neulab/tldr huggingface dataset:
-r      Reload a persistent child process.  As with the standard mode of operation, a utility which terminates is not executed again until a file system or keyboard event is processed.  SIGTERM is used to terminate the utility before it is restarted.  A process group is created to prevent shell scripts from masking signals.  entr waits for the utility to exit to ensure that resources such as sockets have been closed.  Control of the TTY is not transferred to the child process.
-s      Evaluate the first argument using the interpreter specified by the SHELL environment variable.  If standard output is a TTY, the name of the shell and exit code is printed after each invocation.
-z      Exit after the utility completes.  When combined with -r the utility will be restarted again only in response to commands or file system events.
The first argument named /_ is replaced with the absolute path of the first file to trigger an event.  The first file under watch is used as the default.  If the -s option is used, the name of the first file to trigger an event can be read from $0.
entr listens for keyboard input and responds to the following commands:
⟨space⟩  Execute the utility immediately.  If the -r option is set this will terminate and restart the child process as if a file change event had occurred.
q        Quit; equivalent pressing ⟨control-C⟩.
PAGER         Set to /bin/cat by default to prevent interactive utilities from waiting for keyboard input if output does not fit on the screen.
SHELL         Specify the shell to use with the -s flag.  The default is /bin/sh.
EV_TRACE      Print file system event messages.
If the -z flag is set and the utility is successfully executed, the status of the child process is returned.  Otherwise entr normally returns one of the following values:
0       Normal termination after receiving SIGINT 1       No regular files were provided as input or an error occurred 2       A file was added to a directory and the directory watch option was specified
Rebuild a project if source files change, limiting output to the first 20 lines:
$ find src/ | entr -s 'make | sed 20q'
Launch and auto-reload a node.js server:
$ ls *.js | entr -r node app.js
Clear the screen and run a query after the SQL script is updated:
$ echo my.sql | entr -cp psql -f /_
Rebuild project if a source file is modified or added to the src/ directory:
$ while sleep 0.1; do ls src/*.rb | entr -d make; done
Auto-reload a web server, or terminate if the server exits
$ ls * | entr -rz ./httpd
VIPW(8)                       System Administration                      VIPW(8)
vipw, vigr - edit the password or group file
vipw [options]
vigr [options]
vipw edits the password file after setting the appropriate locks, and does any necessary processing after the password file is unlocked. If the password file is already locked for editing by another user, vipw will ask you to try again later. The default editor for vipw and vigr is vi(1). vigr edits the group file in the same manner as vipw does the passwd file.
If the following environment variable exists, it will be utilized by vipw and vigr:
EDITOR The editor specified by the string EDITOR will be invoked instead of the default editor vi(1).
The vipw command appeared in 4.0BSD. The vigr command appeared in Util-Linux 2.6.
vi(1), passwd(1), flock(2), passwd(5)
The vigr and vipw commands are part of the util-linux package and are available from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>
pmount(1)                    General Commands Manual                   pmount(1)
pmount - mount arbitrary hotpluggable devices as normal user
pmount [ options ] device
pmount [ options ] device label
pmount --lock [ options ] device pid
pmount --unlock [ options ] device pid
pmount
pmount ("policy mount") is a wrapper around the standard mount program which permits normal users to mount removable devices without a matching /etc/fstab entry.
pmount also supports encrypted devices which use dm-crypt and have LUKS metadata. If a LUKS-capable cryptsetup is installed, pmount will use it to decrypt the device first and mount the mapped unencrypted device instead.
pmount is invoked like this:
pmount device [ label ]
This will mount device to a directory below /media if policy is met (see below). If label is given, the mount point will be /media/label, otherwise it will be /media/device.
The device will be mounted with the following flags: async,atime,nodev,noexec,noauto,nosuid,user,rw
Some applications like CD burners modify a raw device which must not be mounted while the burning process is in progress. To prevent automatic mounting, pmount offers a locking mechanism: pmount --lock device pid will prevent the pmounting of device until it is unlocked again using pmount --unlock device pid. The process id pid assigns the lock to a particular process; this allows to lock a device by several processes.
