILE is -, read standard input. Mandatory arguments to long options are mandatory for short options too. -a, --suffix-length=N generate suffixes of length N (default 2) --additional-suffix=SUFFIX append an additional SUFFIX to file names -b, --bytes=SIZE put SIZE bytes per output file -C, --line-bytes=SIZE put at most SIZE bytes of records per output file -d use numeric suffixes starting at 0, not alphabetic --numeric-suffixes[=FROM] same as -d, but allow setting the start value -x use hex suffixes starting at 0, not alphabetic --hex-suffixes[=FROM] same as -x, but allow setting the start value -e, --elide-empty-files do not generate empty output files with '-n' --filter=COMMAND write to shell COMMAND; file name is $FILE -l, --lines=NUMBER put NUMBER lines/records per output file -n, --number=CHUNKS generate CHUNKS output files; see explanation below -t, --separator=SEP use SEP instead of newline as the record separator; '\0' (zero) specifies the NUL character -u, --unbuffered immediately copy input to output with '-n r/...' --verbose print a diagnostic just before each output file is opened --help display this help and exit --version output version information and exit The SIZE argument is an integer and optional unit (example: 10K is 10*1024). Units are K,M,G,T,P,E,Z,Y,R,Q (powers of 1024) or KB,MB,... (powers of 1000). Binary prefixes can be used, too: KiB=K, MiB=M, and so on. CHUNKS may be: N split into N files based on size of input K/N output Kth of N to stdout l/N split into N files without splitting lines/records l/K/N output Kth of N to stdout without splitting lines/records r/N like 'l' but use round robin distribution r/K/N likewise but only output Kth of N to stdout AUTHOR top Written by Torbjorn Granlund and Richard M. Stallman. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/split> or available locally via: info '(coreutils) split invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 SPLIT(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create compressed archive from "my_large_file_1" and "my_large_file_2" and split into files of size 1024 MiB with prefix "myfiles_split.tgz_" Bash Command:<START>tar cz my_large_file_1 my_large_file_2 | split -b 1024MiB - myfiles_split.tgz_<END> |
Create compressed archive of all the files in the current directory tree that have been modified in the last 7 days | find . -type f -mtime -7 -print -exec cat {} \; | tar cf - | gzip -9 | ['find', 'cat', 'tar'] | Output a Bash command to accomplish the following task. Task: Create compressed archive of all the files in the current directory tree that have been modified in the last 7 days Bash Command:<START>find . -type f -mtime -7 -print -exec cat {} \; | tar cf - | gzip -9<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # cat\n\n> Print and concatenate files.\n> More information: <https://www.gnu.org/software/coreutils/cat>.\n\n- Print the contents of a file to `stdout`:\n\n`cat {{path/to/file}}`\n\n- Concatenate several files into an output file:\n\n`cat {{path/to/file1 path/to/file2 ...}} > {{path/to/output_file}}`\n\n- Append several files to an output file:\n\n`cat {{path/to/file1 path/to/file2 ...}} >> {{path/to/output_file}}`\n\n- Write `stdin` to a file:\n\n`cat - > {{path/to/file}}`\n\n- [n]umber all output lines:\n\n`cat -n {{path/to/file}}`\n\n- Display non-printable and whitespace characters (with `M-` prefix if non-ASCII):\n\n`cat -v -t -e {{path/to/file}}`\n # tar\n\n> Archiving utility.\n> Often combined with a compression method, such as `gzip` or `bzip2`.\n> More information: <https://www.gnu.org/software/tar>.\n\n- [c]reate an archive and write it to a [f]ile:\n\n`tar cf {{path/to/target.tar}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive and write it to a [f]ile:\n\n`tar czf {{path/to/target.tar.gz}} {{path/to/file1 path/to/file2 ...}}`\n\n- [c]reate a g[z]ipped archive from a directory using relative paths:\n\n`tar czf {{path/to/target.tar.gz}} --directory={{path/to/directory}} .`\n\n- E[x]tract a (compressed) archive [f]ile into the current directory [v]erbosely:\n\n`tar xvf {{path/to/source.tar[.gz|.bz2|.xz]}}`\n\n- E[x]tract a (compressed) archive [f]ile into the target directory:\n\n`tar xf {{path/to/source.tar[.gz|.bz2|.xz]}} --directory={{path/to/directory}}`\n\n- [c]reate a compressed archive and write it to a [f]ile, using the file extension to [a]utomatically determine the compression program:\n\n`tar caf {{path/to/target.tar.xz}} {{path/to/file1 path/to/file2 ...}}`\n\n- Lis[t] the contents of a tar [f]ile [v]erbosely:\n\n`tar tvf {{path/to/source.tar}}`\n\n- E[x]tract files matching a pattern from an archive [f]ile:\n\n`tar xf {{path/to/source.tar}} --wildcards "{{*.html}}"`\n Task: Create compressed archive of all the files in the current directory tree that have been modified in the last 7 days Bash Command:<START>find . -type f -mtime -7 -print -exec cat {} \; | tar cf - | gzip -9<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. cat(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training cat(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON CAT(1) User Commands CAT(1) NAME top cat - concatenate files and print on the standard output SYNOPSIS top cat [OPTION]... [FILE]... DESCRIPTION top Concatenate FILE(s) to standard output. With no FILE, or when FILE is -, read standard input. -A, --show-all equivalent to -vET -b, --number-nonblank number nonempty output lines, overrides -n -e equivalent to -vE -E, --show-ends display $ at end of each line -n, --number number all output lines -s, --squeeze-blank suppress repeated empty output lines -t equivalent to -vT -T, --show-tabs display TAB characters as ^I -u (ignored) -v, --show-nonprinting use ^ and M- notation, except for LFD and TAB --help display this help and exit --version output version information and exit EXAMPLES top cat f - g Output f's contents, then standard input, then g's contents. cat Copy standard input to standard output. AUTHOR top Written by Torbjorn Granlund and Richard M. Stallman. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top tac(1) Full documentation <https://www.gnu.org/software/coreutils/cat> or available locally via: info '(coreutils) cat invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 CAT(1) Pages that refer to this page: pmlogrewrite(1), pv(1), systemd-socket-activate(1), tac(1), ul(1), proc(5), cpuset(7), time_namespaces(7), readprofile(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. tar(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training tar(1) Linux manual page NAME | SYNOPSIS | NOTE | DESCRIPTION | OPTIONS | RETURN VALUE | SEE ALSO | BUG REPORTS | COPYRIGHT | COLOPHON TAR(1) GNU TAR Manual TAR(1) NAME top tar - an archiving utility SYNOPSIS top Traditional usage tar {A|c|d|r|t|u|x}[GnSkUWOmpsMBiajJzZhPlRvwo] [ARG...] UNIX-style usage tar -A [OPTIONS] -f ARCHIVE ARCHIVE... tar -c [-f ARCHIVE] [OPTIONS] [FILE...] tar -d [-f ARCHIVE] [OPTIONS] [FILE...] tar -r [-f ARCHIVE] [OPTIONS] [FILE...] tar -t [-f ARCHIVE] [OPTIONS] [MEMBER...] tar -u [-f ARCHIVE] [OPTIONS] [FILE...] tar -x [-f ARCHIVE] [OPTIONS] [MEMBER...] GNU-style usage tar {--catenate|--concatenate} [OPTIONS] --file ARCHIVE ARCHIVE... tar --create [--file ARCHIVE] [OPTIONS] [FILE...] tar {--diff|--compare} [--file ARCHIVE] [OPTIONS] [FILE...] tar --delete [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --append [--file ARCHIVE] [OPTIONS] [FILE...] tar --list [--file ARCHIVE] [OPTIONS] [MEMBER...] tar --test-label [--file ARCHIVE] [OPTIONS] [LABEL...] tar --update [--file ARCHIVE] [OPTIONS] [FILE...] tar {--extract|--get} [--file ARCHIVE] [OPTIONS] [MEMBER...] NOTE top This manpage is a short description of GNU tar. For a detailed discussion, including examples and usage recommendations, refer to the GNU Tar Manual available in texinfo format. If the info reader and the tar documentation are properly installed on your system, the command info tar should give you access to the complete manual. You can also view the manual using the info mode in emacs(1), or find it in various formats online at https://www.gnu.org/software/tar/manual If any discrepancies occur between this manpage and the GNU Tar Manual, the later shall be considered the authoritative source. DESCRIPTION top GNU tar is an archiving program designed to store multiple files in a single file (an archive), and to manipulate such archives. The archive can be either a regular file or a device (e.g. a tape drive, hence the name of the program, which stands for tape archiver), which can be located either on the local or on a remote machine. Option styles Options to GNU tar can be given in three different styles. In traditional style, the first argument is a cluster of option letters and all subsequent arguments supply arguments to those options that require them. The arguments are read in the same order as the option letters. Any command line words that remain after all options have been processed are treated as non-option arguments: file or archive member names. For example, the c option requires creating the archive, the v option requests the verbose operation, and the f option takes an argument that sets the name of the archive to operate upon. The following command, written in the traditional style, instructs tar to store all files from the directory /etc into the archive file etc.tar, verbosely listing the files being archived: tar cfv etc.tar /etc In UNIX or short-option style, each option letter is prefixed with a single dash, as in other command line utilities. If an option takes an argument, the argument follows it, either as a separate command line word, or immediately following the option. However, if the option takes an optional argument, the argument must follow the option letter without any intervening whitespace, as in -g/tmp/snar.db. Any number of options not taking arguments can be clustered together after a single dash, e.g. -vkp. An option that takes an argument (whether mandatory or optional) can appear at the end of such a cluster, e.g. -vkpf a.tar. The example command above written in the short-option style could look like: tar -cvf etc.tar /etc or tar -c -v -f etc.tar /etc In GNU or long-option style, each option begins with two dashes and has a meaningful name, consisting of lower-case letters and dashes. When used, the long option can be abbreviated to its initial letters, provided that this does not create ambiguity. Arguments to long options are supplied either as a separate command line word, immediately following the option, or separated from the option by an equals sign with no intervening whitespace. Optional arguments must always use the latter method. Here are several ways of writing the example command in this style: tar --create --file etc.tar --verbose /etc or (abbreviating some options): tar --cre --file=etc.tar --verb /etc The options in all three styles can be intermixed, although doing so with old options is not encouraged. Operation mode The options listed in the table below tell GNU tar what operation it is to perform. Exactly one of them must be given. The meaning of non-option arguments depends on the operation mode requested. -A, --catenate, --concatenate Append archives to the end of another archive. The arguments are treated as the names of archives to append. All archives must be of the same format as the archive they are appended to, otherwise the resulting archive might be unusable with non-GNU implementations of tar. Notice also that when more than one archive is given, the members from archives other than the first one will be accessible in the resulting archive only when using the -i (--ignore-zeros) option. Compressed archives cannot be concatenated. -c, --create Create a new archive. Arguments supply the names of the files to be archived. Directories are archived recursively, unless the --no-recursion option is given. -d, --diff, --compare Find differences between archive and file system. The arguments are optional and specify archive members to compare. If not given, the current working directory is assumed. --delete Delete from the archive. The arguments supply names of the archive members to be removed. At least one argument must be given. This option does not operate on compressed archives. There is no short option equivalent. -r, --append Append files to the end of an archive. Arguments have the same meaning as for -c (--create). -t, --list List the contents of an archive. Arguments are optional. When given, they specify the names of the members to list. --test-label Test the archive volume label and exit. When used without arguments, it prints the volume label (if any) and exits with status 0. When one or more command line arguments are given. tar compares the volume label with each argument. It exits with code 0 if a match is found, and with code 1 otherwise. No output is displayed, unless used together with the -v (--verbose) option. There is no short option equivalent for this option. -u, --update Append files which are newer than the corresponding copy in the archive. Arguments have the same meaning as with the -c and -r options. Notice, that newer files don't replace their old archive copies, but instead are appended to the end of archive. The resulting archive can thus contain several members of the same name, corresponding to various versions of the same file. -x, --extract, --get Extract files from an archive. Arguments are optional. When given, they specify names of the archive members to be extracted. --show-defaults Show built-in defaults for various tar options and exit. -?, --help Display a short option summary and exit. --usage Display a list of available options and exit. --version Print program version and copyright information and exit. OPTIONS top Operation modifiers --check-device Check device numbers when creating incremental archives (default). -g, --listed-incremental=FILE Handle new GNU-format incremental backups. FILE is the name of a snapshot file, where tar stores additional information which is used to decide which files changed since the previous incremental dump and, consequently, must be dumped again. If FILE does not exist when creating an archive, it will be created and all files will be added to the resulting archive (the level 0 dump). To create incremental archives of non-zero level N, you need a copy of the snapshot file created for level N-1, and use it as FILE. When listing or extracting, the actual content of FILE is not inspected, it is needed only due to syntactical requirements. It is therefore common practice to use /dev/null in its place. --hole-detection=METHOD Use METHOD to detect holes in sparse files. This option implies --sparse. Valid values for METHOD are seek and raw. Default is seek with fallback to raw when not applicable. -G, --incremental Handle old GNU-format incremental backups. --ignore-failed-read Do not exit with nonzero on unreadable files. --level=NUMBER Set dump level for a created listed-incremental archive. Currently only --level=0 is meaningful: it instructs tar to truncate the snapshot file before dumping, thereby forcing a level 0 dump. -n, --seek Assume the archive is seekable. Normally tar determines automatically whether the archive can be seeked or not. This option is intended for use in cases when such recognition fails. It takes effect only if the archive is open for reading (e.g. with --list or --extract options). --no-check-device Do not check device numbers when creating incremental archives. --no-seek Assume the archive is not seekable. --occurrence[=N] Process only the Nth occurrence of each file in the archive. This option is valid only when used with one of the following subcommands: --delete, --diff, --extract or --list and when a list of files is given either on the command line or via the -T option. The default N is 1. --restrict Disable the use of some potentially harmful options. --sparse-version=MAJOR[.MINOR] Set which version of the sparse format to use. This option implies --sparse. Valid argument values are 0.0, 0.1, and 1.0. For a detailed discussion of sparse formats, refer to the GNU Tar Manual, appendix D, "Sparse Formats". Using the info reader, it can be accessed running the following command: info tar 'Sparse Formats'. -S, --sparse Handle sparse files efficiently. Some files in the file system may have segments which were actually never written (quite often these are database files created by such systems as DBM). When given this option, tar attempts to determine if the file is sparse prior to archiving it, and if so, to reduce the resulting archive size by not dumping empty parts of the file. Overwrite control These options control tar actions when extracting a file over an existing copy on disk. -k, --keep-old-files Don't replace existing files when extracting. --keep-newer-files Don't replace existing files that are newer than their archive copies. --keep-directory-symlink Don't replace existing symlinks to directories when extracting. --no-overwrite-dir Preserve metadata of existing directories. --one-top-level[=DIR] Extract all files into DIR, or, if used without argument, into a subdirectory named by the base name of the archive (minus standard compression suffixes recognizable by --auto-compress). --overwrite Overwrite existing files when extracting. --overwrite-dir Overwrite metadata of existing directories when extracting (default). --recursive-unlink Recursively remove all files in the directory prior to extracting it. --remove-files Remove files from disk after adding them to the archive. --skip-old-files Don't replace existing files when extracting, silently skip over them. -U, --unlink-first Remove each file prior to extracting over it. -W, --verify Verify the archive after writing it. Output stream selection --ignore-command-error Ignore subprocess exit codes. --no-ignore-command-error Treat non-zero exit codes of children as error (default). -O, --to-stdout Extract files to standard output. --to-command=COMMAND Pipe extracted files to COMMAND. The argument is the pathname of an external program, optionally with command line arguments. The program will be invoked and the contents of the file being extracted supplied to it on its standard input. Additional data will be supplied via the following environment variables: TAR_FILETYPE Type of the file. It is a single letter with the following meaning: f Regular file d Directory l Symbolic link h Hard link b Block device c Character device Currently only regular files are supported. TAR_MODE File mode, an octal number. TAR_FILENAME The name of the file. TAR_REALNAME Name of the file as stored in the archive. TAR_UNAME Name of the file owner. TAR_GNAME Name of the file owner group. TAR_ATIME Time of last access. It is a decimal number, representing seconds since the Epoch. If the archive provides times with nanosecond precision, the nanoseconds are appended to the timestamp after a decimal point. TAR_MTIME Time of last modification. TAR_CTIME Time of last status change. TAR_SIZE Size of the file. TAR_UID UID of the file owner. TAR_GID GID of the file owner. Additionally, the following variables contain information about tar operation mode and the archive being processed: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. Handling of file attributes --atime-preserve[=METHOD] Preserve access times on dumped files, either by restoring the times after reading (METHOD=replace, this is the default) or by not setting the times in the first place (METHOD=system). --delay-directory-restore Delay setting modification times and permissions of extracted directories until the end of extraction. Use this option when extracting from an archive which has unusual member ordering. --group=NAME[:GID] Force NAME as group for added files. If GID is not supplied, NAME can be either a user name or numeric GID. In this case the missing part (GID or name) will be inferred from the current host's group database. When used with --group-map=FILE, affects only those files whose owner group is not listed in FILE. --group-map=FILE Read group translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single group. It must consist of two fields, delimited by any amount of whitespace: OLDGRP NEWGRP[:NEWGID] OLDGRP is either a valid group name or a GID prefixed with +. Unless NEWGID is supplied, NEWGRP must also be either a valid group name or a +GID. Otherwise, both NEWGRP and NEWGID need not be listed in the system group database. As a result, each input file with owner group OLDGRP will be stored in archive with owner group NEWGRP and GID NEWGID. --mode=CHANGES Force symbolic mode CHANGES for added files. --mtime=DATE-OR-FILE Set mtime for added files. DATE-OR-FILE is either a date/time in almost arbitrary format, or the name of an existing file. In the latter case the mtime of that file will be used. -m, --touch Don't extract file modified time. --no-delay-directory-restore Cancel the effect of the prior --delay-directory-restore option. --no-same-owner Extract files as yourself (default for ordinary users). --no-same-permissions Apply the user's umask when extracting permissions from the archive (default for ordinary users). --numeric-owner Always use numbers for user/group names. --owner=NAME[:UID] Force NAME as owner for added files. If UID is not supplied, NAME can be either a user name or numeric UID. In this case the missing part (UID or name) will be inferred from the current host's user database. When used with --owner-map=FILE, affects only those files whose owner is not listed in FILE. --owner-map=FILE Read owner translation map from FILE. Empty lines are ignored. Comments are introduced with # sign and extend to the end of line. Each non-empty line in FILE defines translation for a single UID. It must consist of two fields, delimited by any amount of whitespace: OLDUSR NEWUSR[:NEWUID] OLDUSR is either a valid user name or a UID prefixed with +. Unless NEWUID is supplied, NEWUSR must also be either a valid user name or a +UID. Otherwise, both NEWUSR and NEWUID need not be listed in the system user database. As a result, each input file owned by OLDUSR will be stored in archive with owner name NEWUSR and UID NEWUID. -p, --preserve-permissions, --same-permissions Set permissions of extracted files to those recorded in the archive (default for superuser). --same-owner Try extracting files with the same ownership as exists in the archive (default for superuser). -s, --preserve-order, --same-order Tell tar that the list of file names to process is sorted in the same order as the files in the archive. --sort=ORDER When creating an archive, sort directory entries according to ORDER, which is one of none, name, or inode. The default is --sort=none, which stores archive members in the same order as returned by the operating system. Using --sort=name ensures the member ordering in the created archive is uniform and reproducible. Using --sort=inode reduces the number of disk seeks made when creating the archive and thus can considerably speed up archivation. This sorting order is supported only if the underlying system provides the necessary information. Extended file attributes --acls Enable POSIX ACLs support. --no-acls Disable POSIX ACLs support. --selinux Enable SELinux context support. --no-selinux Disable SELinux context support. --xattrs Enable extended attributes support. --no-xattrs Disable extended attributes support. --xattrs-exclude=PATTERN Specify the exclude pattern for xattr keys. PATTERN is a globbing pattern, e.g. --xattrs-exclude='user.*' to include only attributes from the user namespace. --xattrs-include=PATTERN Specify the include pattern for xattr keys. PATTERN is a globbing pattern. Device selection and switching -f, --file=ARCHIVE Use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable `TAPE'. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default. The default value can be inspected either using the --show-defaults option, or at the end of the tar --help output. An archive name that has a colon in it specifies a file or device on a remote machine. The part before the colon is taken as the machine name or IP address, and the part after it as the file or device pathname, e.g.: --file=remotehost:/dev/sr0 An optional username can be prefixed to the hostname, placing a @ sign between them. By default, the remote host is accessed via the rsh(1) command. Nowadays it is common to use ssh(1) instead. You can do so by giving the following command line option: --rsh-command=/usr/bin/ssh The remote machine should have the rmt(8) command installed. If its pathname does not match tar's default, you can inform tar about the correct pathname using the --rmt-command option. --force-local Archive file is local even if it has a colon. -F, --info-script=COMMAND, --new-volume-script=COMMAND Run COMMAND at the end of each tape (implies -M). The command can include arguments. When started, it will inherit tar's environment plus the following variables: TAR_VERSION GNU tar version number. TAR_ARCHIVE The name of the archive tar is processing. TAR_BLOCKING_FACTOR Current blocking factor, i.e. number of 512-byte blocks in a record. TAR_VOLUME Ordinal number of the volume tar is processing (set if reading a multi-volume archive). TAR_FORMAT Format of the archive being processed. One of: gnu, oldgnu, posix, ustar, v7. TAR_SUBCOMMAND A short option (with a leading dash) describing the operation tar is executing. TAR_FD File descriptor which can be used to communicate the new volume name to tar. If the info script fails, tar exits; otherwise, it begins writing the next volume. -L, --tape-length=N Change tape after writing Nx1024 bytes. If N is followed by a size suffix (see the subsection Size suffixes below), the suffix specifies the multiplicative factor to be used instead of 1024. This option implies -M. -M, --multi-volume Create/list/extract multi-volume archive. --rmt-command=COMMAND Use COMMAND instead of rmt when accessing remote archives. See the description of the -f option, above. --rsh-command=COMMAND Use COMMAND instead of rsh when accessing remote archives. See the description of the -f option, above. --volno-file=FILE When this option is used in conjunction with --multi-volume, tar will keep track of which volume of a multi-volume archive it is working in FILE. Device blocking -b, --blocking-factor=BLOCKS Set record size to BLOCKSx512 bytes. -B, --read-full-records When listing or extracting, accept incomplete input records after end-of-file marker. -i, --ignore-zeros Ignore zeroed blocks in archive. Normally two consecutive 512-blocks filled with zeroes mean EOF and tar stops reading after encountering them. This option instructs it to read further and is useful when reading archives created with the -A option. --record-size=NUMBER Set record size. NUMBER is the number of bytes per record. It must be multiple of 512. It can can be suffixed with a size suffix, e.g. --record-size=10K, for 10 Kilobytes. See the subsection Size suffixes, for a list of valid suffixes. Archive format selection -H, --format=FORMAT Create archive of the given format. Valid formats are: gnu GNU tar 1.13.x format oldgnu GNU format as per tar <= 1.12. pax, posix POSIX 1003.1-2001 (pax) format. ustar POSIX 1003.1-1988 (ustar) format. v7 Old V7 tar format. --old-archive, --portability Same as --format=v7. --pax-option=keyword[[:]=value][,keyword[[:]=value]]... Control pax keywords when creating PAX archives (-H pax). This option is equivalent to the -o option of the pax(1) utility. --posix Same as --format=posix. -V, --label=TEXT Create archive with volume name TEXT. If listing or extracting, use TEXT as a globbing pattern for volume name. Compression options -a, --auto-compress Use archive suffix to determine the compression program. -I, --use-compress-program=COMMAND Filter data through COMMAND. It must accept the -d option, for decompression. The argument can contain command line options. -j, --bzip2 Filter the archive through bzip2(1). -J, --xz Filter the archive through xz(1). --lzip Filter the archive through lzip(1). --lzma Filter the archive through lzma(1). --lzop Filter the archive through lzop(1). --no-auto-compress Do not use archive suffix to determine the compression program. -z, --gzip, --gunzip, --ungzip Filter the archive through gzip(1). -Z, --compress, --uncompress Filter the archive through compress(1). --zstd Filter the archive through zstd(1). Local file selection --add-file=FILE Add FILE to the archive (useful if its name starts with a dash). --backup[=CONTROL] Backup before removal. The CONTROL argument, if supplied, controls the backup policy. Its valid values are: none, off Never make backups. t, numbered Make numbered backups. nil, existing Make numbered backups if numbered backups exist, simple backups otherwise. never, simple Always make simple backups If CONTROL is not given, the value is taken from the VERSION_CONTROL environment variable. If it is not set, existing is assumed. -C, --directory=DIR Change to DIR before performing any operations. This option is order-sensitive, i.e. it affects all options that follow. --exclude=PATTERN Exclude files matching PATTERN, a glob(3)-style wildcard pattern. --exclude-backups Exclude backup and lock files. --exclude-caches Exclude contents of directories containing file CACHEDIR.TAG, except for the tag file itself. --exclude-caches-all Exclude directories containing file CACHEDIR.TAG and the file itself. --exclude-caches-under Exclude everything under directories containing CACHEDIR.TAG --exclude-ignore=FILE Before dumping a directory, see if it contains FILE. If so, read exclusion patterns from this file. The patterns affect only the directory itself. --exclude-ignore-recursive=FILE Same as --exclude-ignore, except that patterns from FILE affect both the directory and all its subdirectories. --exclude-tag=FILE Exclude contents of directories containing FILE, except for FILE itself. --exclude-tag-all=FILE Exclude directories containing FILE. --exclude-tag-under=FILE Exclude everything under directories containing FILE. --exclude-vcs Exclude version control system directories. --exclude-vcs-ignores Exclude files that match patterns read from VCS-specific ignore files. Supported files are: .cvsignore, .gitignore, .bzrignore, and .hgignore. -h, --dereference Follow symlinks; archive and dump the files they point to. --hard-dereference Follow hard links; archive and dump the files they refer to. -K, --starting-file=MEMBER Begin at the given member in the archive. --newer-mtime=DATE Work on files whose data changed after the DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --no-null Disable the effect of the previous --null option. --no-recursion Avoid descending automatically in directories. --no-unquote Do not unquote input file or member names. --no-verbatim-files-from Treat each line read from a file list as if it were supplied in the command line. I.e., leading and trailing whitespace is removed and, if the resulting string begins with a dash, it is treated as tar command line option. This is the default behavior. The --no-verbatim-files-from option is provided as a way to restore it after --verbatim-files-from option. This option is positional: it affects all --files-from options that occur after it in, until --verbatim-files-from option or end of line, whichever occurs first. It is implied by the --no-null option. --null Instruct subsequent -T options to read null-terminated names verbatim (disables special handling of names that start with a dash). See also --verbatim-files-from. -N, --newer=DATE, --after-date=DATE Only store files newer than DATE. If DATE starts with / or . it is taken to be a file name; the mtime of that file is used as the date. --one-file-system Stay in local file system when creating archive. -P, --absolute-names Don't strip leading slashes from file names when creating archives. --recursion Recurse into directories (default). --suffix=STRING Backup before removal, override usual suffix. Default suffix is ~, unless overridden by environment variable SIMPLE_BACKUP_SUFFIX. -T, --files-from=FILE Get names to extract or create from FILE. Unless specified otherwise, the FILE must contain a list of names separated by ASCII LF (i.e. one name per line). The names read are handled the same way as command line arguments. They undergo quote removal and word splitting, and any string that starts with a - is handled as tar command line option. If this behavior is undesirable, it can be turned off using the --verbatim-files-from option. The --null option instructs tar that the names in FILE are separated by ASCII NUL character, instead of LF. It is useful if the list is generated by find(1) -print0 predicate. --unquote Unquote file or member names (default). --verbatim-files-from Treat each line obtained from a file list as a file name, even if it starts with a dash. File lists are supplied with the --files-from (-T) option. The default behavior is to handle names supplied in file lists as if they were typed in the command line, i.e. any names starting with a dash are treated as tar options. The --verbatim-files-from option disables this behavior. This option affects all --files-from options that occur after it in the command line. Its effect is reverted by the --no-verbatim-files-from option. This option is implied by the --null option. See also --add-file. -X, --exclude-from=FILE Exclude files matching patterns listed in FILE. File name transformations --strip-components=NUMBER Strip NUMBER leading components from file names on extraction. --transform=EXPRESSION, --xform=EXPRESSION Use sed replace EXPRESSION to transform file names. File name matching options These options affect both exclude and include patterns. --anchored Patterns match file name start. --ignore-case Ignore case. --no-anchored Patterns match after any / (default for exclusion). --no-ignore-case Case sensitive matching (default). --no-wildcards Verbatim string matching. --no-wildcards-match-slash Wildcards do not match /. --wildcards Use wildcards (default for exclusion). --wildcards-match-slash Wildcards match / (default for exclusion). Informative output --checkpoint[=N] Display progress messages every Nth record (default 10). --checkpoint-action=ACTION Run ACTION on each checkpoint. --clamp-mtime Only set time when the file is more recent than what was given with --mtime. --full-time Print file time to its full resolution. --index-file=FILE Send verbose output to FILE. -l, --check-links Print a message if not all links are dumped. --no-quote-chars=STRING Disable quoting for characters from STRING. --quote-chars=STRING Additionally quote characters from STRING. --quoting-style=STYLE Set quoting style for file and member names. Valid values for STYLE are literal, shell, shell-always, c, c-maybe, escape, locale, clocale. -R, --block-number Show block number within archive with each message. --show-omitted-dirs When listing or extracting, list each directory that does not match search criteria. --show-transformed-names, --show-stored-names Show file or archive names after transformation by --strip and --transform options. --totals[=SIGNAL] Print total bytes after processing the archive. If SIGNAL is given, print total bytes when this signal is delivered. Allowed signals are: SIGHUP, SIGQUIT, SIGINT, SIGUSR1, and SIGUSR2. The SIG prefix can be omitted. --utc Print file modification times in UTC. -v, --verbose Verbosely list files processed. Each instance of this option on the command line increases the verbosity level by one. The maximum verbosity level is 3. For a detailed discussion of how various verbosity levels affect tar's output, please refer to GNU Tar Manual, subsection 2.5.2 "The '--verbose' Option". --warning=KEYWORD Enable or disable warning messages identified by KEYWORD. The messages are suppressed if KEYWORD is prefixed with no- and enabled otherwise. Multiple --warning options accumulate. Keywords controlling general tar operation: all Enable all warning messages. This is the default. none Disable all warning messages. filename-with-nuls "%s: file name read contains nul character" alone-zero-block "A lone zero block at %s" Keywords applicable for tar --create: cachedir "%s: contains a cache directory tag %s; %s" file-shrank "%s: File shrank by %s bytes; padding with zeros" xdev "%s: file is on a different filesystem; not dumped" file-ignored "%s: Unknown file type; file ignored" "%s: socket ignored" "%s: door ignored" file-unchanged "%s: file is unchanged; not dumped" ignore-archive "%s: archive cannot contain itself; not dumped" file-removed "%s: File removed before we read it" file-changed "%s: file changed as we read it" failed-read Suppresses warnings about unreadable files or directories. This keyword applies only if used together with the --ignore-failed-read option. Keywords applicable for tar --extract: existing-file "%s: skipping existing file" timestamp "%s: implausibly old time stamp %s" "%s: time stamp %s is %s s in the future" contiguous-cast "Extracting contiguous files as regular files" symlink-cast "Attempting extraction of symbolic links as hard links" unknown-cast "%s: Unknown file type '%c', extracted as normal file" ignore-newer "Current %s is newer or same age" unknown-keyword "Ignoring unknown extended header keyword '%s'" decompress-program Controls verbose description of failures occurring when trying to run alternative decompressor programs. This warning is disabled by default (unless --verbose is used). A common example of what you can get when using this warning is: $ tar --warning=decompress-program -x -f archive.Z tar (child): cannot run compress: No such file or directory tar (child): trying gzip This means that tar first tried to decompress archive.Z using compress, and, when that failed, switched to gzip. record-size "Record size = %lu blocks" Keywords controlling incremental extraction: rename-directory "%s: Directory has been renamed from %s" "%s: Directory has been renamed" new-directory "%s: Directory is new" xdev "%s: directory is on a different device: not purging" bad-dumpdir "Malformed dumpdir: 'X' never used" -w, --interactive, --confirmation Ask for confirmation for every action. Compatibility options -o When creating, same as --old-archive. When extracting, same as --no-same-owner. Size suffixes Suffix Units Byte Equivalent b Blocks SIZE x 512 B Kilobytes SIZE x 1024 c Bytes SIZE G Gigabytes SIZE x 1024^3 K Kilobytes SIZE x 1024 k Kilobytes SIZE x 1024 M Megabytes SIZE x 1024^2 P Petabytes SIZE x 1024^5 T Terabytes SIZE x 1024^4 w Words SIZE x 2 RETURN VALUE top Tar's exit code indicates whether it was able to successfully perform the requested operation, and if not, what kind of error occurred. 0 Successful termination. 1 Some files differ. If tar was invoked with the --compare (--diff, -d) command line option, this means that some files in the archive differ from their disk counterparts. If tar was given one of the --create, --append or --update options, this exit code means that some files were changed while being archived and so the resulting archive does not contain the exact copy of the file set. 2 Fatal error. This means that some fatal, unrecoverable error occurred. If a subprocess that had been invoked by tar exited with a nonzero exit code, tar itself exits with that code as well. This can happen, for example, if a compression option (e.g. -z) was used and the external compressor program failed. Another example is rmt failure during backup to a remote device. SEE ALSO top bzip2(1), compress(1), gzip(1), lzma(1), lzop(1), rmt(8), symlink(7), xz(1), zstd(1). Complete tar manual: run info tar or use emacs(1) info mode to read it. Online copies of GNU tar documentation in various formats can be found at: https://www.gnu.org/software/tar/manual BUG REPORTS top Report bugs to <bug-tar@gnu.org>. COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. COLOPHON top This page is part of the tar (an archiver program) project. Information about the project can be found at http://savannah.gnu.org/projects/tar/. If you have a bug report for this manual page, see http://savannah.gnu.org/bugs/?group=tar. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/tar.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-09-12.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org TAR July 11, 2022 TAR(1) Pages that refer to this page: attr(1), dpkg-deb(1), dpkg-source(1), machinectl(1), rsync(1), st(4), suffixes(7), symlink(7), cupsd-helper(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create compressed archive of all the files in the current directory tree that have been modified in the last 7 days Bash Command:<START>find . -type f -mtime -7 -print -exec cat {} \; | tar cf - | gzip -9<END> |
Create directorie(s) 'some/path' as required in the current directory | mkdir -p ./some/path | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create directorie(s) 'some/path' as required in the current directory Bash Command:<START>mkdir -p ./some/path<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create directorie(s) 'some/path' as required in the current directory Bash Command:<START>mkdir -p ./some/path<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create directorie(s) 'some/path' as required in the current directory Bash Command:<START>mkdir -p ./some/path<END> |
Create directories "/tmp/x/y/z/" on remote host before copying "$source" to "user@remote:/tmp/x/y/z/" | rsync -a --rsync-path="mkdir -p /tmp/x/y/z/ && rsync" $source user@remote:/tmp/x/y/z/ | ['rsync'] | Output a Bash command to accomplish the following task. Task: Create directories "/tmp/x/y/z/" on remote host before copying "$source" to "user@remote:/tmp/x/y/z/" Bash Command:<START>rsync -a --rsync-path="mkdir -p /tmp/x/y/z/ && rsync" $source user@remote:/tmp/x/y/z/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # rsync\n\n> Transfer files either to or from a remote host (but not between two remote hosts), by default using SSH.\n> To specify a remote path, use `user@host:path/to/file_or_directory`.\n> More information: <https://download.samba.org/pub/rsync/rsync.1>.\n\n- Transfer a file:\n\n`rsync {{path/to/source}} {{path/to/destination}}`\n\n- Use archive mode (recursively copy directories, copy symlinks without resolving, and preserve permissions, ownership and modification times):\n\n`rsync --archive {{path/to/source}} {{path/to/destination}}`\n\n- Compress the data as it is sent to the destination, display verbose and human-readable progress, and keep partially transferred files if interrupted:\n\n`rsync --compress --verbose --human-readable --partial --progress {{path/to/source}} {{path/to/destination}}`\n\n- Recursively copy directories:\n\n`rsync --recursive {{path/to/source}} {{path/to/destination}}`\n\n- Transfer directory contents, but not the directory itself:\n\n`rsync --recursive {{path/to/source}}/ {{path/to/destination}}`\n\n- Use archive mode, resolve symlinks and skip files that are newer on the destination:\n\n`rsync --archive --update --copy-links {{path/to/source}} {{path/to/destination}}`\n\n- Transfer a directory to a remote host running `rsyncd` and delete files on the destination that do not exist on the source:\n\n`rsync --recursive --delete rsync://{{host}}:{{path/to/source}} {{path/to/destination}}`\n\n- Transfer a file over SSH using a different port than the default (22) and show global progress:\n\n`rsync --rsh 'ssh -p {{port}}' --info=progress2 {{host}}:{{path/to/source}} {{path/to/destination}}`\n Task: Create directories "/tmp/x/y/z/" on remote host before copying "$source" to "user@remote:/tmp/x/y/z/" Bash Command:<START>rsync -a --rsync-path="mkdir -p /tmp/x/y/z/ && rsync" $source user@remote:/tmp/x/y/z/<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: rsync(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training rsync(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | GENERAL | SETUP | USAGE | COPYING TO A DIFFERENT NAME | SORTED TRANSFER ORDER | MULTI-HOST SECURITY | ADVANCED USAGE | CONNECTING TO AN RSYNC DAEMON | USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION | STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS | EXAMPLES | OPTION SUMMARY | OPTIONS | DAEMON OPTIONS | FILTER RULES | TRANSFER RULES | BATCH MODE | SYMBOLIC LINKS | DIAGNOSTICS | EXIT VALUES | ENVIRONMENT VARIABLES | FILES | SEE ALSO | BUGS | VERSION | INTERNAL OPTIONS | CREDITS | THANKS | AUTHOR | COLOPHON rsync(1) User Commands rsync(1) NAME top rsync - a fast, versatile, remote (and local) file-copying tool SYNOPSIS top Local: rsync [OPTION...] SRC... [DEST] Access via remote shell: Pull: rsync [OPTION...] [USER@]HOST:SRC... [DEST] Push: rsync [OPTION...] SRC... [USER@]HOST:DEST Access via rsync daemon: Pull: rsync [OPTION...] [USER@]HOST::SRC... [DEST] rsync [OPTION...] rsync://[USER@]HOST[:PORT]/SRC... [DEST] Push: rsync [OPTION...] SRC... [USER@]HOST::DEST rsync [OPTION...] SRC... rsync://[USER@]HOST[:PORT]/DEST) Usages with just one SRC arg and no DEST arg will list the source files instead of copying. The online version of this manpage (that includes cross-linking of topics) is available at https://download.samba.org/pub/rsync/rsync.1. DESCRIPTION top Rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. It offers a large number of options that control every aspect of its behavior and permit very flexible specification of the set of files to be copied. It is famous for its delta-transfer algorithm, which reduces the amount of data sent over the network by sending only the differences between the source files and the existing files in the destination. Rsync is widely used for backups and mirroring and as an improved copy command for everyday use. Rsync finds files that need to be transferred using a "quick check" algorithm (by default) that looks for files that have changed in size or in last-modified time. Any changes in the other preserved attributes (as requested by options) are made on the destination file directly when the quick check indicates that the file's data does not need to be updated. Some of the additional features of rsync are: o support for copying links, devices, owners, groups, and permissions o exclude and exclude-from options similar to GNU tar o a CVS exclude mode for ignoring the same files that CVS would ignore o can use any transparent remote shell, including ssh or rsh o does not require super-user privileges o pipelining of file transfers to minimize latency costs o support for anonymous or authenticated rsync daemons (ideal for mirroring) GENERAL top Rsync copies files either to or from a remote host, or locally on the current host (it does not support copying files between two remote hosts). There are two different ways for rsync to contact a remote system: using a remote-shell program as the transport (such as ssh or rsh) or contacting an rsync daemon directly via TCP. The remote-shell transport is used whenever the source or destination path contains a single colon (:) separator after a host specification. Contacting an rsync daemon directly happens when the source or destination path contains a double colon (::) separator after a host specification, OR when an rsync:// URL is specified (see also the USING RSYNC-DAEMON FEATURES VIA A REMOTE- SHELL CONNECTION section for an exception to this latter rule). As a special case, if a single source arg is specified without a destination, the files are listed in an output format similar to "ls -l". As expected, if neither the source or destination path specify a remote host, the copy occurs locally (see also the --list-only option). Rsync refers to the local side as the client and the remote side as the server. Don't confuse server with an rsync daemon. A daemon is always a server, but a server can be either a daemon or a remote-shell spawned process. SETUP top See the file README.md for installation instructions. Once installed, you can use rsync to any machine that you can access via a remote shell (as well as some that you can access using the rsync daemon-mode protocol). For remote transfers, a modern rsync uses ssh for its communications, but it may have been configured to use a different remote shell by default, such as rsh or remsh. You can also specify any remote shell you like, either by using the -e command line option, or by setting the RSYNC_RSH environment variable. Note that rsync must be installed on both the source and destination machines. USAGE top You use rsync in the same way you use rcp. You must specify a source and a destination, one of which may be remote. Perhaps the best way to explain the syntax is with some examples: rsync -t *.c foo:src/ This would transfer all files matching the pattern *.c from the current directory to the directory src on the machine foo. If any of the files already exist on the remote system then the rsync remote-update protocol is used to update the file by sending only the differences in the data. Note that the expansion of wildcards on the command-line (*.c) into a list of files is handled by the shell before it runs rsync and not by rsync itself (exactly the same as all other Posix-style programs). rsync -avz foo:src/bar /data/tmp This would recursively transfer all files from the directory src/bar on the machine foo into the /data/tmp/bar directory on the local machine. The files are transferred in archive mode, which ensures that symbolic links, devices, attributes, permissions, ownerships, etc. are preserved in the transfer. Additionally, compression will be used to reduce the size of data portions of the transfer. rsync -avz foo:src/bar/ /data/tmp A trailing slash on the source changes this behavior to avoid creating an additional directory level at the destination. You can think of a trailing / on a source as meaning "copy the contents of this directory" as opposed to "copy the directory by name", but in both cases the attributes of the containing directory are transferred to the containing directory on the destination. In other words, each of the following commands copies the files in the same way, including their setting of the attributes of /dest/foo: rsync -av /src/foo /dest rsync -av /src/foo/ /dest/foo Note also that host and module references don't require a trailing slash to copy the contents of the default directory. For example, both of these copy the remote directory's contents into "/dest": rsync -av host: /dest rsync -av host::module /dest You can also use rsync in local-only mode, where both the source and destination don't have a ':' in the name. In this case it behaves like an improved copy command. Finally, you can list all the (listable) modules available from a particular rsync daemon by leaving off the module name: rsync somehost.mydomain.com:: COPYING TO A DIFFERENT NAME top When you want to copy a directory to a different name, use a trailing slash on the source directory to put the contents of the directory into any destination directory you like: rsync -ai foo/ bar/ Rsync also has the ability to customize a destination file's name when copying a single item. The rules for this are: o The transfer list must consist of a single item (either a file or an empty directory) o The final element of the destination path must not exist as a directory o The destination path must not have been specified with a trailing slash Under those circumstances, rsync will set the name of the destination's single item to the last element of the destination path. Keep in mind that it is best to only use this idiom when copying a file and use the above trailing-slash idiom when copying a directory. The following example copies the foo.c file as bar.c in the save dir (assuming that bar.c isn't a directory): rsync -ai src/foo.c save/bar.c The single-item copy rule might accidentally bite you if you unknowingly copy a single item and specify a destination dir that doesn't exist (without using a trailing slash). For example, if src/*.c matches one file and save/dir doesn't exist, this will confuse you by naming the destination file save/dir: rsync -ai src/*.c save/dir To prevent such an accident, either make sure the destination dir exists or specify the destination path with a trailing slash: rsync -ai src/*.c save/dir/ SORTED TRANSFER ORDER top Rsync always sorts the specified filenames into its internal transfer list. This handles the merging together of the contents of identically named directories, makes it easy to remove duplicate filenames. It can, however, confuse someone when the files are transferred in a different order than what was given on the command-line. If you need a particular file to be transferred prior to another, either separate the files into different rsync calls, or consider using --delay-updates (which doesn't affect the sorted transfer order, but does make the final file-updating phase happen much more rapidly). MULTI-HOST SECURITY top Rsync takes steps to ensure that the file requests that are shared in a transfer are protected against various security issues. Most of the potential problems arise on the receiving side where rsync takes steps to ensure that the list of files being transferred remains within the bounds of what was requested. Toward this end, rsync 3.1.2 and later have aborted when a file list contains an absolute or relative path that tries to escape out of the top of the transfer. Also, beginning with version 3.2.5, rsync does two more safety checks of the file list to (1) ensure that no extra source arguments were added into the transfer other than those that the client requested and (2) ensure that the file list obeys the exclude rules that were sent to the sender. For those that don't yet have a 3.2.5 client rsync (or those that want to be extra careful), it is safest to do a copy into a dedicated destination directory for the remote files when you don't trust the remote host. For example, instead of doing an rsync copy into your home directory: rsync -aiv host1:dir1 ~ Dedicate a "host1-files" dir to the remote content: rsync -aiv host1:dir1 ~/host1-files See the --trust-sender option for additional details. CAUTION: it is not particularly safe to use rsync to copy files from a case-preserving filesystem to a case-ignoring filesystem. If you must perform such a copy, you should either disable symlinks via --no-links or enable the munging of symlinks via --munge-links (and make sure you use the right local or remote option). This will prevent rsync from doing potentially dangerous things if a symlink name overlaps with a file or directory. It does not, however, ensure that you get a full copy of all the files (since that may not be possible when the names overlap). A potentially better solution is to list all the source files and create a safe list of filenames that you pass to the --files-from option. Any files that conflict in name would need to be copied to different destination directories using more than one copy. While a copy of a case-ignoring filesystem to a case-ignoring filesystem can work out fairly well, if no --delete-during or --delete-before option is active, rsync can potentially update an existing file on the receiveing side without noticing that the upper-/lower-case of the filename should be changed to match the sender. ADVANCED USAGE top The syntax for requesting multiple files from a remote host is done by specifying additional remote-host args in the same style as the first, or with the hostname omitted. For instance, all these work: rsync -aiv host:file1 :file2 host:file{3,4} /dest/ rsync -aiv host::modname/file{1,2} host::modname/extra /dest/ rsync -aiv host::modname/first ::extra-file{1,2} /dest/ Note that a daemon connection only supports accessing one module per copy command, so if the start of a follow-up path doesn't begin with the modname of the first path, it is assumed to be a path in the module (such as the extra-file1 & extra-file2 that are grabbed above). Really old versions of rsync (2.6.9 and before) only allowed specifying one remote-source arg, so some people have instead relied on the remote-shell performing space splitting to break up an arg into multiple paths. Such unintuitive behavior is no longer supported by default (though you can request it, as described below). Starting in 3.2.4, filenames are passed to a remote shell in such a way as to preserve the characters you give it. Thus, if you ask for a file with spaces in the name, that's what the remote rsync looks for: rsync -aiv host:'a simple file.pdf' /dest/ If you use scripts that have been written to manually apply extra quoting to the remote rsync args (or to require remote arg splitting), you can ask rsync to let your script handle the extra escaping. This is done by either adding the --old-args option to the rsync runs in the script (which requires a new rsync) or exporting RSYNC_OLD_ARGS=1 and RSYNC_PROTECT_ARGS=0 (which works with old or new rsync versions). CONNECTING TO AN RSYNC DAEMON top It is also possible to use rsync without a remote shell as the transport. In this case you will directly connect to a remote rsync daemon, typically using TCP port 873. (This obviously requires the daemon to be running on the remote system, so refer to the STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS section below for information on that.) Using rsync in this way is the same as using it with a remote shell except that: o Use either double-colon syntax or rsync:// URL syntax instead of the single-colon (remote shell) syntax. o The first element of the "path" is actually a module name. o Additional remote source args can use an abbreviated syntax that omits the hostname and/or the module name, as discussed in ADVANCED USAGE. o The remote daemon may print a "message of the day" when you connect. o If you specify only the host (with no module or path) then a list of accessible modules on the daemon is output. o If you specify a remote source path but no destination, a listing of the matching files on the remote daemon is output. o The --rsh (-e) option must be omitted to avoid changing the connection style from using a socket connection to USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION. An example that copies all the files in a remote module named "src": rsync -av host::src /dest Some modules on the remote daemon may require authentication. If so, you will receive a password prompt when you connect. You can avoid the password prompt by setting the environment variable RSYNC_PASSWORD to the password you want to use or using the --password-file option. This may be useful when scripting rsync. WARNING: On some systems environment variables are visible to all users. On those systems using --password-file is recommended. You may establish the connection via a web proxy by setting the environment variable RSYNC_PROXY to a hostname:port pair pointing to your web proxy. Note that your web proxy's configuration must support proxy connections to port 873. You may also establish a daemon connection using a program as a proxy by setting the environment variable RSYNC_CONNECT_PROG to the commands you wish to run in place of making a direct socket connection. The string may contain the escape "%H" to represent the hostname specified in the rsync command (so use "%%" if you need a single "%" in your string). For example: export RSYNC_CONNECT_PROG='ssh proxyhost nc %H 873' rsync -av targethost1::module/src/ /dest/ rsync -av rsync://targethost2/module/src/ /dest/ The command specified above uses ssh to run nc (netcat) on a proxyhost, which forwards all data to port 873 (the rsync daemon) on the targethost (%H). Note also that if the RSYNC_SHELL environment variable is set, that program will be used to run the RSYNC_CONNECT_PROG command instead of using the default shell of the system() call. USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION top It is sometimes useful to use various features of an rsync daemon (such as named modules) without actually allowing any new socket connections into a system (other than what is already required to allow remote-shell access). Rsync supports connecting to a host using a remote shell and then spawning a single-use "daemon" server that expects to read its config file in the home dir of the remote user. This can be useful if you want to encrypt a daemon-style transfer's data, but since the daemon is started up fresh by the remote user, you may not be able to use features such as chroot or change the uid used by the daemon. (For another way to encrypt a daemon transfer, consider using ssh to tunnel a local port to a remote machine and configure a normal rsync daemon on that remote host to only allow connections from "localhost".) From the user's perspective, a daemon transfer via a remote-shell connection uses nearly the same command-line syntax as a normal rsync-daemon transfer, with the only exception being that you must explicitly set the remote shell program on the command-line with the --rsh=COMMAND option. (Setting the RSYNC_RSH in the environment will not turn on this functionality.) For example: rsync -av --rsh=ssh host::module /dest If you need to specify a different remote-shell user, keep in mind that the user@ prefix in front of the host is specifying the rsync-user value (for a module that requires user-based authentication). This means that you must give the '-l user' option to ssh when specifying the remote-shell, as in this example that uses the short version of the --rsh option: rsync -av -e "ssh -l ssh-user" rsync-user@host::module /dest The "ssh-user" will be used at the ssh level; the "rsync-user" will be used to log-in to the "module". In this setup, the daemon is started by the ssh command that is accessing the system (which can be forced via the ~/.ssh/authorized_keys file, if desired). However, when accessing a daemon directly, it needs to be started beforehand. STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS top In order to connect to an rsync daemon, the remote system needs to have a daemon already running (or it needs to have configured something like inetd to spawn an rsync daemon for incoming connections on a particular port). For full information on how to start a daemon that will handling incoming socket connections, see the rsyncd.conf(5) manpage -- that is the config file for the daemon, and it contains the full details for how to run the daemon (including stand-alone and inetd configurations). If you're using one of the remote-shell transports for the transfer, there is no need to manually start an rsync daemon. EXAMPLES top Here are some examples of how rsync can be used. To backup a home directory, which consists of large MS Word files and mail folders, a per-user cron job can be used that runs this each day: rsync -aiz . bkhost:backup/joe/ To move some files from a remote host to the local host, you could run: rsync -aiv --remove-source-files rhost:/tmp/{file1,file2}.c ~/src/ OPTION SUMMARY top Here is a short summary of the options available in rsync. Each option also has its own detailed description later in this manpage. --verbose, -v increase verbosity --info=FLAGS fine-grained informational verbosity --debug=FLAGS fine-grained debug verbosity --stderr=e|a|c change stderr output mode (default: errors) --quiet, -q suppress non-error messages --no-motd suppress daemon-mode MOTD --checksum, -c skip based on checksum, not mod-time & size --archive, -a archive mode is -rlptgoD (no -A,-X,-U,-N,-H) --no-OPTION turn off an implied OPTION (e.g. --no-D) --recursive, -r recurse into directories --relative, -R use relative path names --no-implied-dirs don't send implied dirs with --relative --backup, -b make backups (see --suffix & --backup-dir) --backup-dir=DIR make backups into hierarchy based in DIR --suffix=SUFFIX backup suffix (default ~ w/o --backup-dir) --update, -u skip files that are newer on the receiver --inplace update destination files in-place --append append data onto shorter files --append-verify --append w/old data in file checksum --dirs, -d transfer directories without recursing --old-dirs, --old-d works like --dirs when talking to old rsync --mkpath create destination's missing path components --links, -l copy symlinks as symlinks --copy-links, -L transform symlink into referent file/dir --copy-unsafe-links only "unsafe" symlinks are transformed --safe-links ignore symlinks that point outside the tree --munge-links munge symlinks to make them safe & unusable --copy-dirlinks, -k transform symlink to dir into referent dir --keep-dirlinks, -K treat symlinked dir on receiver as dir --hard-links, -H preserve hard links --perms, -p preserve permissions --executability, -E preserve executability --chmod=CHMOD affect file and/or directory permissions --acls, -A preserve ACLs (implies --perms) --xattrs, -X preserve extended attributes --owner, -o preserve owner (super-user only) --group, -g preserve group --devices preserve device files (super-user only) --copy-devices copy device contents as a regular file --write-devices write to devices as files (implies --inplace) --specials preserve special files -D same as --devices --specials --times, -t preserve modification times --atimes, -U preserve access (use) times --open-noatime avoid changing the atime on opened files --crtimes, -N preserve create times (newness) --omit-dir-times, -O omit directories from --times --omit-link-times, -J omit symlinks from --times --super receiver attempts super-user activities --fake-super store/recover privileged attrs using xattrs --sparse, -S turn sequences of nulls into sparse blocks --preallocate allocate dest files before writing them --dry-run, -n perform a trial run with no changes made --whole-file, -W copy files whole (w/o delta-xfer algorithm) --checksum-choice=STR choose the checksum algorithm (aka --cc) --one-file-system, -x don't cross filesystem boundaries --block-size=SIZE, -B force a fixed checksum block-size --rsh=COMMAND, -e specify the remote shell to use --rsync-path=PROGRAM specify the rsync to run on remote machine --existing skip creating new files on receiver --ignore-existing skip updating files that exist on receiver --remove-source-files sender removes synchronized files (non-dir) --del an alias for --delete-during --delete delete extraneous files from dest dirs --delete-before receiver deletes before xfer, not during --delete-during receiver deletes during the transfer --delete-delay find deletions during, delete after --delete-after receiver deletes after transfer, not during --delete-excluded also delete excluded files from dest dirs --ignore-missing-args ignore missing source args without error --delete-missing-args delete missing source args from destination --ignore-errors delete even if there are I/O errors --force force deletion of dirs even if not empty --max-delete=NUM don't delete more than NUM files --max-size=SIZE don't transfer any file larger than SIZE --min-size=SIZE don't transfer any file smaller than SIZE --max-alloc=SIZE change a limit relating to memory alloc --partial keep partially transferred files --partial-dir=DIR put a partially transferred file into DIR --delay-updates put all updated files into place at end --prune-empty-dirs, -m prune empty directory chains from file-list --numeric-ids don't map uid/gid values by user/group name --usermap=STRING custom username mapping --groupmap=STRING custom groupname mapping --chown=USER:GROUP simple username/groupname mapping --timeout=SECONDS set I/O timeout in seconds --contimeout=SECONDS set daemon connection timeout in seconds --ignore-times, -I don't skip files that match size and time --size-only skip files that match in size --modify-window=NUM, -@ set the accuracy for mod-time comparisons --temp-dir=DIR, -T create temporary files in directory DIR --fuzzy, -y find similar file for basis if no dest file --compare-dest=DIR also compare destination files relative to DIR --copy-dest=DIR ... and include copies of unchanged files --link-dest=DIR hardlink to files in DIR when unchanged --compress, -z compress file data during the transfer --compress-choice=STR choose the compression algorithm (aka --zc) --compress-level=NUM explicitly set compression level (aka --zl) --skip-compress=LIST skip compressing files with suffix in LIST --cvs-exclude, -C auto-ignore files in the same way CVS does --filter=RULE, -f add a file-filtering RULE -F same as --filter='dir-merge /.rsync-filter' repeated: --filter='- .rsync-filter' --exclude=PATTERN exclude files matching PATTERN --exclude-from=FILE read exclude patterns from FILE --include=PATTERN don't exclude files matching PATTERN --include-from=FILE read include patterns from FILE --files-from=FILE read list of source-file names from FILE --from0, -0 all *-from/filter files are delimited by 0s --old-args disable the modern arg-protection idiom --secluded-args, -s use the protocol to safely send the args --trust-sender trust the remote sender's file list --copy-as=USER[:GROUP] specify user & optional group for the copy --address=ADDRESS bind address for outgoing socket to daemon --port=PORT specify double-colon alternate port number --sockopts=OPTIONS specify custom TCP options --blocking-io use blocking I/O for the remote shell --outbuf=N|L|B set out buffering to None, Line, or Block --stats give some file-transfer stats --8-bit-output, -8 leave high-bit chars unescaped in output --human-readable, -h output numbers in a human-readable format --progress show progress during transfer -P same as --partial --progress --itemize-changes, -i output a change-summary for all updates --remote-option=OPT, -M send OPTION to the remote side only --out-format=FORMAT output updates using the specified FORMAT --log-file=FILE log what we're doing to the specified FILE --log-file-format=FMT log updates using the specified FMT --password-file=FILE read daemon-access password from FILE --early-input=FILE use FILE for daemon's early exec input --list-only list the files instead of copying them --bwlimit=RATE limit socket I/O bandwidth --stop-after=MINS Stop rsync after MINS minutes have elapsed --stop-at=y-m-dTh:m Stop rsync at the specified point in time --fsync fsync every written file --write-batch=FILE write a batched update to FILE --only-write-batch=FILE like --write-batch but w/o updating dest --read-batch=FILE read a batched update from FILE --protocol=NUM force an older protocol version to be used --iconv=CONVERT_SPEC request charset conversion of filenames --checksum-seed=NUM set block/file checksum seed (advanced) --ipv4, -4 prefer IPv4 --ipv6, -6 prefer IPv6 --version, -V print the version + other info and exit --help, -h (*) show this help (* -h is help only on its own) Rsync can also be run as a daemon, in which case the following options are accepted: --daemon run as an rsync daemon --address=ADDRESS bind to the specified address --bwlimit=RATE limit socket I/O bandwidth --config=FILE specify alternate rsyncd.conf file --dparam=OVERRIDE, -M override global daemon config parameter --no-detach do not detach from the parent --port=PORT listen on alternate port number --log-file=FILE override the "log file" setting --log-file-format=FMT override the "log format" setting --sockopts=OPTIONS specify custom TCP options --verbose, -v increase verbosity --ipv4, -4 prefer IPv4 --ipv6, -6 prefer IPv6 --help, -h show this help (when used with --daemon) OPTIONS top Rsync accepts both long (double-dash + word) and short (single- dash + letter) options. The full list of the available options are described below. If an option can be specified in more than one way, the choices are comma-separated. Some options only have a long variant, not a short. If the option takes a parameter, the parameter is only listed after the long variant, even though it must also be specified for the short. When specifying a parameter, you can either use the form --option=param, --option param, -o=param, -o param, or -oparam (the latter choices assume that your option has a short variant). The parameter may need to be quoted in some manner for it to survive the shell's command-line parsing. Also keep in mind that a leading tilde (~) in a pathname is substituted by your shell, so make sure that you separate the option name from the pathname using a space if you want the local shell to expand it. --help Print a short help page describing the options available in rsync and exit. You can also use -h for --help when it is used without any other options (since it normally means --human-readable). --version, -V Print the rsync version plus other info and exit. When repeated, the information is output is a JSON format that is still fairly readable (client side only). The output includes a list of compiled-in capabilities, a list of optimizations, the default list of checksum algorithms, the default list of compression algorithms, the default list of daemon auth digests, a link to the rsync web site, and a few other items. --verbose, -v This option increases the amount of information you are given during the transfer. By default, rsync works silently. A single -v will give you information about what files are being transferred and a brief summary at the end. Two -v options will give you information on what files are being skipped and slightly more information at the end. More than two -v options should only be used if you are debugging rsync. The end-of-run summary tells you the number of bytes sent to the remote rsync (which is the receiving side on a local copy), the number of bytes received from the remote host, and the average bytes per second of the transferred data computed over the entire length of the rsync run. The second line shows the total size (in bytes), which is the sum of all the file sizes that rsync considered transferring. It also shows a "speedup" value, which is a ratio of the total file size divided by the sum of the sent and received bytes (which is really just a feel-good bigger-is-better number). Note that these byte values can be made more (or less) human-readable by using the --human-readable (or --no-human-readable) options. In a modern rsync, the -v option is equivalent to the setting of groups of --info and --debug options. You can choose to use these newer options in addition to, or in place of using --verbose, as any fine-grained settings override the implied settings of -v. Both --info and --debug have a way to ask for help that tells you exactly what flags are set for each increase in verbosity. However, do keep in mind that a daemon's "max verbosity" setting will limit how high of a level the various individual flags can be set on the daemon side. For instance, if the max is 2, then any info and/or debug flag that is set to a higher value than what would be set by -vv will be downgraded to the -vv level in the daemon's logging. --info=FLAGS This option lets you have fine-grained control over the information output you want to see. An individual flag name may be followed by a level number, with 0 meaning to silence that output, 1 being the default output level, and higher numbers increasing the output of that flag (for those that support higher levels). Use --info=help to see all the available flag names, what they output, and what flag names are added for each increase in the verbose level. Some examples: rsync -a --info=progress2 src/ dest/ rsync -avv --info=stats2,misc1,flist0 src/ dest/ Note that --info=name's output is affected by the --out- format and --itemize-changes (-i) options. See those options for more information on what is output and when. This option was added to 3.1.0, so an older rsync on the server side might reject your attempts at fine-grained control (if one or more flags needed to be send to the server and the server was too old to understand them). See also the "max verbosity" caveat above when dealing with a daemon. --debug=FLAGS This option lets you have fine-grained control over the debug output you want to see. An individual flag name may be followed by a level number, with 0 meaning to silence that output, 1 being the default output level, and higher numbers increasing the output of that flag (for those that support higher levels). Use --debug=help to see all the available flag names, what they output, and what flag names are added for each increase in the verbose level. Some examples: rsync -avvv --debug=none src/ dest/ rsync -avA --del --debug=del2,acl src/ dest/ Note that some debug messages will only be output when the --stderr=all option is specified, especially those pertaining to I/O and buffer debugging. Beginning in 3.2.0, this option is no longer auto- forwarded to the server side in order to allow you to specify different debug values for each side of the transfer, as well as to specify a new debug option that is only present in one of the rsync versions. If you want to duplicate the same option on both sides, using brace expansion is an easy way to save you some typing. This works in zsh and bash: rsync -aiv {-M,}--debug=del2 src/ dest/ --stderr=errors|all|client This option controls which processes output to stderr and if info messages are also changed to stderr. The mode strings can be abbreviated, so feel free to use a single letter value. The 3 possible choices are: o errors - (the default) causes all the rsync processes to send an error directly to stderr, even if the process is on the remote side of the transfer. Info messages are sent to the client side via the protocol stream. If stderr is not available (i.e. when directly connecting with a daemon via a socket) errors fall back to being sent via the protocol stream. o all - causes all rsync messages (info and error) to get written directly to stderr from all (possible) processes. This causes stderr to become line- buffered (instead of raw) and eliminates the ability to divide up the info and error messages by file handle. For those doing debugging or using several levels of verbosity, this option can help to avoid clogging up the transfer stream (which should prevent any chance of a deadlock bug hanging things up). It also allows --debug to enable some extra I/O related messages. o client - causes all rsync messages to be sent to the client side via the protocol stream. One client process outputs all messages, with errors on stderr and info messages on stdout. This was the default in older rsync versions, but can cause error delays when a lot of transfer data is ahead of the messages. If you're pushing files to an older rsync, you may want to use --stderr=all since that idiom has been around for several releases. This option was added in rsync 3.2.3. This version also began the forwarding of a non-default setting to the remote side, though rsync uses the backward-compatible options --msgs2stderr and --no-msgs2stderr to represent the all and client settings, respectively. A newer rsync will continue to accept these older option names to maintain compatibility. --quiet, -q This option decreases the amount of information you are given during the transfer, notably suppressing information messages from the remote server. This option is useful when invoking rsync from cron. --no-motd This option affects the information that is output by the client at the start of a daemon transfer. This suppresses the message-of-the-day (MOTD) text, but it also affects the list of modules that the daemon sends in response to the "rsync host::" request (due to a limitation in the rsync protocol), so omit this option if you want to request the list of modules from the daemon. --ignore-times, -I Normally rsync will skip any files that are already the same size and have the same modification timestamp. This option turns off this "quick check" behavior, causing all files to be updated. This option can be confusing compared to --ignore-existing and --ignore-non-existing in that that they cause rsync to transfer fewer files, while this option causes rsync to transfer more files. --size-only This modifies rsync's "quick check" algorithm for finding files that need to be transferred, changing it from the default of transferring files with either a changed size or a changed last-modified time to just looking for files that have changed in size. This is useful when starting to use rsync after using another mirroring system which may not preserve timestamps exactly. --modify-window=NUM, -@ When comparing two timestamps, rsync treats the timestamps as being equal if they differ by no more than the modify- window value. The default is 0, which matches just integer seconds. If you specify a negative value (and the receiver is at least version 3.1.3) then nanoseconds will also be taken into account. Specifying 1 is useful for copies to/from MS Windows FAT filesystems, because FAT represents times with a 2-second resolution (allowing times to differ from the original by up to 1 second). If you want all your transfers to default to comparing nanoseconds, you can create a ~/.popt file and put these lines in it: rsync alias -a -a@-1 rsync alias -t -t@-1 With that as the default, you'd need to specify --modify- window=0 (aka -@0) to override it and ignore nanoseconds, e.g. if you're copying between ext3 and ext4, or if the receiving rsync is older than 3.1.3. --checksum, -c This changes the way rsync checks if the files have been changed and are in need of a transfer. Without this option, rsync uses a "quick check" that (by default) checks if each file's size and time of last modification match between the sender and receiver. This option changes this to compare a 128-bit checksum for each file that has a matching size. Generating the checksums means that both sides will expend a lot of disk I/O reading all the data in the files in the transfer, so this can slow things down significantly (and this is prior to any reading that will be done to transfer changed files) The sending side generates its checksums while it is doing the file-system scan that builds the list of the available files. The receiver generates its checksums when it is scanning for changed files, and will checksum any file that has the same size as the corresponding sender's file: files with either a changed size or a changed checksum are selected for transfer. Note that rsync always verifies that each transferred file was correctly reconstructed on the receiving side by checking a whole-file checksum that is generated as the file is transferred, but that automatic after-the-transfer verification has nothing to do with this option's before- the-transfer "Does this file need to be updated?" check. The checksum used is auto-negotiated between the client and the server, but can be overridden using either the --checksum-choice (--cc) option or an environment variable that is discussed in that option's section. --archive, -a This is equivalent to -rlptgoD. It is a quick way of saying you want recursion and want to preserve almost everything. Be aware that it does not include preserving ACLs (-A), xattrs (-X), atimes (-U), crtimes (-N), nor the finding and preserving of hardlinks (-H). The only exception to the above equivalence is when --files-from is specified, in which case -r is not implied. --no-OPTION You may turn off one or more implied options by prefixing the option name with "no-". Not all positive options have a negated opposite, but a lot do, including those that can be used to disable an implied option (e.g. --no-D, --no- perms) or have different defaults in various circumstances (e.g. --no-whole-file, --no-blocking-io, --no-dirs). Every valid negated option accepts both the short and the long option name after the "no-" prefix (e.g. --no-R is the same as --no-relative). As an example, if you want to use --archive (-a) but don't want --owner (-o), instead of converting -a into -rlptgD, you can specify -a --no-o (aka --archive --no-owner). The order of the options is important: if you specify --no-r -a, the -r option would end up being turned on, the opposite of -a --no-r. Note also that the side-effects of the --files-from option are NOT positional, as it affects the default state of several options and slightly changes the meaning of -a (see the --files-from option for more details). --recursive, -r This tells rsync to copy directories recursively. See also --dirs (-d) for an option that allows the scanning of a single directory. See the --inc-recursive option for a discussion of the incremental recursion for creating the list of files to transfer. --inc-recursive, --i-r This option explicitly enables on incremental recursion when scanning for files, which is enabled by default when using the --recursive option and both sides of the transfer are running rsync 3.0.0 or newer. Incremental recursion uses much less memory than non- incremental, while also beginning the transfer more quickly (since it doesn't need to scan the entire transfer hierarchy before it starts transferring files). If no recursion is enabled in the source files, this option has no effect. Some options require rsync to know the full file list, so these options disable the incremental recursion mode. These include: o --delete-before (the old default of --delete) o --delete-after o --prune-empty-dirs o --delay-updates In order to make --delete compatible with incremental recursion, rsync 3.0.0 made --delete-during the default delete mode (which was first added in 2.6.4). One side-effect of incremental recursion is that any missing sub-directories inside a recursively-scanned directory are (by default) created prior to recursing into the sub-dirs. This earlier creation point (compared to a non-incremental recursion) allows rsync to then set the modify time of the finished directory right away (without having to delay that until a bunch of recursive copying has finished). However, these early directories don't yet have their completed mode, mtime, or ownership set -- they have more restrictive rights until the subdirectory's copying actually begins. This early-creation idiom can be avoided by using the --omit-dir-times option. Incremental recursion can be disabled using the --no-inc- recursive (--no-i-r) option. --no-inc-recursive, --no-i-r Disables the new incremental recursion algorithm of the --recursive option. This makes rsync scan the full file list before it begins to transfer files. See --inc- recursive for more info. --relative, -R Use relative paths. This means that the full path names specified on the command line are sent to the server rather than just the last parts of the filenames. This is particularly useful when you want to send several different directories at the same time. For example, if you used this command: rsync -av /foo/bar/baz.c remote:/tmp/ would create a file named baz.c in /tmp/ on the remote machine. If instead you used rsync -avR /foo/bar/baz.c remote:/tmp/ then a file named /tmp/foo/bar/baz.c would be created on the remote machine, preserving its full path. These extra path elements are called "implied directories" (i.e. the "foo" and the "foo/bar" directories in the above example). Beginning with rsync 3.0.0, rsync always sends these implied directories as real directories in the file list, even if a path element is really a symlink on the sending side. This prevents some really unexpected behaviors when copying the full path of a file that you didn't realize had a symlink in its path. If you want to duplicate a server-side symlink, include both the symlink via its path, and referent directory via its real path. If you're dealing with an older rsync on the sending side, you may need to use the --no-implied-dirs option. It is also possible to limit the amount of path information that is sent as implied directories for each path you specify. With a modern rsync on the sending side (beginning with 2.6.7), you can insert a dot and a slash into the source path, like this: rsync -avR /foo/./bar/baz.c remote:/tmp/ That would create /tmp/bar/baz.c on the remote machine. (Note that the dot must be followed by a slash, so "/foo/." would not be abbreviated.) For older rsync versions, you would need to use a chdir to limit the source path. For example, when pushing files: (cd /foo; rsync -avR bar/baz.c remote:/tmp/) (Note that the parens put the two commands into a sub- shell, so that the "cd" command doesn't remain in effect for future commands.) If you're pulling files from an older rsync, use this idiom (but only for a non-daemon transfer): rsync -avR --rsync-path="cd /foo; rsync" \ remote:bar/baz.c /tmp/ --no-implied-dirs This option affects the default behavior of the --relative option. When it is specified, the attributes of the implied directories from the source names are not included in the transfer. This means that the corresponding path elements on the destination system are left unchanged if they exist, and any missing implied directories are created with default attributes. This even allows these implied path elements to have big differences, such as being a symlink to a directory on the receiving side. For instance, if a command-line arg or a files-from entry told rsync to transfer the file "path/foo/file", the directories "path" and "path/foo" are implied when --relative is used. If "path/foo" is a symlink to "bar" on the destination system, the receiving rsync would ordinarily delete "path/foo", recreate it as a directory, and receive the file into the new directory. With --no- implied-dirs, the receiving rsync updates "path/foo/file" using the existing path elements, which means that the file ends up being created in "path/bar". Another way to accomplish this link preservation is to use the --keep- dirlinks option (which will also affect symlinks to directories in the rest of the transfer). When pulling files from an rsync older than 3.0.0, you may need to use this option if the sending side has a symlink in the path you request and you wish the implied directories to be transferred as normal directories. --backup, -b With this option, preexisting destination files are renamed as each file is transferred or deleted. You can control where the backup file goes and what (if any) suffix gets appended using the --backup-dir and --suffix options. If you don't specify --backup-dir: 1. the --omit-dir-times option will be forced on 2. the use of --delete (without --delete-excluded), causes rsync to add a "protect" filter-rule for the backup suffix to the end of all your existing filters that looks like this: -f "P *~". This rule prevents previously backed-up files from being deleted. Note that if you are supplying your own filter rules, you may need to manually insert your own exclude/protect rule somewhere higher up in the list so that it has a high enough priority to be effective (e.g. if your rules specify a trailing inclusion/exclusion of *, the auto- added rule would never be reached). --backup-dir=DIR This implies the --backup option, and tells rsync to store all backups in the specified directory on the receiving side. This can be used for incremental backups. You can additionally specify a backup suffix using the --suffix option (otherwise the files backed up in the specified directory will keep their original filenames). Note that if you specify a relative path, the backup directory will be relative to the destination directory, so you probably want to specify either an absolute path or a path that starts with "../". If an rsync daemon is the receiver, the backup dir cannot go outside the module's path hierarchy, so take extra care not to delete it or copy into it. --suffix=SUFFIX This option allows you to override the default backup suffix used with the --backup (-b) option. The default suffix is a ~ if no --backup-dir was specified, otherwise it is an empty string. --update, -u This forces rsync to skip any files which exist on the destination and have a modified time that is newer than the source file. (If an existing destination file has a modification time equal to the source file's, it will be updated if the sizes are different.) Note that this does not affect the copying of dirs, symlinks, or other special files. Also, a difference of file format between the sender and receiver is always considered to be important enough for an update, no matter what date is on the objects. In other words, if the source has a directory where the destination has a file, the transfer would occur regardless of the timestamps. This option is a TRANSFER RULE, so don't expect any exclude side effects. A caution for those that choose to combine --inplace with --update: an interrupted transfer will leave behind a partial file on the receiving side that has a very recent modified time, so re-running the transfer will probably not continue the interrupted file. As such, it is usually best to avoid combining this with --inplace unless you have implemented manual steps to handle any interrupted in-progress files. --inplace This option changes how rsync transfers a file when its data needs to be updated: instead of the default method of creating a new copy of the file and moving it into place when it is complete, rsync instead writes the updated data directly to the destination file. This has several effects: o Hard links are not broken. This means the new data will be visible through other hard links to the destination file. Moreover, attempts to copy differing source files onto a multiply-linked destination file will result in a "tug of war" with the destination data changing back and forth. o In-use binaries cannot be updated (either the OS will prevent this from happening, or binaries that attempt to swap-in their data will misbehave or crash). o The file's data will be in an inconsistent state during the transfer and will be left that way if the transfer is interrupted or if an update fails. o A file that rsync cannot write to cannot be updated. While a super user can update any file, a normal user needs to be granted write permission for the open of the file for writing to be successful. o The efficiency of rsync's delta-transfer algorithm may be reduced if some data in the destination file is overwritten before it can be copied to a position later in the file. This does not apply if you use --backup, since rsync is smart enough to use the backup file as the basis file for the transfer. WARNING: you should not use this option to update files that are being accessed by others, so be careful when choosing to use this for a copy. This option is useful for transferring large files with block-based changes or appended data, and also on systems that are disk bound, not network bound. It can also help keep a copy-on-write filesystem snapshot from diverging the entire contents of a file that only has minor changes. The option implies --partial (since an interrupted transfer does not delete the file), but conflicts with --partial-dir and --delay-updates. Prior to rsync 2.6.4 --inplace was also incompatible with --compare-dest and --link-dest. --append This special copy mode only works to efficiently update files that are known to be growing larger where any existing content on the receiving side is also known to be the same as the content on the sender. The use of --append can be dangerous if you aren't 100% sure that all the files in the transfer are shared, growing files. You should thus use filter rules to ensure that you weed out any files that do not fit this criteria. Rsync updates these growing file in-place without verifying any of the existing content in the file (it only verifies the content that it is appending). Rsync skips any files that exist on the receiving side that are not shorter than the associated file on the sending side (which means that new files are transferred). It also skips any files whose size on the sending side gets shorter during the send negotiations (rsync warns about a "diminished" file when this happens). This does not interfere with the updating of a file's non- content attributes (e.g. permissions, ownership, etc.) when the file does not need to be transferred, nor does it affect the updating of any directories or non-regular files. --append-verify This special copy mode works like --append except that all the data in the file is included in the checksum verification (making it less efficient but also potentially safer). This option can be dangerous if you aren't 100% sure that all the files in the transfer are shared, growing files. See the --append option for more details. Note: prior to rsync 3.0.0, the --append option worked like --append-verify, so if you are interacting with an older rsync (or the transfer is using a protocol prior to 30), specifying either append option will initiate an --append-verify transfer. --dirs, -d Tell the sending side to include any directories that are encountered. Unlike --recursive, a directory's contents are not copied unless the directory name specified is "." or ends with a trailing slash (e.g. ".", "dir/.", "dir/", etc.). Without this option or the --recursive option, rsync will skip all directories it encounters (and output a message to that effect for each one). If you specify both --dirs and --recursive, --recursive takes precedence. The --dirs option is implied by the --files-from option or the --list-only option (including an implied --list-only usage) if --recursive wasn't specified (so that directories are seen in the listing). Specify --no-dirs (or --no-d) if you want to turn this off. There is also a backward-compatibility helper option, --old-dirs (--old-d) that tells rsync to use a hack of -r --exclude='/*/*' to get an older rsync to list a single directory without recursing. --mkpath Create all missing path components of the destination path. By default, rsync allows only the final component of the destination path to not exist, which is an attempt to help you to validate your destination path. With this option, rsync creates all the missing destination-path components, just as if mkdir -p $DEST_PATH had been run on the receiving side. When specifying a destination path, including a trailing slash ensures that the whole path is treated as directory names to be created, even when the file list has a single item. See the COPYING TO A DIFFERENT NAME section for full details on how rsync decides if a final destination-path component should be created as a directory or not. If you would like the newly-created destination dirs to match the dirs on the sending side, you should be using --relative (-R) instead of --mkpath. For instance, the following two commands result in the same destination tree, but only the second command ensures that the "some/extra/path" components match the dirs on the sending side: rsync -ai --mkpath host:some/extra/path/*.c some/extra/path/ rsync -aiR host:some/extra/path/*.c ./ --links, -l Add symlinks to the transferred files instead of noisily ignoring them with a "non-regular file" warning for each symlink encountered. You can alternately silence the warning by specifying --info=nonreg0. The default handling of symlinks is to recreate each symlink's unchanged value on the receiving side. See the SYMBOLIC LINKS section for multi-option info. --copy-links, -L The sender transforms each symlink encountered in the transfer into the referent item, following the symlink chain to the file or directory that it references. If a symlink chain is broken, an error is output and the file is dropped from the transfer. This option supersedes any other options that affect symlinks in the transfer, since there are no symlinks left in the transfer. This option does not change the handling of existing symlinks on the receiving side, unlike versions of rsync prior to 2.6.3 which had the side-effect of telling the receiving side to also follow symlinks. A modern rsync won't forward this option to a remote receiver (since only the sender needs to know about it), so this caveat should only affect someone using an rsync client older than 2.6.7 (which is when -L stopped being forwarded to the receiver). See the --keep-dirlinks (-K) if you need a symlink to a directory to be treated as a real directory on the receiving side. See the SYMBOLIC LINKS section for multi-option info. --copy-unsafe-links This tells rsync to copy the referent of symbolic links that point outside the copied tree. Absolute symlinks are also treated like ordinary files, and so are any symlinks in the source path itself when --relative is used. Note that the cut-off point is the top of the transfer, which is the part of the path that rsync isn't mentioning in the verbose output. If you copy "/src/subdir" to "/dest/" then the "subdir" directory is a name inside the transfer tree, not the top of the transfer (which is /src) so it is legal for created relative symlinks to refer to other names inside the /src and /dest directories. If you instead copy "/src/subdir/" (with a trailing slash) to "/dest/subdir" that would not allow symlinks to any files outside of "subdir". Note that safe symlinks are only copied if --links was also specified or implied. The --copy-unsafe-links option has no extra effect when combined with --copy-links. See the SYMBOLIC LINKS section for multi-option info. --safe-links This tells the receiving rsync to ignore any symbolic links in the transfer which point outside the copied tree. All absolute symlinks are also ignored. Since this ignoring is happening on the receiving side, it will still be effective even when the sending side has munged symlinks (when it is using --munge-links). It also affects deletions, since the file being present in the transfer prevents any matching file on the receiver from being deleted when the symlink is deemed to be unsafe and is skipped. This option must be combined with --links (or --archive) to have any symlinks in the transfer to conditionally ignore. Its effect is superseded by --copy-unsafe-links. Using this option in conjunction with --relative may give unexpected results. See the SYMBOLIC LINKS section for multi-option info. --munge-links This option affects just one side of the transfer and tells rsync to munge symlink values when it is receiving files or unmunge symlink values when it is sending files. The munged values make the symlinks unusable on disk but allows the original contents of the symlinks to be recovered. The server-side rsync often enables this option without the client's knowledge, such as in an rsync daemon's configuration file or by an option given to the rrsync (restricted rsync) script. When specified on the client side, specify the option normally if it is the client side that has/needs the munged symlinks, or use -M--munge-links to give the option to the server when it has/needs the munged symlinks. Note that on a local transfer, the client is the sender, so specifying the option directly unmunges symlinks while specifying it as a remote option munges symlinks. This option has no effect when sent to a daemon via --remote-option because the daemon configures whether it wants munged symlinks via its "munge symlinks" parameter. The symlink value is munged/unmunged once it is in the transfer, so any option that transforms symlinks into non- symlinks occurs prior to the munging/unmunging except for --safe-links, which is a choice that the receiver makes, so it bases its decision on the munged/unmunged value. This does mean that if a receiver has munging enabled, that using --safe-links will cause all symlinks to be ignored (since they are all absolute). The method that rsync uses to munge the symlinks is to prefix each one's value with the string "/rsyncd-munged/". This prevents the links from being used as long as the directory does not exist. When this option is enabled, rsync will refuse to run if that path is a directory or a symlink to a directory (though it only checks at startup). See also the "munge-symlinks" python script in the support directory of the source code for a way to munge/unmunge one or more symlinks in-place. --copy-dirlinks, -k This option causes the sending side to treat a symlink to a directory as though it were a real directory. This is useful if you don't want symlinks to non-directories to be affected, as they would be using --copy-links. Without this option, if the sending side has replaced a directory with a symlink to a directory, the receiving side will delete anything that is in the way of the new symlink, including a directory hierarchy (as long as --force or --delete is in effect). See also --keep-dirlinks for an analogous option for the receiving side. --copy-dirlinks applies to all symlinks to directories in the source. If you want to follow only a few specified symlinks, a trick you can use is to pass them as additional source args with a trailing slash, using --relative to make the paths match up right. For example: rsync -r --relative src/./ src/./follow-me/ dest/ This works because rsync calls lstat(2) on the source arg as given, and the trailing slash makes lstat(2) follow the symlink, giving rise to a directory in the file-list which overrides the symlink found during the scan of "src/./". See the SYMBOLIC LINKS section for multi-option info. --keep-dirlinks, -K This option causes the receiving side to treat a symlink to a directory as though it were a real directory, but only if it matches a real directory from the sender. Without this option, the receiver's symlink would be deleted and replaced with a real directory. For example, suppose you transfer a directory "foo" that contains a file "file", but "foo" is a symlink to directory "bar" on the receiver. Without --keep-dirlinks, the receiver deletes symlink "foo", recreates it as a directory, and receives the file into the new directory. With --keep-dirlinks, the receiver keeps the symlink and "file" ends up in "bar". One note of caution: if you use --keep-dirlinks, you must trust all the symlinks in the copy or enable the --munge- links option on the receiving side! If it is possible for an untrusted user to create their own symlink to any real directory, the user could then (on a subsequent copy) replace the symlink with a real directory and affect the content of whatever directory the symlink references. For backup copies, you are better off using something like a bind mount instead of a symlink to modify your receiving hierarchy. See also --copy-dirlinks for an analogous option for the sending side. See the SYMBOLIC LINKS section for multi-option info. --hard-links, -H This tells rsync to look for hard-linked files in the source and link together the corresponding files on the destination. Without this option, hard-linked files in the source are treated as though they were separate files. This option does NOT necessarily ensure that the pattern of hard links on the destination exactly matches that on the source. Cases in which the destination may end up with extra hard links include the following: o If the destination contains extraneous hard-links (more linking than what is present in the source file list), the copying algorithm will not break them explicitly. However, if one or more of the paths have content differences, the normal file- update process will break those extra links (unless you are using the --inplace option). o If you specify a --link-dest directory that contains hard links, the linking of the destination files against the --link-dest files can cause some paths in the destination to become linked together due to the --link-dest associations. Note that rsync can only detect hard links between files that are inside the transfer set. If rsync updates a file that has extra hard-link connections to files outside the transfer, that linkage will be broken. If you are tempted to use the --inplace option to avoid this breakage, be very careful that you know how your files are being updated so that you are certain that no unintended changes happen due to lingering hard links (and see the --inplace option for more caveats). If incremental recursion is active (see --inc-recursive), rsync may transfer a missing hard-linked file before it finds that another link for that contents exists elsewhere in the hierarchy. This does not affect the accuracy of the transfer (i.e. which files are hard-linked together), just its efficiency (i.e. copying the data for a new, early copy of a hard-linked file that could have been found later in the transfer in another member of the hard- linked set of files). One way to avoid this inefficiency is to disable incremental recursion using the --no-inc- recursive option. --perms, -p This option causes the receiving rsync to set the destination permissions to be the same as the source permissions. (See also the --chmod option for a way to modify what rsync considers to be the source permissions.) When this option is off, permissions are set as follows: o Existing files (including updated files) retain their existing permissions, though the --executability option might change just the execute permission for the file. o New files get their "normal" permission bits set to the source file's permissions masked with the receiving directory's default permissions (either the receiving process's umask, or the permissions specified via the destination directory's default ACL), and their special permission bits disabled except in the case where a new directory inherits a setgid bit from its parent directory. Thus, when --perms and --executability are both disabled, rsync's behavior is the same as that of other file-copy utilities, such as cp(1) and tar(1). In summary: to give destination files (both old and new) the source permissions, use --perms. To give new files the destination-default permissions (while leaving existing files unchanged), make sure that the --perms option is off and use --chmod=ugo=rwX (which ensures that all non-masked bits get enabled). If you'd care to make this latter behavior easier to type, you could define a popt alias for it, such as putting this line in the file ~/.popt (the following defines the -Z option, and includes --no-g to use the default group of the destination dir): rsync alias -Z --no-p --no-g --chmod=ugo=rwX You could then use this new option in a command such as this one: rsync -avZ src/ dest/ (Caveat: make sure that -a does not follow -Z, or it will re-enable the two --no-* options mentioned above.) The preservation of the destination's setgid bit on newly- created directories when --perms is off was added in rsync 2.6.7. Older rsync versions erroneously preserved the three special permission bits for newly-created files when --perms was off, while overriding the destination's setgid bit setting on a newly-created directory. Default ACL observance was added to the ACL patch for rsync 2.6.7, so older (or non-ACL-enabled) rsyncs use the umask even if default ACLs are present. (Keep in mind that it is the version of the receiving rsync that affects these behaviors.) --executability, -E This option causes rsync to preserve the executability (or non-executability) of regular files when --perms is not enabled. A regular file is considered to be executable if at least one 'x' is turned on in its permissions. When an existing destination file's executability differs from that of the corresponding source file, rsync modifies the destination file's permissions as follows: o To make a file non-executable, rsync turns off all its 'x' permissions. o To make a file executable, rsync turns on each 'x' permission that has a corresponding 'r' permission enabled. If --perms is enabled, this option is ignored. --acls, -A This option causes rsync to update the destination ACLs to be the same as the source ACLs. The option also implies --perms. The source and destination systems must have compatible ACL entries for this option to work properly. See the --fake-super option for a way to backup and restore ACLs that are not compatible. --xattrs, -X This option causes rsync to update the destination extended attributes to be the same as the source ones. For systems that support extended-attribute namespaces, a copy being done by a super-user copies all namespaces except system.*. A normal user only copies the user.* namespace. To be able to backup and restore non-user namespaces as a normal user, see the --fake-super option. The above name filtering can be overridden by using one or more filter options with the x modifier. When you specify an xattr-affecting filter rule, rsync requires that you do your own system/user filtering, as well as any additional filtering for what xattr names are copied and what names are allowed to be deleted. For example, to skip the system namespace, you could specify: --filter='-x system.*' To skip all namespaces except the user namespace, you could specify a negated-user match: --filter='-x! user.*' To prevent any attributes from being deleted, you could specify a receiver-only rule that excludes all names: --filter='-xr *' Note that the -X option does not copy rsync's special xattr values (e.g. those used by --fake-super) unless you repeat the option (e.g. -XX). This "copy all xattrs" mode cannot be used with --fake-super. --chmod=CHMOD This option tells rsync to apply one or more comma- separated "chmod" modes to the permission of the files in the transfer. The resulting value is treated as though it were the permissions that the sending side supplied for the file, which means that this option can seem to have no effect on existing files if --perms is not enabled. In addition to the normal parsing rules specified in the chmod(1) manpage, you can specify an item that should only apply to a directory by prefixing it with a 'D', or specify an item that should only apply to a file by prefixing it with a 'F'. For example, the following will ensure that all directories get marked set-gid, that no files are other-writable, that both are user-writable and group-writable, and that both have consistent executability across all bits: --chmod=Dg+s,ug+w,Fo-w,+X Using octal mode numbers is also allowed: --chmod=D2775,F664 It is also legal to specify multiple --chmod options, as each additional option is just appended to the list of changes to make. See the --perms and --executability options for how the resulting permission value can be applied to the files in the transfer. --owner, -o This option causes rsync to set the owner of the destination file to be the same as the source file, but only if the receiving rsync is being run as the super-user (see also the --super and --fake-super options). Without this option, the owner of new and/or transferred files are set to the invoking user on the receiving side. The preservation of ownership will associate matching names by default, but may fall back to using the ID number in some circumstances (see also the --numeric-ids option for a full discussion). --group, -g This option causes rsync to set the group of the destination file to be the same as the source file. If the receiving program is not running as the super-user (or if --no-super was specified), only groups that the invoking user on the receiving side is a member of will be preserved. Without this option, the group is set to the default group of the invoking user on the receiving side. The preservation of group information will associate matching names by default, but may fall back to using the ID number in some circumstances (see also the --numeric- ids option for a full discussion). --devices This option causes rsync to transfer character and block device files to the remote system to recreate these devices. If the receiving rsync is not being run as the super-user, rsync silently skips creating the device files (see also the --super and --fake-super options). By default, rsync generates a "non-regular file" warning for each device file encountered when this option is not set. You can silence the warning by specifying --info=nonreg0. --specials This option causes rsync to transfer special files, such as named sockets and fifos. If the receiving rsync is not being run as the super-user, rsync silently skips creating the special files (see also the --super and --fake-super options). By default, rsync generates a "non-regular file" warning for each special file encountered when this option is not set. You can silence the warning by specifying --info=nonreg0. -D The -D option is equivalent to "--devices --specials". --copy-devices This tells rsync to treat a device on the sending side as a regular file, allowing it to be copied to a normal destination file (or another device if --write-devices was also specified). This option is refused by default by an rsync daemon. --write-devices This tells rsync to treat a device on the receiving side as a regular file, allowing the writing of file data into a device. This option implies the --inplace option. Be careful using this, as you should know what devices are present on the receiving side of the transfer, especially when running rsync as root. This option is refused by default by an rsync daemon. --times, -t This tells rsync to transfer modification times along with the files and update them on the remote system. Note that if this option is not used, the optimization that excludes files that have not been modified cannot be effective; in other words, a missing -t (or -a) will cause the next transfer to behave as if it used --ignore-times (-I), causing all files to be updated (though rsync's delta- transfer algorithm will make the update fairly efficient if the files haven't actually changed, you're much better off using -t). A modern rsync that is using transfer protocol 30 or 31 conveys a modify time using up to 8-bytes. If rsync is forced to speak an older protocol (perhaps due to the remote rsync being older than 3.0.0) a modify time is conveyed using 4-bytes. Prior to 3.2.7, these shorter values could convey a date range of 13-Dec-1901 to 19-Jan-2038. Beginning with 3.2.7, these 4-byte values now convey a date range of 1-Jan-1970 to 7-Feb-2106. If you have files dated older than 1970, make sure your rsync executables are upgraded so that the full range of dates can be conveyed. --atimes, -U This tells rsync to set the access (use) times of the destination files to the same value as the source files. If repeated, it also sets the --open-noatime option, which can help you to make the sending and receiving systems have the same access times on the transferred files without needing to run rsync an extra time after a file is transferred. Note that some older rsync versions (prior to 3.2.0) may have been built with a pre-release --atimes patch that does not imply --open-noatime when this option is repeated. --open-noatime This tells rsync to open files with the O_NOATIME flag (on systems that support it) to avoid changing the access time of the files that are being transferred. If your OS does not support the O_NOATIME flag then rsync will silently ignore this option. Note also that some filesystems are mounted to avoid updating the atime on read access even without the O_NOATIME flag being set. --crtimes, -N, This tells rsync to set the create times (newness) of the destination files to the same value as the source files. --omit-dir-times, -O This tells rsync to omit directories when it is preserving modification, access, and create times. If NFS is sharing the directories on the receiving side, it is a good idea to use -O. This option is inferred if you use --backup without --backup-dir. This option also has the side-effect of avoiding early creation of missing sub-directories when incremental recursion is enabled, as discussed in the --inc-recursive section. --omit-link-times, -J This tells rsync to omit symlinks when it is preserving modification, access, and create times. --super This tells the receiving side to attempt super-user activities even if the receiving rsync wasn't run by the super-user. These activities include: preserving users via the --owner option, preserving all groups (not just the current user's groups) via the --group option, and copying devices via the --devices option. This is useful for systems that allow such activities without being the super-user, and also for ensuring that you will get errors if the receiving side isn't being run as the super-user. To turn off super-user activities, the super-user can use --no-super. --fake-super When this option is enabled, rsync simulates super-user activities by saving/restoring the privileged attributes via special extended attributes that are attached to each file (as needed). This includes the file's owner and group (if it is not the default), the file's device info (device & special files are created as empty text files), and any permission bits that we won't allow to be set on the real file (e.g. the real file gets u-s,g-s,o-t for safety) or that would limit the owner's access (since the real super-user can always access/change a file, the files we create can always be accessed/changed by the creating user). This option also handles ACLs (if --acls was specified) and non-user extended attributes (if --xattrs was specified). This is a good way to backup data without using a super- user, and to store ACLs from incompatible systems. The --fake-super option only affects the side where the option is used. To affect the remote side of a remote- shell connection, use the --remote-option (-M) option: rsync -av -M--fake-super /src/ host:/dest/ For a local copy, this option affects both the source and the destination. If you wish a local copy to enable this option just for the destination files, specify -M--fake- super. If you wish a local copy to enable this option just for the source files, combine --fake-super with -M--super. This option is overridden by both --super and --no-super. See also the fake super setting in the daemon's rsyncd.conf file. --sparse, -S Try to handle sparse files efficiently so they take up less space on the destination. If combined with --inplace the file created might not end up with sparse blocks with some combinations of kernel version and/or filesystem type. If --whole-file is in effect (e.g. for a local copy) then it will always work because rsync truncates the file prior to writing out the updated version. Note that versions of rsync older than 3.1.3 will reject the combination of --sparse and --inplace. --preallocate This tells the receiver to allocate each destination file to its eventual size before writing data to the file. Rsync will only use the real filesystem-level preallocation support provided by Linux's fallocate(2) system call or Cygwin's posix_fallocate(3), not the slow glibc implementation that writes a null byte into each block. Without this option, larger files may not be entirely contiguous on the filesystem, but with this option rsync will probably copy more slowly. If the destination is not an extent-supporting filesystem (such as ext4, xfs, NTFS, etc.), this option may have no positive effect at all. If combined with --sparse, the file will only have sparse blocks (as opposed to allocated sequences of null bytes) if the kernel version and filesystem type support creating holes in the allocated data. --dry-run, -n This makes rsync perform a trial run that doesn't make any changes (and produces mostly the same output as a real run). It is most commonly used in combination with the --verbose (-v) and/or --itemize-changes (-i) options to see what an rsync command is going to do before one actually runs it. The output of --itemize-changes is supposed to be exactly the same on a dry run and a subsequent real run (barring intentional trickery and system call failures); if it isn't, that's a bug. Other output should be mostly unchanged, but may differ in some areas. Notably, a dry run does not send the actual data for file transfers, so --progress has no effect, the "bytes sent", "bytes received", "literal data", and "matched data" statistics are too small, and the "speedup" value is equivalent to a run where no file transfers were needed. --whole-file, -W This option disables rsync's delta-transfer algorithm, which causes all transferred files to be sent whole. The transfer may be faster if this option is used when the bandwidth between the source and destination machines is higher than the bandwidth to disk (especially when the "disk" is actually a networked filesystem). This is the default when both the source and destination are specified as local paths, but only if no batch-writing option is in effect. --no-whole-file, --no-W Disable whole-file updating when it is enabled by default for a local transfer. This usually slows rsync down, but it can be useful if you are trying to minimize the writes to the destination file (if combined with --inplace) or for testing the checksum-based update algorithm. See also the --whole-file option. --checksum-choice=STR, --cc=STR This option overrides the checksum algorithms. If one algorithm name is specified, it is used for both the transfer checksums and (assuming --checksum is specified) the pre-transfer checksums. If two comma-separated names