During mount, the list of locks is cleaned, i. e. all locks whose associated process does not exist any more are removed. This prevents forgotten indefinite locks from crashed programs.
Running pmount without arguments prints the list of mounted removable devices, a bit in the fashion of mount (1).
Please note that you can use labels and uuids as described in fstab (5) for devices present in /etc/fstab.  In this case, the device name need to match exactly the corresponding entry in /etc/fstab, including the LABEL= or UUID= part.
The mount will succeed if all of the following conditions are met:
• device is a block device in /dev/
• device is not in /etc/fstab (if it is, pmount executes  mount device as the calling user to handle this transparently). See below for more details.
• device is not already mounted according to /etc/mtab and /proc/mounts
• if the mount point already exists, there is no device already mounted at it and the directory is empty
• device is removable (USB, FireWire, or MMC device, or /sys/block/drive/removable is 1) or whitelisted in /etc/pmount.allow.
• device is not locked
-r, --read-only Force the device to be mounted read only. If neither -r nor -w is specified, the kernel will choose an appropriate default.
-w, --read-write Force the device to be mounted read/write. If neither -r nor -w is specified, the kernel will choose an appropriate default.
-s, --sync Mount the device with the sync option, i. e. without write caching. Default is async (write-back). With this option, write operations are much slower and due to the massive increase of updates of inode/FAT structures, flash devices may suffer heavily if you write large files. This option is intended to make it safe to just rip out USB drives without proper unmounting.
-A, --noatime Mount the device with the noatime option. Default is atime.
-e, --exec Mount the device with the exec option. Default is noexec.
-t filesystem, --type filesystem Mount as specified file system type. The file system type is automatically determined if this option is not given. See at the bottom for a list of currently supported filesystems.
-c charset, --charset charset Use given I/O character set (default: utf8 if called in an UTF-8 locale, otherwise mount default). This corresponds with the mount option iocharset (or nls for NTFS). This option is ignored for file systems that do not support setting the character set (see mount (8) for details).  Important note: pmount will now mount VFAT filesystems with iocharset=iso8859-1 as iocharset=utf8 currently makes the filesystem case-sensitive (which is pretty bad...).
-u umask, --umask umask Use specified umask instead of the default one. For UDF, the default is '000', for VFAT and NTFS the default is '077'. This value is ignored for file systems which do not support setting an umask. Note that you can use a value of 077 to forbid anyone else to read/write the files, 027 to allow your group to read the files and 022 to allow anyone to read the files (but only you can write).
--dmask dmask
--fmask fmask Some filesystems (essentially VFAT and HFS) supports separate umasks (see the -u option just above) for directories and files, to avoid the annoying effect of having all files executable. For these filesystems, you can specify separately the masks using these options. By default, fmask is umask without all executable permissions and dmask is umask.  Most of the times, these settings should just do what you want, so there should be seldom any need for using directly the --fmask and --dmask options.
-p file --passphrase file If the device is encrypted (dm-crypt with LUKS metadata), read the passphrase from specified file instead of prompting at the terminal.
-h, --help Print a help message and exit successfully.
-d, --debug Enable verbose debug messages.
-V, --version Print the current version number and exit successfully.
/etc/pmount.allow List of devices (one device per line) which are additionally permitted for pmounting. Globs, such as /dev/sda[123] are permitted. See see glob (7) for a more complete syntax.
pumount(1), mount(8)
For now, pmount supports the following filesystems: udf, iso9660, vfat, ntfs, hfsplus, hfs, ext3, ext2, ext4, reiserfs, reiser4, xfs, jfs and omfs.  They are tried sequentially in that exact order when the filesystem is not specified.