are supplied, the first name affects the transfer checksums, and the second name affects the pre-transfer checksums (-c). The checksum options that you may be able to use are: o auto (the default automatic choice) o xxh128 o xxh3 o xxh64 (aka xxhash) o md5 o md4 o sha1 o none Run rsync --version to see the default checksum list compiled into your version (which may differ from the list above). If "none" is specified for the first (or only) name, the --whole-file option is forced on and no checksum verification is performed on the transferred data. If "none" is specified for the second (or only) name, the --checksum option cannot be used. The "auto" option is the default, where rsync bases its algorithm choice on a negotiation between the client and the server as follows: When both sides of the transfer are at least 3.2.0, rsync chooses the first algorithm in the client's list of choices that is also in the server's list of choices. If no common checksum choice is found, rsync exits with an error. If the remote rsync is too old to support checksum negotiation, a value is chosen based on the protocol version (which chooses between MD5 and various flavors of MD4 based on protocol age). The default order can be customized by setting the environment variable RSYNC_CHECKSUM_LIST to a space- separated list of acceptable checksum names. If the string contains a "&" character, it is separated into the "client string & server string", otherwise the same string applies to both. If the string (or string portion) contains no non-whitespace characters, the default checksum list is used. This method does not allow you to specify the transfer checksum separately from the pre- transfer checksum, and it discards "auto" and all unknown checksum names. A list with only invalid names results in a failed negotiation. The use of the --checksum-choice option overrides this environment list. --one-file-system, -x This tells rsync to avoid crossing a filesystem boundary when recursing. This does not limit the user's ability to specify items to copy from multiple filesystems, just rsync's recursion through the hierarchy of each directory that the user specified, and also the analogous recursion on the receiving side during deletion. Also keep in mind that rsync treats a "bind" mount to the same device as being on the same filesystem. If this option is repeated, rsync omits all mount-point directories from the copy. Otherwise, it includes an empty directory at each mount-point it encounters (using the attributes of the mounted directory because those of the underlying mount-point directory are inaccessible). If rsync has been told to collapse symlinks (via --copy- links or --copy-unsafe-links), a symlink to a directory on another device is treated like a mount-point. Symlinks to non-directories are unaffected by this option. --ignore-non-existing, --existing This tells rsync to skip creating files (including directories) that do not exist yet on the destination. If this option is combined with the --ignore-existing option, no files will be updated (which can be useful if all you want to do is delete extraneous files). This option is a TRANSFER RULE, so don't expect any exclude side effects. --ignore-existing This tells rsync to skip updating files that already exist on the destination (this does not ignore existing directories, or nothing would get done). See also --ignore-non-existing. This option is a TRANSFER RULE, so don't expect any exclude side effects. This option can be useful for those doing backups using the --link-dest option when they need to continue a backup run that got interrupted. Since a --link-dest run is copied into a new directory hierarchy (when it is used properly), using [--ignore-existing will ensure that the already-handled files don't get tweaked (which avoids a change in permissions on the hard-linked files). This does mean that this option is only looking at the existing files in the destination hierarchy itself. When --info=skip2 is used rsync will output "FILENAME exists (INFO)" messages where the INFO indicates one of "type change", "sum change" (requires -c), "file change" (based on the quick check), "attr change", or "uptodate". Using --info=skip1 (which is also implied by 2 -v options) outputs the exists message without the INFO suffix. --remove-source-files This tells rsync to remove from the sending side the files (meaning non-directories) that are a part of the transfer and have been successfully duplicated on the receiving side. Note that you should only use this option on source files that are quiescent. If you are using this to move files that show up in a particular directory over to another host, make sure that the finished files get renamed into the source directory, not directly written into it, so that rsync can't possibly transfer a file that is not yet fully written. If you can't first write the files into a different directory, you should use a naming idiom that lets rsync avoid transferring files that are not yet finished (e.g. name the file "foo.new" when it is written, rename it to "foo" when it is done, and then use the option --exclude='*.new' for the rsync transfer). Starting with 3.1.0, rsync will skip the sender-side removal (and output an error) if the file's size or modify time has not stayed unchanged. Starting with 3.2.6, a local rsync copy will ensure that the sender does not remove a file the receiver just verified, such as when the user accidentally makes the source and destination directory the same path. --delete This tells rsync to delete extraneous files from the receiving side (ones that aren't on the sending side), but only for the directories that are being synchronized. You must have asked rsync to send the whole directory (e.g. "dir" or "dir/") without using a wildcard for the directory's contents (e.g. "dir/*") since the wildcard is expanded by the shell and rsync thus gets a request to transfer individual files, not the files' parent directory. Files that are excluded from the transfer are also excluded from being deleted unless you use the --delete-excluded option or mark the rules as only matching on the sending side (see the include/exclude modifiers in the FILTER RULES section). Prior to rsync 2.6.7, this option would have no effect unless --recursive was enabled. Beginning with 2.6.7, deletions will also occur when --dirs (-d) is enabled, but only for directories whose contents are being copied. This option can be dangerous if used incorrectly! It is a very good idea to first try a run using the --dry-run (-n) option to see what files are going to be deleted. If the sending side detects any I/O errors, then the deletion of any files at the destination will be automatically disabled. This is to prevent temporary filesystem failures (such as NFS errors) on the sending side from causing a massive deletion of files on the destination. You can override this with the --ignore- errors option. The --delete option may be combined with one of the --delete-WHEN options without conflict, as well as --delete-excluded. However, if none of the --delete-WHEN options are specified, rsync will choose the --delete- during algorithm when talking to rsync 3.0.0 or newer, or the --delete-before algorithm when talking to an older rsync. See also --delete-delay and --delete-after. --delete-before Request that the file-deletions on the receiving side be done before the transfer starts. See --delete (which is implied) for more details on file-deletion. Deleting before the transfer is helpful if the filesystem is tight for space and removing extraneous files would help to make the transfer possible. However, it does introduce a delay before the start of the transfer, and this delay might cause the transfer to timeout (if --timeout was specified). It also forces rsync to use the old, non-incremental recursion algorithm that requires rsync to scan all the files in the transfer into memory at once (see --recursive). --delete-during, --del Request that the file-deletions on the receiving side be done incrementally as the transfer happens. The per- directory delete scan is done right before each directory is checked for updates, so it behaves like a more efficient --delete-before, including doing the deletions prior to any per-directory filter files being updated. This option was first added in rsync version 2.6.4. See --delete (which is implied) for more details on file- deletion. --delete-delay Request that the file-deletions on the receiving side be computed during the transfer (like --delete-during), and then removed after the transfer completes. This is useful when combined with --delay-updates and/or --fuzzy, and is more efficient than using --delete-after (but can behave differently, since --delete-after computes the deletions in a separate pass after all updates are done). If the number of removed files overflows an internal buffer, a temporary file will be created on the receiving side to hold the names (it is removed while open, so you shouldn't see it during the transfer). If the creation of the temporary file fails, rsync will try to fall back to using --delete-after (which it cannot do if --recursive is doing an incremental scan). See --delete (which is implied) for more details on file-deletion. --delete-after Request that the file-deletions on the receiving side be done after the transfer has completed. This is useful if you are sending new per-directory merge files as a part of the transfer and you want their exclusions to take effect for the delete phase of the current transfer. It also forces rsync to use the old, non-incremental recursion algorithm that requires rsync to scan all the files in the transfer into memory at once (see --recursive). See --delete (which is implied) for more details on file- deletion. See also the --delete-delay option that might be a faster choice for those that just want the deletions to occur at the end of the transfer. --delete-excluded This option turns any unqualified exclude/include rules into server-side rules that do not affect the receiver's deletions. By default, an exclude or include has both a server-side effect (to "hide" and "show" files when building the server's file list) and a receiver-side effect (to "protect" and "risk" files when deletions are occurring). Any rule that has no modifier to specify what sides it is executed on will be instead treated as if it were a server-side rule only, avoiding any "protect" effects of the rules. A rule can still apply to both sides even with this option specified if the rule is given both the sender & receiver modifier letters (e.g., -f'-sr foo'). Receiver-side protect/risk rules can also be explicitly specified to limit the deletions. This saves you from having to edit a bunch of -f'- foo' rules into -f'-s foo' (aka -f'H foo') rules (not to mention the corresponding includes). See the FILTER RULES section for more information. See --delete (which is implied) for more details on deletion. --ignore-missing-args When rsync is first processing the explicitly requested source files (e.g. command-line arguments or --files-from entries), it is normally an error if the file cannot be found. This option suppresses that error, and does not try to transfer the file. This does not affect subsequent vanished-file errors if a file was initially found to be present and later is no longer there. --delete-missing-args This option takes the behavior of the (implied) --ignore- missing-args option a step farther: each missing arg will become a deletion request of the corresponding destination file on the receiving side (should it exist). If the destination file is a non-empty directory, it will only be successfully deleted if --force or --delete are in effect. Other than that, this option is independent of any other type of delete processing. The missing source files are represented by special file- list entries which display as a "*missing" entry in the --list-only output. --ignore-errors Tells --delete to go ahead and delete files even when there are I/O errors. --force This option tells rsync to delete a non-empty directory when it is to be replaced by a non-directory. This is only relevant if deletions are not active (see --delete for details). Note for older rsync versions: --force used to still be required when using --delete-after, and it used to be non- functional unless the --recursive option was also enabled. --max-delete=NUM This tells rsync not to delete more than NUM files or directories. If that limit is exceeded, all further deletions are skipped through the end of the transfer. At the end, rsync outputs a warning (including a count of the skipped deletions) and exits with an error code of 25 (unless some more important error condition also occurred). Beginning with version 3.0.0, you may specify --max- delete=0 to be warned about any extraneous files in the destination without removing any of them. Older clients interpreted this as "unlimited", so if you don't know what version the client is, you can use the less obvious --max- delete=-1 as a backward-compatible way to specify that no deletions be allowed (though really old versions didn't warn when the limit was exceeded). --max-size=SIZE This tells rsync to avoid transferring any file that is larger than the specified SIZE. A numeric value can be suffixed with a string to indicate the numeric units or left unqualified to specify bytes. Feel free to use a fractional value along with the units, such as --max- size=1.5m. This option is a TRANSFER RULE, so don't expect any exclude side effects. The first letter of a units string can be B (bytes), K (kilo), M (mega), G (giga), T (tera), or P (peta). If the string is a single char or has "ib" added to it (e.g. "G" or "GiB") then the units are multiples of 1024. If you use a two-letter suffix that ends with a "B" (e.g. "kb") then you get units that are multiples of 1000. The string's letters can be any mix of upper and lower-case that you want to use. Finally, if the string ends with either "+1" or "-1", it is offset by one byte in the indicated direction. The largest possible value is usually 8192P-1. Examples: --max-size=1.5mb-1 is 1499999 bytes, and --max- size=2g+1 is 2147483649 bytes. Note that rsync versions prior to 3.1.0 did not allow --max-size=0. --min-size=SIZE This tells rsync to avoid transferring any file that is smaller than the specified SIZE, which can help in not transferring small, junk files. See the --max-size option for a description of SIZE and other info. Note that rsync versions prior to 3.1.0 did not allow --min-size=0. --max-alloc=SIZE By default rsync limits an individual malloc/realloc to about 1GB in size. For most people this limit works just fine and prevents a protocol error causing rsync to request massive amounts of memory. However, if you have many millions of files in a transfer, a large amount of server memory, and you don't want to split up your transfer into multiple parts, you can increase the per- allocation limit to something larger and rsync will consume more memory. Keep in mind that this is not a limit on the total size of allocated memory. It is a sanity-check value for each individual allocation. See the --max-size option for a description of how SIZE can be specified. The default suffix if none is given is bytes. Beginning in 3.2.3, a value of 0 specifies no limit. You can set a default value using the environment variable RSYNC_MAX_ALLOC using the same SIZE values as supported by this option. If the remote rsync doesn't understand the --max-alloc option, you can override an environmental value by specifying --max-alloc=1g, which will make rsync avoid sending the option to the remote side (because "1G" is the default). --block-size=SIZE, -B This forces the block size used in rsync's delta-transfer algorithm to a fixed value. It is normally selected based on the size of each file being updated. See the technical report for details. Beginning in 3.2.3 the SIZE can be specified with a suffix as detailed in the --max-size option. Older versions only accepted a byte count. --rsh=COMMAND, -e This option allows you to choose an alternative remote shell program to use for communication between the local and remote copies of rsync. Typically, rsync is configured to use ssh by default, but you may prefer to use rsh on a local network. If this option is used with [user@]host::module/path, then the remote shell COMMAND will be used to run an rsync daemon on the remote host, and all data will be transmitted through that remote shell connection, rather than through a direct socket connection to a running rsync daemon on the remote host. See the USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION section above. Beginning with rsync 3.2.0, the RSYNC_PORT environment variable will be set when a daemon connection is being made via a remote-shell connection. It is set to 0 if the default daemon port is being assumed, or it is set to the value of the rsync port that was specified via either the --port option or a non-empty port value in an rsync:// URL. This allows the script to discern if a non-default port is being requested, allowing for things such as an SSL or stunnel helper script to connect to a default or alternate port. Command-line arguments are permitted in COMMAND provided that COMMAND is presented to rsync as a single argument. You must use spaces (not tabs or other whitespace) to separate the command and args from each other, and you can use single- and/or double-quotes to preserve spaces in an argument (but not backslashes). Note that doubling a single-quote inside a single-quoted string gives you a single-quote; likewise for double-quotes (though you need to pay attention to which quotes your shell is parsing and which quotes rsync is parsing). Some examples: -e 'ssh -p 2234' -e 'ssh -o "ProxyCommand nohup ssh firewall nc -w1 %h %p"' (Note that ssh users can alternately customize site- specific connect options in their .ssh/config file.) You can also choose the remote shell program using the RSYNC_RSH environment variable, which accepts the same range of values as -e. See also the --blocking-io option which is affected by this option. --rsync-path=PROGRAM Use this to specify what program is to be run on the remote machine to start-up rsync. Often used when rsync is not in the default remote-shell's path (e.g. --rsync- path=/usr/local/bin/rsync). Note that PROGRAM is run with the help of a shell, so it can be any program, script, or command sequence you'd care to run, so long as it does not corrupt the standard-in & standard-out that rsync is using to communicate. One tricky example is to set a different default directory on the remote machine for use with the --relative option. For instance: rsync -avR --rsync-path="cd /a/b && rsync" host:c/d /e/ --remote-option=OPTION, -M This option is used for more advanced situations where you want certain effects to be limited to one side of the transfer only. For instance, if you want to pass --log- file=FILE and --fake-super to the remote system, specify it like this: rsync -av -M --log-file=foo -M--fake-super src/ dest/ If you want to have an option affect only the local side of a transfer when it normally affects both sides, send its negation to the remote side. Like this: rsync -av -x -M--no-x src/ dest/ Be cautious using this, as it is possible to toggle an option that will cause rsync to have a different idea about what data to expect next over the socket, and that will make it fail in a cryptic fashion. Note that you should use a separate -M option for each remote option you want to pass. On older rsync versions, the presence of any spaces in the remote-option arg could cause it to be split into separate remote args, but this requires the use of --old-args in a modern rsync. When performing a local transfer, the "local" side is the sender and the "remote" side is the receiver. Note some versions of the popt option-parsing library have a bug in them that prevents you from using an adjacent arg with an equal in it next to a short option letter (e.g. -M--log-file=/tmp/foo). If this bug affects your version of popt, you can use the version of popt that is included with rsync. --cvs-exclude, -C This is a useful shorthand for excluding a broad range of files that you often don't want to transfer between systems. It uses a similar algorithm to CVS to determine if a file should be ignored. The exclude list is initialized to exclude the following items (these initial items are marked as perishable -- see the FILTER RULES section): RCS SCCS CVS CVS.adm RCSLOG cvslog.* tags TAGS .make.state .nse_depinfo *~ #* .#* ,* _$* *$ *.old *.bak *.BAK *.orig *.rej .del-* *.a *.olb *.o *.obj *.so *.exe *.Z *.elc *.ln core .svn/ .git/ .hg/ .bzr/ then, files listed in a $HOME/.cvsignore are added to the list and any files listed in the CVSIGNORE environment variable (all cvsignore names are delimited by whitespace). Finally, any file is ignored if it is in the same directory as a .cvsignore file and matches one of the patterns listed therein. Unlike rsync's filter/exclude files, these patterns are split on whitespace. See the cvs(1) manual for more information. If you're combining -C with your own --filter rules, you should note that these CVS excludes are appended at the end of your own rules, regardless of where the -C was placed on the command-line. This makes them a lower priority than any rules you specified explicitly. If you want to control where these CVS excludes get inserted into your filter rules, you should omit the -C as a command- line option and use a combination of --filter=:C and --filter=-C (either on your command-line or by putting the ":C" and "-C" rules into a filter file with your other rules). The first option turns on the per-directory scanning for the .cvsignore file. The second option does a one-time import of the CVS excludes mentioned above. --filter=RULE, -f This option allows you to add rules to selectively exclude certain files from the list of files to be transferred. This is most useful in combination with a recursive transfer. You may use as many --filter options on the command line as you like to build up the list of files to exclude. If the filter contains whitespace, be sure to quote it so that the shell gives the rule to rsync as a single argument. The text below also mentions that you can use an underscore to replace the space that separates a rule from its arg. See the FILTER RULES section for detailed information on this option. -F The -F option is a shorthand for adding two --filter rules to your command. The first time it is used is a shorthand for this rule: --filter='dir-merge /.rsync-filter' This tells rsync to look for per-directory .rsync-filter files that have been sprinkled through the hierarchy and use their rules to filter the files in the transfer. If -F is repeated, it is a shorthand for this rule: --filter='exclude .rsync-filter' This filters out the .rsync-filter files themselves from the transfer. See the FILTER RULES section for detailed information on how these options work. --exclude=PATTERN This option is a simplified form of the --filter option that specifies an exclude rule and does not allow the full rule-parsing syntax of normal filter rules. This is equivalent to specifying -f'- PATTERN'. See the FILTER RULES section for detailed information on this option. --exclude-from=FILE This option is related to the --exclude option, but it specifies a FILE that contains exclude patterns (one per line). Blank lines in the file are ignored, as are whole- line comments that start with ';' or '#' (filename rules that contain those characters are unaffected). If a line begins with "- " (dash, space) or "+ " (plus, space), then the type of rule is being explicitly specified as an exclude or an include (respectively). Any rules without such a prefix are taken to be an exclude. If a line consists of just "!", then the current filter rules are cleared before adding any further rules. If FILE is '-', the list will be read from standard input. --include=PATTERN This option is a simplified form of the --filter option that specifies an include rule and does not allow the full rule-parsing syntax of normal filter rules. This is equivalent to specifying -f'+ PATTERN'. See the FILTER RULES section for detailed information on this option. --include-from=FILE This option is related to the --include option, but it specifies a FILE that contains include patterns (one per line). Blank lines in the file are ignored, as are whole- line comments that start with ';' or '#' (filename rules that contain those characters are unaffected). If a line begins with "- " (dash, space) or "+ " (plus, space), then the type of rule is being explicitly specified as an exclude or an include (respectively). Any rules without such a prefix are taken to be an include. If a line consists of just "!", then the current filter rules are cleared before adding any further rules. If FILE is '-', the list will be read from standard input. --files-from=FILE Using this option allows you to specify the exact list of files to transfer (as read from the specified FILE or '-' for standard input). It also tweaks the default behavior of rsync to make transferring just the specified files and directories easier: o The --relative (-R) option is implied, which preserves the path information that is specified for each item in the file (use --no-relative or --no-R if you want to turn that off). o The --dirs (-d) option is implied, which will create directories specified in the list on the destination rather than noisily skipping them (use --no-dirs or --no-d if you want to turn that off). o The --archive (-a) option's behavior does not imply --recursive (-r), so specify it explicitly, if you want it. o These side-effects change the default state of rsync, so the position of the --files-from option on the command-line has no bearing on how other options are parsed (e.g. -a works the same before or after --files-from, as does --no-R and all other options). The filenames that are read from the FILE are all relative to the source dir -- any leading slashes are removed and no ".." references are allowed to go higher than the source dir. For example, take this command: rsync -a --files-from=/tmp/foo /usr remote:/backup If /tmp/foo contains the string "bin" (or even "/bin"), the /usr/bin directory will be created as /backup/bin on the remote host. If it contains "bin/" (note the trailing slash), the immediate contents of the directory would also be sent (without needing to be explicitly mentioned in the file -- this began in version 2.6.4). In both cases, if the -r option was enabled, that dir's entire hierarchy would also be transferred (keep in mind that -r needs to be specified explicitly with --files-from, since it is not implied by -a. Also note that the effect of the (enabled by default) -r option is to duplicate only the path info that is read from the file -- it does not force the duplication of the source-spec path (/usr in this case). In addition, the --files-from file can be read from the remote host instead of the local host if you specify a "host:" in front of the file (the host must match one end of the transfer). As a short-cut, you can specify just a prefix of ":" to mean "use the remote end of the transfer". For example: rsync -a --files-from=:/path/file-list src:/ /tmp/copy This would copy all the files specified in the /path/file- list file that was located on the remote "src" host. If the --iconv and --secluded-args options are specified and the --files-from filenames are being sent from one host to another, the filenames will be translated from the sending host's charset to the receiving host's charset. NOTE: sorting the list of files in the --files-from input helps rsync to be more efficient, as it will avoid re- visiting the path elements that are shared between adjacent entries. If the input is not sorted, some path elements (implied directories) may end up being scanned multiple times, and rsync will eventually unduplicate them after they get turned into file-list elements. --from0, -0 This tells rsync that the rules/filenames it reads from a file are terminated by a null ('\0') character, not a NL, CR, or CR+LF. This affects --exclude-from, --include- from, --files-from, and any merged files specified in a --filter rule. It does not affect --cvs-exclude (since all names read from a .cvsignore file are split on whitespace). --old-args This option tells rsync to stop trying to protect the arg values on the remote side from unintended word-splitting or other misinterpretation. It also allows the client to treat an empty arg as a "." instead of generating an error. The default in a modern rsync is for "shell-active" characters (including spaces) to be backslash-escaped in the args that are sent to the remote shell. The wildcard characters *, ?, [, & ] are not escaped in filename args (allowing them to expand into multiple filenames) while being protected in option args, such as --usermap. If you have a script that wants to use old-style arg splitting in its filenames, specify this option once. If the remote shell has a problem with any backslash escapes at all, specify this option twice. You may also control this setting via the RSYNC_OLD_ARGS environment variable. If it has the value "1", rsync will default to a single-option setting. If it has the value "2" (or more), rsync will default to a repeated-option setting. If it is "0", you'll get the default escaping behavior. The environment is always overridden by manually specified positive or negative options (the negative is --no-old-args). Note that this option also disables the extra safety check added in 3.2.5 that ensures that a remote sender isn't including extra top-level items in the file-list that you didn't request. This side-effect is necessary because we can't know for sure what names to expect when the remote shell is interpreting the args. This option conflicts with the --secluded-args option. --secluded-args, -s This option sends all filenames and most options to the remote rsync via the protocol (not the remote shell command line) which avoids letting the remote shell modify them. Wildcards are expanded on the remote host by rsync instead of a shell. This is similar to the default backslash-escaping of args that was added in 3.2.4 (see --old-args) in that it prevents things like space splitting and unwanted special- character side-effects. However, it has the drawbacks of being incompatible with older rsync versions (prior to 3.0.0) and of being refused by restricted shells that want to be able to inspect all the option values for safety. This option is useful for those times that you need the argument's character set to be converted for the remote host, if the remote shell is incompatible with the default backslash-escpaing method, or there is some other reason that you want the majority of the options and arguments to bypass the command-line of the remote shell. If you combine this option with --iconv, the args related to the remote side will be translated from the local to the remote character-set. The translation happens before wild-cards are expanded. See also the --files-from option. You may also control this setting via the RSYNC_PROTECT_ARGS environment variable. If it has a non- zero value, this setting will be enabled by default, otherwise it will be disabled by default. Either state is overridden by a manually specified positive or negative version of this option (note that --no-s and --no- secluded-args are the negative versions). This environment variable is also superseded by a non-zero RSYNC_OLD_ARGS export. This option conflicts with the --old-args option. This option used to be called --protect-args (before 3.2.6) and that older name can still be used (though specifying it as -s is always the easiest and most compatible choice). --trust-sender This option disables two extra validation checks that a local client performs on the file list generated by a remote sender. This option should only be used if you trust the sender to not put something malicious in the file list (something that could possibly be done via a modified rsync, a modified shell, or some other similar manipulation). Normally, the rsync client (as of version 3.2.5) runs two extra validation checks when pulling files from a remote rsync: o It verifies that additional arg items didn't get added at the top of the transfer. o It verifies that none of the items in the file list are names that should have been excluded (if filter rules were specified). Note that various options can turn off one or both of these checks if the option interferes with the validation. For instance: o Using a per-directory filter file reads filter rules that only the server knows about, so the filter checking is disabled. o Using the --old-args option allows the sender to manipulate the requested args, so the arg checking is disabled. o Reading the files-from list from the server side means that the client doesn't know the arg list, so the arg checking is disabled. o Using --read-batch disables both checks since the batch file's contents will have been verified when it was created. This option may help an under-powered client server if the extra pattern matching is slowing things down on a huge transfer. It can also be used to work around a currently- unknown bug in the verification logic for a transfer from a trusted sender. When using this option it is a good idea to specify a dedicated destination directory, as discussed in the MULTI-HOST SECURITY section. --copy-as=USER[:GROUP] This option instructs rsync to use the USER and (if specified after a colon) the GROUP for the copy operations. This only works if the user that is running rsync has the ability to change users. If the group is not specified then the user's default groups are used. This option can help to reduce the risk of an rsync being run as root into or out of a directory that might have live changes happening to it and you want to make sure that root-level read or write actions of system files are not possible. While you could alternatively run all of rsync as the specified user, sometimes you need the root- level host-access credentials to be used, so this allows rsync to drop root for the copying part of the operation after the remote-shell or daemon connection is established. The option only affects one side of the transfer unless the transfer is local, in which case it affects both sides. Use the --remote-option to affect the remote side, such as -M--copy-as=joe. For a local transfer, the lsh (or lsh.sh) support file provides a local-shell helper script that can be used to allow a "localhost:" or "lh:" host-spec to be specified without needing to setup any remote shells, allowing you to specify remote options that affect the side of the transfer that is using the host- spec (and using hostname "lh" avoids the overriding of the remote directory to the user's home dir). For example, the following rsync writes the local files as user "joe": sudo rsync -aiv --copy-as=joe host1:backups/joe/ /home/joe/ This makes all files owned by user "joe", limits the groups to those that are available to that user, and makes it impossible for the joe user to do a timed exploit of the path to induce a change to a file that the joe user has no permissions to change. The following command does a local copy into the "dest/" dir as user "joe" (assuming you've installed support/lsh into a dir on your $PATH): sudo rsync -aive lsh -M--copy-as=joe src/ lh:dest/ --temp-dir=DIR, -T This option instructs rsync to use DIR as a scratch directory when creating temporary copies of the files transferred on the receiving side. The default behavior is to create each temporary file in the same directory as the associated destination file. Beginning with rsync 3.1.1, the temp-file names inside the specified DIR will not be prefixed with an extra dot (though they will still have a random suffix added). This option is most often used when the receiving disk partition does not have enough free space to hold a copy of the largest file in the transfer. In this case (i.e. when the scratch directory is on a different disk partition), rsync will not be able to rename each received temporary file over the top of the associated destination file, but instead must copy it into place. Rsync does this by copying the file over the top of the destination file, which means that the destination file will contain truncated data during this copy. If this were not done this way (even if the destination file were first removed, the data locally copied to a temporary file in the destination directory, and then renamed into place) it would be possible for the old file to continue taking up disk space (if someone had it open), and thus there might not be enough room to fit the new version on the disk at the same time. If you are using this option for reasons other than a shortage of disk space, you may wish to combine it with the --delay-updates option, which will ensure that all copied files get put into subdirectories in the destination hierarchy, awaiting the end of the transfer. If you don't have enough room to duplicate all the arriving files on the destination partition, another way to tell rsync that you aren't overly concerned about disk space is to use the --partial-dir option with a relative path; because this tells rsync that it is OK to stash off a copy of a single file in a subdir in the destination hierarchy, rsync will use the partial-dir as a staging area to bring over the copied file, and then rename it into place from there. (Specifying a --partial-dir with an absolute path does not have this side-effect.) --fuzzy, -y This option tells rsync that it should look for a basis file for any destination file that is missing. The current algorithm looks in the same directory as the destination file for either a file that has an identical size and modified-time, or a similarly-named file. If found, rsync uses the fuzzy basis file to try to speed up the transfer. If the option is repeated, the fuzzy scan will also be done in any matching alternate destination directories that are specified via --compare-dest, --copy-dest, or --link-dest. Note that the use of the --delete option might get rid of any potential fuzzy-match files, so either use --delete- after or specify some filename exclusions if you need to prevent this. --compare-dest=DIR This option instructs rsync to use DIR on the destination machine as an additional hierarchy to compare destination files against doing transfers (if the files are missing in the destination directory). If a file is found in DIR that is identical to the sender's file, the file will NOT be transferred to the destination directory. This is useful for creating a sparse backup of just files that have changed from an earlier backup. This option is typically used to copy into an empty (or newly created) directory. Beginning in version 2.6.4, multiple --compare-dest directories may be provided, which will cause rsync to search the list in the order specified for an exact match. If a match is found that differs only in attributes, a local copy is made and the attributes updated. If a match is not found, a basis file from one of the DIRs will be selected to try to speed up the transfer. If DIR is a relative path, it is relative to the destination directory. See also --copy-dest and --link- dest. NOTE: beginning with version 3.1.0, rsync will remove a file from a non-empty destination hierarchy if an exact match is found in one of the compare-dest hierarchies (making the end result more closely match a fresh copy). --copy-dest=DIR This option behaves like --compare-dest, but rsync will also copy unchanged files found in DIR to the destination directory using a local copy. This is useful for doing transfers to a new destination while leaving existing files intact, and then doing a flash-cutover when all files have been successfully transferred. Multiple --copy-dest directories may be provided, which will cause rsync to search the list in the order specified for an unchanged file. If a match is not found, a basis file from one of the DIRs will be selected to try to speed up the transfer. If DIR is a relative path, it is relative to the destination directory. See also --compare-dest and --link-dest. --link-dest=DIR This option behaves like --copy-dest, but unchanged files are hard linked from DIR to the destination directory. The files must be identical in all preserved attributes (e.g. permissions, possibly ownership) in order for the files to be linked together. An example: rsync -av --link-dest=$PWD/prior_dir host:src_dir/ new_dir/ If files aren't linking, double-check their attributes. Also check if some attributes are getting forced outside of rsync's control, such a mount option that squishes root to a single user, or mounts a removable drive with generic ownership (such as OS X's "Ignore ownership on this volume" option). Beginning in version 2.6.4, multiple --link-dest directories may be provided, which will cause rsync to search the list in the order specified for an exact match (there is a limit of 20 such directories). If a match is found that differs only in attributes, a local copy is made and the attributes updated. If a match is not found, a basis file from one of the DIRs will be selected to try to speed up the transfer. This option works best when copying into an empty destination hierarchy, as existing files may get their attributes tweaked, and that can affect alternate destination files via hard-links. Also, itemizing of changes can get a bit muddled. Note that prior to version 3.1.0, an alternate-directory exact match would never be found (nor linked into the destination) when a destination file already exists. Note that if you combine this option with --ignore-times, rsync will not link any files together because it only links identical files together as a substitute for transferring the file, never as an additional check after the file is updated. If DIR is a relative path, it is relative to the destination directory. See also --compare-dest and --copy-dest. Note that rsync versions prior to 2.6.1 had a bug that could prevent --link-dest from working properly for a non- super-user when --owner (-o) was specified (or implied). You can work-around this bug by avoiding the -o option (or using --no-o) when sending to an old rsync. --compress, -z With this option, rsync compresses the file data as it is sent to the destination machine, which reduces the amount of data being transmitted -- something that is useful over a slow connection. Rsync supports multiple compression methods and will choose one for you unless you force the choice using the --compress-choice (--zc) option. Run rsync --version to see the default compress list compiled into your version. When both sides of the transfer are at least 3.2.0, rsync chooses the first algorithm in the client's list of choices that is also in the server's list of choices. If no common compress choice is found, rsync exits with an error. If the remote rsync is too old to support checksum negotiation, its list is assumed to be "zlib". The default order can be customized by setting the environment variable RSYNC_COMPRESS_LIST to a space- separated list of acceptable compression names. If the string contains a "&" character, it is separated into the "client string & server string", otherwise the same string applies to both. If the string (or string portion) contains no non-whitespace characters, the default compress list is used. Any unknown compression names are discarded from the list, but a list with only invalid names results in a failed negotiation. There are some older rsync versions that were configured to reject a -z option and require the use of -zz because their compression library was not compatible with the default zlib compression method. You can usually ignore this weirdness unless the rsync server complains and tells you to specify -zz. --compress-choice=STR, --zc=STR This option can be used to override the automatic negotiation of the compression algorithm that occurs when --compress is used. The option implies --compress unless "none" was specified, which instead implies --no-compress. The compression options that you may be able to use are: o zstd o lz4 o zlibx o zlib o none Run rsync --version to see the default compress list compiled into your version (which may differ from the list above). Note that if you see an error about an option named --old- compress or --new-compress, this is rsync trying to send the --compress-choice=zlib or --compress-choice=zlibx option in a backward-compatible manner that more rsync versions understand. This error indicates that the older rsync version on the server will not allow you to force the compression type. Note that the "zlibx" compression algorithm is just the "zlib" algorithm with matched data excluded from the compression stream (to try to make it more compatible with an external zlib implementation). --compress-level=NUM, --zl=NUM Explicitly set the compression level to use (see --compress, -z) instead of letting it default. The --compress option is implied as long as the level chosen is not a "don't compress" level for the compression algorithm that is in effect (e.g. zlib compression treats level 0 as "off"). The level values vary depending on the checksum in effect. Because rsync will negotiate a checksum choice by default (when the remote rsync is new enough), it can be good to combine this option with a --compress-choice (--zc) option unless you're sure of the choice in effect. For example: rsync -aiv --zc=zstd --zl=22 host:src/ dest/ For zlib & zlibx compression the valid values are from 1 to 9 with 6 being the default. Specifying --zl=0 turns compression off, and specifying --zl=-1 chooses the default level of 6. For zstd compression the valid values are from -131072 to 22 with 3 being the default. Specifying 0 chooses the default of 3. For lz4 compression there are no levels, so the value is always 0. If you specify a too-large or too-small value, the number is silently limited to a valid value. This allows you to specify something like --zl=999999999 and be assured that you'll end up with the maximum compression level no matter what algorithm was chosen. If you want to know the compression level that is in effect, specify --debug=nstr to see the "negotiated string" results. This will report something like "Client compress: zstd (level 3)" (along with the checksum choice in effect). --skip-compress=LIST NOTE: no compression method currently supports per-file compression changes, so this option has no effect. Override the list of file suffixes that will be compressed as little as possible. Rsync sets the compression level on a per-file basis based on the file's suffix. If the compression algorithm has an "off" level, then no compression occurs for those files. Other algorithms that support changing the streaming level on-the-fly will have the level minimized to reduces the CPU usage as much as possible for a matching file. The LIST should be one or more file suffixes (without the dot) separated by slashes (/). You may specify an empty string to indicate that no files should be skipped. Simple character-class matching is supported: each must consist of a list of letters inside the square brackets (e.g. no special classes, such as "[:alpha:]", are supported, and '-' has no special meaning). The characters asterisk (*) and question-mark (?) have no special meaning. Here's an example that specifies 6 suffixes to skip (since 1 of the 5 rules matches 2 suffixes): --skip-compress=gz/jpg/mp[34]/7z/bz2 The default file suffixes in the skip-compress list in this version of rsync are: 3g2 3gp 7z aac ace apk avi bz2 deb dmg ear f4v flac flv gpg gz iso jar jpeg jpg lrz lz lz4 lzma lzo m1a m1v m2a m2ts m2v m4a m4b m4p m4r m4v mka mkv mov mp1 mp2 mp3 mp4 mpa mpeg mpg mpv mts odb odf odg odi odm odp ods odt oga ogg ogm ogv ogx opus otg oth otp ots ott oxt png qt rar rpm rz rzip spx squashfs sxc sxd sxg sxm sxw sz tbz tbz2 tgz tlz ts txz tzo vob war webm webp xz z zip zst This list will be replaced by your --skip-compress list in all but one situation: a copy from a daemon rsync will add your skipped suffixes to its list of non-compressing files (and its list may be configured to a different default). --numeric-ids With this option rsync will transfer numeric group and user IDs rather than using user and group names and mapping them at both ends. By default rsync will use the username and groupname to determine what ownership to give files. The special uid 0 and the special group 0 are never mapped via user/group names even if the --numeric-ids option is not specified. If a user or group has no name on the source system or it has no match on the destination system, then the numeric ID from the source system is used instead. See also the use chroot setting in the rsyncd.conf manpage for some comments on how the chroot setting affects rsync's ability to look up the names of the users and groups and what you can do about it. --usermap=STRING, --groupmap=STRING These options allow you to specify users and groups that should be mapped to other values by the receiving side. The STRING is one or more FROM:TO pairs of values separated by commas. Any matching FROM value from the sender is replaced with a TO value from the receiver. You may specify usernames or user IDs for the FROM and TO values, and the FROM value may also be a wild-card string, which will be matched against the sender's names (wild- cards do NOT match against ID numbers, though see below for why a '*' matches everything). You may instead specify a range of ID numbers via an inclusive range: LOW- HIGH. For example: --usermap=0-99:nobody,wayne:admin,*:normal --groupmap=usr:1,1:usr The first match in the list is the one that is used. You should specify all your user mappings using a single --usermap option, and/or all your group mappings using a single --groupmap option. Note that the sender's name for the 0 user and group are not transmitted to the receiver, so you should either match these values using a 0, or use the names in effect on the receiving side (typically "root"). All other FROM names match those in use on the sending side. All TO names match those in use on the receiving side. Any IDs that do not have a name on the sending side are treated as having an empty name for the purpose of matching. This allows them to be matched via a "*" or using an empty name. For instance: --usermap=:nobody --groupmap=*:nobody When the --numeric-ids option is used, the sender does not send any names, so all the IDs are treated as having an empty name. This means that you will need to specify numeric FROM values if you want to map these nameless IDs to different values. For the --usermap option to work, the receiver will need to be running as a super-user (see also the --super and --fake-super options). For the --groupmap option to work, the receiver will need to have permissions to set that group. Starting with rsync 3.2.4, the --usermap option implies the --owner (-o) option while the --groupmap option implies the --group (-g) option (since rsync needs to have those options enabled for the mapping options to work). An older rsync client may need to use -s to avoid a complaint about wildcard characters, but a modern rsync handles this automatically. --chown=USER:GROUP This option forces all files to be owned by USER with group GROUP. This is a simpler interface than using --usermap & --groupmap directly, but it is implemented using those options internally so they cannot be mixed. If either the USER or GROUP is empty, no mapping for the omitted user/group will occur. If GROUP is empty, the trailing colon may be omitted, but if USER is empty, a leading colon must be supplied. If you specify "--chown=foo:bar", this is exactly the same as specifying "--usermap=*:foo --groupmap=*:bar", only easier (and with the same implied --owner and/or --group options). An older rsync client may need to use -s to avoid a complaint about wildcard characters, but a modern rsync handles this automatically. --timeout=SECONDS This option allows you to set a maximum I/O timeout in seconds. If no data is transferred for the specified time then rsync will exit. The default is 0, which means no timeout. --contimeout=SECONDS This option allows you to set the amount of time that rsync will wait for its connection to an rsync daemon to succeed. If the timeout is reached, rsync exits with an error. --address=ADDRESS By default rsync will bind to the wildcard address when connecting to an rsync daemon. The --address option allows you to specify a specific IP address (or hostname) to bind to. See also the daemon version of the --address option. --port=PORT This specifies an alternate TCP port number to use rather than the default of 873. This is only needed if you are using the double-colon (::) syntax to connect with an rsync daemon (since the URL syntax has a way to specify the port as a part of the URL). See also the daemon version of the --port option. --sockopts=OPTIONS This option can provide endless fun for people who like to tune their systems to the utmost degree. You can set all sorts of socket options which may make transfers faster (or slower!). Read the manpage for the setsockopt() system call for details on some of the options you may be able to set. By default no special socket options are set. This only affects direct socket connections to a remote rsync daemon. See also the daemon version of the --sockopts option. --blocking-io This tells rsync to use blocking I/O when launching a remote shell transport. If the remote shell is either rsh or remsh, rsync defaults to using blocking I/O, otherwise it defaults to using non-blocking I/O. (Note that ssh prefers non-blocking I/O.) --outbuf=MODE This sets the output buffering mode. The mode can be None (aka Unbuffered), Line, or Block (aka Full). You may specify as little as a single letter for the mode, and use upper or lower case. The main use of this option is to change Full buffering to Line buffering when rsync's output is going to a file or pipe. --itemize-changes, -i Requests a simple itemized list of the changes that are being made to each file, including attribute changes. This is exactly the same as specifying --out- format='%i %n%L'. If you repeat the option, unchanged files will also be output, but only if the receiving rsync is at least version 2.6.7 (you can use -vv with older versions of rsync, but that also turns on the output of other verbose messages). The "%i" escape has a cryptic output that is 11 letters long. The general format is like the string YXcstpoguax, where Y is replaced by the type of update being done, X is replaced by the file-type, and the other letters represent attributes that may be output if they are being modified. The update types that replace the Y are as follows: o A < means that a file is being transferred to the remote host (sent). o A > means that a file is being transferred to the local host (received). o A c means that a local change/creation is occurring for the item (such as the creation of a directory or the changing of a symlink, etc.). o A h means that the item is a hard link to another item (requires --hard-links). o A . means that the item is not being updated (though it might have attributes that are being modified). o A * means that the rest of the itemized-output area contains a message (e.g. "deleting"). The file-types that replace the X are: f for a file, a d for a directory, an L for a symlink, a D for a device, and a S for a special file (e.g. named sockets and fifos). The other letters in the string indicate if some attributes of the file have changed, as follows: o "." - the attribute is unchanged. o "+" - the file is newly created. o " " - all the attributes are unchanged (all dots turn to spaces). o "?" - the change is unknown (when the remote rsync is old). o A letter indicates an attribute is being updated. The attribute that is associated with each letter is as follows: o A c means either that a regular file has a different checksum (requires --checksum) or that a symlink, device, or special file has a changed value. Note that if you are sending files to an rsync prior to 3.0.1, this change flag will be present only for checksum-differing regular files. o A s means the size of a regular file is different and will be updated by the file transfer. o A t means the modification time is different and is being updated to the sender's value (requires --times). An alternate value of T means that the modification time will be set to the transfer time, which happens when a file/symlink/device is updated without --times and when a symlink is changed and the receiver can't set its time. (Note: when using an rsync 3.0.0 client, you might see the s flag combined with t instead of the proper T flag for this time-setting failure.) o A p means the permissions are different and are being updated to the sender's value (requires --perms). o An o means the owner is different and is being updated to the sender's value (requires --owner and super-user privileges). o A g means the group is different and is being updated to the sender's value (requires --group and the authority to set the group). o o A u|n|b indicates the following information: u means the access (use) time is different and is being updated to the sender's value (requires --atimes) o n means the create time (newness) is different and is being updated to the sender's value (requires --crtimes) o b means that both the access and create times are being updated o The a means that the ACL information is being changed. o The x means that the extended attribute information is being changed. One other output is possible: when deleting files, the "%i" will output the string "*deleting" for each item that is being removed (assuming that you are talking to a recent enough rsync that it logs deletions instead of outputting them as a verbose message). --out-format=FORMAT This allows you to specify exactly what the rsync client outputs to the user on a per-update basis. The format is a text string containing embedded single-character escape sequences prefixed with a percent (%) character. A default format of "%n%L" is assumed if either --info=name or -v is specified (this tells you just the name of the file and, if the item is a link, where it points). For a full list of the possible escape characters, see the log format setting in the rsyncd.conf manpage. Specifying the --out-format option implies the --info=name option, which will mention each file, dir, etc. that gets updated in a significant way (a transferred file, a recreated symlink/device, or a touched directory). In addition, if the itemize-changes escape (%i) is included in the string (e.g. if the --itemize-changes option was used), the logging of names increases to mention any item that is changed in any way (as long as the receiving side is at least 2.6.4). See the --itemize-changes option for a description of the output of "%i". Rsync will output the out-format string prior to a file's transfer unless one of the transfer-statistic escapes is requested, in which case the logging is done at the end of the file's transfer. When this late logging is in effect and --progress is also specified, rsync will also output the name of the file being transferred prior to its progress information (followed, of course, by the out- format output). --log-file=FILE This option causes rsync to log what it is doing to a file. This is similar to the logging that a daemon does, but can be requested for the client side and/or the server side of a non-daemon transfer. If specified as a client option, transfer logging will be enabled with a default format of "%i %n%L". See the --log-file-format option if you wish to override this. Here's an example command that requests the remote side to log what is happening: rsync -av --remote-option=--log-file=/tmp/rlog src/ dest/ This is very useful if you need to debug why a connection is closing unexpectedly. See also the daemon version of the --log-file option. --log-file-format=FORMAT This allows you to specify exactly what per-update logging is put into the file specified by the --log-file option (which must also be specified for this option to have any effect). If you specify an empty string, updated files will not be mentioned in the log file. For a list of the possible escape characters, see the log format setting in the rsyncd.conf manpage. The default FORMAT used if --log-file is specified and this option is not is '%i %n%L'. See also the daemon version of the --log-file-format option. --stats This tells rsync to print a verbose set of statistics on the file transfer, allowing you to tell how effective rsync's delta-transfer algorithm is for your data. This option is equivalent to --info=stats2 if combined with 0 or 1 -v options, or --info=stats3 if combined with 2 or more -v options. The current statistics are as follows: o Number of files is the count of all "files" (in the generic sense), which includes directories, symlinks, etc. The total count will be followed by a list of counts by filetype (if the total is non- zero). For example: "(reg: 5, dir: 3, link: 2, dev: 1, special: 1)" lists the totals for regular files, directories, symlinks, devices, and special files. If any of value is 0, it is completely omitted from the list. o Number of created files is the count of how many "files" (generic sense) were created (as opposed to updated). The total count will be followed by a list of counts by filetype (if the total is non- zero). o Number of deleted files is the count of how many "files" (generic sense) were deleted. The total count will be followed by a list of counts by filetype (if the total is non-zero). Note that this line is only output if deletions are in effect, and only if protocol 31 is being used (the default for rsync 3.1.x). o Number of regular files transferred is the count of normal files that were updated via rsync's delta- transfer algorithm, which does not include dirs, symlinks, etc. Note that rsync 3.1.0 added the word "regular" into this heading. o Total file size is the total sum of all file sizes in the transfer. This does not count any size for directories or special files, but does include the size of symlinks. o Total transferred file size is the total sum of all files sizes for just the transferred files. o Literal data is how much unmatched file-update data we had to send to the receiver for it to recreate the updated files. o Matched data is how much data the receiver got locally when recreating the updated files. o File list size is how big the file-list data was when the sender sent it to the receiver. This is smaller than the in-memory size for the file list due to some compressing of duplicated data when rsync sends the list. o File list generation time is the number of seconds that the sender spent creating the file list. This requires a modern rsync on the sending side for this to be present. o File list transfer time is the number of seconds that the sender spent sending the file list to the receiver. o Total bytes sent is the count of all the bytes that rsync sent from the client side to the server side. o Total bytes received is the count of all non- message bytes that rsync received by the client side from the server side. "Non-message" bytes means that we don't count the bytes for a verbose message that the server sent to us, which makes the stats more consistent. --8-bit-output, -8 This tells rsync to leave all high-bit characters unescaped in the output instead of trying to test them to see if they're valid in the current locale and escaping the invalid ones. All control characters (but never tabs) are always escaped, regardless of this option's setting. The escape idiom that started in 2.6.7 is to output a literal backslash (\) and a hash (#), followed by exactly 3 octal digits. For example, a newline would output as "\#012". A literal backslash that is in a filename is not escaped unless it is followed by a hash and 3 digits (0-9). --human-readable, -h Output numbers in a more human-readable format. There are 3 possible levels: 1. output numbers with a separator between each set of 3 digits (either a comma or a period, depending on if the decimal point is represented by a period or a comma). 