Additionally, pmount supports the filesystem types ntfs-fuse and ntfs-3g to mount NTFS volumes respectively with ntfsmount (1) or ntfs-3g (1). If the file /sbin/mount.ntfs-3g is found, then pmount will mount NTFS filestystems with type ntfs-3g rather than plain ntfs.  To disable this behavior, just specify -t ntfs on the command-line, as this happens only for autodetection.
pmount now fully resolve all symlinks both in its input and in the /etc/fstab file, which means that if /dev/cdrom is a symlink to /dev/hdc and you try to mount /dev/hdc directly, pmount will delegate this to mount(1).  This is a feature, and it contrasts with previous unclear behavior of pmount about symlinks in /etc/fstab.
Though we believe pmount is pretty much free from security problems, there are quite a few glitches that probably will never be fixed.
• pmount needs to try several different times to mount to get the filesystem right in the end; it is vital that pmount does know which precise filesystem to mount in order to give it the right options not to cause security holes. This is rather different from the behaviour of mount with the -t auto options, which can have a look at the device it is trying to mount and find out what its filesystem is.  pmount will never try to open a device and look at it to find out which filesystem it is, as it might open quite a few security holes.  Moreover, the order in which the filesystems are tried are what we could call the most commonly used filesystems on removable media. This order is unlikely to change as well. In particular, that means that when you mount an ext3 filesystem using pmount, you might get a lot of fs-related kernel error messages. Sorry !
NOTE: Starting from version 0.9.17, pmount uses the same mechanism as mount (1) to autodetect the filesystem type, so this kind of problems should not happen anymore.
pmount was originally developed by Martin Pitt <martin.pitt@canonical.com>.  It is now maintained by Vincent Fourmond <fourmond@debian.org>.
CSPLIT(1)                         User Commands                        CSPLIT(1)
csplit - split a file into sections determined by context lines
csplit [OPTION]... FILE PATTERN...
Output pieces of FILE separated by PATTERN(s) to files 'xx00', 'xx01', ..., and output byte counts of each piece to standard output.
Read standard input if FILE is -
-b, --suffix-format=FORMAT use sprintf FORMAT instead of %02d
-f, --prefix=PREFIX use PREFIX instead of 'xx'
-k, --keep-files do not remove output files on errors
--suppress-matched suppress the lines matching PATTERN
-n, --digits=DIGITS use specified number of digits instead of 2
-s, --quiet, --silent do not print counts of output file sizes
-z, --elide-empty-files remove empty output files
Each PATTERN may be: INTEGER copy up to but not including specified line number
/REGEXP/[OFFSET] copy up to but not including a matching line
%REGEXP%[OFFSET] skip to, but not including a matching line
{INTEGER} repeat the previous pattern specified number of times
{*}    repeat the previous pattern as many times as possible
A line OFFSET is a required '+' or '-' followed by a positive integer.
Written by Stuart Kemp and David MacKenzie.
Full documentation <https://www.gnu.org/software/coreutils/csplit> or available locally via: info '(coreutils) csplit invocation'
GCLOUD(1)                    General Commands Manual                   GCLOUD(1)
gcloud - manage Google Cloud Platform resources and developer workflow
gcloud GROUP | COMMAND [--account ACCOUNT] [--format FORMAT] [--help] [--project PROJECT_ID] [--quiet, -q] [--verbosity VERBOSITY] [-h] [-v, --version] [--log-http] [--trace-token TRACE_TOKEN] [--user-output-enabled]
The gcloud CLI manages authentication, local configuration, developer workflow, and interactions with the Google Cloud Platform APIs.
--account ACCOUNT Google Cloud Platform user account to use for invocation.
--format FORMAT Sets the format for printing command output resources. The default is a command-specific human-friendly output format. The supported formats are: csv, default, flattened, json, list, multi, none, table, text, value, yaml. For more details run $ gcloud topic formats.
--help Display detailed help.
--project PROJECT_ID The Google Cloud Platform project name to use for this invocation. If omitted then the current project is assumed.
--quiet, -q Disable all interactive prompts when running gcloud commands. If input is required, defaults will be used, or an error will be raised.
--verbosity VERBOSITY Override the default verbosity for this command. This must be a standard logging verbosity level: [debug, info, warning, error, critical, none] (Default: [warning]).
-h Print a summary help and exit.
-v, --version Print version information and exit. This flag is only available at the global level.
--log-http Log all HTTP server requests and responses to stderr. Overrides the default log_http property value for this command invocation. Use --no-log-http to disable.
--trace-token TRACE_TOKEN Token used to route traces of service requests for investigation of issues.
--user-output-enabled Print user intended output to the console. Overrides the default user_output_enabled property value for this command invocation. Use --no-user-output-enabled to disable.
GROUP is one of the following:
auth Manage oauth2 credentials for the Google Cloud SDK.
components List, install, update, or remove Google Cloud SDK components.
compute Read and manipulate Google Compute Engine resources.
config View and edit Google Cloud SDK properties.
container Deploy and manage clusters of machines for running containers.
deployment-manager Manage deployments of cloud resources.
dns Manage your Cloud DNS managed-zones and record-sets.
preview Manage Preview CLI command groups.
projects Manage your Projects.
source Cloud git repository commands.
sql Manage Cloud SQL databases.
topic gcloud supplementary help.
COMMAND is one of the following:
docker Provides the docker CLI access to the Google Container Registry.
feedback Provide feedback to the Google Cloud SDK team.
help Prints detailed help messages for the specified commands.
info Display information about the current gcloud environment.
init Initialize or reinitialize gcloud.
version Print version information for Cloud SDK components.
XSV(1)                       General Commands Manual                      XSV(1)
xsv - viewer for displaying captured streams real-time under X
xsv [options] parameter-file
Vstream is a collection of utilities for capturing reasonably high quality video from a v4l device (specifically configured for bttv).  A simultaneous audio track is also captured.
This utility - xsv - is a a viewer for displaying captured streams real- time under X windows.
xsv [-double] [-raw] <audio stream> <video stream 1> [<video stream 2> ...]
-double display images twice normal size.
-raw   The audio stream is "raw" ie. processed by "audioconv"/"audioclip" to remove frame marks. Remaining parameters the same as "stream".
Sometimes this bombs out the first time - just run it again - it (almost) always runs the second time! (see BUGS in the README file)
audioclip(1), audioconv(1), str2ppm(1), stream(1), ppm2str(1), xfv(1).
This manual page was written by Lenart Janos <ocsi@debian.org>, for the Debian GNU system (but may be used by others).
GIT-REV-LIST(1)                    Git Manual                    GIT-REV-LIST(1)
git-rev-list - Lists commit objects in reverse chronological order
git rev-list [<options>] <commit>... [[--] <path>...]
List commits that are reachable by following the parent links from the given commit(s), but exclude commits that are reachable from the one(s) given with a ^ in front of them. The output is given in reverse chronological order by default.
You can think of this as a set operation. Commits reachable from any of the commits given on the command line form a set, and then commits reachable from any of the ones given with ^ in front are subtracted from that set. The remaining commits are what comes out in the command’s output. Various other options and paths parameters can be used to further limit the result.
Thus, the following command:
$ git rev-list foo bar ^baz
means "list all the commits which are reachable from foo or bar, but not from baz".
A special notation "<commit1>..<commit2>" can be used as a short-hand for "^<commit1> <commit2>". For example, either of the following may be used interchangeably:
$ git rev-list origin..HEAD $ git rev-list HEAD ^origin
Another special notation is "<commit1>...<commit2>" which is useful for merges. The resulting set of commits is the symmetric difference between the two operands. The following two commands are equivalent:
$ git rev-list A B --not $(git merge-base --all A B) $ git rev-list A...B
rev-list is a very essential Git command, since it provides the ability to build and traverse commit ancestry graphs. For this reason, it has a lot of different options that enables it to be used by commands as different as git bisect and git repack.