2. output numbers in units of 1000 (with a character suffix for larger units -- see below). 3. output numbers in units of 1024. The default is human-readable level 1. Each -h option increases the level by one. You can take the level down to 0 (to output numbers as pure digits) by specifying the --no-human-readable (--no-h) option. The unit letters that are appended in levels 2 and 3 are: K (kilo), M (mega), G (giga), T (tera), or P (peta). For example, a 1234567-byte file would output as 1.23M in level-2 (assuming that a period is your local decimal point). Backward compatibility note: versions of rsync prior to 3.1.0 do not support human-readable level 1, and they default to level 0. Thus, specifying one or two -h options will behave in a comparable manner in old and new versions as long as you didn't specify a --no-h option prior to one or more -h options. See the --list-only option for one difference. --partial By default, rsync will delete any partially transferred file if the transfer is interrupted. In some circumstances it is more desirable to keep partially transferred files. Using the --partial option tells rsync to keep the partial file which should make a subsequent transfer of the rest of the file much faster. --partial-dir=DIR This option modifies the behavior of the --partial option while also implying that it be enabled. This enhanced partial-file method puts any partially transferred files into the specified DIR instead of writing the partial file out to the destination file. On the next transfer, rsync will use a file found in this dir as data to speed up the resumption of the transfer and then delete it after it has served its purpose. Note that if --whole-file is specified (or implied), any partial-dir files that are found for a file that is being updated will simply be removed (since rsync is sending files without using rsync's delta-transfer algorithm). Rsync will create the DIR if it is missing, but just the last dir -- not the whole path. This makes it easy to use a relative path (such as "--partial-dir=.rsync-partial") to have rsync create the partial-directory in the destination file's directory when it is needed, and then remove it again when the partial file is deleted. Note that this directory removal is only done for a relative pathname, as it is expected that an absolute path is to a directory that is reserved for partial-dir work. If the partial-dir value is not an absolute path, rsync will add an exclude rule at the end of all your existing excludes. This will prevent the sending of any partial- dir files that may exist on the sending side, and will also prevent the untimely deletion of partial-dir items on the receiving side. An example: the above --partial-dir option would add the equivalent of this "perishable" exclude at the end of any other filter rules: -f '-p .rsync-partial/' If you are supplying your own exclude rules, you may need to add your own exclude/hide/protect rule for the partial- dir because: 1. the auto-added rule may be ineffective at the end of your other rules, or 2. you may wish to override rsync's exclude choice. For instance, if you want to make rsync clean-up any left- over partial-dirs that may be lying around, you should specify --delete-after and add a "risk" filter rule, e.g. -f 'R .rsync-partial/'. Avoid using --delete-before or --delete-during unless you don't need rsync to use any of the left-over partial-dir data during the current run. IMPORTANT: the --partial-dir should not be writable by other users or it is a security risk! E.g. AVOID "/tmp"! You can also set the partial-dir value the RSYNC_PARTIAL_DIR environment variable. Setting this in the environment does not force --partial to be enabled, but rather it affects where partial files go when --partial is specified. For instance, instead of using --partial-dir=.rsync-tmp along with --progress, you could set RSYNC_PARTIAL_DIR=.rsync-tmp in your environment and then use the -P option to turn on the use of the .rsync- tmp dir for partial transfers. The only times that the --partial option does not look for this environment value are: 1. when --inplace was specified (since --inplace conflicts with --partial-dir), and 2. when --delay-updates was specified (see below). When a modern rsync resumes the transfer of a file in the partial-dir, that partial file is now updated in-place instead of creating yet another tmp-file copy (so it maxes out at dest + tmp instead of dest + partial + tmp). This requires both ends of the transfer to be at least version 3.2.0. For the purposes of the daemon-config's "refuse options" setting, --partial-dir does not imply --partial. This is so that a refusal of the --partial option can be used to disallow the overwriting of destination files with a partial transfer, while still allowing the safer idiom provided by --partial-dir. --delay-updates This option puts the temporary file from each updated file into a holding directory until the end of the transfer, at which time all the files are renamed into place in rapid succession. This attempts to make the updating of the files a little more atomic. By default the files are placed into a directory named .~tmp~ in each file's destination directory, but if you've specified the --partial-dir option, that directory will be used instead. See the comments in the --partial-dir section for a discussion of how this .~tmp~ dir will be excluded from the transfer, and what you can do if you want rsync to cleanup old .~tmp~ dirs that might be lying around. Conflicts with --inplace and --append. This option implies --no-inc-recursive since it needs the full file list in memory in order to be able to iterate over it at the end. This option uses more memory on the receiving side (one bit per file transferred) and also requires enough free disk space on the receiving side to hold an additional copy of all the updated files. Note also that you should not use an absolute path to --partial-dir unless: 1. there is no chance of any of the files in the transfer having the same name (since all the updated files will be put into a single directory if the path is absolute), and 2. there are no mount points in the hierarchy (since the delayed updates will fail if they can't be renamed into place). See also the "atomic-rsync" python script in the "support" subdir for an update algorithm that is even more atomic (it uses --link-dest and a parallel hierarchy of files). --prune-empty-dirs, -m This option tells the receiving rsync to get rid of empty directories from the file-list, including nested directories that have no non-directory children. This is useful for avoiding the creation of a bunch of useless directories when the sending rsync is recursively scanning a hierarchy of files using include/exclude/filter rules. This option can still leave empty directories on the receiving side if you make use of TRANSFER_RULES. Because the file-list is actually being pruned, this option also affects what directories get deleted when a delete is active. However, keep in mind that excluded files and directories can prevent existing items from being deleted due to an exclude both hiding source files and protecting destination files. See the perishable filter-rule option for how to avoid this. You can prevent the pruning of certain empty directories from the file-list by using a global "protect" filter. For instance, this option would ensure that the directory "emptydir" was kept in the file-list: --filter 'protect emptydir/' Here's an example that copies all .pdf files in a hierarchy, only creating the necessary destination directories to hold the .pdf files, and ensures that any superfluous files and directories in the destination are removed (note the hide filter of non-directories being used instead of an exclude): rsync -avm --del --include='*.pdf' -f 'hide,! */' src/ dest If you didn't want to remove superfluous destination files, the more time-honored options of --include='*/' --exclude='*' would work fine in place of the hide-filter (if that is more natural to you). --progress This option tells rsync to print information showing the progress of the transfer. This gives a bored user something to watch. With a modern rsync this is the same as specifying --info=flist2,name,progress, but any user- supplied settings for those info flags takes precedence (e.g. --info=flist0 --progress). While rsync is transferring a regular file, it updates a progress line that looks like this: 782448 63% 110.64kB/s 0:00:04 In this example, the receiver has reconstructed 782448 bytes or 63% of the sender's file, which is being reconstructed at a rate of 110.64 kilobytes per second, and the transfer will finish in 4 seconds if the current rate is maintained until the end. These statistics can be misleading if rsync's delta- transfer algorithm is in use. For example, if the sender's file consists of the basis file followed by additional data, the reported rate will probably drop dramatically when the receiver gets to the literal data, and the transfer will probably take much longer to finish than the receiver estimated as it was finishing the matched part of the file. When the file transfer finishes, rsync replaces the progress line with a summary line that looks like this: 1,238,099 100% 146.38kB/s 0:00:08 (xfr#5, to-chk=169/396) In this example, the file was 1,238,099 bytes long in total, the average rate of transfer for the whole file was 146.38 kilobytes per second over the 8 seconds that it took to complete, it was the 5th transfer of a regular file during the current rsync session, and there are 169 more files for the receiver to check (to see if they are up-to-date or not) remaining out of the 396 total files in the file-list. In an incremental recursion scan, rsync won't know the total number of files in the file-list until it reaches the ends of the scan, but since it starts to transfer files during the scan, it will display a line with the text "ir-chk" (for incremental recursion check) instead of "to-chk" until the point that it knows the full size of the list, at which point it will switch to using "to-chk". Thus, seeing "ir-chk" lets you know that the total count of files in the file list is still going to increase (and each time it does, the count of files left to check will increase by the number of the files added to the list). -P The -P option is equivalent to "--partial --progress". Its purpose is to make it much easier to specify these two options for a long transfer that may be interrupted. There is also a --info=progress2 option that outputs statistics based on the whole transfer, rather than individual files. Use this flag without outputting a filename (e.g. avoid -v or specify --info=name0) if you want to see how the transfer is doing without scrolling the screen with a lot of names. (You don't need to specify the --progress option in order to use --info=progress2.) Finally, you can get an instant progress report by sending rsync a signal of either SIGINFO or SIGVTALRM. On BSD systems, a SIGINFO is generated by typing a Ctrl+T (Linux doesn't currently support a SIGINFO signal). When the client-side process receives one of those signals, it sets a flag to output a single progress report which is output when the current file transfer finishes (so it may take a little time if a big file is being handled when the signal arrives). A filename is output (if needed) followed by the --info=progress2 format of progress info. If you don't know which of the 3 rsync processes is the client process, it's OK to signal all of them (since the non- client processes ignore the signal). CAUTION: sending SIGVTALRM to an older rsync (pre-3.2.0) will kill it. --password-file=FILE This option allows you to provide a password for accessing an rsync daemon via a file or via standard input if FILE is -. The file should contain just the password on the first line (all other lines are ignored). Rsync will exit with an error if FILE is world readable or if a root-run rsync command finds a non-root-owned file. This option does not supply a password to a remote shell transport such as ssh; to learn how to do that, consult the remote shell's documentation. When accessing an rsync daemon using a remote shell as the transport, this option only comes into effect after the remote shell finishes its authentication (i.e. if you have also specified a password in the daemon's config file). --early-input=FILE This option allows rsync to send up to 5K of data to the "early exec" script on its stdin. One possible use of this data is to give the script a secret that can be used to mount an encrypted filesystem (which you should unmount in the the "post-xfer exec" script). The daemon must be at least version 3.2.1. --list-only This option will cause the source files to be listed instead of transferred. This option is inferred if there is a single source arg and no destination specified, so its main uses are: 1. to turn a copy command that includes a destination arg into a file-listing command, or 2. to be able to specify more than one source arg. Note: be sure to include the destination. CAUTION: keep in mind that a source arg with a wild-card is expanded by the shell into multiple args, so it is never safe to try to specify a single wild-card arg to try to infer this option. A safe example is: rsync -av --list-only foo* dest/ This option always uses an output format that looks similar to this: drwxrwxr-x 4,096 2022/09/30 12:53:11 support -rw-rw-r-- 80 2005/01/11 10:37:37 support/Makefile The only option that affects this output style is (as of 3.1.0) the --human-readable (-h) option. The default is to output sizes as byte counts with digit separators (in a 14-character-width column). Specifying at least one -h option makes the sizes output with unit suffixes. If you want old-style bytecount sizes without digit separators (and an 11-character-width column) use --no-h. Compatibility note: when requesting a remote listing of files from an rsync that is version 2.6.3 or older, you may encounter an error if you ask for a non-recursive listing. This is because a file listing implies the --dirs option w/o --recursive, and older rsyncs don't have that option. To avoid this problem, either specify the --no-dirs option (if you don't need to expand a directory's content), or turn on recursion and exclude the content of subdirectories: -r --exclude='/*/*'. --bwlimit=RATE This option allows you to specify the maximum transfer rate for the data sent over the socket, specified in units per second. The RATE value can be suffixed with a string to indicate a size multiplier, and may be a fractional value (e.g. --bwlimit=1.5m). If no suffix is specified, the value will be assumed to be in units of 1024 bytes (as if "K" or "KiB" had been appended). See the --max-size option for a description of all the available suffixes. A value of 0 specifies no limit. For backward-compatibility reasons, the rate limit will be rounded to the nearest KiB unit, so no rate smaller than 1024 bytes per second is possible. Rsync writes data over the socket in blocks, and this option both limits the size of the blocks that rsync writes, and tries to keep the average transfer rate at the requested limit. Some burstiness may be seen where rsync writes out a block of data and then sleeps to bring the average rate into compliance. Due to the internal buffering of data, the --progress option may not be an accurate reflection on how fast the data is being sent. This is because some files can show up as being rapidly sent when the data is quickly buffered, while other can show up as very slow when the flushing of the output buffer occurs. This may be fixed in a future version. See also the daemon version of the --bwlimit option. --stop-after=MINS, (--time-limit=MINS) This option tells rsync to stop copying when the specified number of minutes has elapsed. For maximal flexibility, rsync does not communicate this option to the remote rsync since it is usually enough that one side of the connection quits as specified. This allows the option's use even when only one side of the connection supports it. You can tell the remote side about the time limit using --remote-option (-M), should the need arise. The --time-limit version of this option is deprecated. --stop-at=y-m-dTh:m This option tells rsync to stop copying when the specified point in time has been reached. The date & time can be fully specified in a numeric format of year-month- dayThour:minute (e.g. 2000-12-31T23:59) in the local timezone. You may choose to separate the date numbers using slashes instead of dashes. The value can also be abbreviated in a variety of ways, such as specifying a 2-digit year and/or leaving off various values. In all cases, the value will be taken to be the next possible point in time where the supplied information matches. If the value specifies the current time or a past time, rsync exits with an error. For example, "1-30" specifies the next January 30th (at midnight local time), "14:00" specifies the next 2 P.M., "1" specifies the next 1st of the month at midnight, "31" specifies the next month where we can stop on its 31st day, and ":59" specifies the next 59th minute after the hour. For maximal flexibility, rsync does not communicate this option to the remote rsync since it is usually enough that one side of the connection quits as specified. This allows the option's use even when only one side of the connection supports it. You can tell the remote side about the time limit using --remote-option (-M), should the need arise. Do keep in mind that the remote host may have a different default timezone than your local host. --fsync Cause the receiving side to fsync each finished file. This may slow down the transfer, but can help to provide peace of mind when updating critical files. --write-batch=FILE Record a file that can later be applied to another identical destination with --read-batch. See the "BATCH MODE" section for details, and also the --only-write-batch option. This option overrides the negotiated checksum & compress lists and always negotiates a choice based on old-school md5/md4/zlib choices. If you want a more modern choice, use the --checksum-choice (--cc) and/or --compress-choice (--zc) options. --only-write-batch=FILE Works like --write-batch, except that no updates are made on the destination system when creating the batch. This lets you transport the changes to the destination system via some other means and then apply the changes via --read-batch. Note that you can feel free to write the batch directly to some portable media: if this media fills to capacity before the end of the transfer, you can just apply that partial transfer to the destination and repeat the whole process to get the rest of the changes (as long as you don't mind a partially updated destination system while the multi-update cycle is happening). Also note that you only save bandwidth when pushing changes to a remote system because this allows the batched data to be diverted from the sender into the batch file without having to flow over the wire to the receiver (when pulling, the sender is remote, and thus can't write the batch). --read-batch=FILE Apply all of the changes stored in FILE, a file previously generated by --write-batch. If FILE is -, the batch data will be read from standard input. See the "BATCH MODE" section for details. --protocol=NUM Force an older protocol version to be used. This is useful for creating a batch file that is compatible with an older version of rsync. For instance, if rsync 2.6.4 is being used with the --write-batch option, but rsync 2.6.3 is what will be used to run the --read-batch option, you should use "--protocol=28" when creating the batch file to force the older protocol version to be used in the batch file (assuming you can't upgrade the rsync on the reading system). --iconv=CONVERT_SPEC Rsync can convert filenames between character sets using this option. Using a CONVERT_SPEC of "." tells rsync to look up the default character-set via the locale setting. Alternately, you can fully specify what conversion to do by giving a local and a remote charset separated by a comma in the order --iconv=LOCAL,REMOTE, e.g. --iconv=utf8,iso88591. This order ensures that the option will stay the same whether you're pushing or pulling files. Finally, you can specify either --no-iconv or a CONVERT_SPEC of "-" to turn off any conversion. The default setting of this option is site-specific, and can also be affected via the RSYNC_ICONV environment variable. For a list of what charset names your local iconv library supports, you can run "iconv --list". If you specify the --secluded-args (-s) option, rsync will translate the filenames you specify on the command-line that are being sent to the remote host. See also the --files-from option. Note that rsync does not do any conversion of names in filter files (including include/exclude files). It is up to you to ensure that you're specifying matching rules that can match on both sides of the transfer. For instance, you can specify extra include/exclude rules if there are filename differences on the two sides that need to be accounted for. When you pass an --iconv option to an rsync daemon that allows it, the daemon uses the charset specified in its "charset" configuration parameter regardless of the remote charset you actually pass. Thus, you may feel free to specify just the local charset for a daemon transfer (e.g. --iconv=utf8). --ipv4, -4 or --ipv6, -6 Tells rsync to prefer IPv4/IPv6 when creating sockets or running ssh. This affects sockets that rsync has direct control over, such as the outgoing socket when directly contacting an rsync daemon, as well as the forwarding of the -4 or -6 option to ssh when rsync can deduce that ssh is being used as the remote shell. For other remote shells you'll need to specify the "--rsh SHELL -4" option directly (or whatever IPv4/IPv6 hint options it uses). See also the daemon version of these options. If rsync was compiled without support for IPv6, the --ipv6 option will have no effect. The rsync --version output will contain "no IPv6" if is the case. --checksum-seed=NUM Set the checksum seed to the integer NUM. This 4 byte checksum seed is included in each block and MD4 file checksum calculation (the more modern MD5 file checksums don't use a seed). By default the checksum seed is generated by the server and defaults to the current time(). This option is used to set a specific checksum seed, which is useful for applications that want repeatable block checksums, or in the case where the user wants a more random checksum seed. Setting NUM to 0 causes rsync to use the default of time() for checksum seed. DAEMON OPTIONS top The options allowed when starting an rsync daemon are as follows: --daemon This tells rsync that it is to run as a daemon. The daemon you start running may be accessed using an rsync client using the host::module or rsync://host/module/ syntax. If standard input is a socket then rsync will assume that it is being run via inetd, otherwise it will detach from the current terminal and become a background daemon. The daemon will read the config file (rsyncd.conf) on each connect made by a client and respond to requests accordingly. See the rsyncd.conf(5) manpage for more details. --address=ADDRESS By default rsync will bind to the wildcard address when run as a daemon with the --daemon option. The --address option allows you to specify a specific IP address (or hostname) to bind to. This makes virtual hosting possible in conjunction with the --config option. See also the address global option in the rsyncd.conf manpage and the client version of the --address option. --bwlimit=RATE This option allows you to specify the maximum transfer rate for the data the daemon sends over the socket. The client can still specify a smaller --bwlimit value, but no larger value will be allowed. See the client version of the --bwlimit option for some extra details. --config=FILE This specifies an alternate config file than the default. This is only relevant when --daemon is specified. The default is /etc/rsyncd.conf unless the daemon is running over a remote shell program and the remote user is not the super-user; in that case the default is rsyncd.conf in the current directory (typically $HOME). --dparam=OVERRIDE, -M This option can be used to set a daemon-config parameter when starting up rsync in daemon mode. It is equivalent to adding the parameter at the end of the global settings prior to the first module's definition. The parameter names can be specified without spaces, if you so desire. For instance: rsync --daemon -M pidfile=/path/rsync.pid --no-detach When running as a daemon, this option instructs rsync to not detach itself and become a background process. This option is required when running as a service on Cygwin, and may also be useful when rsync is supervised by a program such as daemontools or AIX's System Resource Controller. --no-detach is also recommended when rsync is run under a debugger. This option has no effect if rsync is run from inetd or sshd. --port=PORT This specifies an alternate TCP port number for the daemon to listen on rather than the default of 873. See also the client version of the --port option and the port global setting in the rsyncd.conf manpage. --log-file=FILE This option tells the rsync daemon to use the given log- file name instead of using the "log file" setting in the config file. See also the client version of the --log-file option. --log-file-format=FORMAT This option tells the rsync daemon to use the given FORMAT string instead of using the "log format" setting in the config file. It also enables "transfer logging" unless the string is empty, in which case transfer logging is turned off. See also the client version of the --log-file-format option. --sockopts This overrides the socket options setting in the rsyncd.conf file and has the same syntax. See also the client version of the --sockopts option. --verbose, -v This option increases the amount of information the daemon logs during its startup phase. After the client connects, the daemon's verbosity level will be controlled by the options that the client used and the "max verbosity" setting in the module's config section. See also the client version of the --verbose option. --ipv4, -4 or --ipv6, -6 Tells rsync to prefer IPv4/IPv6 when creating the incoming sockets that the rsync daemon will use to listen for connections. One of these options may be required in older versions of Linux to work around an IPv6 bug in the kernel (if you see an "address already in use" error when nothing else is using the port, try specifying --ipv6 or --ipv4 when starting the daemon). See also the client version of these options. If rsync was compiled without support for IPv6, the --ipv6 option will have no effect. The rsync --version output will contain "no IPv6" if is the case. --help, -h When specified after --daemon, print a short help page describing the options available for starting an rsync daemon. FILTER RULES top The filter rules allow for custom control of several aspects of how files are handled: o Control which files the sending side puts into the file list that describes the transfer hierarchy o Control which files the receiving side protects from deletion when the file is not in the sender's file list o Control which extended attribute names are skipped when copying xattrs The rules are either directly specified via option arguments or they can be read in from one or more files. The filter-rule files can even be a part of the hierarchy of files being copied, affecting different parts of the tree in different ways. SIMPLE INCLUDE/EXCLUDE RULES We will first cover the basics of how include & exclude rules affect what files are transferred, ignoring any deletion side- effects. Filter rules mainly affect the contents of directories that rsync is "recursing" into, but they can also affect a top- level item in the transfer that was specified as a argument. The default for any unmatched file/dir is for it to be included in the transfer, which puts the file/dir into the sender's file list. The use of an exclude rule causes one or more matching files/dirs to be left out of the sender's file list. An include rule can be used to limit the effect of an exclude rule that is matching too many files. The order of the rules is important because the first rule that matches is the one that takes effect. Thus, if an early rule excludes a file, no include rule that comes after it can have any effect. This means that you must place any include overrides somewhere prior to the exclude that it is intended to limit. When a directory is excluded, all its contents and sub-contents are also excluded. The sender doesn't scan through any of it at all, which can save a lot of time when skipping large unneeded sub-trees. It is also important to understand that the include/exclude rules are applied to every file and directory that the sender is recursing into. Thus, if you want a particular deep file to be included, you have to make sure that none of the directories that must be traversed on the way down to that file are excluded or else the file will never be discovered to be included. As an example, if the directory "a/path" was given as a transfer argument and you want to ensure that the file "a/path/down/deep/wanted.txt" is a part of the transfer, then the sender must not exclude the directories "a/path", "a/path/down", or "a/path/down/deep" as it makes it way scanning through the file tree. When you are working on the rules, it can be helpful to ask rsync to tell you what is being excluded/included and why. Specifying --debug=FILTER or (when pulling files) -M--debug=FILTER turns on level 1 of the FILTER debug information that will output a message any time that a file or directory is included or excluded and which rule it matched. Beginning in 3.2.4 it will also warn if a filter rule has trailing whitespace, since an exclude of "foo " (with a trailing space) will not exclude a file named "foo". Exclude and include rules can specify wildcard PATTERN MATCHING RULES (similar to shell wildcards) that allow you to match things like a file suffix or a portion of a filename. A rule can be limited to only affecting a directory by putting a trailing slash onto the filename. SIMPLE INCLUDE/EXCLUDE EXAMPLE With the following file tree created on the sending side: mkdir x/ touch x/file.txt mkdir x/y/ touch x/y/file.txt touch x/y/zzz.txt mkdir x/z/ touch x/z/file.txt Then the following rsync command will transfer the file "x/y/file.txt" and the directories needed to hold it, resulting in the path "/tmp/x/y/file.txt" existing on the remote host: rsync -ai -f'+ x/' -f'+ x/y/' -f'+ x/y/file.txt' -f'- *' x host:/tmp/ Aside: this copy could also have been accomplished using the -R option (though the 2 commands behave differently if deletions are enabled): rsync -aiR x/y/file.txt host:/tmp/ The following command does not need an include of the "x" directory because it is not a part of the transfer (note the traililng slash). Running this command would copy just "/tmp/x/file.txt" because the "y" and "z" dirs get excluded: rsync -ai -f'+ file.txt' -f'- *' x/ host:/tmp/x/ This command would omit the zzz.txt file while copying "x" and everything else it contains: rsync -ai -f'- zzz.txt' x host:/tmp/ FILTER RULES WHEN DELETING By default the include & exclude filter rules affect both the sender (as it creates its file list) and the receiver (as it creates its file lists for calculating deletions). If no delete option is in effect, the receiver skips creating the delete- related file lists. This two-sided default can be manually overridden so that you are only specifying sender rules or receiver rules, as described in the FILTER RULES IN DEPTH section. When deleting, an exclude protects a file from being removed on the receiving side while an include overrides that protection (putting the file at risk of deletion). The default is for a file to be at risk -- its safety depends on it matching a corresponding file from the sender. An example of the two-sided exclude effect can be illustrated by the copying of a C development directory between 2 systems. When doing a touch-up copy, you might want to skip copying the built executable and the .o files (sender hide) so that the receiving side can build their own and not lose any object files that are already correct (receiver protect). For instance: rsync -ai --del -f'- *.o' -f'- cmd' src host:/dest/ Note that using -f'-p *.o' is even better than -f'- *.o' if there is a chance that the directory structure may have changed. The "p" modifier is discussed in FILTER RULE MODIFIERS. One final note, if your shell doesn't mind unexpanded wildcards, you could simplify the typing of the filter options by using an underscore in place of the space and leaving off the quotes. For instance, -f -_*.o -f -_cmd (and similar) could be used instead of the filter options above. FILTER RULES IN DEPTH Rsync supports old-style include/exclude rules and new-style filter rules. The older rules are specified using --include and --exclude as well as the --include-from and --exclude-from. These are limited in behavior but they don't require a "-" or "+" prefix. An old-style exclude rule is turned into a "- name" filter rule (with no modifiers) and an old-style include rule is turned into a "+ name" filter rule (with no modifiers). Rsync builds an ordered list of filter rules as specified on the command-line and/or read-in from files. New style filter rules have the following syntax: RULE [PATTERN_OR_FILENAME] RULE,MODIFIERS [PATTERN_OR_FILENAME] You have your choice of using either short or long RULE names, as described below. If you use a short-named rule, the ',' separating the RULE from the MODIFIERS is optional. The PATTERN or FILENAME that follows (when present) must come after either a single space or an underscore (_). Any additional spaces and/or underscores are considered to be a part of the pattern name. Here are the available rule prefixes: exclude, '-' specifies an exclude pattern that (by default) is both a hide and a protect. include, '+' specifies an include pattern that (by default) is both a show and a risk. merge, '.' specifies a merge-file on the client side to read for more rules. dir-merge, ':' specifies a per-directory merge-file. Using this kind of filter rule requires that you trust the sending side's filter checking, so it has the side-effect mentioned under the --trust-sender option. hide, 'H' specifies a pattern for hiding files from the transfer. Equivalent to a sender-only exclude, so -f'H foo' could also be specified as -f'-s foo'. show, 'S' files that match the pattern are not hidden. Equivalent to a sender-only include, so -f'S foo' could also be specified as -f'+s foo'. protect, 'P' specifies a pattern for protecting files from deletion. Equivalent to a receiver-only exclude, so -f'P foo' could also be specified as -f'-r foo'. risk, 'R' files that match the pattern are not protected. Equivalent to a receiver-only include, so -f'R foo' could also be specified as -f'+r foo'. clear, '!' clears the current include/exclude list (takes no arg) When rules are being read from a file (using merge or dir-merge), empty lines are ignored, as are whole-line comments that start with a '#' (filename rules that contain a hash character are unaffected). Note also that the --filter, --include, and --exclude options take one rule/pattern each. To add multiple ones, you can repeat the options on the command-line, use the merge-file syntax of the --filter option, or the --include-from / --exclude-from options. PATTERN MATCHING RULES Most of the rules mentioned above take an argument that specifies what the rule should match. If rsync is recursing through a directory hierarchy, keep in mind that each pattern is matched against the name of every directory in the descent path as rsync finds the filenames to send. The matching rules for the pattern argument take several forms: o If a pattern contains a / (not counting a trailing slash) or a "**" (which can match a slash), then the pattern is matched against the full pathname, including any leading directories within the transfer. If the pattern doesn't contain a (non-trailing) / or a "**", then it is matched only against the final component of the filename or pathname. For example, foo means that the final path component must be "foo" while foo/bar would match the last 2 elements of the path (as long as both elements are within the transfer). o A pattern that ends with a / only matches a directory, not a regular file, symlink, or device. o A pattern that starts with a / is anchored to the start of the transfer path instead of the end. For example, /foo/** or /foo/bar/** match only leading elements in the path. If the rule is read from a per-directory filter file, the transfer path being matched will begin at the level of the filter file instead of the top of the transfer. See the section on ANCHORING INCLUDE/EXCLUDE PATTERNS for a full discussion of how to specify a pattern that matches at the root of the transfer. Rsync chooses between doing a simple string match and wildcard matching by checking if the pattern contains one of these three wildcard characters: '*', '?', and '[' : o a '?' matches any single character except a slash (/). o a '*' matches zero or more non-slash characters. o a '**' matches zero or more characters, including slashes. o a '[' introduces a character class, such as [a-z] or [[:alpha:]], that must match one character. o a trailing *** in the pattern is a shorthand that allows you to match a directory and all its contents using a single rule. For example, specifying "dir_name/***" will match both the "dir_name" directory (as if "dir_name/" had been specified) and everything in the directory (as if "dir_name/**" had been specified). o a backslash can be used to escape a wildcard character, but it is only interpreted as an escape character if at least one wildcard character is present in the match pattern. For instance, the pattern "foo\bar" matches that single backslash literally, while the pattern "foo\bar*" would need to be changed to "foo\\bar*" to avoid the "\b" becoming just "b". Here are some examples of exclude/include matching: o Option -f'- *.o' would exclude all filenames ending with .o o Option -f'- /foo' would exclude a file (or directory) named foo in the transfer-root directory o Option -f'- foo/' would exclude any directory named foo o Option -f'- foo/*/bar' would exclude any file/dir named bar which is at two levels below a directory named foo (if foo is in the transfer) o Option -f'- /foo/**/bar' would exclude any file/dir named bar that was two or more levels below a top-level directory named foo (note that /foo/bar is not excluded by this) o Options -f'+ */' -f'+ *.c' -f'- *' would include all directories and .c source files but nothing else o Options -f'+ foo/' -f'+ foo/bar.c' -f'- *' would include only the foo directory and foo/bar.c (the foo directory must be explicitly included or it would be excluded by the "- *") FILTER RULE MODIFIERS The following modifiers are accepted after an include (+) or exclude (-) rule: o A / specifies that the include/exclude rule should be matched against the absolute pathname of the current item. For example, -f'-/ /etc/passwd' would exclude the passwd file any time the transfer was sending files from the "/etc" directory, and "-/ subdir/foo" would always exclude "foo" when it is in a dir named "subdir", even if "foo" is at the root of the current transfer. o A ! specifies that the include/exclude should take effect if the pattern fails to match. For instance, -f'-! */' would exclude all non-directories. o A C is used to indicate that all the global CVS-exclude rules should be inserted as excludes in place of the "-C". No arg should follow. o An s is used to indicate that the rule applies to the sending side. When a rule affects the sending side, it affects what files are put into the sender's file list. The default is for a rule to affect both sides unless --delete-excluded was specified, in which case default rules become sender-side only. See also the hide (H) and show (S) rules, which are an alternate way to specify sending-side includes/excludes. o An r is used to indicate that the rule applies to the receiving side. When a rule affects the receiving side, it prevents files from being deleted. See the s modifier for more info. See also the protect (P) and risk (R) rules, which are an alternate way to specify receiver-side includes/excludes. o A p indicates that a rule is perishable, meaning that it is ignored in directories that are being deleted. For instance, the --cvs-exclude (-C) option's default rules that exclude things like "CVS" and "*.o" are marked as perishable, and will not prevent a directory that was removed on the source from being deleted on the destination. o An x indicates that a rule affects xattr names in xattr copy/delete operations (and is thus ignored when matching file/dir names). If no xattr-matching rules are specified, a default xattr filtering rule is used (see the --xattrs option). MERGE-FILE FILTER RULES You can merge whole files into your filter rules by specifying either a merge (.) or a dir-merge (:) filter rule (as introduced in the FILTER RULES section above). There are two kinds of merged files -- single-instance ('.') and per-directory (':'). A single-instance merge file is read one time, and its rules are incorporated into the filter list in the place of the "." rule. For per-directory merge files, rsync will scan every directory that it traverses for the named file, merging its contents when the file exists into the current list of inherited rules. These per-directory rule files must be created on the sending side because it is the sending side that is being scanned for the available files to transfer. These rule files may also need to be transferred to the receiving side if you want them to affect what files don't get deleted (see PER- DIRECTORY RULES AND DELETE below). Some examples: merge /etc/rsync/default.rules . /etc/rsync/default.rules dir-merge .per-dir-filter dir-merge,n- .non-inherited-per-dir-excludes :n- .non-inherited-per-dir-excludes The following modifiers are accepted after a merge or dir-merge rule: o A - specifies that the file should consist of only exclude patterns, with no other rule-parsing except for in-file comments. o A + specifies that the file should consist of only include patterns, with no other rule-parsing except for in-file comments. o A C is a way to specify that the file should be read in a CVS-compatible manner. This turns on 'n', 'w', and '-', but also allows the list-clearing token (!) to be specified. If no filename is provided, ".cvsignore" is assumed. o A e will exclude the merge-file name from the transfer; e.g. "dir-merge,e .rules" is like "dir-merge .rules" and "- .rules". o An n specifies that the rules are not inherited by subdirectories. o A w specifies that the rules are word-split on whitespace instead of the normal line-splitting. This also turns off comments. Note: the space that separates the prefix from the rule is treated specially, so "- foo + bar" is parsed as two rules (assuming that prefix-parsing wasn't also disabled). o You may also specify any of the modifiers for the "+" or "-" rules (above) in order to have the rules that are read in from the file default to having that modifier set (except for the ! modifier, which would not be useful). For instance, "merge,-/ .excl" would treat the contents of .excl as absolute-path excludes, while "dir-merge,s .filt" and ":sC" would each make all their per-directory rules apply only on the sending side. If the merge rule specifies sides to affect (via the s or r modifier or both), then the rules in the file must not specify sides (via a modifier or a rule prefix such as hide). Per-directory rules are inherited in all subdirectories of the directory where the merge-file was found unless the 'n' modifier was used. Each subdirectory's rules are prefixed to the inherited per-directory rules from its parents, which gives the newest rules a higher priority than the inherited rules. The entire set of dir-merge rules are grouped together in the spot where the merge-file was specified, so it is possible to override dir-merge rules via a rule that got specified earlier in the list of global rules. When the list-clearing rule ("!") is read from a per-directory file, it only clears the inherited rules for the current merge file. Another way to prevent a single rule from a dir-merge file from being inherited is to anchor it with a leading slash. Anchored rules in a per-directory merge-file are relative to the merge- file's directory, so a pattern "/foo" would only match the file "foo" in the directory where the dir-merge filter file was found. Here's an example filter file which you'd specify via --filter=". file": merge /home/user/.global-filter - *.gz dir-merge .rules + *.[ch] - *.o - foo* This will merge the contents of the /home/user/.global-filter file at the start of the list and also turns the ".rules" filename into a per-directory filter file. All rules read in prior to the start of the directory scan follow the global anchoring rules (i.e. a leading slash matches at the root of the transfer). If a per-directory merge-file is specified with a path that is a parent directory of the first transfer directory, rsync will scan all the parent dirs from that starting point to the transfer directory for the indicated per-directory file. For instance, here is a common filter (see -F): --filter=': /.rsync-filter' That rule tells rsync to scan for the file .rsync-filter in all directories from the root down through the parent directory of the transfer prior to the start of the normal directory scan of the file in the directories that are sent as a part of the transfer. (Note: for an rsync daemon, the root is always the same as the module's "path".) Some examples of this pre-scanning for per-directory files: rsync -avF /src/path/ /dest/dir rsync -av --filter=': ../../.rsync-filter' /src/path/ /dest/dir rsync -av --filter=': .rsync-filter' /src/path/ /dest/dir The first two commands above will look for ".rsync-filter" in "/" and "/src" before the normal scan begins looking for the file in "/src/path" and its subdirectories. The last command avoids the parent-dir scan and only looks for the ".rsync-filter" files in each directory that is a part of the transfer. If you want to include the contents of a ".cvsignore" in your patterns, you should use the rule ":C", which creates a dir-merge of the .cvsignore file, but parsed in a CVS-compatible manner. You can use this to affect where the --cvs-exclude (-C) option's inclusion of the per-directory .cvsignore file gets placed into your rules by putting the ":C" wherever you like in your filter rules. Without this, rsync would add the dir-merge rule for the .cvsignore file at the end of all your other rules (giving it a lower priority than your command-line rules). For example: cat <<EOT | rsync -avC --filter='. -' a/ b + foo.o :C - *.old EOT rsync -avC --include=foo.o -f :C --exclude='*.old' a/ b Both of the above rsync commands are identical. Each one will merge all the per-directory .cvsignore rules in the middle of the list rather than at the end. This allows their dir-specific rules to supersede the rules that follow the :C instead of being subservient to all your rules. To affect the other CVS exclude rules (i.e. the default list of exclusions, the contents of $HOME/.cvsignore, and the value of $CVSIGNORE) you should omit the -C command-line option and instead insert a "-C" rule into your filter rules; e.g. "--filter=-C". LIST-CLEARING FILTER RULE You can clear the current include/exclude list by using the "!" filter rule (as introduced in the FILTER RULES section above). The "current" list is either the global list of rules (if the rule is encountered while parsing the filter options) or a set of per-directory rules (which are inherited in their own sub-list, so a subdirectory can use this to clear out the parent's rules). ANCHORING INCLUDE/EXCLUDE PATTERNS As mentioned earlier, global include/exclude patterns are anchored at the "root of the transfer" (as opposed to per- directory patterns, which are anchored at the merge-file's directory). If you think of the transfer as a subtree of names that are being sent from sender to receiver, the transfer-root is where the tree starts to be duplicated in the destination directory. This root governs where patterns that start with a / match. Because the matching is relative to the transfer-root, changing the trailing slash on a source path or changing your use of the --relative option affects the path you need to use in your matching (in addition to changing how much of the file tree is duplicated on the destination host). The following examples demonstrate this. Let's say that we want to match two source files, one with an absolute path of "/home/me/foo/bar", and one with a path of "/home/you/bar/baz". Here is how the various command choices differ for a 2-source transfer: Example cmd: rsync -a /home/me /home/you /dest +/- pattern: /me/foo/bar +/- pattern: /you/bar/baz Target file: /dest/me/foo/bar Target file: /dest/you/bar/baz Example cmd: rsync -a /home/me/ /home/you/ /dest +/- pattern: /foo/bar (note missing "me") +/- pattern: /bar/baz (note missing "you") Target file: /dest/foo/bar Target file: /dest/bar/baz Example cmd: rsync -a --relative /home/me/ /home/you /dest +/- pattern: /home/me/foo/bar (note full path) +/- pattern: /home/you/bar/baz (ditto) Target file: /dest/home/me/foo/bar Target file: /dest/home/you/bar/baz Example cmd: cd /home; rsync -a --relative me/foo you/ /dest +/- pattern: /me/foo/bar (starts at specified path) +/- pattern: /you/bar/baz (ditto) Target file: /dest/me/foo/bar Target file: /dest/you/bar/baz The easiest way to see what name you should filter is to just look at the output when using --verbose and put a / in front of the name (use the --dry-run option if you're not yet ready to copy any files). PER-DIRECTORY RULES AND DELETE Without a delete option, per-directory rules are only relevant on the sending side, so you can feel free to exclude the merge files themselves without affecting the transfer. To make this easy, the 'e' modifier adds this exclude for you, as seen in these two equivalent commands: rsync -av --filter=': .excl' --exclude=.excl host:src/dir /dest rsync -av --filter=':e .excl' host:src/dir /dest However, if you want to do a delete on the receiving side AND you want some files to be excluded from being deleted, you'll need to be sure that the receiving side knows what files to exclude. The easiest way is to include the per-directory merge files in the transfer and use --delete-after, because this ensures that the receiving side gets all the same exclude rules as the sending side before it tries to delete anything: rsync -avF --delete-after host:src/dir /dest However, if the merge files are not a part of the transfer, you'll need to either specify some global exclude rules (i.e. specified on the command line), or you'll need to maintain your own per-directory merge files on the receiving side. An example of the first is this (assume that the remote .rules files exclude themselves): rsync -av --filter=': .rules' --filter='. /my/extra.rules' --delete host:src/dir /dest In the above example the extra.rules file can affect both sides of the transfer, but (on the sending side) the rules are subservient to the rules merged from the .rules files because they were specified after the per-directory merge rule. In one final example, the remote side is excluding the .rsync- filter files from the transfer, but we want to use our own .rsync-filter files to control what gets deleted on the receiving side. To do this we must specifically exclude the per-directory merge files (so that they don't get deleted) and then put rules into the local files to control what else should not get deleted. Like one of these commands: rsync -av --filter=':e /.rsync-filter' --delete \ host:src/dir /dest rsync -avFF --delete host:src/dir /dest TRANSFER RULES top In addition to the FILTER RULES that affect the recursive file scans that generate the file list on the sending and (when deleting) receiving sides, there are transfer rules. These rules affect which files the generator decides need to be transferred without the side effects of an exclude filter rule. Transfer rules affect only files and never directories. Because a transfer rule does not affect what goes into the sender's (and receiver's) file list, it cannot have any effect on which files get deleted on the receiving side. For example, if the file "foo" is present in the sender's list but its size is such that it is omitted due to a transfer rule, the receiving side does not request the file. However, its presence in the file list means that a delete pass will not remove a matching file named "foo" on the receiving side. On the other hand, a server-side exclude (hide) of the file "foo" leaves the file out of the server's file list, and absent a receiver-side exclude (protect) the receiver will remove a matching file named "foo" if deletions are requested. Given that the files are still in the sender's file list, the --prune-empty-dirs option will not judge a directory as being empty even if it contains only files that the transfer rules omitted. Similarly, a transfer rule does not have any extra effect on which files are deleted on the receiving side, so setting a maximum file size for the transfer does not prevent big files from being deleted. Examples of transfer rules include the default "quick check" algorithm (which compares size & modify time), the --update option, the --max-size option, the --ignore-non-existing option, and a few others. BATCH MODE top Batch mode can be used to apply the same set of updates to many identical systems. Suppose one has a tree which is replicated on a number of hosts. Now suppose some changes have been made to this source tree and those changes need to be propagated to the other hosts. In order to do this using batch mode, rsync is run with the write-batch option to apply the changes made to the source tree to one of the destination trees. The write-batch option causes the rsync client to store in a "batch file" all the information needed to repeat this operation against other, identical destination trees. Generating the batch file once saves having to perform the file status, checksum, and data block generation more than once when updating multiple destination trees. Multicast transport protocols can be used to transfer the batch update files in parallel to many hosts at once, instead of sending the same data to every host individually. To apply the recorded changes to another destination tree, run rsync with the read-batch option, specifying the name of the same batch file, and the destination tree. Rsync updates the destination tree using the information stored in the batch file. For your convenience, a script file is also created when the write-batch option is used: it will be named the same as the batch file with ".sh" appended. This script file contains a command-line suitable for updating a destination tree using the associated batch file. It can be executed using a Bourne (or Bourne-like) shell, optionally passing in an alternate destination tree pathname which is then used instead of the original destination path. This is useful when the destination tree path on the current host differs from the one used to create the batch file. Examples: $ rsync --write-batch=foo -a host:/source/dir/ /adest/dir/ $ scp foo* remote: $ ssh remote ./foo.sh /bdest/dir/ $ rsync --write-batch=foo -a /source/dir/ /adest/dir/ $ ssh remote rsync --read-batch=- -a /bdest/dir/ <foo In these examples, rsync is used to update /adest/dir/ from /source/dir/ and the information to repeat this operation is stored in "foo" and "foo.sh". The host "remote" is then updated with the batched data going into the directory /bdest/dir. The differences between the two examples reveals some of the flexibility you have in how you deal with batches: o The first example shows that the initial copy doesn't have to be local -- you can push or pull data to/from a remote host using either the remote-shell syntax or rsync daemon syntax, as desired. o The first example uses the created "foo.sh" file to get the right rsync options when running the read-batch command on the remote host. o The second example reads the batch data via standard input so that the batch file doesn't need to be copied to the remote machine first. This example avoids the foo.sh script because it needed to use a modified --read-batch option, but you could edit the script file if you wished to make use of it (just be sure that no other option is trying to use standard input, such as the --exclude-from=- option). Caveats: The read-batch option expects the destination tree that it is updating to be identical to the destination tree that was used to create the batch update fileset. When a difference between the destination trees is encountered the update might be discarded with a warning (if the file appears to be up-to-date already) or the file-update may be attempted and then, if the file fails to verify, the update discarded with an error. This means that it should be safe to re-run a read-batch operation if the command got interrupted. If you wish to force the batched-update to always be attempted regardless of the file's size and date, use the -I option (when reading the batch). If an error occurs, the destination tree will probably be in a partially updated state. In that case, rsync can be used in its regular (non-batch) mode of operation to fix up the destination tree. The rsync version used on all destinations must be at least as new as the one used to generate the batch file. Rsync will die with an error if the protocol version in the batch file is too new for the batch-reading rsync to handle. See also the --protocol option for a way to have the creating rsync generate a batch file that an older rsync can understand. (Note that batch files changed format in version 2.6.3, so mixing versions older than that with newer versions will not work.) When reading a batch file, rsync will force the value of certain options to match the data in the batch file if you didn't set them to the same as the batch-writing command. Other options can (and should) be changed. For instance --write-batch changes to --read-batch, --files-from is dropped, and the --filter / --include / --exclude options are not needed unless one of the --delete options is specified. The code that creates the BATCH.sh file transforms any filter/include/exclude options into a single list that is appended as a "here" document to the shell script file. An advanced user can use this to modify the exclude list if a change in what gets deleted by --delete is desired. A normal user can ignore this detail and just use the shell script as an easy way to run the appropriate --read-batch command for the batched data. The original batch mode in rsync was based on "rsync+", but the latest version uses a new implementation. SYMBOLIC LINKS top Three basic behaviors are possible when rsync encounters a symbolic link in the source directory. By default, symbolic links are not transferred at all. A message "skipping non-regular" file is emitted for any symlinks that exist. If --links is specified, then symlinks are added to the transfer (instead of being noisily ignored), and the default handling is to recreate them with the same target on the destination. Note that --archive implies --links. If --copy-links is specified, then symlinks are "collapsed" by copying their referent, rather than the symlink. Rsync can also distinguish "safe" and "unsafe" symbolic links. An example where this might be used is a web site mirror that wishes to ensure that the rsync module that is copied does not include symbolic links to /etc/passwd in the public section of the site. Using --copy-unsafe-links will cause any links to