Commit Limiting Besides specifying a range of commits that should be listed using the special notations explained in the description, additional commit limiting may be applied.
Using more options generally further limits the output (e.g. --since=<date1> limits to commits newer than <date1>, and using it with --grep=<pattern> further limits to commits whose log message has a line that matches <pattern>), unless otherwise noted.
Note that these are applied before commit ordering and formatting options, such as --reverse.
-<number>, -n <number>, --max-count=<number> Limit the number of commits to output.
--skip=<number> Skip number commits before starting to show the commit output.
--since=<date>, --after=<date> Show commits more recent than a specific date.
--until=<date>, --before=<date> Show commits older than a specific date.
--max-age=<timestamp>, --min-age=<timestamp> Limit the commits output to specified time range.
--author=<pattern>, --committer=<pattern> Limit the commits output to ones with author/committer header lines that match the specified pattern (regular expression). With more than one --author=<pattern>, commits whose author matches any of the given patterns are chosen (similarly for multiple --committer=<pattern>).
--grep-reflog=<pattern> Limit the commits output to ones with reflog entries that match the specified pattern (regular expression). With more than one --grep-reflog, commits whose reflog message matches any of the given patterns are chosen. It is an error to use this option unless --walk-reflogs is in use.
--grep=<pattern> Limit the commits output to ones with log message that matches the specified pattern (regular expression). With more than one --grep=<pattern>, commits whose message matches any of the given patterns are chosen (but see --all-match).
--all-match Limit the commits output to ones that match all given --grep, instead of ones that match at least one.
--invert-grep Limit the commits output to ones with log message that do not match the pattern specified with --grep=<pattern>.
-i, --regexp-ignore-case Match the regular expression limiting patterns without regard to letter case.
--basic-regexp Consider the limiting patterns to be basic regular expressions; this is the default.
-E, --extended-regexp Consider the limiting patterns to be extended regular expressions instead of the default basic regular expressions.
-F, --fixed-strings Consider the limiting patterns to be fixed strings (don’t interpret pattern as a regular expression).
-P, --perl-regexp Consider the limiting patterns to be Perl-compatible regular expressions.
Support for these types of regular expressions is an optional compile-time dependency. If Git wasn’t compiled with support for them providing this option will cause it to die.
--remove-empty Stop when a given path disappears from the tree.
--merges Print only merge commits. This is exactly the same as --min-parents=2.
--no-merges Do not print commits with more than one parent. This is exactly the same as --max-parents=1.
--min-parents=<number>, --max-parents=<number>, --no-min-parents, --no-max-parents Show only commits which have at least (or at most) that many parent commits. In particular, --max-parents=1 is the same as --no-merges, --min-parents=2 is the same as --merges.  --max-parents=0 gives all root commits and --min-parents=3 all octopus merges.
--no-min-parents and --no-max-parents reset these limits (to no limit) again. Equivalent forms are --min-parents=0 (any commit has 0 or more parents) and --max-parents=-1 (negative numbers denote no upper limit).
--first-parent Follow only the first parent commit upon seeing a merge commit. This option can give a better overview when viewing the evolution of a particular topic branch, because merges into a topic branch tend to be only about adjusting to updated upstream from time to time, and this option allows you to ignore the individual commits brought in to your history by such a merge.
--not Reverses the meaning of the ^ prefix (or lack thereof) for all following revision specifiers, up to the next --not.
--all Pretend as if all the refs in refs/, along with HEAD, are listed on the command line as <commit>.
--branches[=<pattern>] Pretend as if all the refs in refs/heads are listed on the command line as <commit>. If <pattern> is given, limit branches to ones matching given shell glob. If pattern lacks ?, *, or [, /* at the end is implied.
--tags[=<pattern>] Pretend as if all the refs in refs/tags are listed on the command line as <commit>. If <pattern> is given, limit tags to ones matching given shell glob. If pattern lacks ?, *, or [, /* at the end is implied.