be copied as the file they point to on the destination. Using --safe-links will cause unsafe links to be omitted by the receiver. (Note that you must specify or imply --links for --safe-links to have any effect.) Symbolic links are considered unsafe if they are absolute symlinks (start with /), empty, or if they contain enough ".." components to ascend from the top of the transfer. Here's a summary of how the symlink options are interpreted. The list is in order of precedence, so if your combination of options isn't mentioned, use the first line that is a complete subset of your options: --copy-links Turn all symlinks into normal files and directories (leaving no symlinks in the transfer for any other options to affect). --copy-dirlinks Turn just symlinks to directories into real directories, leaving all other symlinks to be handled as described below. --links --copy-unsafe-links Turn all unsafe symlinks into files and create all safe symlinks. --copy-unsafe-links Turn all unsafe symlinks into files, noisily skip all safe symlinks. --links --safe-links The receiver skips creating unsafe symlinks found in the transfer and creates the safe ones. --links Create all symlinks. For the effect of --munge-links, see the discussion in that option's section. Note that the --keep-dirlinks option does not effect symlinks in the transfer but instead affects how rsync treats a symlink to a directory that already exists on the receiving side. See that option's section for a warning. DIAGNOSTICS top Rsync occasionally produces error messages that may seem a little cryptic. The one that seems to cause the most confusion is "protocol version mismatch -- is your shell clean?". This message is usually caused by your startup scripts or remote shell facility producing unwanted garbage on the stream that rsync is using for its transport. The way to diagnose this problem is to run your remote shell like this: ssh remotehost /bin/true > out.dat then look at out.dat. If everything is working correctly then out.dat should be a zero length file. If you are getting the above error from rsync then you will probably find that out.dat contains some text or data. Look at the contents and try to work out what is producing it. The most common cause is incorrectly configured shell startup scripts (such as .cshrc or .profile) that contain output statements for non-interactive logins. If you are having trouble debugging filter patterns, then try specifying the -vv option. At this level of verbosity rsync will show why each individual file is included or excluded. EXIT VALUES top o 0 - Success o 1 - Syntax or usage error o 2 - Protocol incompatibility o 3 - Errors selecting input/output files, dirs o o 4 - Requested action not supported. Either: an attempt was made to manipulate 64-bit files on a platform that cannot support them o an option was specified that is supported by the client and not by the server o 5 - Error starting client-server protocol o 6 - Daemon unable to append to log-file o 10 - Error in socket I/O o 11 - Error in file I/O o 12 - Error in rsync protocol data stream o 13 - Errors with program diagnostics o 14 - Error in IPC code o 20 - Received SIGUSR1 or SIGINT o 21 - Some error returned by waitpid() o 22 - Error allocating core memory buffers o 23 - Partial transfer due to error o 24 - Partial transfer due to vanished source files o 25 - The --max-delete limit stopped deletions o 30 - Timeout in data send/receive o 35 - Timeout waiting for daemon connection ENVIRONMENT VARIABLES top CVSIGNORE The CVSIGNORE environment variable supplements any ignore patterns in .cvsignore files. See the --cvs-exclude option for more details. RSYNC_ICONV Specify a default --iconv setting using this environment variable. First supported in 3.0.0. RSYNC_OLD_ARGS Specify a "1" if you want the --old-args option to be enabled by default, a "2" (or more) if you want it to be enabled in the repeated-option state, or a "0" to make sure that it is disabled by default. When this environment variable is set to a non-zero value, it supersedes the RSYNC_PROTECT_ARGS variable. This variable is ignored if --old-args, --no-old-args, or --secluded-args is specified on the command line. First supported in 3.2.4. RSYNC_PROTECT_ARGS Specify a non-zero numeric value if you want the --secluded-args option to be enabled by default, or a zero value to make sure that it is disabled by default. This variable is ignored if --secluded-args, --no- secluded-args, or --old-args is specified on the command line. First supported in 3.1.0. Starting in 3.2.4, this variable is ignored if RSYNC_OLD_ARGS is set to a non-zero value. RSYNC_RSH This environment variable allows you to override the default shell used as the transport for rsync. Command line options are permitted after the command name, just as in the --rsh (-e) option. RSYNC_PROXY This environment variable allows you to redirect your rsync client to use a web proxy when connecting to an rsync daemon. You should set RSYNC_PROXY to a hostname:port pair. RSYNC_PASSWORD This environment variable allows you to set the password for an rsync daemon connection, which avoids the password prompt. Note that this does not supply a password to a remote shell transport such as ssh (consult its documentation for how to do that). USER or LOGNAME The USER or LOGNAME environment variables are used to determine the default username sent to an rsync daemon. If neither is set, the username defaults to "nobody". If both are set, USER takes precedence. RSYNC_PARTIAL_DIR This environment variable specifies the directory to use for a --partial transfer without implying that partial transfers be enabled. See the --partial-dir option for full details. RSYNC_COMPRESS_LIST This environment variable allows you to customize the negotiation of the compression algorithm by specifying an alternate order or a reduced list of names. Use the command rsync --version to see the available compression names. See the --compress option for full details. RSYNC_CHECKSUM_LIST This environment variable allows you to customize the negotiation of the checksum algorithm by specifying an alternate order or a reduced list of names. Use the command rsync --version to see the available checksum names. See the --checksum-choice option for full details. RSYNC_MAX_ALLOC This environment variable sets an allocation maximum as if you had used the --max-alloc option. RSYNC_PORT This environment variable is not read by rsync, but is instead set in its sub-environment when rsync is running the remote shell in combination with a daemon connection. This allows a script such as rsync-ssl to be able to know the port number that the user specified on the command line. HOME This environment variable is used to find the user's default .cvsignore file. RSYNC_CONNECT_PROG This environment variable is mainly used in debug setups to set the program to use when making a daemon connection. See CONNECTING TO AN RSYNC DAEMON for full details. RSYNC_SHELL This environment variable is mainly used in debug setups to set the program to use to run the program specified by RSYNC_CONNECT_PROG. See CONNECTING TO AN RSYNC DAEMON for full details. FILES top /etc/rsyncd.conf or rsyncd.conf SEE ALSO top rsync-ssl(1), rsyncd.conf(5), rrsync(1) BUGS top o Times are transferred as *nix time_t values. o When transferring to FAT filesystems rsync may re-sync unmodified files. See the comments on the --modify-window option. o File permissions, devices, etc. are transferred as native numerical values. o See also the comments on the --delete option. Please report bugs! See the web site at https://rsync.samba.org/. VERSION top This manpage is current for version 3.2.7 of rsync. INTERNAL OPTIONS top The options --server and --sender are used internally by rsync, and should never be typed by a user under normal circumstances. Some awareness of these options may be needed in certain scenarios, such as when setting up a login that can only run an rsync command. For instance, the support directory of the rsync distribution has an example script named rrsync (for restricted rsync) that can be used with a restricted ssh login. CREDITS top Rsync is distributed under the GNU General Public License. See the file COPYING for details. An rsync web site is available at https://rsync.samba.org/. The site includes an FAQ-O-Matic which may cover questions unanswered by this manual page. The rsync github project is https://github.com/WayneD/rsync. We would be delighted to hear from you if you like this program. Please contact the mailing-list at rsync@lists.samba.org. This program uses the excellent zlib compression library written by Jean-loup Gailly and Mark Adler. THANKS top Special thanks go out to: John Van Essen, Matt McCutchen, Wesley W. Terpstra, David Dykstra, Jos Backus, Sebastian Krahmer, Martin Pool, and our gone-but-not-forgotten compadre, J.W. Schultz. Thanks also to Richard Brent, Brendan Mackay, Bill Waite, Stephen Rothwell and David Bell. I've probably missed some people, my apologies if I have. AUTHOR top Rsync was originally written by Andrew Tridgell and Paul Mackerras. Many people have later contributed to it. It is currently maintained by Wayne Davison. Mailing lists for support and development are available at https://lists.samba.org/. COLOPHON top This page is part of the rsync (a fast, versatile, remote (and local) file-copying tool) project. Information about the project can be found at https://rsync.samba.org/. If you have a bug report for this manual page, see https://rsync.samba.org/bugzilla.html. This page was obtained from the tarball fetched from https://download.samba.org/pub/rsync/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org rsync 3.2.7 20 Oct 2022 rsync(1) Pages that refer to this page: pmlogger_daily(1), rrsync(1), rsync-ssl(1), rsyncd.conf(5) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create directories "/tmp/x/y/z/" on remote host before copying "$source" to "user@remote:/tmp/x/y/z/" Bash Command:<START>rsync -a --rsync-path="mkdir -p /tmp/x/y/z/ && rsync" $source user@remote:/tmp/x/y/z/<END> |
Create directory dir2 | mkdir dir2 | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create directory dir2 Bash Command:<START>mkdir dir2<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create directory dir2 Bash Command:<START>mkdir dir2<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create directory dir2 Bash Command:<START>mkdir dir2<END> |
Create empty files (or update timestamps if they exist) with names matching each word in variable "correctFilePathAndName" | echo -e "$correctFilePathAndName" | xargs touch | ['touch', 'xargs', 'echo'] | Output a Bash command to accomplish the following task. Task: Create empty files (or update timestamps if they exist) with names matching each word in variable "correctFilePathAndName" Bash Command:<START>echo -e "$correctFilePathAndName" | xargs touch<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # touch\n\n> Create files and set access/modification times.\n> More information: <https://manned.org/man/freebsd-13.1/touch>.\n\n- Create specific files:\n\n`touch {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [a]ccess or [m]odification times to the current one and don't [c]reate file if it doesn't exist:\n\n`touch -c -{{a|m}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file [t]ime to a specific value and don't [c]reate file if it doesn't exist:\n\n`touch -c -t {{YYYYMMDDHHMM.SS}} {{path/to/file1 path/to/file2 ...}}`\n\n- Set the file time of a specific file to the time of anothe[r] file and don't [c]reate file if it doesn't exist:\n\n`touch -c -r {{~/.emacs}} {{path/to/file1 path/to/file2 ...}}`\n # xargs\n\n> Execute a command with piped arguments coming from another command, a file, etc.\n> The input is treated as a single block of text and split into separate pieces on spaces, tabs, newlines and end-of-file.\n> More information: <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/xargs.html>.\n\n- Run a command using the input data as arguments:\n\n`{{arguments_source}} | xargs {{command}}`\n\n- Run multiple chained commands on the input data:\n\n`{{arguments_source}} | xargs sh -c "{{command1}} && {{command2}} | {{command3}}"`\n\n- Delete all files with a `.backup` extension (`-print0` uses a null character to split file names, and `-0` uses it as delimiter):\n\n`find . -name {{'*.backup'}} -print0 | xargs -0 rm -v`\n\n- Execute the command once for each input line, replacing any occurrences of the placeholder (here marked as `_`) with the input line:\n\n`{{arguments_source}} | xargs -I _ {{command}} _ {{optional_extra_arguments}}`\n\n- Parallel runs of up to `max-procs` processes at a time; the default is 1. If `max-procs` is 0, xargs will run as many processes as possible at a time:\n\n`{{arguments_source}} | xargs -P {{max-procs}} {{command}}`\n # echo\n\n> Print given arguments.\n> More information: <https://www.gnu.org/software/coreutils/echo>.\n\n- Print a text message. Note: quotes are optional:\n\n`echo "{{Hello World}}"`\n\n- Print a message with environment variables:\n\n`echo "{{My path is $PATH}}"`\n\n- Print a message without the trailing newline:\n\n`echo -n "{{Hello World}}"`\n\n- Append a message to the file:\n\n`echo "{{Hello World}}" >> {{file.txt}}`\n\n- Enable interpretation of backslash escapes (special characters):\n\n`echo -e "{{Column 1\tColumn 2}}"`\n\n- Print the exit status of the last executed command (Note: In Windows Command Prompt and PowerShell the equivalent commands are `echo %errorlevel%` and `$lastexitcode` respectively):\n\n`echo $?`\n Task: Create empty files (or update timestamps if they exist) with names matching each word in variable "correctFilePathAndName" Bash Command:<START>echo -e "$correctFilePathAndName" | xargs touch<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: touch(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training touch(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | DATE STRING | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TOUCH(1) User Commands TOUCH(1) NAME top touch - change file timestamps SYNOPSIS top touch [OPTION]... FILE... DESCRIPTION top Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. DATE STRING top The --date=STRING is a mostly free format human readable date string such as "Sun, 29 Feb 2004 16:21:42 -0800" or "2004-02-29 16:21:42" or even "next Thursday". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. An empty string indicates the beginning of the day. The date string format is more complex than is easily documented here but is fully described in the info documentation. AUTHOR top Written by Paul Rubin, Arnold Robbins, Jim Kingdon, David MacKenzie, and Randy Smith. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/touch> or available locally via: info '(coreutils) touch invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TOUCH(1) Pages that refer to this page: last(1@@util-linux), utime(2), utimensat(2), systemd-update-done.service(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. xargs(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training xargs(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | EXIT STATUS | STANDARDS CONFORMANCE | HISTORY | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON XARGS(1) General Commands Manual XARGS(1) NAME top xargs - build and execute command lines from standard input SYNOPSIS top xargs [options] [command [initial-arguments]] DESCRIPTION top This manual page documents the GNU version of xargs. xargs reads items from the standard input, delimited by blanks (which can be protected with double or single quotes or a backslash) or newlines, and executes the command (default is echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored. The command line for command is built up until it reaches a system-defined limit (unless the -n and -L options are used). The specified command will be invoked as many times as necessary to use up the list of input items. In general, there will be many fewer invocations of command than there were items in the input. This will normally have significant performance benefits. Some commands can usefully be executed in parallel too; see the -P option. Because Unix filenames can contain blanks and newlines, this default behaviour is often problematic; filenames containing blanks and/or newlines are incorrectly processed by xargs. In these situations it is better to use the -0 option, which prevents such problems. When using this option you will need to ensure that the program which produces the input for xargs also uses a null character as a separator. If that program is GNU find for example, the -print0 option does this for you. If any invocation of the command exits with a status of 255, xargs will stop immediately without reading any further input. An error message is issued on stderr when this happens. OPTIONS top -0, --null Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally). Disables the end-of-file string, which is treated like any other argument. Useful when input items might contain white space, quote marks, or backslashes. The GNU find -print0 option produces input suitable for this mode. -a file, --arg-file=file Read items from file instead of standard input. If you use this option, stdin remains unchanged when commands are run. Otherwise, stdin is redirected from /dev/null. --delimiter=delim, -d delim Input items are terminated by the specified character. The specified delimiter may be a single character, a C- style character escape such as \n, or an octal or hexadecimal escape code. Octal and hexadecimal escape codes are understood as for the printf command. Multibyte characters are not supported. When processing the input, quotes and backslash are not special; every character in the input is taken literally. The -d option disables any end-of-file string, which is treated like any other argument. You can use this option when the input consists of simply newline-separated items, although it is almost always better to design your program to use --null where this is possible. -E eof-str Set the end-of-file string to eof-str. If the end-of-file string occurs as a line of input, the rest of the input is ignored. If neither -E nor -e is used, no end-of-file string is used. -e[eof-str], --eof[=eof-str] This option is a synonym for the -E option. Use -E instead, because it is POSIX compliant while this option is not. If eof-str is omitted, there is no end-of-file string. If neither -E nor -e is used, no end-of-file string is used. -I replace-str Replace occurrences of replace-str in the initial- arguments with names read from standard input. Also, unquoted blanks do not terminate input items; instead the separator is the newline character. Implies -x and -L 1. -i[replace-str], --replace[=replace-str] This option is a synonym for -Ireplace-str if replace-str is specified. If the replace-str argument is missing, the effect is the same as -I{}. The -i option is deprecated; use -I instead. -L max-lines Use at most max-lines nonblank input lines per command line. Trailing blanks cause an input line to be logically continued on the next input line. Implies -x. -l[max-lines], --max-lines[=max-lines] Synonym for the -L option. Unlike -L, the max-lines argument is optional. If max-lines is not specified, it defaults to one. The -l option is deprecated since the POSIX standard specifies -L instead. -n max-args, --max-args=max-args Use at most max-args arguments per command line. Fewer than max-args arguments will be used if the size (see the -s option) is exceeded, unless the -x option is given, in which case xargs will exit. -P max-procs, --max-procs=max-procs Run up to max-procs processes at a time; the default is 1. If max-procs is 0, xargs will run as many processes as possible at a time. Use the -n option or the -L option with -P; otherwise chances are that only one exec will be done. While xargs is running, you can send its process a SIGUSR1 signal to increase the number of commands to run simultaneously, or a SIGUSR2 to decrease the number. You cannot increase it above an implementation-defined limit (which is shown with --show-limits). You cannot decrease it below 1. xargs never terminates its commands; when asked to decrease, it merely waits for more than one existing command to terminate before starting another. Please note that it is up to the called processes to properly manage parallel access to shared resources. For example, if more than one of them tries to print to stdout, the output will be produced in an indeterminate order (and very likely mixed up) unless the processes collaborate in some way to prevent this. Using some kind of locking scheme is one way to prevent such problems. In general, using a locking scheme will help ensure correct output but reduce performance. If you don't want to tolerate the performance difference, simply arrange for each process to produce a separate output file (or otherwise use separate resources). -o, --open-tty Reopen stdin as /dev/tty in the child process before executing the command. This is useful if you want xargs to run an interactive application. -p, --interactive Prompt the user about whether to run each command line and read a line from the terminal. Only run the command line if the response starts with `y' or `Y'. Implies -t. --process-slot-var=name Set the environment variable name to a unique value in each running child process. Values are reused once child processes exit. This can be used in a rudimentary load distribution scheme, for example. -r, --no-run-if-empty If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there is no input. This option is a GNU extension. -s max-chars, --max-chars=max-chars Use at most max-chars characters per command line, including the command and initial-arguments and the terminating nulls at the ends of the argument strings. The largest allowed value is system-dependent, and is calculated as the argument length limit for exec, less the size of your environment, less 2048 bytes of headroom. If this value is more than 128 KiB, 128 KiB is used as the default value; otherwise, the default value is the maximum. 1 KiB is 1024 bytes. xargs automatically adapts to tighter constraints. --show-limits Display the limits on the command-line length which are imposed by the operating system, xargs' choice of buffer size and the -s option. Pipe the input from /dev/null (and perhaps specify --no-run-if-empty) if you don't want xargs to do anything. -t, --verbose Print the command line on the standard error output before executing it. -x, --exit Exit if the size (see the -s option) is exceeded. -- Delimit the option list. Later arguments, if any, are treated as operands even if they begin with -. For example, xargs -- --help runs the command --help (found in PATH) instead of printing the usage text, and xargs -- --mycommand runs the command --mycommand instead of rejecting this as unrecognized option. --help Print a summary of the options to xargs and exit. --version Print the version number of xargs and exit. The options --max-lines (-L, -l), --replace (-I, -i) and --max- args (-n) are mutually exclusive. If some of them are specified at the same time, then xargs will generally use the option specified last on the command line, i.e., it will reset the value of the offending option (given before) to its default value. Additionally, xargs will issue a warning diagnostic on stderr. The exception to this rule is that the special max-args value 1 ('-n1') is ignored after the --replace option and its aliases -I and -i, because it would not actually conflict. EXAMPLES top find /tmp -name core -type f -print | xargs /bin/rm -f Find files named core in or below the directory /tmp and delete them. Note that this will work incorrectly if there are any filenames containing newlines or spaces. find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing spaces or newlines are correctly handled. find /tmp -depth -name core -type f -delete Find files named core in or below the directory /tmp and delete them, but more efficiently than in the previous example (because we avoid the need to use fork(2) and exec(2) to launch rm and we don't need the extra xargs process). cut -d: -f1 < /etc/passwd | sort | xargs echo Generates a compact listing of all the users on the system. EXIT STATUS top xargs exits with the following status: 0 if it succeeds 123 if any invocation of the command exited with status 1125 124 if the command exited with status 255 125 if the command is killed by a signal 126 if the command cannot be run 127 if the command is not found 1 if some other error occurred. Exit codes greater than 128 are used by the shell to indicate that a program died due to a fatal signal. STANDARDS CONFORMANCE top As of GNU xargs version 4.2.9, the default behaviour of xargs is not to have a logical end-of-file marker. POSIX (IEEE Std 1003.1, 2004 Edition) allows this. The -l and -i options appear in the 1997 version of the POSIX standard, but do not appear in the 2004 version of the standard. Therefore you should use -L and -I instead, respectively. The -o option is an extension to the POSIX standard for better compatibility with BSD. The POSIX standard allows implementations to have a limit on the size of arguments to the exec functions. This limit could be as low as 4096 bytes including the size of the environment. For scripts to be portable, they must not rely on a larger value. However, I know of no implementation whose actual limit is that small. The --show-limits option can be used to discover the actual limits in force on the current system. HISTORY top The xargs program was invented by Herb Gellis at Bell Labs. See the Texinfo manual for findutils, Finding Files, for more information. BUGS top It is not possible for xargs to be used securely, since there will always be a time gap between the production of the list of input files and their use in the commands that xargs issues. If other users have access to the system, they can manipulate the filesystem during this time window to force the action of the commands xargs runs to apply to files that you didn't intend. For a more detailed discussion of this and related problems, please refer to the ``Security Considerations'' chapter in the findutils Texinfo documentation. The -execdir option of find can often be used as a more secure alternative. When you use the -I option, each line read from the input is buffered internally. This means that there is an upper limit on the length of input line that xargs will accept when used with the -I option. To work around this limitation, you can use the -s option to increase the amount of buffer space that xargs uses, and you can also use an extra invocation of xargs to ensure that very long lines do not occur. For example: somecommand | xargs -s 50000 echo | xargs -I '{}' -s 100000 rm '{}' Here, the first invocation of xargs has no input line length limit because it doesn't use the -i option. The second invocation of xargs does have such a limit, but we have ensured that it never encounters a line which is longer than it can handle. This is not an ideal solution. Instead, the -i option should not impose a line length limit, which is why this discussion appears in the BUGS section. The problem doesn't occur with the output of find(1) because it emits just one filename per line. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 19902023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top find(1), kill(1), locate(1), updatedb(1), fork(2), execvp(3), locatedb(5), signal(7) Full documentation <https://www.gnu.org/software/findutils/xargs> or available locally via: info xargs COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org XARGS(1) Pages that refer to this page: dpkg-name(1), find(1), grep(1), locate(1), updatedb(1), lsof(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. echo(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training echo(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON ECHO(1) User Commands ECHO(1) NAME top echo - display a line of text SYNOPSIS top echo [SHORT-OPTION]... [STRING]... echo LONG-OPTION DESCRIPTION top Echo the STRING(s) to standard output. -n do not output the trailing newline -e enable interpretation of backslash escapes -E disable interpretation of backslash escapes (default) --help display this help and exit --version output version information and exit If -e is in effect, the following sequences are recognized: \\ backslash \a alert (BEL) \b backspace \c produce no further output \e escape \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \0NNN byte with octal value NNN (1 to 3 digits) \xHH byte with hexadecimal value HH (1 to 2 digits) NOTE: your shell may have its own version of echo, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. NOTE: printf(1) is a preferred alternative, which does not have issues outputting option-like strings. AUTHOR top Written by Brian Fox and Chet Ramey. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top printf(1) Full documentation <https://www.gnu.org/software/coreutils/echo> or available locally via: info '(coreutils) echo invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 ECHO(1) Pages that refer to this page: ldapcompare(1), systemd-ask-password(1), systemd-run(1), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create empty files (or update timestamps if they exist) with names matching each word in variable "correctFilePathAndName" Bash Command:<START>echo -e "$correctFilePathAndName" | xargs touch<END> |
Create hard links of all files and directories matching "test/icecream/cupcake/*" or "test/mtndew/livewire/*" in "test-keep" preserving directory hierarchy | find test -path 'test/icecream/cupcake/*' -o -path 'test/mtndew/livewire/*' | cpio -padluv test-keep | ['find', 'test'] | Output a Bash command to accomplish the following task. Task: Create hard links of all files and directories matching "test/icecream/cupcake/*" or "test/mtndew/livewire/*" in "test-keep" preserving directory hierarchy Bash Command:<START>find test -path 'test/icecream/cupcake/*' -o -path 'test/mtndew/livewire/*' | cpio -padluv test-keep<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # test\n\n> Check file types and compare values.\n> Returns 0 if the condition evaluates to true, 1 if it evaluates to false.\n> More information: <https://www.gnu.org/software/coreutils/test>.\n\n- Test if a given variable is equal to a given string:\n\n`test "{{$MY_VAR}}" = "{{/bin/zsh}}"`\n\n- Test if a given variable is empty:\n\n`test -z "{{$GIT_BRANCH}}"`\n\n- Test if a file exists:\n\n`test -f "{{path/to/file_or_directory}}"`\n\n- Test if a directory does not exist:\n\n`test ! -d "{{path/to/directory}}"`\n\n- If A is true, then do B, or C in the case of an error (notice that C may run even if A fails):\n\n`test {{condition}} && {{echo "true"}} || {{echo "false"}}`\n Task: Create hard links of all files and directories matching "test/icecream/cupcake/*" or "test/mtndew/livewire/*" in "test-keep" preserving directory hierarchy Bash Command:<START>find test -path 'test/icecream/cupcake/*' -o -path 'test/mtndew/livewire/*' | cpio -padluv test-keep<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. test(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training test(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TEST(1) User Commands TEST(1) NAME top test - check file types and compare values SYNOPSIS top test EXPRESSION test [ EXPRESSION ] [ ] [ OPTION DESCRIPTION top Exit with the status determined by EXPRESSION. --help display this help and exit --version output version information and exit An omitted EXPRESSION defaults to false. Otherwise, EXPRESSION is true or false and sets exit status. It is one of: ( EXPRESSION ) EXPRESSION is true ! EXPRESSION EXPRESSION is false EXPRESSION1 -a EXPRESSION2 both EXPRESSION1 and EXPRESSION2 are true EXPRESSION1 -o EXPRESSION2 either EXPRESSION1 or EXPRESSION2 is true -n STRING the length of STRING is nonzero STRING equivalent to -n STRING -z STRING the length of STRING is zero STRING1 = STRING2 the strings are equal STRING1 != STRING2 the strings are not equal INTEGER1 -eq INTEGER2 INTEGER1 is equal to INTEGER2 INTEGER1 -ge INTEGER2 INTEGER1 is greater than or equal to INTEGER2 INTEGER1 -gt INTEGER2 INTEGER1 is greater than INTEGER2 INTEGER1 -le INTEGER2 INTEGER1 is less than or equal to INTEGER2 INTEGER1 -lt INTEGER2 INTEGER1 is less than INTEGER2 INTEGER1 -ne INTEGER2 INTEGER1 is not equal to INTEGER2 FILE1 -ef FILE2 FILE1 and FILE2 have the same device and inode numbers FILE1 -nt FILE2 FILE1 is newer (modification date) than FILE2 FILE1 -ot FILE2 FILE1 is older than FILE2 -b FILE FILE exists and is block special -c FILE FILE exists and is character special -d FILE FILE exists and is a directory -e FILE FILE exists -f FILE FILE exists and is a regular file -g FILE FILE exists and is set-group-ID -G FILE FILE exists and is owned by the effective group ID -h FILE FILE exists and is a symbolic link (same as -L) -k FILE FILE exists and has its sticky bit set -L FILE FILE exists and is a symbolic link (same as -h) -N FILE FILE exists and has been modified since it was last read -O FILE FILE exists and is owned by the effective user ID -p FILE FILE exists and is a named pipe -r FILE FILE exists and the user has read access -s FILE FILE exists and has a size greater than zero -S FILE FILE exists and is a socket -t FD file descriptor FD is opened on a terminal -u FILE FILE exists and its set-user-ID bit is set -w FILE FILE exists and the user has write access -x FILE FILE exists and the user has execute (or search) access Except for -h and -L, all FILE-related tests dereference symbolic links. Beware that parentheses need to be escaped (e.g., by backslashes) for shells. INTEGER may also be -l STRING, which evaluates to the length of STRING. NOTE: Binary -a and -o are inherently ambiguous. Use 'test EXPR1 && test EXPR2' or 'test EXPR1 || test EXPR2' instead. NOTE: [ honors the --help and --version options, but test does not. test treats each of those as it treats any other nonempty STRING. NOTE: your shell may have its own version of test and/or [, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. AUTHOR top Written by Kevin Braunsdorf and Matthew Bradburn. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top access(2) Full documentation <https://www.gnu.org/software/coreutils/test> or available locally via: info '(coreutils) test invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TEST(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create hard links of all files and directories matching "test/icecream/cupcake/*" or "test/mtndew/livewire/*" in "test-keep" preserving directory hierarchy Bash Command:<START>find test -path 'test/icecream/cupcake/*' -o -path 'test/mtndew/livewire/*' | cpio -padluv test-keep<END> |
Create intermediate directories "b and "c" as required and directory "c" | mkdir -p a/b/c | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories "b and "c" as required and directory "c" Bash Command:<START>mkdir -p a/b/c<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories "b and "c" as required and directory "c" Bash Command:<START>mkdir -p a/b/c<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories "b and "c" as required and directory "c" Bash Command:<START>mkdir -p a/b/c<END> |
Create intermediate directories "full", "path" as required and directory "to" | mkdir -p `dirname /full/path/to/file.txt` | ['dirname', 'mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories "full", "path" as required and directory "to" Bash Command:<START>mkdir -p `dirname /full/path/to/file.txt`<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # dirname\n\n> Calculates the parent directory of a file or directory path.\n> More information: <https://www.gnu.org/software/coreutils/dirname>.\n\n- Calculate the parent directory of a given path:\n\n`dirname {{path/to/file_or_directory}}`\n\n- Calculate the parent directory of multiple paths:\n\n`dirname {{path/to/file_or_directory1 path/to/file_or_directory2 ...}}`\n\n- Delimit output with a NUL character instead of a newline (useful when combining with `xargs`):\n\n`dirname --zero {{path/to/file_or_directory1 path/to/file_or_directory2 ...}}`\n # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories "full", "path" as required and directory "to" Bash Command:<START>mkdir -p `dirname /full/path/to/file.txt`<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: dirname(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training dirname(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON DIRNAME(1) User Commands DIRNAME(1) NAME top dirname - strip last component from file name SYNOPSIS top dirname [OPTION] NAME... DESCRIPTION top Output each NAME with its last non-slash component and trailing slashes removed; if NAME contains no /'s, output '.' (meaning the current directory). -z, --zero end each output line with NUL, not newline --help display this help and exit --version output version information and exit EXAMPLES top dirname /usr/bin/ -> "/usr" dirname dir1/str dir2/str -> "dir1" followed by "dir2" dirname stdio.h -> "." AUTHOR top Written by David MacKenzie and Jim Meyering. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top basename(1), readlink(1) Full documentation <https://www.gnu.org/software/coreutils/dirname> or available locally via: info '(coreutils) dirname invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 DIRNAME(1) Pages that refer to this page: basename(1), basename(3) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories "full", "path" as required and directory "to" Bash Command:<START>mkdir -p `dirname /full/path/to/file.txt`<END> |
Create intermediate directories "tmp" as required and directories real_dir1 and real_dir2 | mkdir -p tmp/real_dir1 tmp/real_dir2 | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories "tmp" as required and directories real_dir1 and real_dir2 Bash Command:<START>mkdir -p tmp/real_dir1 tmp/real_dir2<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories "tmp" as required and directories real_dir1 and real_dir2 Bash Command:<START>mkdir -p tmp/real_dir1 tmp/real_dir2<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories "tmp" as required and directories real_dir1 and real_dir2 Bash Command:<START>mkdir -p tmp/real_dir1 tmp/real_dir2<END> |
Create intermediate directories "x" and "p" as required and create "q" | mkdir -p x/p/q | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories "x" and "p" as required and create "q" Bash Command:<START>mkdir -p x/p/q<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories "x" and "p" as required and create "q" Bash Command:<START>mkdir -p x/p/q<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories "x" and "p" as required and create "q" Bash Command:<START>mkdir -p x/p/q<END> |
Create intermediate directories as required | mkdir -p $2 | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories as required Bash Command:<START>mkdir -p $2<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories as required Bash Command:<START>mkdir -p $2<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories as required Bash Command:<START>mkdir -p $2<END> |
Create intermediate directories as required and directory /my/other/path/here | mkdir -p /my/other/path/here | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories as required and directory /my/other/path/here Bash Command:<START>mkdir -p /my/other/path/here<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories as required and directory /my/other/path/here Bash Command:<START>mkdir -p /my/other/path/here<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories as required and directory /my/other/path/here Bash Command:<START>mkdir -p /my/other/path/here<END> |
Create intermediate directories as required and directory /tmp/test/blah/oops/something | mkdir -p /tmp/test/blah/oops/something | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories as required and directory /tmp/test/blah/oops/something Bash Command:<START>mkdir -p /tmp/test/blah/oops/something<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories as required and directory /tmp/test/blah/oops/something Bash Command:<START>mkdir -p /tmp/test/blah/oops/something<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories as required and directory /tmp/test/blah/oops/something Bash Command:<START>mkdir -p /tmp/test/blah/oops/something<END> |
Create intermediate directories as required and directory project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a} | mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a} | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories as required and directory project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a} Bash Command:<START>mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories as required and directory project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a} Bash Command:<START>mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories as required and directory project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a} Bash Command:<START>mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}<END> |
Create intermediate directories foo and bar as required and directory foo/bar/baz | mkdir -p foo/bar/baz | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories foo and bar as required and directory foo/bar/baz Bash Command:<START>mkdir -p foo/bar/baz<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories foo and bar as required and directory foo/bar/baz Bash Command:<START>mkdir -p foo/bar/baz<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories foo and bar as required and directory foo/bar/baz Bash Command:<START>mkdir -p foo/bar/baz<END> |
Create intermediate directories ~/foo/bar/ as required and directories baz, bif, bang | mkdir -p ~/foo/bar/baz ~/foo/bar/bif ~/foo/boo/bang | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directories ~/foo/bar/ as required and directories baz, bif, bang Bash Command:<START>mkdir -p ~/foo/bar/baz ~/foo/bar/bif ~/foo/boo/bang<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directories ~/foo/bar/ as required and directories baz, bif, bang Bash Command:<START>mkdir -p ~/foo/bar/baz ~/foo/bar/bif ~/foo/boo/bang<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directories ~/foo/bar/ as required and directories baz, bif, bang Bash Command:<START>mkdir -p ~/foo/bar/baz ~/foo/bar/bif ~/foo/boo/bang<END> |
Create intermediate directoriy path2 as required and directories a..z | mkdir -p path2/{a..z} | ['mkdir'] | Output a Bash command to accomplish the following task. Task: Create intermediate directoriy path2 as required and directories a..z Bash Command:<START>mkdir -p path2/{a..z}<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # mkdir\n\n> Create directories and set their permissions.\n> More information: <https://www.gnu.org/software/coreutils/mkdir>.\n\n- Create specific directories:\n\n`mkdir {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create specific directories and their [p]arents if needed:\n\n`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`\n\n- Create directories with specific permissions:\n\n`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`\n Task: Create intermediate directoriy path2 as required and directories a..z Bash Command:<START>mkdir -p path2/{a..z}<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: mkdir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training mkdir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON MKDIR(1) User Commands MKDIR(1) NAME top mkdir - make directories SYNOPSIS top mkdir [OPTION]... DIRECTORY... DESCRIPTION top Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short options too. -m, --mode=MODE set file mode (as in chmod), not a=rwx - umask -p, --parents no error if existing, make parent directories as needed, with their file modes unaffected by any -m option. -v, --verbose print a message for each created directory -Z set SELinux security context of each created directory to the default type --context[=CTX] like -Z, or if CTX is specified then set the SELinux or SMACK security context to CTX --help display this help and exit --version output version information and exit AUTHOR top Written by David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top mkdir(2) Full documentation <https://www.gnu.org/software/coreutils/mkdir> or available locally via: info '(coreutils) mkdir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 MKDIR(1) Pages that refer to this page: systemd-mount(1), mkdir(2), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create intermediate directoriy path2 as required and directories a..z Bash Command:<START>mkdir -p path2/{a..z}<END> |
Create links for all files in the current directory tree that are more than 1000 days old in "/home/user/archives" | find . -type f -mtime +1000 -print0 | cpio -dumpl0 /home/user/archives | ['find'] | Output a Bash command to accomplish the following task. Task: Create links for all files in the current directory tree that are more than 1000 days old in "/home/user/archives" Bash Command:<START>find . -type f -mtime +1000 -print0 | cpio -dumpl0 /home/user/archives<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n Task: Create links for all files in the current directory tree that are more than 1000 days old in "/home/user/archives" Bash Command:<START>find . -type f -mtime +1000 -print0 | cpio -dumpl0 /home/user/archives<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create links for all files in the current directory tree that are more than 1000 days old in "/home/user/archives" Bash Command:<START>find . -type f -mtime +1000 -print0 | cpio -dumpl0 /home/user/archives<END> |
Create master SSH control socket "my-ctrl-socket" in the background with no terminal or command execution with connection forwarding from localhost port 50000 to localhost port 3306 via "jm@sampledomani.com" | ssh -M -S my-ctrl-socket -fnNT -L 50000:localhost:3306 jm@sampledomain.com | ['ssh'] | Output a Bash command to accomplish the following task. Task: Create master SSH control socket "my-ctrl-socket" in the background with no terminal or command execution with connection forwarding from localhost port 50000 to localhost port 3306 via "jm@sampledomani.com" Bash Command:<START>ssh -M -S my-ctrl-socket -fnNT -L 50000:localhost:3306 jm@sampledomain.com<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh\n\n> Secure Shell is a protocol used to securely log onto remote systems.\n> It can be used for logging or executing commands on a remote server.\n> More information: <https://man.openbsd.org/ssh>.\n\n- Connect to a remote server:\n\n`ssh {{username}}@{{remote_host}}`\n\n- Connect to a remote server with a specific identity (private key):\n\n`ssh -i {{path/to/key_file}} {{username}}@{{remote_host}}`\n\n- Connect to a remote server using a specific [p]ort:\n\n`ssh {{username}}@{{remote_host}} -p {{2222}}`\n\n- Run a command on a remote server with a [t]ty allocation allowing interaction with the remote command:\n\n`ssh {{username}}@{{remote_host}} -t {{command}} {{command_arguments}}`\n\n- SSH tunneling: [D]ynamic port forwarding (SOCKS proxy on `localhost:1080`):\n\n`ssh -D {{1080}} {{username}}@{{remote_host}}`\n\n- SSH tunneling: Forward a specific port (`localhost:9999` to `example.org:80`) along with disabling pseudo-[T]ty allocation and executio[N] of remote commands:\n\n`ssh -L {{9999}}:{{example.org}}:{{80}} -N -T {{username}}@{{remote_host}}`\n\n- SSH [J]umping: Connect through a jumphost to a remote server (Multiple jump hops may be specified separated by comma characters):\n\n`ssh -J {{username}}@{{jump_host}} {{username}}@{{remote_host}}`\n\n- Agent forwarding: Forward the authentication information to the remote machine (see `man ssh_config` for available options):\n\n`ssh -A {{username}}@{{remote_host}}`\n Task: Create master SSH control socket "my-ctrl-socket" in the background with no terminal or command execution with connection forwarding from localhost port 50000 to localhost port 3306 via "jm@sampledomani.com" Bash Command:<START>ssh -M -S my-ctrl-socket -fnNT -L 50000:localhost:3306 jm@sampledomain.com<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHENTICATION | ESCAPE CHARACTERS | TCP FORWARDING | X11 FORWARDING | VERIFYING HOST KEYS | SSH-BASED VIRTUAL PRIVATE NETWORKS | ENVIRONMENT | FILES | EXIT STATUS | SEE ALSO | STANDARDS | AUTHORS | COLOPHON SSH(1) General Commands Manual SSH(1) NAME top ssh OpenSSH remote login client SYNOPSIS top ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface] [-b bind_address] [-c cipher_spec] [-D [bind_address:]port] [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11] [-i identity_file] [-J destination] [-L address] [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-P tag] [-p port] [-R address] [-S ctl_path] [-W host:port] [-w local_tun[:remote_tun]] destination [command [argument ...]] [-Q query_option] DESCRIPTION top (SSH client) is a program for logging into a remote machine and for executing commands on a remote machine. It is intended to provide secure encrypted communications between two untrusted hosts over an insecure network. X11 connections, arbitrary TCP ports and Unix-domain sockets can also be forwarded over the secure channel. connects and logs into the specified destination, which may be specified as either [user@]hostname or a URI of the form ssh://[user@]hostname[:port]. The user must prove their identity to the remote machine using one of several methods (see below). If a command is specified, it will be executed on the remote host instead of a login shell. A complete command line may be specified as command, or it may have additional arguments. If supplied, the arguments will be appended to the command, separated by spaces, before it is sent to the server to be executed. The options are as follows: -4 Forces to use IPv4 addresses only. -6 Forces to use IPv6 addresses only. -A Enables forwarding of connections from an authentication agent such as ssh-agent(1). This can also be specified on a per-host basis in a configuration file. Agent forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the agent's Unix-domain socket) can access the local agent through the forwarded connection. An attacker cannot obtain key material from the agent, however they can perform operations on the keys that enable them to authenticate using the identities loaded into the agent. A safer alternative may be to use a jump host (see -J). -a Disables forwarding of the authentication agent connection. -B bind_interface Bind to the address of bind_interface before attempting to connect to the destination host. This is only useful on systems with more than one address. -b bind_address Use bind_address on the local machine as the source address of the connection. Only useful on systems with more than one address. -C Requests compression of all data (including stdin, stdout, stderr, and data for forwarded X11, TCP and Unix-domain connections). The compression algorithm is the same used by gzip(1). Compression is desirable on modem lines and other slow connections, but will only slow down things on fast networks. The default value can be set on a host-by-host basis in the configuration files; see the Compression option in ssh_config(5). -c cipher_spec Selects the cipher specification for encrypting the session. cipher_spec is a comma-separated list of ciphers listed in order of preference. See the Ciphers keyword in ssh_config(5) for more information. -D [bind_address:]port Specifies a local dynamic application-level port forwarding. This works by allocating a socket to listen to port on the local side, optionally bound to the specified bind_address. Whenever a connection is made to this port, the connection is forwarded over the secure channel, and the application protocol is then used to determine where to connect to from the remote machine. Currently the SOCKS4 and SOCKS5 protocols are supported, and will act as a SOCKS server. Only root can forward privileged ports. Dynamic port forwardings can also be specified in the configuration file. IPv6 addresses can be specified by enclosing the address in square brackets. Only the superuser can forward privileged ports. By default, the local port is bound in accordance with the GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a specific address. The bind_address of localhost indicates that the listening port be bound for local use only, while an empty address or * indicates that the port should be available from all interfaces. -E log_file Append debug logs to log_file instead of standard error. -e escape_char Sets the escape character for sessions with a pty (default: ~). The escape character is only recognized at the beginning of a line. The escape character followed by a dot (.) closes the connection; followed by control-Z suspends the connection; and followed by itself sends the escape character once. Setting the character to none disables any escapes and makes the session fully transparent. -F configfile Specifies an alternative per-user configuration file. If a configuration file is given on the command line, the system-wide configuration file (/etc/ssh/ssh_config) will be ignored. The default for the per-user configuration file is ~/.ssh/config. If set to none, no configuration files will be read. -f Requests to go to background just before command execution. This is useful if is going to ask for passwords or passphrases, but the user wants it in the background. This implies -n. The recommended way to start X11 programs at a remote site is with something like ssh -f host xterm. If the ExitOnForwardFailure configuration option is set to yes, then a client started with -f will wait for all remote port forwards to be successfully established before placing itself in the background. Refer to the description of ForkAfterAuthentication in ssh_config(5) for details. -G Causes to print its configuration after evaluating Host and Match blocks and exit. -g Allows remote hosts to connect to local forwarded ports. If used on a multiplexed connection, then this option must be specified on the master process. -I pkcs11 Specify the PKCS#11 shared library should use to communicate with a PKCS#11 token providing keys for user authentication. -i identity_file Selects a file from which the identity (private key) for public key authentication is read. You can also specify a public key file to use the corresponding private key that is loaded in ssh-agent(1) when the private key file is not present locally. The default is ~/.ssh/id_rsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk and ~/.ssh/id_dsa. Identity files may also be specified on a per-host basis in the configuration file. It is possible to have multiple -i options (and multiple identities specified in configuration files). If no certificates have been explicitly specified by the CertificateFile directive, will also try to load certificate information from the filename obtained by appending -cert.pub to identity filenames. -J destination Connect to the target host by first making an connection to the jump host described by destination and then establishing a TCP forwarding to the ultimate destination from there. Multiple jump hops may be specified separated by comma characters. This is a shortcut to specify a ProxyJump configuration directive. Note that configuration directives supplied on the command-line generally apply to the destination host and not any specified jump hosts. Use ~/.ssh/config to specify configuration for jump hosts. -K Enables GSSAPI-based authentication and forwarding (delegation) of GSSAPI credentials to the server. -k Disables forwarding (delegation) of GSSAPI credentials to the server. -L [bind_address:]port:host:hostport -L [bind_address:]port:remote_socket -L local_socket:host:hostport -L local_socket:remote_socket Specifies that connections to the given TCP port or Unix socket on the local (client) host are to be forwarded to the given host and port, or Unix socket, on the remote side. This works by allocating a socket to listen to either a TCP port on the local side, optionally bound to the specified bind_address, or to a Unix socket. Whenever a connection is made to the local port or socket, the connection is forwarded over the secure channel, and a connection is made to either host port hostport, or the Unix socket remote_socket, from the remote machine. Port forwardings can also be specified in the configuration file. Only the superuser can forward privileged ports. IPv6 addresses can be specified by enclosing the address in square brackets. By default, the local port is bound in accordance with the GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a specific address. The bind_address of localhost indicates that the listening port be bound for local use only, while an empty address or * indicates that the port should be available from all interfaces. -l login_name Specifies the user to log in as on the remote machine. This also may be specified on a per-host basis in the configuration file. -M Places the client into master mode for connection sharing. Multiple -M options places into master mode but with confirmation required using ssh-askpass(1) before each operation that changes the multiplexing state (e.g. opening a new session). Refer to the description of ControlMaster in ssh_config(5) for details. -m mac_spec A comma-separated list of MAC (message authentication code) algorithms, specified in order of preference. See the MACs keyword in ssh_config(5) for more information. -N Do not execute a remote command. This is useful for just forwarding ports. Refer to the description of SessionType in ssh_config(5) for details. -n Redirects stdin from /dev/null (actually, prevents reading from stdin). This must be used when is run in the background. A common trick is to use this to run X11 programs on a remote machine. For example, ssh -n shadows.cs.hut.fi emacs & will start an emacs on shadows.cs.hut.fi, and the X11 connection will be automatically forwarded over an encrypted channel. The program will be put in the background. (This does not work if needs to ask for a password or passphrase; see also the -f option.) Refer to the description of StdinNull in ssh_config(5) for details. -O ctl_cmd Control an active connection multiplexing master process. When the -O option is specified, the ctl_cmd argument is interpreted and passed to the master process. Valid commands are: check (check that the master process is running), forward (request forwardings without command execution), cancel (cancel forwardings), exit (request the master to exit), and stop (request the master to stop accepting further multiplexing requests). -o option Can be used to give options in the format used in the configuration file. This is useful for specifying options for which there is no separate command-line flag. For full details of the options listed below, and their possible values, see ssh_config(5). AddKeysToAgent AddressFamily BatchMode BindAddress CanonicalDomains CanonicalizeFallbackLocal CanonicalizeHostname CanonicalizeMaxDots CanonicalizePermittedCNAMEs CASignatureAlgorithms CertificateFile CheckHostIP Ciphers ClearAllForwardings Compression ConnectionAttempts ConnectTimeout ControlMaster ControlPath ControlPersist DynamicForward EnableEscapeCommandline EscapeChar ExitOnForwardFailure FingerprintHash ForkAfterAuthentication ForwardAgent ForwardX11 ForwardX11Timeout ForwardX11Trusted GatewayPorts GlobalKnownHostsFile GSSAPIAuthentication GSSAPIDelegateCredentials HashKnownHosts Host HostbasedAcceptedAlgorithms HostbasedAuthentication HostKeyAlgorithms HostKeyAlias Hostname IdentitiesOnly IdentityAgent IdentityFile IPQoS KbdInteractiveAuthentication KbdInteractiveDevices KexAlgorithms KnownHostsCommand LocalCommand LocalForward LogLevel MACs Match NoHostAuthenticationForLocalhost NumberOfPasswordPrompts PasswordAuthentication PermitLocalCommand PermitRemoteOpen PKCS11Provider Port PreferredAuthentications ProxyCommand ProxyJump ProxyUseFdpass PubkeyAcceptedAlgorithms PubkeyAuthentication RekeyLimit RemoteCommand RemoteForward RequestTTY RequiredRSASize SendEnv ServerAliveInterval ServerAliveCountMax SessionType SetEnv StdinNull StreamLocalBindMask StreamLocalBindUnlink StrictHostKeyChecking TCPKeepAlive Tunnel TunnelDevice UpdateHostKeys User UserKnownHostsFile VerifyHostKeyDNS VisualHostKey XAuthLocation -P tag Specify a tag name that may be used to select configuration in ssh_config(5). Refer to the Tag and Match keywords in ssh_config(5) for more information. -p port Port to connect to on the remote host. This can be specified on a per-host basis in the configuration file. -Q query_option Queries for the algorithms supported by one of the following features: cipher (supported symmetric ciphers), cipher-auth (supported symmetric ciphers that support authenticated encryption), help (supported query terms for use with the -Q flag), mac (supported message integrity codes), kex (key exchange algorithms), key (key types), key-ca-sign (valid CA signature algorithms for certificates), key-cert (certificate key types), key-plain (non-certificate key types), key-sig (all key types and signature algorithms), protocol-version (supported SSH protocol versions), and sig (supported signature algorithms). Alternatively, any keyword from ssh_config(5) or sshd_config(5) that takes an algorithm list may be used as an alias for the corresponding query_option. -q Quiet mode. Causes most warning and diagnostic messages to be suppressed. -R [bind_address:]port:host:hostport -R [bind_address:]port:local_socket -R remote_socket:host:hostport -R remote_socket:local_socket -R [bind_address:]port Specifies that connections to the given TCP port or Unix socket on the remote (server) host are to be forwarded to the local side. This works by allocating a socket to listen to either a TCP port or to a Unix socket on the remote side. Whenever a connection is made to this port or Unix socket, the connection is forwarded over the secure channel, and a connection is made from the local machine to either an explicit destination specified by host port hostport, or local_socket, or, if no explicit destination was specified, will act as a SOCKS 4/5 proxy and forward connections to the destinations requested by the remote SOCKS client. Port forwardings can also be specified in the configuration file. Privileged ports can be forwarded only when logging in as root on the remote machine. IPv6 addresses can be specified by enclosing the address in square brackets. By default, TCP listening sockets on the server will be bound to the loopback interface only. This may be overridden by specifying a bind_address. An empty bind_address, or the address *, indicates that the remote socket should listen on all interfaces. Specifying a remote bind_address will only succeed if the server's GatewayPorts option is enabled (see sshd_config(5)). If the port argument is 0, the listen port will be dynamically allocated on the server and reported to the client at run time. When used together with -O forward, the allocated port will be printed to the standard output. -S ctl_path Specifies the location of a control socket for connection sharing, or the string none to disable connection sharing. Refer to the description of ControlPath and ControlMaster in ssh_config(5) for details. -s May be used to request invocation of a subsystem on the remote system. Subsystems facilitate the use of SSH as a secure transport for other applications (e.g. sftp(1)). The subsystem is specified as the remote command. Refer to the description of SessionType in ssh_config(5) for details. -T Disable pseudo-terminal allocation. -t Force pseudo-terminal allocation. This can be used to execute arbitrary screen-based programs on a remote machine, which can be very useful, e.g. when implementing menu services. Multiple -t options force tty allocation, even if has no local tty. -V Display the version number and exit. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful in debugging connection, authentication, and configuration problems. Multiple -v options increase the verbosity. The maximum is 3. -W host:port Requests that standard input and output on the client be forwarded to host on port over the secure channel. Implies -N, -T, ExitOnForwardFailure and ClearAllForwardings, though these can be overridden in the configuration file or using -o command line options. -w local_tun[:remote_tun] Requests tunnel device forwarding with the specified tun(4) devices between the client (local_tun) and the server (remote_tun). The devices may be specified by numerical ID or the keyword any, which uses the next available tunnel device. If remote_tun is not specified, it defaults to any. See also the Tunnel and TunnelDevice directives in ssh_config(5). If the Tunnel directive is unset, it will be set to the default tunnel mode, which is point-to-point. If a different Tunnel forwarding mode it desired, then it should be specified before -w. -X Enables X11 forwarding. This can also be specified on a per-host basis in a configuration file. X11 forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the user's X authorization database) can access the local X11 display through the forwarded connection. An attacker may then be able to perform activities such as keystroke monitoring. For this reason, X11 forwarding is subjected to X11 SECURITY extension restrictions by default. Refer to the -Y option and the ForwardX11Trusted directive in ssh_config(5) for more information. -x Disables X11 forwarding. -Y Enables trusted X11 forwarding. Trusted X11 forwardings are not subjected to the X11 SECURITY extension controls. -y Send log information using the syslog(3) system module. By default this information is sent to stderr. may additionally obtain configuration data from a per-user configuration file and a system-wide configuration file. The file format and configuration options are described in ssh_config(5). AUTHENTICATION top The OpenSSH SSH client supports SSH protocol 2. The methods available for authentication are: GSSAPI-based authentication, host-based authentication, public key authentication, keyboard-interactive authentication, and password authentication. Authentication methods are tried in the order specified above, though PreferredAuthentications can be used to change the default order. Host-based authentication works as follows: If the machine the user logs in from is listed in /etc/hosts.equiv or /etc/shosts.equiv on the remote machine, the user is non-root and the user names are the same on both sides, or if the files ~/.rhosts or ~/.shosts exist in the user's home directory on the remote machine and contain a line containing the name of the client machine and the name of the user on that machine, the user is considered for login. Additionally, the server must be able to verify the client's host key (see the description of /etc/ssh/ssh_known_hosts and ~/.ssh/known_hosts, below) for login to be permitted. This authentication method closes security holes due to IP spoofing, DNS spoofing, and routing spoofing. [Note to the administrator: /etc/hosts.equiv, ~/.rhosts, and the rlogin/rsh protocol in general, are inherently insecure and should be disabled if security is desired.] Public key authentication works as follows: The scheme is based on public-key cryptography, using cryptosystems where encryption and decryption are done using separate keys, and it is unfeasible to derive the decryption key from the encryption key. The idea is that each user creates a public/private key pair for authentication purposes. The server knows the public key, and only the user knows the private key. implements public key authentication protocol automatically, using one of the DSA, ECDSA, Ed25519 or RSA algorithms. The HISTORY section of ssl(8) contains a brief discussion of the DSA and RSA algorithms. The file ~/.ssh/authorized_keys lists the public keys that are permitted for logging in. When the user logs in, the program tells the server which key pair it would like to use for authentication. The client proves that it has access to the private key and the server checks that the corresponding public key is authorized to accept the account. The server may inform the client of errors that prevented public key authentication from succeeding after authentication completes using a different method. These may be viewed by increasing the LogLevel to DEBUG or higher (e.g. by using the -v flag). The user creates their key pair by running ssh-keygen(1). This stores the private key in ~/.ssh/id_dsa (DSA), ~/.ssh/id_ecdsa (ECDSA), ~/.ssh/id_ecdsa_sk (authenticator-hosted ECDSA), ~/.ssh/id_ed25519 (Ed25519), ~/.ssh/id_ed25519_sk (authenticator- hosted Ed25519), or ~/.ssh/id_rsa (RSA) and stores the public key in ~/.ssh/id_dsa.pub (DSA), ~/.ssh/id_ecdsa.pub (ECDSA), ~/.ssh/id_ecdsa_sk.pub (authenticator-hosted ECDSA), ~/.ssh/id_ed25519.pub (Ed25519), ~/.ssh/id_ed25519_sk.pub (authenticator-hosted Ed25519), or ~/.ssh/id_rsa.pub (RSA) in the user's home directory. The user should then copy the public key to ~/.ssh/authorized_keys in their home directory on the remote machine. The authorized_keys file corresponds to the conventional ~/.rhosts file, and has one key per line, though the lines can be very long. After this, the user can log in without giving the password. A variation on public key authentication is available in the form of certificate authentication: instead of a set of public/private keys, signed certificates are used. This has the advantage that a single trusted certification authority can be used in place of many public/private keys. See the CERTIFICATES section of ssh-keygen(1) for more information. The most convenient way to use public key or certificate authentication may be with an authentication agent. See ssh-agent(1) and (optionally) the AddKeysToAgent directive in ssh_config(5) for more information. Keyboard-interactive authentication works as follows: The server sends an arbitrary "challenge" text and prompts for a response, possibly multiple times. Examples of keyboard-interactive authentication include BSD Authentication (see login.conf(5)) and PAM (some non-OpenBSD systems). Finally, if other authentication methods fail, prompts the user for a password. The password is sent to the remote host for checking; however, since all communications are encrypted, the password cannot be seen by someone listening on the network. automatically maintains and checks a database containing identification for all hosts it has ever been used with. Host keys are stored in ~/.ssh/known_hosts in the user's home directory. Additionally, the file /etc/ssh/ssh_known_hosts is automatically checked for known hosts. Any new hosts are automatically added to the user's file. If a host's identification ever changes, warns about this and disables password authentication to prevent server spoofing or man-in-the- middle attacks, which could otherwise be used to circumvent the encryption. The StrictHostKeyChecking option can be used to control logins to machines whose host key is not known or has changed. When the user's identity has been accepted by the server, the server either executes the given command in a non-interactive session or, if no command has been specified, logs into the machine and gives the user a normal shell as an interactive session. All communication with the remote command or shell will be automatically encrypted. If an interactive session is requested, by default will only request a pseudo-terminal (pty) for interactive sessions when the client has one. The flags -T and -t can be used to override this behaviour. If a pseudo-terminal has been allocated, the user may use the escape characters noted below. If no pseudo-terminal has been allocated, the session is transparent and can be used to reliably transfer binary data. On most systems, setting the escape character to none will also make the session transparent even if a tty is used. The session terminates when the command or shell on the remote machine exits and all X11 and TCP connections have been closed. ESCAPE CHARACTERS top When a pseudo-terminal has been requested, supports a number of functions through the use of an escape character. A single tilde character can be sent as ~~ or by following the tilde by a character other than those described below. The escape character must always follow a newline to be interpreted as special. The escape character can be changed in configuration files using the EscapeChar configuration directive or on the command line by the -e option. The supported escapes (assuming the default ~) are: ~. Disconnect. ~^Z Background . ~# List forwarded connections. ~& Background at logout when waiting for forwarded connection / X11 sessions to terminate. ~? Display a list of escape characters. ~B Send a BREAK to the remote system (only useful if the peer supports it). ~C Open command line. Currently this allows the addition of port forwardings using the -L, -R and -D options (see above). It also allows the cancellation of existing port-forwardings with -KL[bind_address:]port for local, -KR[bind_address:]port for remote and -KD[bind_address:]port for dynamic port-forwardings. !command allows the user to execute a local command if the PermitLocalCommand option is enabled in ssh_config(5). Basic help is available, using the -h option. ~R Request rekeying of the connection (only useful if the peer supports it). ~V Decrease the verbosity (LogLevel) when errors are being written to stderr. ~v Increase the verbosity (LogLevel) when errors are being written to stderr. TCP FORWARDING top Forwarding of arbitrary TCP connections over a secure channel can be specified either on the command line or in a configuration file. One possible application of TCP forwarding is a secure connection to a mail server; another is going through firewalls. In the example below, we look at encrypting communication for an IRC client, even though the IRC server it connects to does not directly support encrypted communication. This works as follows: the user connects to the remote host using , specifying the ports to be used to forward the connection. After that it is possible to start the program locally, and will encrypt and forward the connection to the remote server. The following example tunnels an IRC session from the client to an IRC server at server.example.com, joining channel #users, nickname pinky, using the standard IRC port, 6667: $ ssh -f -L 6667:localhost:6667 server.example.com sleep 10 $ irc -c '#users' pinky IRC/127.0.0.1 The -f option backgrounds and the remote command sleep 10 is specified to allow an amount of time (10 seconds, in the example) to start the program which is going to use the tunnel. If no connections are made within the time specified, will exit. X11 FORWARDING top If the ForwardX11 variable is set to yes (or see the description of the -X, -x, and -Y options above) and the user is using X11 (the DISPLAY environment variable is set), the connection to the X11 display is automatically forwarded to the remote side in such a way that any X11 programs started from the shell (or command) will go through the encrypted channel, and the connection to the real X server will be made from the local machine. The user should not manually set DISPLAY. Forwarding of X11 connections can be configured on the command line or in configuration files. The DISPLAY value set by will point to the server machine, but with a display number greater than zero. This is normal, and happens because creates a proxy X server on the server machine for forwarding the connections over the encrypted channel. will also automatically set up Xauthority data on the server machine. For this purpose, it will generate a random authorization cookie, store it in Xauthority on the server, and verify that any forwarded connections carry this cookie and replace it by the real cookie when the connection is opened. The real authentication cookie is never sent to the server machine (and no cookies are sent in the plain). If the ForwardAgent variable is set to yes (or see the description of the -A and -a options above) and the user is using an authentication agent, the connection to the agent is automatically forwarded to the remote side. VERIFYING HOST KEYS top When connecting to a server for the first time, a fingerprint of the server's public key is presented to the user (unless the option StrictHostKeyChecking has been disabled). Fingerprints can be determined using ssh-keygen(1): $ ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key If the fingerprint is already known, it can be matched and the key can be accepted or rejected. If only legacy (MD5) fingerprints for the server are available, the ssh-keygen(1) -E option may be used to downgrade the fingerprint algorithm to match. Because of the difficulty of comparing host keys just by looking at fingerprint strings, there is also support to compare host keys visually, using random art. By setting the VisualHostKey option to yes, a small ASCII graphic gets displayed on every login to a server, no matter if the session itself is interactive or not. By learning the pattern a known server produces, a user can easily find out that the host key has changed when a completely different pattern is displayed. Because these patterns are not unambiguous however, a pattern that looks similar to the pattern remembered only gives a good probability that the host key is the same, not guaranteed proof. To get a listing of the fingerprints along with their random art for all known hosts, the following command line can be used: $ ssh-keygen -lv -f ~/.ssh/known_hosts If the fingerprint is unknown, an alternative method of verification is available: SSH fingerprints verified by DNS. An additional resource record (RR), SSHFP, is added to a zonefile and the connecting client is able to match the fingerprint with that of the key presented. In this example, we are connecting a client to a server, host.example.com. The SSHFP resource records should first be added to the zonefile for host.example.com: $ ssh-keygen -r host.example.com. The output lines will have to be added to the zonefile. To check that the zone is answering fingerprint queries: $ dig -t SSHFP host.example.com Finally the client connects: $ ssh -o "VerifyHostKeyDNS ask" host.example.com [...] Matching host key fingerprint found in DNS. Are you sure you want to continue connecting (yes/no)? See the VerifyHostKeyDNS option in ssh_config(5) for more information. SSH-BASED VIRTUAL PRIVATE NETWORKS top contains support for Virtual Private Network (VPN) tunnelling using the tun(4) network pseudo-device, allowing two networks to be joined securely. The sshd_config(5) configuration option PermitTunnel controls whether the server supports this, and at what level (layer 2 or 3 traffic). The following example would connect client network 10.0.50.0/24 with remote network 10.0.99.0/24 using a point-to-point connection from 10.1.1.1 to 10.1.1.2, provided that the SSH server running on the gateway to the remote network, at 192.168.1.15, allows it. On the client: # ssh -f -w 0:1 192.168.1.15 true # ifconfig tun0 10.1.1.1 10.1.1.2 netmask 255.255.255.252 # route add 10.0.99.0/24 10.1.1.2 On the server: # ifconfig tun1 10.1.1.2 10.1.1.1 netmask 255.255.255.252 # route add 10.0.50.0/24 10.1.1.1 Client access may be more finely tuned via the /root/.ssh/authorized_keys file (see below) and the PermitRootLogin server option. The following entry would permit connections on tun(4) device 1 from user jane and on tun device 2 from user john, if PermitRootLogin is set to forced-commands-only: tunnel="1",command="sh /etc/netstart tun1" ssh-rsa ... jane tunnel="2",command="sh /etc/netstart tun2" ssh-rsa ... john Since an SSH-based setup entails a fair amount of overhead, it may be more suited to temporary setups, such as for wireless VPNs. More permanent VPNs are better provided by tools such as ipsecctl(8) and isakmpd(8). ENVIRONMENT top will normally set the following environment variables: DISPLAY The DISPLAY variable indicates the location of the X11 server. It is automatically set by to point to a value of the form hostname:n, where hostname indicates the host where the shell runs, and n is an integer 1. uses this special value to forward X11 connections over the secure channel. The user should normally not set DISPLAY explicitly, as that will render the X11 connection insecure (and will require the user to manually copy any required authorization cookies). HOME Set to the path of the user's home directory. LOGNAME Synonym for USER; set for compatibility with systems that use this variable. MAIL Set to the path of the user's mailbox. PATH Set to the default PATH, as specified when compiling . SSH_ASKPASS If needs a passphrase, it will read the passphrase from the current terminal if it was run from a terminal. If does not have a terminal associated with it but DISPLAY and SSH_ASKPASS are set, it will execute the program specified by SSH_ASKPASS and open an X11 window to read the passphrase. This is particularly useful when calling from a .xsession or related script. (Note that on some machines it may be necessary to redirect the input from /dev/null to make this work.) SSH_ASKPASS_REQUIRE Allows further control over the use of an askpass program. If this variable is set to never then will never attempt to use one. If it is set to prefer, then will prefer to use the askpass program instead of the TTY when requesting passwords. Finally, if the variable is set to force, then the askpass program will be used for all passphrase input regardless of whether DISPLAY is set. SSH_AUTH_SOCK Identifies the path of a Unix-domain socket used to communicate with the agent. SSH_CONNECTION Identifies the client and server ends of the connection. The variable contains four space-separated values: client IP address, client port number, server IP address, and server port number. SSH_ORIGINAL_COMMAND This variable contains the original command line if a forced command is executed. It can be used to extract the original arguments. SSH_TTY This is set to the name of the tty (path to the device) associated with the current shell or command. If the current session has no tty, this variable is not set. SSH_TUNNEL Optionally set by sshd(8) to contain the interface names assigned if tunnel forwarding was requested by the client. SSH_USER_AUTH Optionally set by sshd(8), this variable may contain a pathname to a file that lists the authentication methods successfully used when the session was established, including any public keys that were used. TZ This variable is set to indicate the present time zone if it was set when the daemon was started (i.e. the daemon passes the value on to new connections). USER Set to the name of the user logging in. Additionally, reads ~/.ssh/environment, and adds lines of the format VARNAME=value to the environment if the file exists and users are allowed to change their environment. For more information, see the PermitUserEnvironment option in sshd_config(5). FILES top ~/.rhosts This file is used for host-based authentication (see above). On some machines this file may need to be world- readable if the user's home directory is on an NFS partition, because sshd(8) reads it as root. Additionally, this file must be owned by the user, and must not have write permissions for anyone else. The recommended permission for most machines is read/write for the user, and not accessible by others. ~/.shosts This file is used in exactly the same way as .rhosts, but allows host-based authentication without permitting login with rlogin/rsh. ~/.ssh/ This directory is the default location for all user- specific configuration and authentication information. There is no general requirement to keep the entire contents of this directory secret, but the recommended permissions are read/write/execute for the user, and not accessible by others. ~/.ssh/authorized_keys Lists the public keys (DSA, ECDSA, Ed25519, RSA) that can be used for logging in as this user. The format of this file is described in the sshd(8) manual page. This file is not highly sensitive, but the recommended permissions are read/write for the user, and not accessible by others. ~/.ssh/config This is the per-user configuration file. The file format and configuration options are described in ssh_config(5). Because of the potential for abuse, this file must have strict permissions: read/write for the user, and not writable by others. ~/.ssh/environment Contains additional definitions for environment variables; see ENVIRONMENT, above. ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the private key for authentication. These files contain sensitive data and should be readable by the user but not accessible by others (read/write/execute). will simply ignore a private key file if it is accessible by others. It is possible to specify a passphrase when generating the key which will be used to encrypt the sensitive part of this file using AES-128. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the public key for authentication. These files are not sensitive and can (but need not) be readable by anyone. ~/.ssh/known_hosts Contains a list of host keys for all hosts the user has logged into that are not already in the systemwide list of known host keys. See sshd(8) for further details of the format of this file. ~/.ssh/rc Commands in this file are executed by when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information. /etc/hosts.equiv This file is for host-based authentication (see above). It should only be writable by root. /etc/shosts.equiv This file is used in exactly the same way as hosts.equiv, but allows host-based authentication without permitting login with rlogin/rsh. /etc/ssh/ssh_config Systemwide configuration file. The file format and configuration options are described in ssh_config(5). /etc/ssh/ssh_host_key /etc/ssh/ssh_host_dsa_key /etc/ssh/ssh_host_ecdsa_key /etc/ssh/ssh_host_ed25519_key /etc/ssh/ssh_host_rsa_key These files contain the private parts of the host keys and are used for host-based authentication. /etc/ssh/ssh_known_hosts Systemwide list of known host keys. This file should be prepared by the system administrator to contain the public host keys of all machines in the organization. It should be world-readable. See sshd(8) for further details of the format of this file. /etc/ssh/sshrc Commands in this file are executed by when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information. EXIT STATUS top exits with the exit status of the remote command or with 255 if an error occurred. SEE ALSO top scp(1), sftp(1), ssh-add(1), ssh-agent(1), ssh-keygen(1), ssh-keyscan(1), tun(4), ssh_config(5), ssh-keysign(8), sshd(8) STANDARDS top S. Lehtinen and C. Lonvick, The Secure Shell (SSH) Protocol Assigned Numbers, RFC 4250, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Protocol Architecture, RFC 4251, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Authentication Protocol, RFC 4252, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Transport Layer Protocol, RFC 4253, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Connection Protocol, RFC 4254, January 2006. J. Schlyter and W. Griffin, Using DNS to Securely Publish Secure Shell (SSH) Key Fingerprints, RFC 4255, January 2006. F. Cusack and M. Forssen, Generic Message Exchange Authentication for the Secure Shell Protocol (SSH), RFC 4256, January 2006. J. Galbraith and P. Remaker, The Secure Shell (SSH) Session Channel Break Extension, RFC 4335, January 2006. M. Bellare, T. Kohno, and C. Namprempre, The Secure Shell (SSH) Transport Layer Encryption Modes, RFC 4344, January 2006. B. Harris, Improved Arcfour Modes for the Secure Shell (SSH) Transport Layer Protocol, RFC 4345, January 2006. M. Friedl, N. Provos, and W. Simpson, Diffie-Hellman Group Exchange for the Secure Shell (SSH) Transport Layer Protocol, RFC 4419, March 2006. J. Galbraith and R. Thayer, The Secure Shell (SSH) Public Key File Format, RFC 4716, November 2006. D. Stebila and J. Green, Elliptic Curve Algorithm Integration in the Secure Shell Transport Layer, RFC 5656, December 2009. A. Perrig and D. Song, Hash Visualization: a New Technique to improve Real-World Security, 1999, International Workshop on Cryptographic Techniques and E-Commerce (CrypTEC '99). AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU October 11, 2023 SSH(1) Pages that refer to this page: stap-jupyter(1), systemd-stdio-bridge(1), tar(1), sd_bus_default(3), environment.d(5), proc(5), user@.service(5), pty(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create master SSH control socket "my-ctrl-socket" in the background with no terminal or command execution with connection forwarding from localhost port 50000 to localhost port 3306 via "jm@sampledomani.com" Bash Command:<START>ssh -M -S my-ctrl-socket -fnNT -L 50000:localhost:3306 jm@sampledomain.com<END> |
Create new crontab set for user 'test' including $job and only jobs from current crontab of 'test' user that don`t contain $command | cat <(fgrep -i -v "$command" <(crontab -u test -l)) <(echo "$job") | crontab -u test - | ['cat', 'echo', 'crontab', 'test'] | Output a Bash command to accomplish the following task. Task: Create new crontab set for user 'test' including $job and only jobs from current crontab of 'test' user that don`t contain $command Bash Command:<START>cat <(fgrep -i -v "$command" <(crontab -u test -l)) <(echo "$job") | crontab -u test -<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # cat\n\n> Print and concatenate files.\n> More information: <https://www.gnu.org/software/coreutils/cat>.\n\n- Print the contents of a file to `stdout`:\n\n`cat {{path/to/file}}`\n\n- Concatenate several files into an output file:\n\n`cat {{path/to/file1 path/to/file2 ...}} > {{path/to/output_file}}`\n\n- Append several files to an output file:\n\n`cat {{path/to/file1 path/to/file2 ...}} >> {{path/to/output_file}}`\n\n- Write `stdin` to a file:\n\n`cat - > {{path/to/file}}`\n\n- [n]umber all output lines:\n\n`cat -n {{path/to/file}}`\n\n- Display non-printable and whitespace characters (with `M-` prefix if non-ASCII):\n\n`cat -v -t -e {{path/to/file}}`\n # echo\n\n> Print given arguments.\n> More information: <https://www.gnu.org/software/coreutils/echo>.\n\n- Print a text message. Note: quotes are optional:\n\n`echo "{{Hello World}}"`\n\n- Print a message with environment variables:\n\n`echo "{{My path is $PATH}}"`\n\n- Print a message without the trailing newline:\n\n`echo -n "{{Hello World}}"`\n\n- Append a message to the file:\n\n`echo "{{Hello World}}" >> {{file.txt}}`\n\n- Enable interpretation of backslash escapes (special characters):\n\n`echo -e "{{Column 1\tColumn 2}}"`\n\n- Print the exit status of the last executed command (Note: In Windows Command Prompt and PowerShell the equivalent commands are `echo %errorlevel%` and `$lastexitcode` respectively):\n\n`echo $?`\n # crontab\n\n> Schedule cron jobs to run on a time interval for the current user.\n> More information: <https://crontab.guru/>.\n\n- Edit the crontab file for the current user:\n\n`crontab -e`\n\n- Edit the crontab file for a specific user:\n\n`sudo crontab -e -u {{user}}`\n\n- Replace the current crontab with the contents of the given file:\n\n`crontab {{path/to/file}}`\n\n- View a list of existing cron jobs for current user:\n\n`crontab -l`\n\n- Remove all cron jobs for the current user:\n\n`crontab -r`\n\n- Sample job which runs at 10:00 every day (* means any value):\n\n`0 10 * * * {{command_to_execute}}`\n\n- Sample crontab entry, which runs a command every 10 minutes:\n\n`*/10 * * * * {{command_to_execute}}`\n\n- Sample crontab entry, which runs a certain script at 02:30 every Friday:\n\n`30 2 * * Fri {{/absolute/path/to/script.sh}}`\n # test\n\n> Check file types and compare values.\n> Returns 0 if the condition evaluates to true, 1 if it evaluates to false.\n> More information: <https://www.gnu.org/software/coreutils/test>.\n\n- Test if a given variable is equal to a given string:\n\n`test "{{$MY_VAR}}" = "{{/bin/zsh}}"`\n\n- Test if a given variable is empty:\n\n`test -z "{{$GIT_BRANCH}}"`\n\n- Test if a file exists:\n\n`test -f "{{path/to/file_or_directory}}"`\n\n- Test if a directory does not exist:\n\n`test ! -d "{{path/to/directory}}"`\n\n- If A is true, then do B, or C in the case of an error (notice that C may run even if A fails):\n\n`test {{condition}} && {{echo "true"}} || {{echo "false"}}`\n Task: Create new crontab set for user 'test' including $job and only jobs from current crontab of 'test' user that don`t contain $command Bash Command:<START>cat <(fgrep -i -v "$command" <(crontab -u test -l)) <(echo "$job") | crontab -u test -<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: cat(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training cat(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON CAT(1) User Commands CAT(1) NAME top cat - concatenate files and print on the standard output SYNOPSIS top cat [OPTION]... [FILE]... DESCRIPTION top Concatenate FILE(s) to standard output. With no FILE, or when FILE is -, read standard input. -A, --show-all equivalent to -vET -b, --number-nonblank number nonempty output lines, overrides -n -e equivalent to -vE -E, --show-ends display $ at end of each line -n, --number number all output lines -s, --squeeze-blank suppress repeated empty output lines -t equivalent to -vT -T, --show-tabs display TAB characters as ^I -u (ignored) -v, --show-nonprinting use ^ and M- notation, except for LFD and TAB --help display this help and exit --version output version information and exit EXAMPLES top cat f - g Output f's contents, then standard input, then g's contents. cat Copy standard input to standard output. AUTHOR top Written by Torbjorn Granlund and Richard M. Stallman. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top tac(1) Full documentation <https://www.gnu.org/software/coreutils/cat> or available locally via: info '(coreutils) cat invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 CAT(1) Pages that refer to this page: pmlogrewrite(1), pv(1), systemd-socket-activate(1), tac(1), ul(1), proc(5), cpuset(7), time_namespaces(7), readprofile(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. echo(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training echo(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON ECHO(1) User Commands ECHO(1) NAME top echo - display a line of text SYNOPSIS top echo [SHORT-OPTION]... [STRING]... echo LONG-OPTION DESCRIPTION top Echo the STRING(s) to standard output. -n do not output the trailing newline -e enable interpretation of backslash escapes -E disable interpretation of backslash escapes (default) --help display this help and exit --version output version information and exit If -e is in effect, the following sequences are recognized: \\ backslash \a alert (BEL) \b backspace \c produce no further output \e escape \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \0NNN byte with octal value NNN (1 to 3 digits) \xHH byte with hexadecimal value HH (1 to 2 digits) NOTE: your shell may have its own version of echo, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. NOTE: printf(1) is a preferred alternative, which does not have issues outputting option-like strings. AUTHOR top Written by Brian Fox and Chet Ramey. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top printf(1) Full documentation <https://www.gnu.org/software/coreutils/echo> or available locally via: info '(coreutils) echo invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 ECHO(1) Pages that refer to this page: ldapcompare(1), systemd-ask-password(1), systemd-run(1), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. crontab(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training crontab(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CAVEATS | SEE ALSO | FILES | STANDARDS | DIAGNOSTICS | AUTHOR | COLOPHON CRONTAB(1) User Commands CRONTAB(1) NAME top crontab - maintains crontab files for individual users SYNOPSIS top crontab [-u user] <file | -> crontab [-T] <file | -> crontab [-u user] <-l | -r | -e> [-i] [-s] crontab -n [ hostname ] crontab -c crontab -V DESCRIPTION top Crontab is the program used to install a crontab table file, remove or list the existing tables used to serve the cron(8) daemon. Each user can have their own crontab, and though these are files in /var/spool/, they are not intended to be edited directly. For SELinux in MLS mode, you can define more crontabs for each range. For more information, see selinux(8). In this version of Cron it is possible to use a network-mounted shared /var/spool/cron across a cluster of hosts and specify that only one of the hosts should run the crontab jobs in the particular directory at any one time. You may also use crontab from any of these hosts to edit the same shared set of crontab files, and to set and query which host should run the crontab jobs. Scheduling cron jobs with crontab can be allowed or disallowed for different users. For this purpose, use the cron.allow and cron.deny files. If the cron.allow file exists, a user must be listed in it to be allowed to use crontab. If the cron.allow file does not exist but the cron.deny file does exist, then a user must not be listed in the cron.deny file in order to use crontab. If neither of these files exist, then only the super user is allowed to use crontab. Another way to restrict the scheduling of cron jobs beyond crontab is to use PAM authentication in /etc/security/access.conf to set up users, which are allowed or disallowed to use crontab or modify system cron jobs in the /etc/cron.d/ directory. The temporary directory can be set in an environment variable. If it is not set by the user, the /tmp directory is used. When listing a crontab on a terminal the output will be colorized unless an environment variable NO_COLOR is set. On edition or deletion of the crontab, a backup of the last crontab will be saved to $XDG_CACHE_HOME/crontab/crontab.bak or $XDG_CACHE_HOME/crontab/crontab.<user>.bak if -u is used. If the XDG_CACHE_HOME environment variable is not set, $HOME/.cache will be used instead. OPTIONS top -u Specifies the name of the user whose crontab is to be modified. If this option is not used, crontab examines "your" crontab, i.e., the crontab of the person executing the command. If no crontab exists for a particular user, it is created for them the first time the crontab -u command is used under their username. -T Test the crontab file syntax without installing it. Once an issue is found, the validation is interrupted, so this will not return all the existing issues at the same execution. -l Displays the current crontab on standard output. -r Removes the current crontab. -e Edits the current crontab using the editor specified by the VISUAL or EDITOR environment variables. After you exit from the editor, the modified crontab will be installed automatically. -i This option modifies the -r option to prompt the user for a 'y/Y' response before actually removing the crontab. -s Appends the current SELinux security context string as an MLS_LEVEL setting to the crontab file before editing / replacement occurs - see the documentation of MLS_LEVEL in crontab(5). -n This option is relevant only if cron(8) was started with the -c option, to enable clustering support. It is used to set the host in the cluster which should run the jobs specified in the crontab files in the /var/spool/cron directory. If a hostname is supplied, the host whose hostname returned by gethostname(2) matches the supplied hostname, will be selected to run the selected cron jobs subsequently. If there is no host in the cluster matching the supplied hostname, or you explicitly specify an empty hostname, then the selected jobs will not be run at all. If the hostname is omitted, the name of the local host returned by gethostname(2) is used. Using this option has no effect on the /etc/crontab file and the files in the /etc/cron.d directory, which are always run, and considered host-specific. For more information on clustering support, see cron(8). -c This option is only relevant if cron(8) was started with the -c option, to enable clustering support. It is used to query which host in the cluster is currently set to run the jobs specified in the crontab files in the directory /var/spool/cron , as set using the -n option. -V Print version and exit. CAVEATS top The files cron.allow and cron.deny cannot be used to restrict the execution of cron jobs; they only restrict the use of crontab. In particular, restricting access to crontab has no effect on an existing crontab of a user. Its jobs will continue to be executed until the crontab is removed. The files cron.allow and cron.deny must be readable by the user invoking crontab. If this is not the case, then they are treated as non-existent. SEE ALSO top crontab(5), cron(8) FILES top /etc/cron.allow /etc/cron.deny STANDARDS top The crontab command conforms to IEEE Std1003.2-1992 (``POSIX'') with one exception: For replacing the current crontab with data from standard input the - has to be specified on the command line if the standard input is a TTY. This new command syntax differs from previous versions of Vixie Cron, as well as from the classic SVR3 syntax. DIAGNOSTICS top An informative usage message appears if you run a crontab with a faulty command defined in it. AUTHOR top Paul Vixie vixie@isc.org Colin Dean colin@colin-dean.org COLOPHON top This page is part of the cronie (crond daemon) project. Information about the project can be found at https://github.com/cronie-crond/cronie. If you have a bug report for this manual page, see https://github.com/cronie-crond/cronie/issues. This page was obtained from the project's upstream Git repository https://github.com/cronie-crond/cronie.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-16.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org cronie 2019-10-29 CRONTAB(1) Pages that refer to this page: cronnext(1), pmsnap(1), anacrontab(5), crontab(5), systemd.exec(5), cron(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. test(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training test(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON TEST(1) User Commands TEST(1) NAME top test - check file types and compare values SYNOPSIS top test EXPRESSION test [ EXPRESSION ] [ ] [ OPTION DESCRIPTION top Exit with the status determined by EXPRESSION. --help display this help and exit --version output version information and exit An omitted EXPRESSION defaults to false. Otherwise, EXPRESSION is true or false and sets exit status. It is one of: ( EXPRESSION ) EXPRESSION is true ! EXPRESSION EXPRESSION is false EXPRESSION1 -a EXPRESSION2 both EXPRESSION1 and EXPRESSION2 are true EXPRESSION1 -o EXPRESSION2 either EXPRESSION1 or EXPRESSION2 is true -n STRING the length of STRING is nonzero STRING equivalent to -n STRING -z STRING the length of STRING is zero STRING1 = STRING2 the strings are equal STRING1 != STRING2 the strings are not equal INTEGER1 -eq INTEGER2 INTEGER1 is equal to INTEGER2 INTEGER1 -ge INTEGER2 INTEGER1 is greater than or equal to INTEGER2 INTEGER1 -gt INTEGER2 INTEGER1 is greater than INTEGER2 INTEGER1 -le INTEGER2 INTEGER1 is less than or equal to INTEGER2 INTEGER1 -lt INTEGER2 INTEGER1 is less than INTEGER2 INTEGER1 -ne INTEGER2 INTEGER1 is not equal to INTEGER2 FILE1 -ef FILE2 FILE1 and FILE2 have the same device and inode numbers FILE1 -nt FILE2 FILE1 is newer (modification date) than FILE2 FILE1 -ot FILE2 FILE1 is older than FILE2 -b FILE FILE exists and is block special -c FILE FILE exists and is character special -d FILE FILE exists and is a directory -e FILE FILE exists -f FILE FILE exists and is a regular file -g FILE FILE exists and is set-group-ID -G FILE FILE exists and is owned by the effective group ID -h FILE FILE exists and is a symbolic link (same as -L) -k FILE FILE exists and has its sticky bit set -L FILE FILE exists and is a symbolic link (same as -h) -N FILE FILE exists and has been modified since it was last read -O FILE FILE exists and is owned by the effective user ID -p FILE FILE exists and is a named pipe -r FILE FILE exists and the user has read access -s FILE FILE exists and has a size greater than zero -S FILE FILE exists and is a socket -t FD file descriptor FD is opened on a terminal -u FILE FILE exists and its set-user-ID bit is set -w FILE FILE exists and the user has write access -x FILE FILE exists and the user has execute (or search) access Except for -h and -L, all FILE-related tests dereference symbolic links. Beware that parentheses need to be escaped (e.g., by backslashes) for shells. INTEGER may also be -l STRING, which evaluates to the length of STRING. NOTE: Binary -a and -o are inherently ambiguous. Use 'test EXPR1 && test EXPR2' or 'test EXPR1 || test EXPR2' instead. NOTE: [ honors the --help and --version options, but test does not. test treats each of those as it treats any other nonempty STRING. NOTE: your shell may have its own version of test and/or [, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. AUTHOR top Written by Kevin Braunsdorf and Matthew Bradburn. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top access(2) Full documentation <https://www.gnu.org/software/coreutils/test> or available locally via: info '(coreutils) test invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 TEST(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create new crontab set for user 'test' including $job and only jobs from current crontab of 'test' user that don`t contain $command Bash Command:<START>cat <(fgrep -i -v "$command" <(crontab -u test -l)) <(echo "$job") | crontab -u test -<END> |
Create new crontab set including $job and only jobs from current crontab that don`t contain $command | cat <(fgrep -i -v "$command" <(crontab -l)) <(echo "$job") | crontab - | ['cat', 'crontab', 'echo'] | Output a Bash command to accomplish the following task. Task: Create new crontab set including $job and only jobs from current crontab that don`t contain $command Bash Command:<START>cat <(fgrep -i -v "$command" <(crontab -l)) <(echo "$job") | crontab -<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # cat\n\n> Print and concatenate files.\n> More information: <https://www.gnu.org/software/coreutils/cat>.\n\n- Print the contents of a file to `stdout`:\n\n`cat {{path/to/file}}`\n\n- Concatenate several files into an output file:\n\n`cat {{path/to/file1 path/to/file2 ...}} > {{path/to/output_file}}`\n\n- Append several files to an output file:\n\n`cat {{path/to/file1 path/to/file2 ...}} >> {{path/to/output_file}}`\n\n- Write `stdin` to a file:\n\n`cat - > {{path/to/file}}`\n\n- [n]umber all output lines:\n\n`cat -n {{path/to/file}}`\n\n- Display non-printable and whitespace characters (with `M-` prefix if non-ASCII):\n\n`cat -v -t -e {{path/to/file}}`\n # crontab\n\n> Schedule cron jobs to run on a time interval for the current user.\n> More information: <https://crontab.guru/>.\n\n- Edit the crontab file for the current user:\n\n`crontab -e`\n\n- Edit the crontab file for a specific user:\n\n`sudo crontab -e -u {{user}}`\n\n- Replace the current crontab with the contents of the given file:\n\n`crontab {{path/to/file}}`\n\n- View a list of existing cron jobs for current user:\n\n`crontab -l`\n\n- Remove all cron jobs for the current user:\n\n`crontab -r`\n\n- Sample job which runs at 10:00 every day (* means any value):\n\n`0 10 * * * {{command_to_execute}}`\n\n- Sample crontab entry, which runs a command every 10 minutes:\n\n`*/10 * * * * {{command_to_execute}}`\n\n- Sample crontab entry, which runs a certain script at 02:30 every Friday:\n\n`30 2 * * Fri {{/absolute/path/to/script.sh}}`\n # echo\n\n> Print given arguments.\n> More information: <https://www.gnu.org/software/coreutils/echo>.\n\n- Print a text message. Note: quotes are optional:\n\n`echo "{{Hello World}}"`\n\n- Print a message with environment variables:\n\n`echo "{{My path is $PATH}}"`\n\n- Print a message without the trailing newline:\n\n`echo -n "{{Hello World}}"`\n\n- Append a message to the file:\n\n`echo "{{Hello World}}" >> {{file.txt}}`\n\n- Enable interpretation of backslash escapes (special characters):\n\n`echo -e "{{Column 1\tColumn 2}}"`\n\n- Print the exit status of the last executed command (Note: In Windows Command Prompt and PowerShell the equivalent commands are `echo %errorlevel%` and `$lastexitcode` respectively):\n\n`echo $?`\n Task: Create new crontab set including $job and only jobs from current crontab that don`t contain $command Bash Command:<START>cat <(fgrep -i -v "$command" <(crontab -l)) <(echo "$job") | crontab -<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: cat(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training cat(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON CAT(1) User Commands CAT(1) NAME top cat - concatenate files and print on the standard output SYNOPSIS top cat [OPTION]... [FILE]... DESCRIPTION top Concatenate FILE(s) to standard output. With no FILE, or when FILE is -, read standard input. -A, --show-all equivalent to -vET -b, --number-nonblank number nonempty output lines, overrides -n -e equivalent to -vE -E, --show-ends display $ at end of each line -n, --number number all output lines -s, --squeeze-blank suppress repeated empty output lines -t equivalent to -vT -T, --show-tabs display TAB characters as ^I -u (ignored) -v, --show-nonprinting use ^ and M- notation, except for LFD and TAB --help display this help and exit --version output version information and exit EXAMPLES top cat f - g Output f's contents, then standard input, then g's contents. cat Copy standard input to standard output. AUTHOR top Written by Torbjorn Granlund and Richard M. Stallman. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top tac(1) Full documentation <https://www.gnu.org/software/coreutils/cat> or available locally via: info '(coreutils) cat invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 CAT(1) Pages that refer to this page: pmlogrewrite(1), pv(1), systemd-socket-activate(1), tac(1), ul(1), proc(5), cpuset(7), time_namespaces(7), readprofile(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. crontab(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training crontab(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CAVEATS | SEE ALSO | FILES | STANDARDS | DIAGNOSTICS | AUTHOR | COLOPHON CRONTAB(1) User Commands CRONTAB(1) NAME top crontab - maintains crontab files for individual users SYNOPSIS top crontab [-u user] <file | -> crontab [-T] <file | -> crontab [-u user] <-l | -r | -e> [-i] [-s] crontab -n [ hostname ] crontab -c crontab -V DESCRIPTION top Crontab is the program used to install a crontab table file, remove or list the existing tables used to serve the cron(8) daemon. Each user can have their own crontab, and though these are files in /var/spool/, they are not intended to be edited directly. For SELinux in MLS mode, you can define more crontabs for each range. For more information, see selinux(8). In this version of Cron it is possible to use a network-mounted shared /var/spool/cron across a cluster of hosts and specify that only one of the hosts should run the crontab jobs in the particular directory at any one time. You may also use crontab from any of these hosts to edit the same shared set of crontab files, and to set and query which host should run the crontab jobs. Scheduling cron jobs with crontab can be allowed or disallowed for different users. For this purpose, use the cron.allow and cron.deny files. If the cron.allow file exists, a user must be listed in it to be allowed to use crontab. If the cron.allow file does not exist but the cron.deny file does exist, then a user must not be listed in the cron.deny file in order to use crontab. If neither of these files exist, then only the super user is allowed to use crontab. Another way to restrict the scheduling of cron jobs beyond crontab is to use PAM authentication in /etc/security/access.conf to set up users, which are allowed or disallowed to use crontab or modify system cron jobs in the /etc/cron.d/ directory. The temporary directory can be set in an environment variable. If it is not set by the user, the /tmp directory is used. When listing a crontab on a terminal the output will be colorized unless an environment variable NO_COLOR is set. On edition or deletion of the crontab, a backup of the last crontab will be saved to $XDG_CACHE_HOME/crontab/crontab.bak or $XDG_CACHE_HOME/crontab/crontab.<user>.bak if -u is used. If the XDG_CACHE_HOME environment variable is not set, $HOME/.cache will be used instead. OPTIONS top -u Specifies the name of the user whose crontab is to be modified. If this option is not used, crontab examines "your" crontab, i.e., the crontab of the person executing the command. If no crontab exists for a particular user, it is created for them the first time the crontab -u command is used under their username. -T Test the crontab file syntax without installing it. Once an issue is found, the validation is interrupted, so this will not return all the existing issues at the same execution. -l Displays the current crontab on standard output. -r Removes the current crontab. -e Edits the current crontab using the editor specified by the VISUAL or EDITOR environment variables. After you exit from the editor, the modified crontab will be installed automatically. -i This option modifies the -r option to prompt the user for a 'y/Y' response before actually removing the crontab. -s Appends the current SELinux security context string as an MLS_LEVEL setting to the crontab file before editing / replacement occurs - see the documentation of MLS_LEVEL in crontab(5). -n This option is relevant only if cron(8) was started with the -c option, to enable clustering support. It is used to set the host in the cluster which should run the jobs specified in the crontab files in the /var/spool/cron directory. If a hostname is supplied, the host whose hostname returned by gethostname(2) matches the supplied hostname, will be selected to run the selected cron jobs subsequently. If there is no host in the cluster matching the supplied hostname, or you explicitly specify an empty hostname, then the selected jobs will not be run at all. If the hostname is omitted, the name of the local host returned by gethostname(2) is used. Using this option has no effect on the /etc/crontab file and the files in the /etc/cron.d directory, which are always run, and considered host-specific. For more information on clustering support, see cron(8). -c This option is only relevant if cron(8) was started with the -c option, to enable clustering support. It is used to query which host in the cluster is currently set to run the jobs specified in the crontab files in the directory /var/spool/cron , as set using the -n option. -V Print version and exit. CAVEATS top The files cron.allow and cron.deny cannot be used to restrict the execution of cron jobs; they only restrict the use of crontab. In particular, restricting access to crontab has no effect on an existing crontab of a user. Its jobs will continue to be executed until the crontab is removed. The files cron.allow and cron.deny must be readable by the user invoking crontab. If this is not the case, then they are treated as non-existent. SEE ALSO top crontab(5), cron(8) FILES top /etc/cron.allow /etc/cron.deny STANDARDS top The crontab command conforms to IEEE Std1003.2-1992 (``POSIX'') with one exception: For replacing the current crontab with data from standard input the - has to be specified on the command line if the standard input is a TTY. This new command syntax differs from previous versions of Vixie Cron, as well as from the classic SVR3 syntax. DIAGNOSTICS top An informative usage message appears if you run a crontab with a faulty command defined in it. AUTHOR top Paul Vixie vixie@isc.org Colin Dean colin@colin-dean.org COLOPHON top This page is part of the cronie (crond daemon) project. Information about the project can be found at https://github.com/cronie-crond/cronie. If you have a bug report for this manual page, see https://github.com/cronie-crond/cronie/issues. This page was obtained from the project's upstream Git repository https://github.com/cronie-crond/cronie.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-16.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org cronie 2019-10-29 CRONTAB(1) Pages that refer to this page: cronnext(1), pmsnap(1), anacrontab(5), crontab(5), systemd.exec(5), cron(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. echo(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training echo(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON ECHO(1) User Commands ECHO(1) NAME top echo - display a line of text SYNOPSIS top echo [SHORT-OPTION]... [STRING]... echo LONG-OPTION DESCRIPTION top Echo the STRING(s) to standard output. -n do not output the trailing newline -e enable interpretation of backslash escapes -E disable interpretation of backslash escapes (default) --help display this help and exit --version output version information and exit If -e is in effect, the following sequences are recognized: \\ backslash \a alert (BEL) \b backspace \c produce no further output \e escape \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \0NNN byte with octal value NNN (1 to 3 digits) \xHH byte with hexadecimal value HH (1 to 2 digits) NOTE: your shell may have its own version of echo, which usually supersedes the version described here. Please refer to your shell's documentation for details about the options it supports. NOTE: printf(1) is a preferred alternative, which does not have issues outputting option-like strings. AUTHOR top Written by Brian Fox and Chet Ramey. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top printf(1) Full documentation <https://www.gnu.org/software/coreutils/echo> or available locally via: info '(coreutils) echo invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 ECHO(1) Pages that refer to this page: ldapcompare(1), systemd-ask-password(1), systemd-run(1), cpuset(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create new crontab set including $job and only jobs from current crontab that don`t contain $command Bash Command:<START>cat <(fgrep -i -v "$command" <(crontab -l)) <(echo "$job") | crontab -<END> |
Create ssh tunnel through "genja.org" connecting localhost port 4444 to "raptor.lan" port 22 | ssh -L 4444:raptor.lan:22 genja.org | ['ssh'] | Output a Bash command to accomplish the following task. Task: Create ssh tunnel through "genja.org" connecting localhost port 4444 to "raptor.lan" port 22 Bash Command:<START>ssh -L 4444:raptor.lan:22 genja.org<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # ssh\n\n> Secure Shell is a protocol used to securely log onto remote systems.\n> It can be used for logging or executing commands on a remote server.\n> More information: <https://man.openbsd.org/ssh>.\n\n- Connect to a remote server:\n\n`ssh {{username}}@{{remote_host}}`\n\n- Connect to a remote server with a specific identity (private key):\n\n`ssh -i {{path/to/key_file}} {{username}}@{{remote_host}}`\n\n- Connect to a remote server using a specific [p]ort:\n\n`ssh {{username}}@{{remote_host}} -p {{2222}}`\n\n- Run a command on a remote server with a [t]ty allocation allowing interaction with the remote command:\n\n`ssh {{username}}@{{remote_host}} -t {{command}} {{command_arguments}}`\n\n- SSH tunneling: [D]ynamic port forwarding (SOCKS proxy on `localhost:1080`):\n\n`ssh -D {{1080}} {{username}}@{{remote_host}}`\n\n- SSH tunneling: Forward a specific port (`localhost:9999` to `example.org:80`) along with disabling pseudo-[T]ty allocation and executio[N] of remote commands:\n\n`ssh -L {{9999}}:{{example.org}}:{{80}} -N -T {{username}}@{{remote_host}}`\n\n- SSH [J]umping: Connect through a jumphost to a remote server (Multiple jump hops may be specified separated by comma characters):\n\n`ssh -J {{username}}@{{jump_host}} {{username}}@{{remote_host}}`\n\n- Agent forwarding: Forward the authentication information to the remote machine (see `man ssh_config` for available options):\n\n`ssh -A {{username}}@{{remote_host}}`\n Task: Create ssh tunnel through "genja.org" connecting localhost port 4444 to "raptor.lan" port 22 Bash Command:<START>ssh -L 4444:raptor.lan:22 genja.org<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: ssh(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ssh(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHENTICATION | ESCAPE CHARACTERS | TCP FORWARDING | X11 FORWARDING | VERIFYING HOST KEYS | SSH-BASED VIRTUAL PRIVATE NETWORKS | ENVIRONMENT | FILES | EXIT STATUS | SEE ALSO | STANDARDS | AUTHORS | COLOPHON SSH(1) General Commands Manual SSH(1) NAME top ssh OpenSSH remote login client SYNOPSIS top ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface] [-b bind_address] [-c cipher_spec] [-D [bind_address:]port] [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11] [-i identity_file] [-J destination] [-L address] [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-P tag] [-p port] [-R address] [-S ctl_path] [-W host:port] [-w local_tun[:remote_tun]] destination [command [argument ...]] [-Q query_option] DESCRIPTION top (SSH client) is a program for logging into a remote machine and for executing commands on a remote machine. It is intended to provide secure encrypted communications between two untrusted hosts over an insecure network. X11 connections, arbitrary TCP ports and Unix-domain sockets can also be forwarded over the secure channel. connects and logs into the specified destination, which may be specified as either [user@]hostname or a URI of the form ssh://[user@]hostname[:port]. The user must prove their identity to the remote machine using one of several methods (see below). If a command is specified, it will be executed on the remote host instead of a login shell. A complete command line may be specified as command, or it may have additional arguments. If supplied, the arguments will be appended to the command, separated by spaces, before it is sent to the server to be executed. The options are as follows: -4 Forces to use IPv4 addresses only. -6 Forces to use IPv6 addresses only. -A Enables forwarding of connections from an authentication agent such as ssh-agent(1). This can also be specified on a per-host basis in a configuration file. Agent forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the agent's Unix-domain socket) can access the local agent through the forwarded connection. An attacker cannot obtain key material from the agent, however they can perform operations on the keys that enable them to authenticate using the identities loaded into the agent. A safer alternative may be to use a jump host (see -J). -a Disables forwarding of the authentication agent connection. -B bind_interface Bind to the address of bind_interface before attempting to connect to the destination host. This is only useful on systems with more than one address. -b bind_address Use bind_address on the local machine as the source address of the connection. Only useful on systems with more than one address. -C Requests compression of all data (including stdin, stdout, stderr, and data for forwarded X11, TCP and Unix-domain connections). The compression algorithm is the same used by gzip(1). Compression is desirable on modem lines and other slow connections, but will only slow down things on fast networks. The default value can be set on a host-by-host basis in the configuration files; see the Compression option in ssh_config(5). -c cipher_spec Selects the cipher specification for encrypting the session. cipher_spec is a comma-separated list of ciphers listed in order of preference. See the Ciphers keyword in ssh_config(5) for more information. -D [bind_address:]port Specifies a local dynamic application-level port forwarding. This works by allocating a socket to listen to port on the local side, optionally bound to the specified bind_address. Whenever a connection is made to this port, the connection is forwarded over the secure channel, and the application protocol is then used to determine where to connect to from the remote machine. Currently the SOCKS4 and SOCKS5 protocols are supported, and will act as a SOCKS server. Only root can forward privileged ports. Dynamic port forwardings can also be specified in the configuration file. IPv6 addresses can be specified by enclosing the address in square brackets. Only the superuser can forward privileged ports. By default, the local port is bound in accordance with the GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a specific address. The bind_address of localhost indicates that the listening port be bound for local use only, while an empty address or * indicates that the port should be available from all interfaces. -E log_file Append debug logs to log_file instead of standard error. -e escape_char Sets the escape character for sessions with a pty (default: ~). The escape character is only recognized at the beginning of a line. The escape character followed by a dot (.) closes the connection; followed by control-Z suspends the connection; and followed by itself sends the escape character once. Setting the character to none disables any escapes and makes the session fully transparent. -F configfile Specifies an alternative per-user configuration file. If a configuration file is given on the command line, the system-wide configuration file (/etc/ssh/ssh_config) will be ignored. The default for the per-user configuration file is ~/.ssh/config. If set to none, no configuration files will be read. -f Requests to go to background just before command execution. This is useful if is going to ask for passwords or passphrases, but the user wants it in the background. This implies -n. The recommended way to start X11 programs at a remote site is with something like ssh -f host xterm. If the ExitOnForwardFailure configuration option is set to yes, then a client started with -f will wait for all remote port forwards to be successfully established before placing itself in the background. Refer to the description of ForkAfterAuthentication in ssh_config(5) for details. -G Causes to print its configuration after evaluating Host and Match blocks and exit. -g Allows remote hosts to connect to local forwarded ports. If used on a multiplexed connection, then this option must be specified on the master process. -I pkcs11 Specify the PKCS#11 shared library should use to communicate with a PKCS#11 token providing keys for user authentication. -i identity_file Selects a file from which the identity (private key) for public key authentication is read. You can also specify a public key file to use the corresponding private key that is loaded in ssh-agent(1) when the private key file is not present locally. The default is ~/.ssh/id_rsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ecdsa_sk, ~/.ssh/id_ed25519, ~/.ssh/id_ed25519_sk and ~/.ssh/id_dsa. Identity files may also be specified on a per-host basis in the configuration file. It is possible to have multiple -i options (and multiple identities specified in configuration files). If no certificates have been explicitly specified by the CertificateFile directive, will also try to load certificate information from the filename obtained by appending -cert.pub to identity filenames. -J destination Connect to the target host by first making an connection to the jump host described by destination and then establishing a TCP forwarding to the ultimate destination from there. Multiple jump hops may be specified separated by comma characters. This is a shortcut to specify a ProxyJump configuration directive. Note that configuration directives supplied on the command-line generally apply to the destination host and not any specified jump hosts. Use ~/.ssh/config to specify configuration for jump hosts. -K Enables GSSAPI-based authentication and forwarding (delegation) of GSSAPI credentials to the server. -k Disables forwarding (delegation) of GSSAPI credentials to the server. -L [bind_address:]port:host:hostport -L [bind_address:]port:remote_socket -L local_socket:host:hostport -L local_socket:remote_socket Specifies that connections to the given TCP port or Unix socket on the local (client) host are to be forwarded to the given host and port, or Unix socket, on the remote side. This works by allocating a socket to listen to either a TCP port on the local side, optionally bound to the specified bind_address, or to a Unix socket. Whenever a connection is made to the local port or socket, the connection is forwarded over the secure channel, and a connection is made to either host port hostport, or the Unix socket remote_socket, from the remote machine. Port forwardings can also be specified in the configuration file. Only the superuser can forward privileged ports. IPv6 addresses can be specified by enclosing the address in square brackets. By default, the local port is bound in accordance with the GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a specific address. The bind_address of localhost indicates that the listening port be bound for local use only, while an empty address or * indicates that the port should be available from all interfaces. -l login_name Specifies the user to log in as on the remote machine. This also may be specified on a per-host basis in the configuration file. -M Places the client into master mode for connection sharing. Multiple -M options places into master mode but with confirmation required using ssh-askpass(1) before each operation that changes the multiplexing state (e.g. opening a new session). Refer to the description of ControlMaster in ssh_config(5) for details. -m mac_spec A comma-separated list of MAC (message authentication code) algorithms, specified in order of preference. See the MACs keyword in ssh_config(5) for more information. -N Do not execute a remote command. This is useful for just forwarding ports. Refer to the description of SessionType in ssh_config(5) for details. -n Redirects stdin from /dev/null (actually, prevents reading from stdin). This must be used when is run in the background. A common trick is to use this to run X11 programs on a remote machine. For example, ssh -n shadows.cs.hut.fi emacs & will start an emacs on shadows.cs.hut.fi, and the X11 connection will be automatically forwarded over an encrypted channel. The program will be put in the background. (This does not work if needs to ask for a password or passphrase; see also the -f option.) Refer to the description of StdinNull in ssh_config(5) for details. -O ctl_cmd Control an active connection multiplexing master process. When the -O option is specified, the ctl_cmd argument is interpreted and passed to the master process. Valid commands are: check (check that the master process is running), forward (request forwardings without command execution), cancel (cancel forwardings), exit (request the master to exit), and stop (request the master to stop accepting further multiplexing requests). -o option Can be used to give options in the format used in the configuration file. This is useful for specifying options for which there is no separate command-line flag. For full details of the options listed below, and their possible values, see ssh_config(5). AddKeysToAgent AddressFamily BatchMode BindAddress CanonicalDomains CanonicalizeFallbackLocal CanonicalizeHostname CanonicalizeMaxDots CanonicalizePermittedCNAMEs CASignatureAlgorithms CertificateFile CheckHostIP Ciphers ClearAllForwardings Compression ConnectionAttempts ConnectTimeout ControlMaster ControlPath ControlPersist DynamicForward EnableEscapeCommandline EscapeChar ExitOnForwardFailure FingerprintHash ForkAfterAuthentication ForwardAgent ForwardX11 ForwardX11Timeout ForwardX11Trusted GatewayPorts GlobalKnownHostsFile GSSAPIAuthentication GSSAPIDelegateCredentials HashKnownHosts Host HostbasedAcceptedAlgorithms HostbasedAuthentication HostKeyAlgorithms HostKeyAlias Hostname IdentitiesOnly IdentityAgent IdentityFile IPQoS KbdInteractiveAuthentication KbdInteractiveDevices KexAlgorithms KnownHostsCommand LocalCommand LocalForward LogLevel MACs Match NoHostAuthenticationForLocalhost NumberOfPasswordPrompts PasswordAuthentication PermitLocalCommand PermitRemoteOpen PKCS11Provider Port PreferredAuthentications ProxyCommand ProxyJump ProxyUseFdpass PubkeyAcceptedAlgorithms PubkeyAuthentication RekeyLimit RemoteCommand RemoteForward RequestTTY RequiredRSASize SendEnv ServerAliveInterval ServerAliveCountMax SessionType SetEnv StdinNull StreamLocalBindMask StreamLocalBindUnlink StrictHostKeyChecking TCPKeepAlive Tunnel TunnelDevice UpdateHostKeys User UserKnownHostsFile VerifyHostKeyDNS VisualHostKey XAuthLocation -P tag Specify a tag name that may be used to select configuration in ssh_config(5). Refer to the Tag and Match keywords in ssh_config(5) for more information. -p port Port to connect to on the remote host. This can be specified on a per-host basis in the configuration file. -Q query_option Queries for the algorithms supported by one of the following features: cipher (supported symmetric ciphers), cipher-auth (supported symmetric ciphers that support authenticated encryption), help (supported query terms for use with the -Q flag), mac (supported message integrity codes), kex (key exchange algorithms), key (key types), key-ca-sign (valid CA signature algorithms for certificates), key-cert (certificate key types), key-plain (non-certificate key types), key-sig (all key types and signature algorithms), protocol-version (supported SSH protocol versions), and sig (supported signature algorithms). Alternatively, any keyword from ssh_config(5) or sshd_config(5) that takes an algorithm list may be used as an alias for the corresponding query_option. -q Quiet mode. Causes most warning and diagnostic messages to be suppressed. -R [bind_address:]port:host:hostport -R [bind_address:]port:local_socket -R remote_socket:host:hostport -R remote_socket:local_socket -R [bind_address:]port Specifies that connections to the given TCP port or Unix socket on the remote (server) host are to be forwarded to the local side. This works by allocating a socket to listen to either a TCP port or to a Unix socket on the remote side. Whenever a connection is made to this port or Unix socket, the connection is forwarded over the secure channel, and a connection is made from the local machine to either an explicit destination specified by host port hostport, or local_socket, or, if no explicit destination was specified, will act as a SOCKS 4/5 proxy and forward connections to the destinations requested by the remote SOCKS client. Port forwardings can also be specified in the configuration file. Privileged ports can be forwarded only when logging in as root on the remote machine. IPv6 addresses can be specified by enclosing the address in square brackets. By default, TCP listening sockets on the server will be bound to the loopback interface only. This may be overridden by specifying a bind_address. An empty bind_address, or the address *, indicates that the remote socket should listen on all interfaces. Specifying a remote bind_address will only succeed if the server's GatewayPorts option is enabled (see sshd_config(5)). If the port argument is 0, the listen port will be dynamically allocated on the server and reported to the client at run time. When used together with -O forward, the allocated port will be printed to the standard output. -S ctl_path Specifies the location of a control socket for connection sharing, or the string none to disable connection sharing. Refer to the description of ControlPath and ControlMaster in ssh_config(5) for details. -s May be used to request invocation of a subsystem on the remote system. Subsystems facilitate the use of SSH as a secure transport for other applications (e.g. sftp(1)). The subsystem is specified as the remote command. Refer to the description of SessionType in ssh_config(5) for details. -T Disable pseudo-terminal allocation. -t Force pseudo-terminal allocation. This can be used to execute arbitrary screen-based programs on a remote machine, which can be very useful, e.g. when implementing menu services. Multiple -t options force tty allocation, even if has no local tty. -V Display the version number and exit. -v Verbose mode. Causes to print debugging messages about its progress. This is helpful in debugging connection, authentication, and configuration problems. Multiple -v options increase the verbosity. The maximum is 3. -W host:port Requests that standard input and output on the client be forwarded to host on port over the secure channel. Implies -N, -T, ExitOnForwardFailure and ClearAllForwardings, though these can be overridden in the configuration file or using -o command line options. -w local_tun[:remote_tun] Requests tunnel device forwarding with the specified tun(4) devices between the client (local_tun) and the server (remote_tun). The devices may be specified by numerical ID or the keyword any, which uses the next available tunnel device. If remote_tun is not specified, it defaults to any. See also the Tunnel and TunnelDevice directives in ssh_config(5). If the Tunnel directive is unset, it will be set to the default tunnel mode, which is point-to-point. If a different Tunnel forwarding mode it desired, then it should be specified before -w. -X Enables X11 forwarding. This can also be specified on a per-host basis in a configuration file. X11 forwarding should be enabled with caution. Users with the ability to bypass file permissions on the remote host (for the user's X authorization database) can access the local X11 display through the forwarded connection. An attacker may then be able to perform activities such as keystroke monitoring. For this reason, X11 forwarding is subjected to X11 SECURITY extension restrictions by default. Refer to the -Y option and the ForwardX11Trusted directive in ssh_config(5) for more information. -x Disables X11 forwarding. -Y Enables trusted X11 forwarding. Trusted X11 forwardings are not subjected to the X11 SECURITY extension controls. -y Send log information using the syslog(3) system module. By default this information is sent to stderr. may additionally obtain configuration data from a per-user configuration file and a system-wide configuration file. The file format and configuration options are described in ssh_config(5). AUTHENTICATION top The OpenSSH SSH client supports SSH protocol 2. The methods available for authentication are: GSSAPI-based authentication, host-based authentication, public key authentication, keyboard-interactive authentication, and password authentication. Authentication methods are tried in the order specified above, though PreferredAuthentications can be used to change the default order. Host-based authentication works as follows: If the machine the user logs in from is listed in /etc/hosts.equiv or /etc/shosts.equiv on the remote machine, the user is non-root and the user names are the same on both sides, or if the files ~/.rhosts or ~/.shosts exist in the user's home directory on the remote machine and contain a line containing the name of the client machine and the name of the user on that machine, the user is considered for login. Additionally, the server must be able to verify the client's host key (see the description of /etc/ssh/ssh_known_hosts and ~/.ssh/known_hosts, below) for login to be permitted. This authentication method closes security holes due to IP spoofing, DNS spoofing, and routing spoofing. [Note to the administrator: /etc/hosts.equiv, ~/.rhosts, and the rlogin/rsh protocol in general, are inherently insecure and should be disabled if security is desired.] Public key authentication works as follows: The scheme is based on public-key cryptography, using cryptosystems where encryption and decryption are done using separate keys, and it is unfeasible to derive the decryption key from the encryption key. The idea is that each user creates a public/private key pair for authentication purposes. The server knows the public key, and only the user knows the private key. implements public key authentication protocol automatically, using one of the DSA, ECDSA, Ed25519 or RSA algorithms. The HISTORY section of ssl(8) contains a brief discussion of the DSA and RSA algorithms. The file ~/.ssh/authorized_keys lists the public keys that are permitted for logging in. When the user logs in, the program tells the server which key pair it would like to use for authentication. The client proves that it has access to the private key and the server checks that the corresponding public key is authorized to accept the account. The server may inform the client of errors that prevented public key authentication from succeeding after authentication completes using a different method. These may be viewed by increasing the LogLevel to DEBUG or higher (e.g. by using the -v flag). The user creates their key pair by running ssh-keygen(1). This stores the private key in ~/.ssh/id_dsa (DSA), ~/.ssh/id_ecdsa (ECDSA), ~/.ssh/id_ecdsa_sk (authenticator-hosted ECDSA), ~/.ssh/id_ed25519 (Ed25519), ~/.ssh/id_ed25519_sk (authenticator- hosted Ed25519), or ~/.ssh/id_rsa (RSA) and stores the public key in ~/.ssh/id_dsa.pub (DSA), ~/.ssh/id_ecdsa.pub (ECDSA), ~/.ssh/id_ecdsa_sk.pub (authenticator-hosted ECDSA), ~/.ssh/id_ed25519.pub (Ed25519), ~/.ssh/id_ed25519_sk.pub (authenticator-hosted Ed25519), or ~/.ssh/id_rsa.pub (RSA) in the user's home directory. The user should then copy the public key to ~/.ssh/authorized_keys in their home directory on the remote machine. The authorized_keys file corresponds to the conventional ~/.rhosts file, and has one key per line, though the lines can be very long. After this, the user can log in without giving the password. A variation on public key authentication is available in the form of certificate authentication: instead of a set of public/private keys, signed certificates are used. This has the advantage that a single trusted certification authority can be used in place of many public/private keys. See the CERTIFICATES section of ssh-keygen(1) for more information. The most convenient way to use public key or certificate authentication may be with an authentication agent. See ssh-agent(1) and (optionally) the AddKeysToAgent directive in ssh_config(5) for more information. Keyboard-interactive authentication works as follows: The server sends an arbitrary "challenge" text and prompts for a response, possibly multiple times. Examples of keyboard-interactive authentication include BSD Authentication (see login.conf(5)) and PAM (some non-OpenBSD systems). Finally, if other authentication methods fail, prompts the user for a password. The password is sent to the remote host for checking; however, since all communications are encrypted, the password cannot be seen by someone listening on the network. automatically maintains and checks a database containing identification for all hosts it has ever been used with. Host keys are stored in ~/.ssh/known_hosts in the user's home directory. Additionally, the file /etc/ssh/ssh_known_hosts is automatically checked for known hosts. Any new hosts are automatically added to the user's file. If a host's identification ever changes, warns about this and disables password authentication to prevent server spoofing or man-in-the- middle attacks, which could otherwise be used to circumvent the encryption. The StrictHostKeyChecking option can be used to control logins to machines whose host key is not known or has changed. When the user's identity has been accepted by the server, the server either executes the given command in a non-interactive session or, if no command has been specified, logs into the machine and gives the user a normal shell as an interactive session. All communication with the remote command or shell will be automatically encrypted. If an interactive session is requested, by default will only request a pseudo-terminal (pty) for interactive sessions when the client has one. The flags -T and -t can be used to override this behaviour. If a pseudo-terminal has been allocated, the user may use the escape characters noted below. If no pseudo-terminal has been allocated, the session is transparent and can be used to reliably transfer binary data. On most systems, setting the escape character to none will also make the session transparent even if a tty is used. The session terminates when the command or shell on the remote machine exits and all X11 and TCP connections have been closed. ESCAPE CHARACTERS top When a pseudo-terminal has been requested, supports a number of functions through the use of an escape character. A single tilde character can be sent as ~~ or by following the tilde by a character other than those described below. The escape character must always follow a newline to be interpreted as special. The escape character can be changed in configuration files using the EscapeChar configuration directive or on the command line by the -e option. The supported escapes (assuming the default ~) are: ~. Disconnect. ~^Z Background . ~# List forwarded connections. ~& Background at logout when waiting for forwarded connection / X11 sessions to terminate. ~? Display a list of escape characters. ~B Send a BREAK to the remote system (only useful if the peer supports it). ~C Open command line. Currently this allows the addition of port forwardings using the -L, -R and -D options (see above). It also allows the cancellation of existing port-forwardings with -KL[bind_address:]port for local, -KR[bind_address:]port for remote and -KD[bind_address:]port for dynamic port-forwardings. !command allows the user to execute a local command if the PermitLocalCommand option is enabled in ssh_config(5). Basic help is available, using the -h option. ~R Request rekeying of the connection (only useful if the peer supports it). ~V Decrease the verbosity (LogLevel) when errors are being written to stderr. ~v Increase the verbosity (LogLevel) when errors are being written to stderr. TCP FORWARDING top Forwarding of arbitrary TCP connections over a secure channel can be specified either on the command line or in a configuration file. One possible application of TCP forwarding is a secure connection to a mail server; another is going through firewalls. In the example below, we look at encrypting communication for an IRC client, even though the IRC server it connects to does not directly support encrypted communication. This works as follows: the user connects to the remote host using , specifying the ports to be used to forward the connection. After that it is possible to start the program locally, and will encrypt and forward the connection to the remote server. The following example tunnels an IRC session from the client to an IRC server at server.example.com, joining channel #users, nickname pinky, using the standard IRC port, 6667: $ ssh -f -L 6667:localhost:6667 server.example.com sleep 10 $ irc -c '#users' pinky IRC/127.0.0.1 The -f option backgrounds and the remote command sleep 10 is specified to allow an amount of time (10 seconds, in the example) to start the program which is going to use the tunnel. If no connections are made within the time specified, will exit. X11 FORWARDING top If the ForwardX11 variable is set to yes (or see the description of the -X, -x, and -Y options above) and the user is using X11 (the DISPLAY environment variable is set), the connection to the X11 display is automatically forwarded to the remote side in such a way that any X11 programs started from the shell (or command) will go through the encrypted channel, and the connection to the real X server will be made from the local machine. The user should not manually set DISPLAY. Forwarding of X11 connections can be configured on the command line or in configuration files. The DISPLAY value set by will point to the server machine, but with a display number greater than zero. This is normal, and happens because creates a proxy X server on the server machine for forwarding the connections over the encrypted channel. will also automatically set up Xauthority data on the server machine. For this purpose, it will generate a random authorization cookie, store it in Xauthority on the server, and verify that any forwarded connections carry this cookie and replace it by the real cookie when the connection is opened. The real authentication cookie is never sent to the server machine (and no cookies are sent in the plain). If the ForwardAgent variable is set to yes (or see the description of the -A and -a options above) and the user is using an authentication agent, the connection to the agent is automatically forwarded to the remote side. VERIFYING HOST KEYS top When connecting to a server for the first time, a fingerprint of the server's public key is presented to the user (unless the option StrictHostKeyChecking has been disabled). Fingerprints can be determined using ssh-keygen(1): $ ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key If the fingerprint is already known, it can be matched and the key can be accepted or rejected. If only legacy (MD5) fingerprints for the server are available, the ssh-keygen(1) -E option may be used to downgrade the fingerprint algorithm to match. Because of the difficulty of comparing host keys just by looking at fingerprint strings, there is also support to compare host keys visually, using random art. By setting the VisualHostKey option to yes, a small ASCII graphic gets displayed on every login to a server, no matter if the session itself is interactive or not. By learning the pattern a known server produces, a user can easily find out that the host key has changed when a completely different pattern is displayed. Because these patterns are not unambiguous however, a pattern that looks similar to the pattern remembered only gives a good probability that the host key is the same, not guaranteed proof. To get a listing of the fingerprints along with their random art for all known hosts, the following command line can be used: $ ssh-keygen -lv -f ~/.ssh/known_hosts If the fingerprint is unknown, an alternative method of verification is available: SSH fingerprints verified by DNS. An additional resource record (RR), SSHFP, is added to a zonefile and the connecting client is able to match the fingerprint with that of the key presented. In this example, we are connecting a client to a server, host.example.com. The SSHFP resource records should first be added to the zonefile for host.example.com: $ ssh-keygen -r host.example.com. The output lines will have to be added to the zonefile. To check that the zone is answering fingerprint queries: $ dig -t SSHFP host.example.com Finally the client connects: $ ssh -o "VerifyHostKeyDNS ask" host.example.com [...] Matching host key fingerprint found in DNS. Are you sure you want to continue connecting (yes/no)? See the VerifyHostKeyDNS option in ssh_config(5) for more information. SSH-BASED VIRTUAL PRIVATE NETWORKS top contains support for Virtual Private Network (VPN) tunnelling using the tun(4) network pseudo-device, allowing two networks to be joined securely. The sshd_config(5) configuration option PermitTunnel controls whether the server supports this, and at what level (layer 2 or 3 traffic). The following example would connect client network 10.0.50.0/24 with remote network 10.0.99.0/24 using a point-to-point connection from 10.1.1.1 to 10.1.1.2, provided that the SSH server running on the gateway to the remote network, at 192.168.1.15, allows it. On the client: # ssh -f -w 0:1 192.168.1.15 true # ifconfig tun0 10.1.1.1 10.1.1.2 netmask 255.255.255.252 # route add 10.0.99.0/24 10.1.1.2 On the server: # ifconfig tun1 10.1.1.2 10.1.1.1 netmask 255.255.255.252 # route add 10.0.50.0/24 10.1.1.1 Client access may be more finely tuned via the /root/.ssh/authorized_keys file (see below) and the PermitRootLogin server option. The following entry would permit connections on tun(4) device 1 from user jane and on tun device 2 from user john, if PermitRootLogin is set to forced-commands-only: tunnel="1",command="sh /etc/netstart tun1" ssh-rsa ... jane tunnel="2",command="sh /etc/netstart tun2" ssh-rsa ... john Since an SSH-based setup entails a fair amount of overhead, it may be more suited to temporary setups, such as for wireless VPNs. More permanent VPNs are better provided by tools such as ipsecctl(8) and isakmpd(8). ENVIRONMENT top will normally set the following environment variables: DISPLAY The DISPLAY variable indicates the location of the X11 server. It is automatically set by to point to a value of the form hostname:n, where hostname indicates the host where the shell runs, and n is an integer 1. uses this special value to forward X11 connections over the secure channel. The user should normally not set DISPLAY explicitly, as that will render the X11 connection insecure (and will require the user to manually copy any required authorization cookies). HOME Set to the path of the user's home directory. LOGNAME Synonym for USER; set for compatibility with systems that use this variable. MAIL Set to the path of the user's mailbox. PATH Set to the default PATH, as specified when compiling . SSH_ASKPASS If needs a passphrase, it will read the passphrase from the current terminal if it was run from a terminal. If does not have a terminal associated with it but DISPLAY and SSH_ASKPASS are set, it will execute the program specified by SSH_ASKPASS and open an X11 window to read the passphrase. This is particularly useful when calling from a .xsession or related script. (Note that on some machines it may be necessary to redirect the input from /dev/null to make this work.) SSH_ASKPASS_REQUIRE Allows further control over the use of an askpass program. If this variable is set to never then will never attempt to use one. If it is set to prefer, then will prefer to use the askpass program instead of the TTY when requesting passwords. Finally, if the variable is set to force, then the askpass program will be used for all passphrase input regardless of whether DISPLAY is set. SSH_AUTH_SOCK Identifies the path of a Unix-domain socket used to communicate with the agent. SSH_CONNECTION Identifies the client and server ends of the connection. The variable contains four space-separated values: client IP address, client port number, server IP address, and server port number. SSH_ORIGINAL_COMMAND This variable contains the original command line if a forced command is executed. It can be used to extract the original arguments. SSH_TTY This is set to the name of the tty (path to the device) associated with the current shell or command. If the current session has no tty, this variable is not set. SSH_TUNNEL Optionally set by sshd(8) to contain the interface names assigned if tunnel forwarding was requested by the client. SSH_USER_AUTH Optionally set by sshd(8), this variable may contain a pathname to a file that lists the authentication methods successfully used when the session was established, including any public keys that were used. TZ This variable is set to indicate the present time zone if it was set when the daemon was started (i.e. the daemon passes the value on to new connections). USER Set to the name of the user logging in. Additionally, reads ~/.ssh/environment, and adds lines of the format VARNAME=value to the environment if the file exists and users are allowed to change their environment. For more information, see the PermitUserEnvironment option in sshd_config(5). FILES top ~/.rhosts This file is used for host-based authentication (see above). On some machines this file may need to be world- readable if the user's home directory is on an NFS partition, because sshd(8) reads it as root. Additionally, this file must be owned by the user, and must not have write permissions for anyone else. The recommended permission for most machines is read/write for the user, and not accessible by others. ~/.shosts This file is used in exactly the same way as .rhosts, but allows host-based authentication without permitting login with rlogin/rsh. ~/.ssh/ This directory is the default location for all user- specific configuration and authentication information. There is no general requirement to keep the entire contents of this directory secret, but the recommended permissions are read/write/execute for the user, and not accessible by others. ~/.ssh/authorized_keys Lists the public keys (DSA, ECDSA, Ed25519, RSA) that can be used for logging in as this user. The format of this file is described in the sshd(8) manual page. This file is not highly sensitive, but the recommended permissions are read/write for the user, and not accessible by others. ~/.ssh/config This is the per-user configuration file. The file format and configuration options are described in ssh_config(5). Because of the potential for abuse, this file must have strict permissions: read/write for the user, and not writable by others. ~/.ssh/environment Contains additional definitions for environment variables; see ENVIRONMENT, above. ~/.ssh/id_dsa ~/.ssh/id_ecdsa ~/.ssh/id_ecdsa_sk ~/.ssh/id_ed25519 ~/.ssh/id_ed25519_sk ~/.ssh/id_rsa Contains the private key for authentication. These files contain sensitive data and should be readable by the user but not accessible by others (read/write/execute). will simply ignore a private key file if it is accessible by others. It is possible to specify a passphrase when generating the key which will be used to encrypt the sensitive part of this file using AES-128. ~/.ssh/id_dsa.pub ~/.ssh/id_ecdsa.pub ~/.ssh/id_ecdsa_sk.pub ~/.ssh/id_ed25519.pub ~/.ssh/id_ed25519_sk.pub ~/.ssh/id_rsa.pub Contains the public key for authentication. These files are not sensitive and can (but need not) be readable by anyone. ~/.ssh/known_hosts Contains a list of host keys for all hosts the user has logged into that are not already in the systemwide list of known host keys. See sshd(8) for further details of the format of this file. ~/.ssh/rc Commands in this file are executed by when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information. /etc/hosts.equiv This file is for host-based authentication (see above). It should only be writable by root. /etc/shosts.equiv This file is used in exactly the same way as hosts.equiv, but allows host-based authentication without permitting login with rlogin/rsh. /etc/ssh/ssh_config Systemwide configuration file. The file format and configuration options are described in ssh_config(5). /etc/ssh/ssh_host_key /etc/ssh/ssh_host_dsa_key /etc/ssh/ssh_host_ecdsa_key /etc/ssh/ssh_host_ed25519_key /etc/ssh/ssh_host_rsa_key These files contain the private parts of the host keys and are used for host-based authentication. /etc/ssh/ssh_known_hosts Systemwide list of known host keys. This file should be prepared by the system administrator to contain the public host keys of all machines in the organization. It should be world-readable. See sshd(8) for further details of the format of this file. /etc/ssh/sshrc Commands in this file are executed by when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information. EXIT STATUS top exits with the exit status of the remote command or with 255 if an error occurred. SEE ALSO top scp(1), sftp(1), ssh-add(1), ssh-agent(1), ssh-keygen(1), ssh-keyscan(1), tun(4), ssh_config(5), ssh-keysign(8), sshd(8) STANDARDS top S. Lehtinen and C. Lonvick, The Secure Shell (SSH) Protocol Assigned Numbers, RFC 4250, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Protocol Architecture, RFC 4251, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Authentication Protocol, RFC 4252, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Transport Layer Protocol, RFC 4253, January 2006. T. Ylonen and C. Lonvick, The Secure Shell (SSH) Connection Protocol, RFC 4254, January 2006. J. Schlyter and W. Griffin, Using DNS to Securely Publish Secure Shell (SSH) Key Fingerprints, RFC 4255, January 2006. F. Cusack and M. Forssen, Generic Message Exchange Authentication for the Secure Shell Protocol (SSH), RFC 4256, January 2006. J. Galbraith and P. Remaker, The Secure Shell (SSH) Session Channel Break Extension, RFC 4335, January 2006. M. Bellare, T. Kohno, and C. Namprempre, The Secure Shell (SSH) Transport Layer Encryption Modes, RFC 4344, January 2006. B. Harris, Improved Arcfour Modes for the Secure Shell (SSH) Transport Layer Protocol, RFC 4345, January 2006. M. Friedl, N. Provos, and W. Simpson, Diffie-Hellman Group Exchange for the Secure Shell (SSH) Transport Layer Protocol, RFC 4419, March 2006. J. Galbraith and R. Thayer, The Secure Shell (SSH) Public Key File Format, RFC 4716, November 2006. D. Stebila and J. Green, Elliptic Curve Algorithm Integration in the Secure Shell Transport Layer, RFC 5656, December 2009. A. Perrig and D. Song, Hash Visualization: a New Technique to improve Real-World Security, 1999, International Workshop on Cryptographic Techniques and E-Commerce (CrypTEC '99). AUTHORS top OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re- added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. COLOPHON top This page is part of the openssh (Portable OpenSSH) project. Information about the project can be found at http://www.openssh.com/portable.html. If you have a bug report for this manual page, see http://www.openssh.com/report.html. This page was obtained from the tarball openssh-9.6p1.tar.gz fetched from http://ftp.eu.openbsd.org/pub/OpenBSD/OpenSSH/portable/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU October 11, 2023 SSH(1) Pages that refer to this page: stap-jupyter(1), systemd-stdio-bridge(1), tar(1), sd_bus_default(3), environment.d(5), proc(5), user@.service(5), pty(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create ssh tunnel through "genja.org" connecting localhost port 4444 to "raptor.lan" port 22 Bash Command:<START>ssh -L 4444:raptor.lan:22 genja.org<END> |
Create symbolic link "$1/link" to the absolute path of "$2" | ln -s "$(readlink -e "$2")" "$1/link" | ['readlink', 'ln'] | Output a Bash command to accomplish the following task. Task: Create symbolic link "$1/link" to the absolute path of "$2" Bash Command:<START>ln -s "$(readlink -e "$2")" "$1/link"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # readlink\n\n> Follow symlinks and get symlink information.\n> More information: <https://www.gnu.org/software/coreutils/readlink>.\n\n- Get the actual file to which the symlink points:\n\n`readlink {{path/to/file}}`\n\n- Get the absolute path to a file:\n\n`readlink -f {{path/to/file}}`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create symbolic link "$1/link" to the absolute path of "$2" Bash Command:<START>ln -s "$(readlink -e "$2")" "$1/link"<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: readlink(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training readlink(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON READLINK(1) User Commands READLINK(1) NAME top readlink - print resolved symbolic links or canonical file names SYNOPSIS top readlink [OPTION]... FILE... DESCRIPTION top Note realpath(1) is the preferred command to use for canonicalization functionality. Print value of a symbolic link or canonical file name -f, --canonicalize canonicalize by following every symlink in every component of the given name recursively; all but the last component must exist -e, --canonicalize-existing canonicalize by following every symlink in every component of the given name recursively, all components must exist -m, --canonicalize-missing canonicalize by following every symlink in every component of the given name recursively, without requirements on components existence -n, --no-newline do not output the trailing delimiter -q, --quiet -s, --silent suppress most error messages (on by default) -v, --verbose report error messages -z, --zero end each output line with NUL, not newline --help display this help and exit --version output version information and exit AUTHOR top Written by Dmitry V. Levin. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top readlink(2), realpath(1), realpath(3) Full documentation <https://www.gnu.org/software/coreutils/readlink> or available locally via: info '(coreutils) readlink invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 READLINK(1) Pages that refer to this page: basename(1), dirname(1), dpkg-realpath(1), realpath(1), unshare(1), mount(2), readlink(2), unshare(2), namespaces(7), mount(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create symbolic link "$1/link" to the absolute path of "$2" Bash Command:<START>ln -s "$(readlink -e "$2")" "$1/link"<END> |
Create symbolic links in current directory for all files located in "dir" directory and have filename extension "jpg" | find dir -name '*.jpg' -exec ln -s "{}" \; | ['find', 'dir', 'ln'] | Output a Bash command to accomplish the following task. Task: Create symbolic links in current directory for all files located in "dir" directory and have filename extension "jpg" Bash Command:<START>find dir -name '*.jpg' -exec ln -s "{}" \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # dir\n\n> List directory contents using one line per file, special characters are represented by backslash escape sequences.\n> Works as `ls -C --escape`.\n> More information: <https://manned.org/dir>.\n\n- List all files, including hidden files:\n\n`dir -all`\n\n- List files including their author (`-l` is required):\n\n`dir -l --author`\n\n- List files excluding those that match a specified blob pattern:\n\n`dir --hide={{pattern}}`\n\n- List subdirectories recursively:\n\n`dir --recursive`\n\n- Display help:\n\n`dir --help`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create symbolic links in current directory for all files located in "dir" directory and have filename extension "jpg" Bash Command:<START>find dir -name '*.jpg' -exec ln -s "{}" \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. dir(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training dir(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON DIR(1) User Commands DIR(1) NAME top dir - list directory contents SYNOPSIS top dir [OPTION]... [FILE]... DESCRIPTION top List information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuvSUX nor --sort is specified. Mandatory arguments to long options are mandatory for short options too. -a, --all do not ignore entries starting with . -A, --almost-all do not list implied . and .. --author with -l, print the author of each file -b, --escape print C-style escapes for nongraphic characters --block-size=SIZE with -l, scale sizes by SIZE when printing them; e.g., '--block-size=M'; see SIZE format below -B, --ignore-backups do not list implied entries ending with ~ -c with -lt: sort by, and show, ctime (time of last change of file status information); with -l: show ctime and sort by name; otherwise: sort by ctime, newest first -C list entries by columns --color[=WHEN] color the output WHEN; more info below -d, --directory list directories themselves, not their contents -D, --dired generate output designed for Emacs' dired mode -f list all entries in directory order -F, --classify[=WHEN] append indicator (one of */=>@|) to entries WHEN --file-type likewise, except do not append '*' --format=WORD across -x, commas -m, horizontal -x, long -l, single-column -1, verbose -l, vertical -C --full-time like -l --time-style=full-iso -g like -l, but do not list owner --group-directories-first group directories before files; can be augmented with a --sort option, but any use of --sort=none (-U) disables grouping -G, --no-group in a long listing, don't print group names -h, --human-readable with -l and -s, print sizes like 1K 234M 2G etc. --si likewise, but use powers of 1000 not 1024 -H, --dereference-command-line follow symbolic links listed on the command line --dereference-command-line-symlink-to-dir follow each command line symbolic link that points to a directory --hide=PATTERN do not list implied entries matching shell PATTERN (overridden by -a or -A) --hyperlink[=WHEN] hyperlink file names WHEN --indicator-style=WORD append indicator with style WORD to entry names: none (default), slash (-p), file-type (--file-type), classify (-F) -i, --inode print the index number of each file -I, --ignore=PATTERN do not list implied entries matching shell PATTERN -k, --kibibytes default to 1024-byte blocks for file system usage; used only with -s and per directory totals -l use a long listing format -L, --dereference when showing file information for a symbolic link, show information for the file the link references rather than for the link itself -m fill width with a comma separated list of entries -n, --numeric-uid-gid like -l, but list numeric user and group IDs -N, --literal print entry names without quoting -o like -l, but do not list group information -p, --indicator-style=slash append / indicator to directories -q, --hide-control-chars print ? instead of nongraphic characters --show-control-chars show nongraphic characters as-is (the default, unless program is 'ls' and output is a terminal) -Q, --quote-name enclose entry names in double quotes --quoting-style=WORD use quoting style WORD for entry names: literal, locale, shell, shell-always, shell-escape, shell-escape-always, c, escape (overrides QUOTING_STYLE environment variable) -r, --reverse reverse order while sorting -R, --recursive list subdirectories recursively -s, --size print the allocated size of each file, in blocks -S sort by file size, largest first --sort=WORD sort by WORD instead of name: none (-U), size (-S), time (-t), version (-v), extension (-X), width --time=WORD select which timestamp used to display or sort; access time (-u): atime, access, use; metadata change time (-c): ctime, status; modified time (default): mtime, modification; birth time: birth, creation; with -l, WORD determines which time to show; with --sort=time, sort by WORD (newest first) --time-style=TIME_STYLE time/date format with -l; see TIME_STYLE below -t sort by time, newest first; see --time -T, --tabsize=COLS assume tab stops at each COLS instead of 8 -u with -lt: sort by, and show, access time; with -l: show access time and sort by name; otherwise: sort by access time, newest first -U do not sort; list entries in directory order -v natural sort of (version) numbers within text -w, --width=COLS set output width to COLS. 0 means no limit -x list entries by lines instead of by columns -X sort alphabetically by entry extension -Z, --context print any security context of each file --zero end each output line with NUL, not newline -1 list one file per line --help display this help and exit --version output version information and exit The SIZE argument is an integer and optional unit (example: 10K is 10*1024). Units are K,M,G,T,P,E,Z,Y,R,Q (powers of 1024) or KB,MB,... (powers of 1000). Binary prefixes can be used, too: KiB=K, MiB=M, and so on. The TIME_STYLE argument can be full-iso, long-iso, iso, locale, or +FORMAT. FORMAT is interpreted like in date(1). If FORMAT is FORMAT1<newline>FORMAT2, then FORMAT1 applies to non-recent files and FORMAT2 to recent files. TIME_STYLE prefixed with 'posix-' takes effect only outside the POSIX locale. Also the TIME_STYLE environment variable sets the default style to use. The WHEN argument defaults to 'always' and can also be 'auto' or 'never'. Using color to distinguish file types is disabled both by default and with --color=never. With --color=auto, ls emits color codes only when standard output is connected to a terminal. The LS_COLORS environment variable can change the settings. Use the dircolors(1) command to set it. Exit status: 0 if OK, 1 if minor problems (e.g., cannot access subdirectory), 2 if serious trouble (e.g., cannot access command-line argument). AUTHOR top Written by Richard M. Stallman and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top Full documentation <https://www.gnu.org/software/coreutils/dir> or available locally via: info '(coreutils) dir invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 DIR(1) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create symbolic links in current directory for all files located in "dir" directory and have filename extension "jpg" Bash Command:<START>find dir -name '*.jpg' -exec ln -s "{}" \;<END> |
Create symbolic links in the current directory for all files excluding "CONFIGFILE" located in "/your/project" | find /your/project -maxdepth 1 ! -name "CONFIGFILE" -exec ln -s \{\} ./ \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create symbolic links in the current directory for all files excluding "CONFIGFILE" located in "/your/project" Bash Command:<START>find /your/project -maxdepth 1 ! -name "CONFIGFILE" -exec ln -s \{\} ./ \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create symbolic links in the current directory for all files excluding "CONFIGFILE" located in "/your/project" Bash Command:<START>find /your/project -maxdepth 1 ! -name "CONFIGFILE" -exec ln -s \{\} ./ \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create symbolic links in the current directory for all files excluding "CONFIGFILE" located in "/your/project" Bash Command:<START>find /your/project -maxdepth 1 ! -name "CONFIGFILE" -exec ln -s \{\} ./ \;<END> |
Create symbolic links in the current directory for all files excluding "CONFIGFILE" located under "/your/project" directory tree | find /your/project -type f ! -name 'CONFIGFILE' -exec ln -s \{\} ./ \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create symbolic links in the current directory for all files excluding "CONFIGFILE" located under "/your/project" directory tree Bash Command:<START>find /your/project -type f ! -name 'CONFIGFILE' -exec ln -s \{\} ./ \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create symbolic links in the current directory for all files excluding "CONFIGFILE" located under "/your/project" directory tree Bash Command:<START>find /your/project -type f ! -name 'CONFIGFILE' -exec ln -s \{\} ./ \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create symbolic links in the current directory for all files excluding "CONFIGFILE" located under "/your/project" directory tree Bash Command:<START>find /your/project -type f ! -name 'CONFIGFILE' -exec ln -s \{\} ./ \;<END> |
Create symbolic links in the current directory for all files located in directory "/path/with/files" with a name containing "txt" | find /path/with/files -type f -name "*txt*" -exec ln -s {} . ';' | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create symbolic links in the current directory for all files located in directory "/path/with/files" with a name containing "txt" Bash Command:<START>find /path/with/files -type f -name "*txt*" -exec ln -s {} . ';'<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create symbolic links in the current directory for all files located in directory "/path/with/files" with a name containing "txt" Bash Command:<START>find /path/with/files -type f -name "*txt*" -exec ln -s {} . ';'<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create symbolic links in the current directory for all files located in directory "/path/with/files" with a name containing "txt" Bash Command:<START>find /path/with/files -type f -name "*txt*" -exec ln -s {} . ';'<END> |
Create symbolic links in the current directory for all files under "bar1" that are not directories and do not end in ".cc" | find bar1 -name '*foo*' -not -type d -not -name '*.cc' -exec ln -s $PWD/'{}' bar2/ \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create symbolic links in the current directory for all files under "bar1" that are not directories and do not end in ".cc" Bash Command:<START>find bar1 -name '*foo*' -not -type d -not -name '*.cc' -exec ln -s $PWD/'{}' bar2/ \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create symbolic links in the current directory for all files under "bar1" that are not directories and do not end in ".cc" Bash Command:<START>find bar1 -name '*foo*' -not -type d -not -name '*.cc' -exec ln -s $PWD/'{}' bar2/ \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create symbolic links in the current directory for all files under "bar1" that are not directories and do not end in ".cc" Bash Command:<START>find bar1 -name '*foo*' -not -type d -not -name '*.cc' -exec ln -s $PWD/'{}' bar2/ \;<END> |
Create symlinks to all /home/folder1/*.txt files and 'folder1_' directory with the same name in a target directory named '+' | find /home/folder1/*.txt -type f -exec ln -s {} "folder1_" +\; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create symlinks to all /home/folder1/*.txt files and 'folder1_' directory with the same name in a target directory named '+' Bash Command:<START>find /home/folder1/*.txt -type f -exec ln -s {} "folder1_" +\;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create symlinks to all /home/folder1/*.txt files and 'folder1_' directory with the same name in a target directory named '+' Bash Command:<START>find /home/folder1/*.txt -type f -exec ln -s {} "folder1_" +\;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create symlinks to all /home/folder1/*.txt files and 'folder1_' directory with the same name in a target directory named '+' Bash Command:<START>find /home/folder1/*.txt -type f -exec ln -s {} "folder1_" +\;<END> |
Create symlinks to all /home/folder1/*.txt files and 'folder2_' directory with the same name in a target directory named '+' | find /home/folder1/*.txt -type f -exec ln -s {} "folder2_" + \; | ['find', 'ln'] | Output a Bash command to accomplish the following task. Task: Create symlinks to all /home/folder1/*.txt files and 'folder2_' directory with the same name in a target directory named '+' Bash Command:<START>find /home/folder1/*.txt -type f -exec ln -s {} "folder2_" + \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: # find\n\n> Find files or directories under a directory tree, recursively.\n> More information: <https://manned.org/find>.\n\n- Find files by extension:\n\n`find {{root_path}} -name '{{*.ext}}'`\n\n- Find files matching multiple path/name patterns:\n\n`find {{root_path}} -path '{{**/path/**/*.ext}}' -or -name '{{*pattern*}}'`\n\n- Find directories matching a given name, in case-insensitive mode:\n\n`find {{root_path}} -type d -iname '{{*lib*}}'`\n\n- Find files matching a given pattern, excluding specific paths:\n\n`find {{root_path}} -name '{{*.py}}' -not -path '{{*/site-packages/*}}'`\n\n- Find files matching a given size range, limiting the recursive depth to "1":\n\n`find {{root_path}} -maxdepth 1 -size {{+500k}} -size {{-10M}}`\n\n- Run a command for each file (use `{}` within the command to access the filename):\n\n`find {{root_path}} -name '{{*.ext}}' -exec {{wc -l}} {} \;`\n\n- Find all files modified today and pass the results to a single command as arguments:\n\n`find {{root_path}} -daystart -mtime {{-1}} -exec {{tar -cvf archive.tar}} {} \+`\n\n- Find empty (0 byte) files and delete them:\n\n`find {{root_path}} -type {{f}} -empty -delete`\n # ln\n\n> Creates links to files and directories.\n> More information: <https://www.gnu.org/software/coreutils/ln>.\n\n- Create a symbolic link to a file or directory:\n\n`ln -s {{/path/to/file_or_directory}} {{path/to/symlink}}`\n\n- Overwrite an existing symbolic link to point to a different file:\n\n`ln -sf {{/path/to/new_file}} {{path/to/symlink}}`\n\n- Create a hard link to a file:\n\n`ln {{/path/to/file}} {{path/to/hardlink}}`\n Task: Create symlinks to all /home/folder1/*.txt files and 'folder2_' directory with the same name in a target directory named '+' Bash Command:<START>find /home/folder1/*.txt -type f -exec ln -s {} "folder2_" + \;<END> | Use the provided context to output a Bash command that accomplishes the following task. Context: find(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training find(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXPRESSION | UNUSUAL FILENAMES | STANDARDS CONFORMANCE | ENVIRONMENT VARIABLES | EXAMPLES | EXIT STATUS | HISTORY | COMPATIBILITY | NON-BUGS | BUGS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON FIND(1) General Commands Manual FIND(1) NAME top find - search for files in a directory hierarchy SYNOPSIS top find [-H] [-L] [-P] [-D debugopts] [-Olevel] [starting-point...] [expression] DESCRIPTION top This manual page documents the GNU version of find. GNU find searches the directory tree rooted at each given starting-point by evaluating the given expression from left to right, according to the rules of precedence (see section OPERATORS), until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name. If no starting-point is specified, `.' is assumed. If you are using find in an environment where security is important (for example if you are using it to search directories that are writable by other users), you should read the `Security Considerations' chapter of the findutils documentation, which is called Finding Files and comes with findutils. That document also includes a lot more detail and discussion than this manual page, so you may find it a more useful source of information. OPTIONS top The -H, -L and -P options control the treatment of symbolic links. Command-line arguments following these are taken to be names of files or directories to be examined, up to the first argument that begins with `-', or the argument `(' or `!'. That argument and any following arguments are taken to be the expression describing what is to be searched for. If no paths are given, the current directory is used. If no expression is given, the expression -print is used (but you should probably consider using -print0 instead, anyway). This manual page talks about `options' within the expression list. These options control the behaviour of find but are specified immediately after the last path name. The five `real' options -H, -L, -P, -D and -O must appear before the first path name, if at all. A double dash -- could theoretically be used to signal that any remaining arguments are not options, but this does not really work due to the way find determines the end of the following path arguments: it does that by reading until an expression argument comes (which also starts with a `-'). Now, if a path argument would start with a `-', then find would treat it as expression argument instead. Thus, to ensure that all start points are taken as such, and especially to prevent that wildcard patterns expanded by the calling shell are not mistakenly treated as expression arguments, it is generally safer to prefix wildcards or dubious path names with either `./' or to use absolute path names starting with '/'. Alternatively, it is generally safe though non-portable to use the GNU option -files0-from to pass arbitrary starting points to find. -P Never follow symbolic links. This is the default behaviour. When find examines or prints information about files, and the file is a symbolic link, the information used shall be taken from the properties of the symbolic link itself. -L Follow symbolic links. When find examines or prints information about files, the information used shall be taken from the properties of the file to which the link points, not from the link itself (unless it is a broken symbolic link or find is unable to examine the file to which the link points). Use of this option implies -noleaf. If you later use the -P option, -noleaf will still be in effect. If -L is in effect and find discovers a symbolic link to a subdirectory during its search, the subdirectory pointed to by the symbolic link will be searched. When the -L option is in effect, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself (unless the symbolic link is broken). Actions that can cause symbolic links to become broken while find is executing (for example -delete) can give rise to confusing behaviour. Using -L causes the -lname and -ilname predicates always to return false. -H Do not follow symbolic links, except while processing the command line arguments. When find examines or prints information about files, the information used shall be taken from the properties of the symbolic link itself. The only exception to this behaviour is when a file specified on the command line is a symbolic link, and the link can be resolved. For that situation, the information used is taken from whatever the link points to (that is, the link is followed). The information about the link itself is used as a fallback if the file pointed to by the symbolic link cannot be examined. If -H is in effect and one of the paths specified on the command line is a symbolic link to a directory, the contents of that directory will be examined (though of course -maxdepth 0 would prevent this). If more than one of -H, -L and -P is specified, each overrides the others; the last one appearing on the command line takes effect. Since it is the default, the -P option should be considered to be in effect unless either -H or -L is specified. GNU find frequently stats files during the processing of the command line itself, before any searching has begun. These options also affect how those arguments are processed. Specifically, there are a number of tests that compare files listed on the command line against a file we are currently considering. In each case, the file specified on the command line will have been examined and some of its properties will have been saved. If the named file is in fact a symbolic link, and the -P option is in effect (or if neither -H nor -L were specified), the information used for the comparison will be taken from the properties of the symbolic link. Otherwise, it will be taken from the properties of the file the link points to. If find cannot follow the link (for example because it has insufficient privileges or the link points to a nonexistent file) the properties of the link itself will be used. When the -H or -L options are in effect, any symbolic links listed as the argument of -newer will be dereferenced, and the timestamp will be taken from the file to which the symbolic link points. The same consideration applies to -newerXY, -anewer and -cnewer. The -follow option has a similar effect to -L, though it takes effect at the point where it appears (that is, if -L is not used but -follow is, any symbolic links appearing after -follow on the command line will be dereferenced, and those before it will not). -D debugopts Print diagnostic information; this can be helpful to diagnose problems with why find is not doing what you want. The list of debug options should be comma separated. Compatibility of the debug options is not guaranteed between releases of findutils. For a complete list of valid debug options, see the output of find -D help. Valid debug options include exec Show diagnostic information relating to -exec, -execdir, -ok and -okdir opt Prints diagnostic information relating to the optimisation of the expression tree; see the -O option. rates Prints a summary indicating how often each predicate succeeded or failed. search Navigate the directory tree verbosely. stat Print messages as files are examined with the stat and lstat system calls. The find program tries to minimise such calls. tree Show the expression tree in its original and optimised form. all Enable all of the other debug options (but help). help Explain the debugging options. -Olevel Enables query optimisation. The find program reorders tests to speed up execution while preserving the overall effect; that is, predicates with side effects are not reordered relative to each other. The optimisations performed at each optimisation level are as follows. 0 Equivalent to optimisation level 1. 1 This is the default optimisation level and corresponds to the traditional behaviour. Expressions are reordered so that tests based only on the names of files (for example -name and -regex) are performed first. 2 Any -type or -xtype tests are performed after any tests based only on the names of files, but before any tests that require information from the inode. On many modern versions of Unix, file types are returned by readdir() and so these predicates are faster to evaluate than predicates which need to stat the file first. If you use the -fstype FOO predicate and specify a filesystem type FOO which is not known (that is, present in `/etc/mtab') at the time find starts, that predicate is equivalent to -false. 3 At this optimisation level, the full cost-based query optimiser is enabled. The order of tests is modified so that cheap (i.e. fast) tests are performed first and more expensive ones are performed later, if necessary. Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not. For -o, predicates which are likely to succeed are evaluated earlier, and for -a, predicates which are likely to fail are evaluated earlier. The cost-based optimiser has a fixed idea of how likely any given test is to succeed. In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be more likely to succeed than -type c). The cost-based optimiser is currently being evaluated. If it does not actually improve the performance of find, it will be removed again. Conversely, optimisations that prove to be reliable, robust and effective may be enabled at lower optimisation levels over time. However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series. The findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same. EXPRESSION top The part of the command line after the list of starting points is the expression. This is a kind of query specification describing how we match files and what we do with the files that were matched. An expression is composed of a sequence of things: Tests Tests return a true or false value, usually on the basis of some property of a file we are considering. The -empty test for example is true only when the current file is empty. Actions Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful. The -print action for example prints the name of the current file on the standard output. Global options Global options affect the operation of tests and actions specified on any part of the command line. Global options always return true. The -depth option for example makes find traverse the file system in a depth-first order. Positional options Positional options affect only tests or actions which follow them. Positional options always return true. The -regextype option for example is positional, specifying the regular expression dialect for regular expressions occurring later on the command line. Operators Operators join together the other items within the expression. They include for example -o (meaning logical OR) and -a (meaning logical AND). Where an operator is missing, -a is assumed. The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit. Actions which inhibit the default -print are -delete, -exec, -execdir, -ok, -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf. The -delete action also acts like an option (since it implies -depth). POSITIONAL OPTIONS Positional options always return true. They affect only tests occurring later on the command line. -daystart Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago. This option only affects tests which appear later on the command line. -follow Deprecated; use the -L option instead. Dereference symbolic links. Implies -noleaf. The -follow option affects only those tests which appear after it on the command line. Unless the -H or -L option has been specified, the position of the -follow option changes the behaviour of the -newer predicate; any files listed as the argument of -newer will be dereferenced if they are symbolic links. The same consideration applies to -newerXY, -anewer and -cnewer. Similarly, the -type predicate will always match against the type of the file that a symbolic link points to rather than the link itself. Using -follow causes the -lname and -ilname predicates always to return false. -regextype type Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line. To see which regular expression types are known, use -regextype help. The Texinfo documentation (see SEE ALSO) explains the meaning of and differences between the various types of regular expression. -warn, -nowarn Turn warning messages on or off. These warnings apply only to the command line usage, not to any conditions that find might encounter when it searches directories. The default behaviour corresponds to -warn if standard input is a tty, and to -nowarn otherwise. If a warning message relating to command-line usage is produced, the exit status of find is not affected. If the POSIXLY_CORRECT environment variable is set, and -warn is also used, it is not specified which, if any, warnings will be active. GLOBAL OPTIONS Global options always return true. Global options take effect even for tests which occur earlier on the command line. To prevent confusion, global options should be specified on the command-line after the list of start points, just before the first test, positional option or action. If you specify a global option in some other place, find will issue a warning message explaining that this can be confusing. The global options occur after the list of start points, and so are not the same kind of option as -L, for example. -d A synonym for -depth, for compatibility with FreeBSD, NetBSD, MacOS X and OpenBSD. -depth Process each directory's contents before the directory itself. The -delete action also implies -depth. -files0-from file Read the starting points from file instead of getting them on the command line. In contrast to the known limitations of passing starting points via arguments on the command line, namely the limitation of the amount of file names, and the inherent ambiguity of file names clashing with option names, using this option allows to safely pass an arbitrary number of starting points to find. Using this option and passing starting points on the command line is mutually exclusive, and is therefore not allowed at the same time. The file argument is mandatory. One can use -files0-from - to read the list of starting points from the standard input stream, and e.g. from a pipe. In this case, the actions -ok and -okdir are not allowed, because they would obviously interfere with reading from standard input in order to get a user confirmation. The starting points in file have to be separated by ASCII NUL characters. Two consecutive NUL characters, i.e., a starting point with a Zero-length file name is not allowed and will lead to an error diagnostic followed by a non- Zero exit code later. In the case the given file is empty, find does not process any starting point and therefore will exit immediately after parsing the program arguments. This is unlike the standard invocation where find assumes the current directory as starting point if no path argument is passed. The processing of the starting points is otherwise as usual, e.g. find will recurse into subdirectories unless otherwise prevented. To process only the starting points, one can additionally pass -maxdepth 0. Further notes: if a file is listed more than once in the input file, it is unspecified whether it is visited more than once. If the file is mutated during the operation of find, the result is unspecified as well. Finally, the seek position within the named file at the time find exits, be it with -quit or in any other way, is also unspecified. By "unspecified" here is meant that it may or may not work or do any specific thing, and that the behavior may change from platform to platform, or from findutils release to release. -help, --help Print a summary of the command-line usage of find and exit. -ignore_readdir_race Normally, find will emit an error message when it fails to stat a file. If you give this option and a file is deleted between the time find reads the name of the file from the directory and the time it tries to stat the file, no error message will be issued. This also applies to files or directories whose names are given on the command line. This option takes effect at the time the command line is read, which means that you cannot search one part of the filesystem with this option on and part of it with this option off (if you need to do that, you will need to issue two find commands instead, one with the option and one without it). Furthermore, find with the -ignore_readdir_race option will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, and the return code of the -delete action will be true. -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the starting-points. Using -maxdepth 0 means only apply the tests and actions to the starting- points themselves. -mindepth levels Do not apply any tests or actions at levels less than levels (a non-negative integer). Using -mindepth 1 means process all files except the starting-points. -mount Don't descend directories on other filesystems. An alternate name for -xdev, for compatibility with some other versions of find. -noignore_readdir_race Turns off the effect of -ignore_readdir_race. -noleaf Do not optimize by assuming that directories contain 2 fewer subdirectories than their hard link count. This option is needed when searching filesystems that do not follow the Unix directory-link convention, such as CD-ROM or MS-DOS filesystems or AFS volume mount points. Each directory on a normal Unix filesystem has at least 2 hard links: its name and its `.' entry. Additionally, its subdirectories (if any) each have a `..' entry linked to that directory. When find is examining a directory, after it has statted 2 fewer subdirectories than the directory's link count, it knows that the rest of the entries in the directory are non-directories (`leaf' files in the directory tree). If only the files' names need to be examined, there is no need to stat them; this gives a significant increase in search speed. -version, --version Print the find version number and exit. -xdev Don't descend directories on other filesystems. TESTS Some tests, for example -newerXY and -samefile, allow comparison between the file currently being examined and some reference file specified on the command line. When these tests are used, the interpretation of the reference file is determined by the options -H, -L and -P and any previous -follow, but the reference file is only examined once, at the time the command line is parsed. If the reference file cannot be examined (for example, the stat(2) system call fails for it), an error message is issued, and find exits with a nonzero status. A numeric argument n can be specified to tests (like -amin, -mtime, -gid, -inum, -links, -size, -uid and -used) as +n for greater than n, -n for less than n, n for exactly n. Supported tests: -amin n File was last accessed less than, more than or exactly n minutes ago. -anewer reference Time of the last access of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -atime n File was last accessed less than, more than or exactly n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago. -cmin n File's status was last changed less than, more than or exactly n minutes ago. -cnewer reference Time of the last status change of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -ctime n File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times. -empty File is empty and is either a regular file or a directory. -executable Matches files which are executable and directories which are searchable (in a file name resolution sense) by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root-squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. Because this test is based only on the result of the access(2) system call, there is no guarantee that a file for which this test succeeds can actually be executed. -false Always false. -fstype type File is on a filesystem of type type. The valid filesystem types vary among different versions of Unix; an incomplete list of filesystem types that are accepted on some version of Unix or another is: ufs, 4.2, 4.3, nfs, tmp, mfs, S51K, S52K. You can use -printf with the %F directive to see the types of your filesystems. -gid n File's numeric group ID is less than, more than or exactly n. -group gname File belongs to group gname (numeric group ID allowed). -ilname pattern Like -lname, but the match is case insensitive. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -iname pattern Like -name, but the match is case insensitive. For example, the patterns `fo*' and `F??' match the file names `Foo', `FOO', `foo', `fOo', etc. The pattern `*foo*` will also match a file called '.foobar'. -inum n File has inode number smaller than, greater than or exactly n. It is normally easier to use the -samefile test instead. -ipath pattern Like -path. but the match is case insensitive. -iregex pattern Like -regex, but the match is case insensitive. -iwholename pattern See -ipath. This alternative is less portable than -ipath. -links n File has less than, more than or exactly n hard links. -lname pattern File is a symbolic link whose contents match shell pattern pattern. The metacharacters do not treat `/' or `.' specially. If the -L option or the -follow option is in effect, this test returns false unless the symbolic link is broken. -mmin n File's data was last modified less than, more than or exactly n minutes ago. -mtime n File's data was last modified less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times. -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern. Because the leading directories of the file names are removed, the pattern should not include a slash, because `-name a/b' will never match anything (and you probably want to use -path instead). An exception to this is when using only a slash as pattern (`-name /'), because that is a valid string for matching the root directory "/" (because the base name of "/" is "/"). A warning is issued if you try to pass a pattern containing a - but not consisting solely of one - slash, unless the environment variable POSIXLY_CORRECT is set or the option -nowarn is used. To ignore a directory and the files under it, use -prune rather than checking every file in the tree; see an example in the description of that action. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell. -newer reference Time of the last data modification of the current file is more recent than that of the last data modification of the reference file. If reference is a symbolic link and the -H option or the -L option is in effect, then the time of the last data modification of the file it points to is always used. -newerXY reference Succeeds if timestamp X of the file being considered is newer than timestamp Y of the file reference. The letters X and Y can be any of the following letters: a The access time of the file reference B The birth time of the file reference c The inode status change time of reference m The modification time of the file reference t reference is interpreted directly as a time Some combinations are invalid; for example, it is invalid for X to be t. Some combinations are not implemented on all systems; for example B is not supported on all systems. If an invalid or unsupported combination of XY is specified, a fatal error results. Time specifications are interpreted as for the argument to the -d option of GNU date. If you try to use the birth time of a reference file, and the birth time cannot be determined, a fatal error message results. If you specify a test which refers to the birth time of files being examined, this test will fail for any files where the birth time is unknown. -nogroup No group corresponds to file's numeric group ID. -nouser No user corresponds to file's numeric user ID. -path pattern File name matches shell pattern pattern. The metacharacters do not treat `/' or `.' specially; so, for example, find . -path "./sr*sc" will print an entry for a directory called ./src/misc (if one exists). To ignore a whole directory tree, use -prune rather than checking every file in the tree. Note that the pattern match test applies to the whole file name, starting from one of the start points named on the command line. It would only make sense to use an absolute path name here if the relevant start point is also an absolute path. This means that this command will never match anything: find bar -path /foo/bar/myfile -print Find compares the -path argument with the concatenation of a directory name and the base name of the file it's examining. Since the concatenation will never end with a slash, -path arguments ending in a slash will match nothing (except perhaps a start point specified on the command line). The predicate -path is also supported by HP-UX find and is part of the POSIX 2008 standard. -perm mode File's permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example `-perm g=w' will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the `/' or `-' forms, for example `-perm -g=w', which matches any file with group write permission. See the EXAMPLES section for some illustrative examples. -perm -mode All of the permission bits mode are set for the file. Symbolic modes are accepted in this form, and this is usually the way in which you would want to use them. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. -perm /mode Any of the permission bits mode are set for the file. Symbolic modes are accepted in this form. You must specify `u', `g' or `o' if you use a symbolic mode. See the EXAMPLES section for some illustrative examples. If no permission bits in mode are set, this test matches any file (the idea here is to be consistent with the behaviour of -perm -000). -perm +mode This is no longer supported (and has been deprecated since 2005). Use -perm /mode instead. -readable Matches files which are readable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -regex pattern File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named ./fubar3, you can use the regular expression `.*bar.' or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions (except that `.' matches newline), but this can be changed with the -regextype option. -samefile name File refers to the same inode as name. When -L is in effect, this can include symbolic links. -size n[cwbkMG] File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used: `b' for 512-byte blocks (this is the default if no suffix is used) `c' for bytes `w' for two-byte words `k' for kibibytes (KiB, units of 1024 bytes) `M' for mebibytes (MiB, units of 1024 * 1024 = 1048576 bytes) `G' for gibibytes (GiB, units of 1024 * 1024 * 1024 = 1073741824 bytes) The size is simply the st_size member of the struct stat populated by the lstat (or stat) system call, rounded up as shown above. In other words, it's consistent with the result you get for ls -l. Bear in mind that the `%k' and `%b' format specifiers of -printf handle sparse files differently. The `b' suffix always denotes 512-byte blocks and never 1024-byte blocks, which is different to the behaviour of -ls. The + and - prefixes signify greater than and less than, as usual; i.e., an exact size of n units does not match. Bear in mind that the size is rounded up to the next unit. Therefore -size -1M is not equivalent to -size -1048576c. The former only matches empty files, the latter matches files from 0 to 1,048,575 bytes. -true Always true. -type c File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris) To search for more than one type at once, you can supply the combined list of type letters separated by a comma `,' (GNU extension). -uid n File's numeric user ID is less than, more than or exactly n. -used n File was last accessed less than, more than or exactly n days after its status was last changed. -user uname File is owned by user uname (numeric user ID allowed). -wholename pattern See -path. This alternative is less portable than -path. -writable Matches files which are writable by the current user. This takes into account access control lists and other permissions artefacts which the -perm test ignores. This test makes use of the access(2) system call, and so can be fooled by NFS servers which do UID mapping (or root- squashing), since many systems implement access(2) in the client's kernel and so cannot make use of the UID mapping information held on the server. -xtype c The same as -type unless the file is a symbolic link. For symbolic links: if the -H or -P option was specified, true if the file is a link to a file of type c; if the -L option has been given, true if c is `l'. In other words, for symbolic links, -xtype checks the type of the file that -type does not check. -context pattern (SELinux only) Security context of the file matches glob pattern. ACTIONS -delete Delete files or directories; true if removal succeeded. If the removal failed, an error message is issued and find's exit status will be nonzero (when it eventually exits). Warning: Don't forget that find evaluates the command line as an expression, so putting -delete first will make find try to delete everything below the starting points you specified. The use of the -delete action on the command line automatically turns on the -depth option. As in turn -depth makes -prune ineffective, the -delete action cannot usefully be combined with -prune. Often, the user might want to test a find command line with -print prior to adding -delete for the actual removal run. To avoid surprising results, it is usually best to remember to use -depth explicitly during those earlier test runs. The -delete action will fail to remove a directory unless it is empty. Together with the -ignore_readdir_race option, find will ignore errors of the -delete action in the case the file has disappeared since the parent directory was read: it will not output an error diagnostic, not change the exit code to nonzero, and the return code of the -delete action will be true. -exec command ; Execute command; true if 0 status is returned. All following arguments to find are taken to be arguments to the command until an argument consisting of `;' is encountered. The string `{}' is replaced by the current file name being processed everywhere it occurs in the arguments to the command, not just in arguments where it is alone, as in some versions of find. Both of these constructions might need to be escaped (with a `\') or quoted to protect them from expansion by the shell. See the EXAMPLES section for examples of the use of the -exec option. The specified command is run once for each matched file. The command is executed in the starting directory. There are unavoidable security problems surrounding use of the -exec action; you should use the -execdir option instead. -exec command {} + This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines. Only one instance of `{}' is allowed within the command, and it must appear at the end, immediately before the `+'; it needs to be escaped (with a `\') or quoted to protect it from interpretation by the shell. The command is executed in the starting directory. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. For this reason -exec my- command ... {} + -quit may not result in my-command actually being run. This variant of -exec always returns true. -execdir command ; -execdir command {} + Like -exec, but the specified command is run from the subdirectory containing the matched file, which is not normally the directory in which you started find. As with -exec, the {} should be quoted if find is being invoked from a shell. This a much more secure method for invoking commands, as it avoids race conditions during resolution of the paths to the matched files. As with the -exec action, the `+' form of -execdir will build a command line to process more than one matched file, but any given invocation of command will only list files that exist in the same subdirectory. If you use this option, you must ensure that your PATH environment variable does not reference `.'; otherwise, an attacker can run any commands they like by leaving an appropriately-named file in a directory in which you will run -execdir. The same applies to having entries in PATH which are empty or which are not absolute directory names. If any invocation with the `+' form returns a non-zero value as exit status, then find returns a non-zero exit status. If find encounters an error, this can sometimes cause an immediate exit, so some pending commands may not be run at all. The result of the action depends on whether the + or the ; variant is being used; -execdir command {} + always returns true, while -execdir command {} ; returns true only if command returns 0. -fls file True; like -ls but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint file True; print the full file name into file file. If file does not exist when find is run, it is created; if it does exist, it is truncated. The file names /dev/stdout and /dev/stderr are handled specially; they refer to the standard output and standard error output, respectively. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprint0 file True; like -print0 but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -fprintf file format True; like -printf but write to file like -fprint. The output file is always created, even if the predicate is never matched. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ls True; list current file in ls -dils format on standard output. The block counts are of 1 KB blocks, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -ok command ; Like -exec but ask the user first. If the user agrees, run the command. Otherwise just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. The response to the prompt is matched against a pair of regular expressions to determine if it is an affirmative or negative response. This regular expression is obtained from the system if the POSIXLY_CORRECT environment variable is set, or otherwise from find's message translations. If the system has no suitable definition, find's own definition will be used. In either case, the interpretation of the regular expression itself will be affected by the environment variables LC_CTYPE (character classes) and LC_COLLATE (character ranges and equivalence classes). -okdir command ; Like -execdir but ask the user first in the same way as for -ok. If the user does not agree, just return false. If the command is run, its standard input is redirected from /dev/null. This action may not be specified together with the -files0-from option. -print True; print the full file name on the standard output, followed by a newline. If you are piping the output of find into another program and there is the faintest possibility that the files which you are searching for might contain a newline, then you should seriously consider using the -print0 option instead of -print. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -print0 True; print the full file name on the standard output, followed by a null character (instead of the newline character that -print uses). This allows file names that contain newlines or other types of white space to be correctly interpreted by programs that process the find output. This option corresponds to the -0 option of xargs. -printf format True; print format on the standard output, interpreting `\' escapes and `%' directives. Field widths and precisions can be specified as with the printf(3) C function. Please note that many of the fields are printed as %s rather than %d, and this may mean that flags don't work as you might expect. This also means that the `-' flag does work (it forces fields to be left-aligned). Unlike -print, -printf does not add a newline at the end of the string. The escapes and directives are: \a Alarm bell. \b Backspace. \c Stop printing from this format immediately and flush the output. \f Form feed. \n Newline. \r Carriage return. \t Horizontal tab. \v Vertical tab. \0 ASCII NUL. \\ A literal backslash (`\'). \NNN The character whose ASCII code is NNN (octal). A `\' character followed by any other character is treated as an ordinary character, so they both are printed. %% A literal percent sign. %a File's last access time in the format returned by the C ctime(3) function. %Ak File's last access time in the format specified by k, which is either `@' or a directive for the C strftime(3) function. The following shows an incomplete list of possible values for k. Please refer to the documentation of strftime(3) for the full list. Some of the conversion specification characters might not be available on all systems, due to differences in the implementation of the strftime(3) library function. @ seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Time fields: H hour (00..23) I hour (01..12) k hour ( 0..23) l hour ( 1..12) M minute (00..59) p locale's AM or PM r time, 12-hour (hh:mm:ss [AP]M) S Second (00.00 .. 61.00). There is a fractional part. T time, 24-hour (hh:mm:ss.xxxxxxxxxx) + Date and time, separated by `+', for example `2004-04-28+22:22:05.0'. This is a GNU extension. The time is given in the current timezone (which may be affected by setting the TZ environment variable). The seconds field includes a fractional part. X locale's time representation (H:M:S). The seconds field includes a fractional part. Z time zone (e.g., EDT), or nothing if no time zone is determinable Date fields: a locale's abbreviated weekday name (Sun..Sat) A locale's full weekday name, variable length (Sunday..Saturday) b locale's abbreviated month name (Jan..Dec) B locale's full month name, variable length (January..December) c locale's date and time (Sat Nov 04 12:02:33 EST 1989). The format is the same as for ctime(3) and so to preserve compatibility with that format, there is no fractional part in the seconds field. d day of month (01..31) D date (mm/dd/yy) F date (yyyy-mm-dd) h same as b j day of year (001..366) m month (01..12) U week number of year with Sunday as first day of week (00..53) w day of week (0..6) W week number of year with Monday as first day of week (00..53) x locale's date representation (mm/dd/yy) y last two digits of year (00..99) Y year (1970...) %b The amount of disk space used for this file in 512-byte blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/512, but it can also be smaller if the file is a sparse file. %Bk File's birth time, i.e., its creation time, in the format specified by k, which is the same as for %A. This directive produces an empty string if the underlying operating system or filesystem does not support birth times. %c File's last status change time in the format returned by the C ctime(3) function. %Ck File's last status change time in the format specified by k, which is the same as for %A. %d File's depth in the directory tree; 0 means the file is a starting-point. %D The device number on which the file exists (the st_dev field of struct stat), in decimal. %f Print the basename; the file's name with any leading directories removed (only the last element). For /, the result is `/'. See the EXAMPLES section for an example. %F Type of the filesystem the file is on; this value can be used for -fstype. %g File's group name, or numeric group ID if the group has no name. %G File's numeric group ID. %h Dirname; the Leading directories of the file's name (all but the last element). If the file name contains no slashes (since it is in the current directory) the %h specifier expands to `.'. For files which are themselves directories and contain a slash (including /), %h expands to the empty string. See the EXAMPLES section for an example. %H Starting-point under which file was found. %i File's inode number (in decimal). %k The amount of disk space used for this file in 1 KB blocks. Since disk space is allocated in multiples of the filesystem block size this is usually greater than %s/1024, but it can also be smaller if the file is a sparse file. %l Object of symbolic link (empty string if file is not a symbolic link). %m File's permission bits (in octal). This option uses the `traditional' numbers which most Unix implementations use, but if your particular implementation uses an unusual ordering of octal permissions bits, you will see a difference between the actual value of the file's mode and the output of %m. Normally you will want to have a leading zero on this number, and to do this, you should use the # flag (as in, for example, `%#m'). %M File's permissions (in symbolic form, as for ls). This directive is supported in findutils 4.2.5 and later. %n Number of hard links to file. %p File's name. %P File's name with the name of the starting-point under which it was found removed. %s File's size in bytes. %S File's sparseness. This is calculated as (BLOCKSIZE*st_blocks / st_size). The exact value you will get for an ordinary file of a certain length is system-dependent. However, normally sparse files will have values less than 1.0, and files which use indirect blocks may have a value which is greater than 1.0. In general the number of blocks used by a file is file system dependent. The value used for BLOCKSIZE is system-dependent, but is usually 512 bytes. If the file size is zero, the value printed is undefined. On systems which lack support for st_blocks, a file's sparseness is assumed to be 1.0. %t File's last modification time in the format returned by the C ctime(3) function. %Tk File's last modification time in the format specified by k, which is the same as for %A. %u File's user name, or numeric user ID if the user has no name. %U File's numeric user ID. %y File's type (like in ls -l), U=unknown type (shouldn't happen) %Y File's type (like %y), plus follow symbolic links: `L'=loop, `N'=nonexistent, `?' for any other error when determining the type of the target of a symbolic link. %Z (SELinux only) file's security context. %{ %[ %( Reserved for future use. A `%' character followed by any other character is discarded, but the other character is printed (don't rely on this, as further format characters may be introduced). A `%' at the end of the format argument causes undefined behaviour since there is no following character. In some locales, it may hide your door keys, while in others it may remove the final page from the novel you are reading. The %m and %d directives support the #, 0 and + flags, but the other directives do not, even if they print numbers. Numeric directives that do not support these flags include G, U, b, D, k and n. The `-' format flag is supported and changes the alignment of a field from right-justified (which is the default) to left-justified. See the UNUSUAL FILENAMES section for information about how unusual characters in filenames are handled. -prune True; if the file is a directory, do not descend into it. If -depth is given, then -prune has no effect. Because -delete implies -depth, you cannot usefully use -prune and -delete together. For example, to skip the directory src/emacs and all files and directories under it, and print the names of the other files found, do something like this: find . -path ./src/emacs -prune -o -print -quit Exit immediately (with return value zero if no errors have occurred). This is different to -prune because -prune only applies to the contents of pruned directories, while -quit simply makes find stop immediately. No child processes will be left running. Any command lines which have been built by -exec ... + or -execdir ... + are invoked before the program is exited. After -quit is executed, no more files specified on the command line will be processed. For example, `find /tmp/foo /tmp/bar -print -quit` will print only `/tmp/foo`. One common use of -quit is to stop searching the file system once we have found what we want. For example, if we want to find just a single file we can do this: find / -name needle -print -quit OPERATORS Listed in order of decreasing precedence: ( expr ) Force precedence. Since parentheses are special to the shell, you will normally need to quote them. Many of the examples in this manual page use backslashes for this purpose: `\(...\)' instead of `(...)'. ! expr True if expr is false. This character will also usually need protection from interpretation by the shell. -not expr Same as ! expr, but not POSIX compliant. expr1 expr2 Two expressions in a row are taken to be joined with an implied -a; expr2 is not evaluated if expr1 is false. expr1 -a expr2 Same as expr1 expr2. expr1 -and expr2 Same as expr1 expr2, but not POSIX compliant. expr1 -o expr2 Or; expr2 is not evaluated if expr1 is true. expr1 -or expr2 Same as expr1 -o expr2, but not POSIX compliant. expr1 , expr2 List; both expr1 and expr2 are always evaluated. The value of expr1 is discarded; the value of the list is the value of expr2. The comma operator can be useful for searching for several different types of thing, but traversing the filesystem hierarchy only once. The -fprintf action can be used to list the various matched items into several different output files. Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile. UNUSUAL FILENAMES top Many of the actions of find result in the printing of data which is under the control of other users. This includes file names, sizes, modification times and so forth. File names are a potential problem since they can contain any character except `\0' and `/'. Unusual characters in file names can do unexpected and often undesirable things to your terminal (for example, changing the settings of your function keys on some terminals). Unusual characters are handled differently by various actions, as described below. -print0, -fprint0 Always print the exact filename, unchanged, even if the output is going to a terminal. -ls, -fls Unusual characters are always escaped. White space, backslash, and double quote characters are printed using C-style escaping (for example `\f', `\"'). Other unusual characters are printed using an octal escape. Other printable characters (for -ls and -fls these are the characters between octal 041 and 0176) are printed as-is. -printf, -fprintf If the output is not going to a terminal, it is printed as-is. Otherwise, the result depends on which directive is in use. The directives %D, %F, %g, %G, %H, %Y, and %y expand to values which are not under control of files' owners, and so are printed as-is. The directives %a, %b, %c, %d, %i, %k, %m, %M, %n, %s, %t, %u and %U have values which are under the control of files' owners but which cannot be used to send arbitrary data to the terminal, and so these are printed as-is. The directives %f, %h, %l, %p and %P are quoted. This quoting is performed in the same way as for GNU ls. This is not the same quoting mechanism as the one used for -ls and -fls. If you are able to decide what format to use for the output of find then it is normally better to use `\0' as a terminator than to use newline, as file names can contain white space and newline characters. The setting of the LC_CTYPE environment variable is used to determine which characters need to be quoted. -print, -fprint Quoting is handled in the same way as for -printf and -fprintf. If you are using find in a script or in a situation where the matched files might have arbitrary names, you should consider using -print0 instead of -print. The -ok and -okdir actions print the current filename as-is. This may change in a future release. STANDARDS CONFORMANCE top For closest compliance to the POSIX standard, you should set the POSIXLY_CORRECT environment variable. The following options are specified in the POSIX standard (IEEE Std 1003.1-2008, 2016 Edition): -H This option is supported. -L This option is supported. -name This option is supported, but POSIX conformance depends on the POSIX conformance of the system's fnmatch(3) library function. As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) match a leading `.', because IEEE PASC interpretation 126 requires this. This is a change from previous versions of findutils. -type Supported. POSIX specifies `b', `c', `d', `l', `p', `f' and `s'. GNU find also supports `D', representing a Door, where the OS provides these. Furthermore, GNU find allows multiple types to be specified at once in a comma- separated list. -ok Supported. Interpretation of the response is according to the `yes' and `no' patterns selected by setting the LC_MESSAGES environment variable. When the POSIXLY_CORRECT environment variable is set, these patterns are taken system's definition of a positive (yes) or negative (no) response. See the system's documentation for nl_langinfo(3), in particular YESEXPR and NOEXPR. When POSIXLY_CORRECT is not set, the patterns are instead taken from find's own message catalogue. -newer Supported. If the file specified is a symbolic link, it is always dereferenced. This is a change from previous behaviour, which used to take the relevant time from the symbolic link; see the HISTORY section below. -perm Supported. If the POSIXLY_CORRECT environment variable is not set, some mode arguments (for example +a+x) which are not valid in POSIX are supported for backward- compatibility. Other primaries The primaries -atime, -ctime, -depth, -exec, -group, -links, -mtime, -nogroup, -nouser, -ok, -path, -print, -prune, -size, -user and -xdev are all supported. The POSIX standard specifies parentheses `(', `)', negation `!' and the logical AND/OR operators -a and -o. All other options, predicates, expressions and so forth are extensions beyond the POSIX standard. Many of these extensions are not unique to GNU find, however. The POSIX standard requires that find detects loops: The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of the last file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shall either recover its position in the hierarchy or terminate. GNU find complies with these requirements. The link count of directories which contain entries which are hard links to an ancestor will often be lower than they otherwise should be. This can mean that GNU find will sometimes optimise away the visiting of a subdirectory which is actually a link to an ancestor. Since find does not actually enter such a subdirectory, it is allowed to avoid emitting a diagnostic message. Although this behaviour may be somewhat confusing, it is unlikely that anybody actually depends on this behaviour. If the leaf optimisation has been turned off with -noleaf, the directory entry will always be examined and the diagnostic message will be issued where it is appropriate. Symbolic links cannot be used to create filesystem cycles as such, but if the -L option or the -follow option is in use, a diagnostic message is issued when find encounters a loop of symbolic links. As with loops containing hard links, the leaf optimisation will often mean that find knows that it doesn't need to call stat() or chdir() on the symbolic link, so this diagnostic is frequently not necessary. The -d option is supported for compatibility with various BSD systems, but you should use the POSIX-compliant option -depth instead. The POSIXLY_CORRECT environment variable does not affect the behaviour of the -regex or -iregex tests because those tests aren't specified in the POSIX standard. ENVIRONMENT VARIABLES top LANG Provides a default value for the internationalization variables that are unset or null. LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables. LC_COLLATE The POSIX standard specifies that this variable affects the pattern matching to be used for the -name option. GNU find uses the fnmatch(3) library function, and so support for LC_COLLATE depends on the system library. This variable also affects the interpretation of the response to -ok; while the LC_MESSAGES variable selects the actual pattern used to interpret the response to -ok, the interpretation of any bracket expressions in the pattern will be affected by LC_COLLATE. LC_CTYPE This variable affects the treatment of character classes used in regular expressions and also with the -name test, if the system's fnmatch(3) library function supports this. This variable also affects the interpretation of any character classes in the regular expressions used to interpret the response to the prompt issued by -ok. The LC_CTYPE environment variable will also affect which characters are considered to be unprintable when filenames are printed; see the section UNUSUAL FILENAMES. LC_MESSAGES Determines the locale to be used for internationalised messages. If the POSIXLY_CORRECT environment variable is set, this also determines the interpretation of the response to the prompt made by the -ok action. NLSPATH Determines the location of the internationalisation message catalogues. PATH Affects the directories which are searched to find the executables invoked by -exec, -execdir, -ok and -okdir. POSIXLY_CORRECT Determines the block size used by -ls and -fls. If POSIXLY_CORRECT is set, blocks are units of 512 bytes. Otherwise they are units of 1024 bytes. Setting this variable also turns off warning messages (that is, implies -nowarn) by default, because POSIX requires that apart from the output for -ok, all messages printed on stderr are diagnostics and must result in a non-zero exit status. When POSIXLY_CORRECT is not set, -perm +zzz is treated just like -perm /zzz if +zzz is not a valid symbolic mode. When POSIXLY_CORRECT is set, such constructs are treated as an error. When POSIXLY_CORRECT is set, the response to the prompt made by the -ok action is interpreted according to the system's message catalogue, as opposed to according to find's own message translations. TZ Affects the time zone used for some of the time-related format directives of -printf and -fprintf. EXAMPLES top Simple `find|xargs` approach Find files named core in or below the directory /tmp and delete them. $ find /tmp -name core -type f -print | xargs /bin/rm -f Note that this will work incorrectly if there are any filenames containing newlines, single or double quotes, or spaces. Safer `find -print0 | xargs -0` approach Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing single or double quotes, spaces or newlines are correctly handled. $ find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f The -name test comes before the -type test in order to avoid having to call stat(2) on every file. Note that there is still a race between the time find traverses the hierarchy printing the matching filenames, and the time the process executed by xargs works with that file. Processing arbitrary starting points Given that another program proggy pre-filters and creates a huge NUL-separated list of files, process those as starting points, and find all regular, empty files among them: $ proggy | find -files0-from - -maxdepth 0 -type f -empty The use of `-files0-from -` means to read the names of the starting points from standard input, i.e., from the pipe; and -maxdepth 0 ensures that only explicitly those entries are examined without recursing into directories (in the case one of the starting points is one). Executing a command for each file Run file on every file in or below the current directory. $ find . -type f -exec file '{}' \; Notice that the braces are enclosed in single quote marks to protect them from interpretation as shell script punctuation. The semicolon is similarly protected by the use of a backslash, though single quotes could have been used in that case also. In many cases, one might prefer the `-exec ... +` or better the `-execdir ... +` syntax for performance and security reasons. Traversing the filesystem just once - for 2 different actions Traverse the filesystem just once, listing set-user-ID files and directories into /root/suid.txt and large files into /root/big.txt. $ find / \ \( -perm -4000 -fprintf /root/suid.txt '%#m %u %p\n' \) , \ \( -size +100M -fprintf /root/big.txt '%-10s %p\n' \) This example uses the line-continuation character '\' on the first two lines to instruct the shell to continue reading the command on the next line. Searching files by age Search for files in your home directory which have been modified in the last twenty-four hours. $ find $HOME -mtime 0 This command works this way because the time since each file was last modified is divided by 24 hours and any remainder is discarded. That means that to match -mtime 0, a file will have to have a modification in the past which is less than 24 hours ago. Searching files by permissions Search for files which are executable but not readable. $ find /sbin /usr/sbin -executable \! -readable -print Search for files which have read and write permission for their owner, and group, but which other users can read but not write to. $ find . -perm 664 Files which meet these criteria but have other permissions bits set (for example if someone can execute the file) will not be matched. Search for files which have read and write permission for their owner and group, and which other users can read, without regard to the presence of any extra permission bits (for example the executable bit). $ find . -perm -664 This will match a file which has mode 0777, for example. Search for files which are writable by somebody (their owner, or their group, or anybody else). $ find . -perm /222 Search for files which are writable by either their owner or their group. $ find . -perm /220 $ find . -perm /u+w,g+w $ find . -perm /u=w,g=w All three of these commands do the same thing, but the first one uses the octal representation of the file mode, and the other two use the symbolic form. The files don't have to be writable by both the owner and group to be matched; either will do. Search for files which are writable by both their owner and their group. $ find . -perm -220 $ find . -perm -g+w,u+w Both these commands do the same thing. A more elaborate search on permissions. $ find . -perm -444 -perm /222 \! -perm /111 $ find . -perm -a+r -perm /a+w \! -perm /a+x These two commands both search for files that are readable for everybody (-perm -444 or -perm -a+r), have at least one write bit set (-perm /222 or -perm /a+w) but are not executable for anybody (! -perm /111 or ! -perm /a+x respectively). Pruning - omitting files and subdirectories Copy the contents of /source-dir to /dest-dir, but omit files and directories named .snapshot (and anything in them). It also omits files or directories whose name ends in `~', but not their contents. $ cd /source-dir $ find . -name .snapshot -prune -o \( \! -name '*~' -print0 \) \ | cpio -pmd0 /dest-dir The construct -prune -o \( ... -print0 \) is quite common. The idea here is that the expression before -prune matches things which are to be pruned. However, the -prune action itself returns true, so the following -o ensures that the right hand side is evaluated only for those directories which didn't get pruned (the contents of the pruned directories are not even visited, so their contents are irrelevant). The expression on the right hand side of the -o is in parentheses only for clarity. It emphasises that the -print0 action takes place only for things that didn't have -prune applied to them. Because the default `and' condition between tests binds more tightly than -o, this is the default anyway, but the parentheses help to show what is going on. Given the following directory of projects and their associated SCM administrative directories, perform an efficient search for the projects' roots: $ find repo/ \ \( -exec test -d '{}/.svn' \; \ -or -exec test -d '{}/.git' \; \ -or -exec test -d '{}/CVS' \; \ \) -print -prune Sample output: repo/project1/CVS repo/gnu/project2/.svn repo/gnu/project3/.svn repo/gnu/project3/src/.svn repo/project4/.git In this example, -prune prevents unnecessary descent into directories that have already been discovered (for example we do not search project3/src because we already found project3/.svn), but ensures sibling directories (project2 and project3) are found. Other useful examples Search for several file types. $ find /tmp -type f,d,l Search for files, directories, and symbolic links in the directory /tmp passing these types as a comma-separated list (GNU extension), which is otherwise equivalent to the longer, yet more portable: $ find /tmp \( -type f -o -type d -o -type l \) Search for files with the particular name needle and stop immediately when we find the first one. $ find / -name needle -print -quit Demonstrate the interpretation of the %f and %h format directives of the -printf action for some corner-cases. Here is an example including some output. $ find . .. / /tmp /tmp/TRACE compile compile/64/tests/find -maxdepth 0 -printf '[%h][%f]\n' [.][.] [.][..] [][/] [][tmp] [/tmp][TRACE] [.][compile] [compile/64/tests][find] EXIT STATUS top find exits with status 0 if all files are processed successfully, greater than 0 if errors occur. This is deliberately a very broad description, but if the return value is non-zero, you should not rely on the correctness of the results of find. When some error occurs, find may stop immediately, without completing all the actions specified. For example, some starting points may not have been examined or some pending program invocations for -exec ... {} + or -execdir ... {} + may not have been performed. HISTORY top A find program appeared in Version 5 Unix as part of the Programmer's Workbench project and was written by Dick Haight. Doug McIlroy's A Research UNIX Reader: Annotated Excerpts from the Programmers Manual, 1971-1986 provides some additional details; you can read it on-line at <https://www.cs.dartmouth.edu/~doug/reader.pdf>. GNU find was originally written by Eric Decker, with enhancements by David MacKenzie, Jay Plett, and Tim Wood. The idea for find -print0 and xargs -0 came from Dan Bernstein. COMPATIBILITY top As of findutils-4.2.2, shell metacharacters (`*', `?' or `[]' for example) used in filename patterns match a leading `.', because IEEE POSIX interpretation 126 requires this. As of findutils-4.3.3, -perm /000 now matches all files instead of none. Nanosecond-resolution timestamps were implemented in findutils-4.3.3. As of findutils-4.3.11, the -delete action sets find's exit status to a nonzero value when it fails. However, find will not exit immediately. Previously, find's exit status was unaffected by the failure of -delete. Feature Added in Also occurs in -files0-from 4.9.0 -newerXY 4.3.3 BSD -D 4.3.1 -O 4.3.1 -readable 4.3.0 -writable 4.3.0 -executable 4.3.0 -regextype 4.2.24 -exec ... + 4.2.12 POSIX -execdir 4.2.12 BSD -okdir 4.2.12 -samefile 4.2.11 -H 4.2.5 POSIX -L 4.2.5 POSIX -P 4.2.5 BSD -delete 4.2.3 -quit 4.2.3 -d 4.2.3 BSD -wholename 4.2.0 -iwholename 4.2.0 -ignore_readdir_race 4.2.0 -fls 4.0 -ilname 3.8 -iname 3.8 -ipath 3.8 -iregex 3.8 The syntax -perm +MODE was removed in findutils-4.5.12, in favour of -perm /MODE. The +MODE syntax had been deprecated since findutils-4.2.21 which was released in 2005. NON-BUGS top Operator precedence surprises The command find . -name afile -o -name bfile -print will never print afile because this is actually equivalent to find . -name afile -o \( -name bfile -a -print \). Remember that the precedence of -a is higher than that of -o and when there is no operator specified between tests, -a is assumed. paths must precede expression error message $ find . -name *.c -print find: paths must precede expression find: possible unquoted pattern after predicate `-name'? This happens when the shell could expand the pattern *.c to more than one file name existing in the current directory, and passing the resulting file names in the command line to find like this: find . -name frcode.c locate.c word_io.c -print That command is of course not going to work, because the -name predicate allows exactly only one pattern as argument. Instead of doing things this way, you should enclose the pattern in quotes or escape the wildcard, thus allowing find to use the pattern with the wildcard during the search for file name matching instead of file names expanded by the parent shell: $ find . -name '*.c' -print $ find . -name \*.c -print BUGS top There are security problems inherent in the behaviour that the POSIX standard specifies for find, which therefore cannot be fixed. For example, the -exec action is inherently insecure, and -execdir should be used instead. The environment variable LC_COLLATE has no effect on the -ok action. REPORTING BUGS top GNU findutils online help: <https://www.gnu.org/software/findutils/#get-help> Report any translation bugs to <https://translationproject.org/team/> Report any other issue via the form at the GNU Savannah bug tracker: <https://savannah.gnu.org/bugs/?group=findutils> General topics about the GNU findutils package are discussed at the bug-findutils mailing list: <https://lists.gnu.org/mailman/listinfo/bug-findutils> COPYRIGHT top Copyright 1990-2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top chmod(1), locate(1), ls(1), updatedb(1), xargs(1), lstat(2), stat(2), ctime(3) fnmatch(3), printf(3), strftime(3), locatedb(5), regex(7) Full documentation <https://www.gnu.org/software/findutils/find> or available locally via: info find COLOPHON top This page is part of the findutils (find utilities) project. Information about the project can be found at http://www.gnu.org/software/findutils/. If you have a bug report for this manual page, see https://savannah.gnu.org/bugs/?group=findutils. This page was obtained from the project's upstream Git repository git://git.savannah.gnu.org/findutils.git on 2023-12-22. (At that time, the date of the most recent commit that was found in the repository was 2023-11-11.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org FIND(1) Pages that refer to this page: dpkg(1), dpkg-name(1), find-filter(1), grep(1), ippfind(1), locate(1), mkaf(1), pmlogger_daily(1), tar(1), updatedb(1), xargs(1), fts(3), proc(5), hier(7), symlink(7) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. ln(1) - Linux manual page man7.org > Linux > man-pages Linux/UNIX system programming training ln(1) Linux manual page NAME | SYNOPSIS | DESCRIPTION | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON LN(1) User Commands LN(1) NAME top ln - make links between files SYNOPSIS top ln [OPTION]... [-T] TARGET LINK_NAME ln [OPTION]... TARGET ln [OPTION]... TARGET... DIRECTORY ln [OPTION]... -t DIRECTORY TARGET... DESCRIPTION top In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY. Create hard links by default, symbolic links with --symbolic. By default, each destination (name of new link) should not already exist. When creating hard links, each TARGET must exist. Symbolic links can hold arbitrary text; if later resolved, a relative link is interpreted in relation to its parent directory. Mandatory arguments to long options are mandatory for short options too. --backup[=CONTROL] make a backup of each existing destination file -b like --backup but does not accept an argument -d, -F, --directory allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser) -f, --force remove existing destination files -i, --interactive prompt whether to remove destinations -L, --logical dereference TARGETs that are symbolic links -n, --no-dereference treat LINK_NAME as a normal file if it is a symbolic link to a directory -P, --physical make hard links directly to symbolic links -r, --relative with -s, create links relative to link location -s, --symbolic make symbolic links instead of hard links -S, --suffix=SUFFIX override the usual backup suffix -t, --target-directory=DIRECTORY specify the DIRECTORY in which to create the links -T, --no-target-directory treat LINK_NAME as a normal file always -v, --verbose print name of each linked file --help display this help and exit --version output version information and exit The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX. The version control method may be selected via the --backup option or through the VERSION_CONTROL environment variable. Here are the values: none, off never make backups (even if --backup is given) numbered, t make numbered backups existing, nil numbered if numbered backups exist, simple otherwise simple, never always make simple backups Using -s ignores -L and -P. Otherwise, the last option specified controls behavior when a TARGET is a symbolic link, defaulting to -P. AUTHOR top Written by Mike Parker and David MacKenzie. REPORTING BUGS top GNU coreutils online help: <https://www.gnu.org/software/coreutils/> Report any translation bugs to <https://translationproject.org/team/> COPYRIGHT top Copyright 2023 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO top link(2), symlink(2) Full documentation <https://www.gnu.org/software/coreutils/ln> or available locally via: info '(coreutils) ln invocation' COLOPHON top This page is part of the coreutils (basic file, shell and text manipulation utilities) project. Information about the project can be found at http://www.gnu.org/software/coreutils/. If you have a bug report for this manual page, see http://www.gnu.org/software/coreutils/. This page was obtained from the tarball coreutils-9.4.tar.xz fetched from http://ftp.gnu.org/gnu/coreutils/ on 2023-12-22. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to man-pages@man7.org GNU coreutils 9.4 August 2023 LN(1) Pages that refer to this page: dh_link(1), pmlogmv(1), update-alternatives(1), link(2), symlink(2), hier(7), symlink(7), sln(8) HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. Task: Create symlinks to all /home/folder1/*.txt files and 'folder2_' directory with the same name in a target directory named '+' Bash Command:<START>find /home/folder1/*.txt -type f -exec ln -s {} "folder2_" + \;<END> |