--remotes[=<pattern>] Pretend as if all the refs in refs/remotes are listed on the command line as <commit>. If <pattern> is given, limit remote-tracking branches to ones matching given shell glob. If pattern lacks ?, *, or [, /* at the end is implied.
--glob=<glob-pattern> Pretend as if all the refs matching shell glob <glob-pattern> are listed on the command line as <commit>. Leading refs/, is automatically prepended if missing. If pattern lacks ?, *, or [, /* at the end is implied.
--exclude=<glob-pattern> Do not include refs matching <glob-pattern> that the next --all, --branches, --tags, --remotes, or --glob would otherwise consider. Repetitions of this option accumulate exclusion patterns up to the next --all, --branches, --tags, --remotes, or --glob option (other options or arguments do not clear accumulated patterns).
The patterns given should not begin with refs/heads, refs/tags, or refs/remotes when applied to --branches, --tags, or --remotes, respectively, and they must begin with refs/ when applied to --glob or --all. If a trailing /* is intended, it must be given explicitly.
--reflog Pretend as if all objects mentioned by reflogs are listed on the command line as <commit>.
--alternate-refs Pretend as if all objects mentioned as ref tips of alternate repositories were listed on the command line. An alternate repository is any repository whose object directory is specified in objects/info/alternates. The set of included objects may be modified by core.alternateRefsCommand, etc. See git-config(1).
--single-worktree By default, all working trees will be examined by the following options when there are more than one (see git-worktree(1)): --all, --reflog and --indexed-objects. This option forces them to examine the current working tree only.
--ignore-missing Upon seeing an invalid object name in the input, pretend as if the bad input was not given.
--stdin In addition to the <commit> listed on the command line, read them from the standard input. If a -- separator is seen, stop reading commits and start reading paths to limit the result.
--quiet Don’t print anything to standard output. This form is primarily meant to allow the caller to test the exit status to see if a range of objects is fully connected (or not). It is faster than redirecting stdout to /dev/null as the output does not have to be formatted.
--disk-usage Suppress normal output; instead, print the sum of the bytes used for on-disk storage by the selected commits or objects. This is equivalent to piping the output into git cat-file --batch-check='%(objectsize:disk)', except that it runs much faster (especially with --use-bitmap-index). See the CAVEATS section in git- cat-file(1) for the limitations of what "on-disk storage" means.
--cherry-mark Like --cherry-pick (see below) but mark equivalent commits with = rather than omitting them, and inequivalent ones with +.
--cherry-pick Omit any commit that introduces the same change as another commit on the “other side” when the set of commits are limited with symmetric difference.
For example, if you have two branches, A and B, a usual way to list all commits on only one side of them is with --left-right (see the example below in the description of the --left-right option). However, it shows the commits that were cherry-picked from the other branch (for example, “3rd on b” may be cherry-picked from branch A). With this option, such pairs of commits are excluded from the output.
--left-only, --right-only List only commits on the respective side of a symmetric difference, i.e. only those which would be marked < resp.  > by --left-right.
For example, --cherry-pick --right-only A...B omits those commits from B which are in A or are patch-equivalent to a commit in A. In other words, this lists the + commits from git cherry A B. More precisely, --cherry-pick --right-only --no-merges gives the exact list.
--cherry A synonym for --right-only --cherry-mark --no-merges; useful to limit the output to the commits on our side and mark those that have been applied to the other side of a forked history with git log --cherry upstream...mybranch, similar to git cherry upstream mybranch.
-g, --walk-reflogs Instead of walking the commit ancestry chain, walk reflog entries from the most recent one to older ones. When this option is used you cannot specify commits to exclude (that is, ^commit, commit1..commit2, and commit1...commit2 notations cannot be used).
With --pretty format other than oneline and reference (for obvious reasons), this causes the output to have two extra lines of information taken from the reflog. The reflog designator in the output may be shown as ref@{Nth} (where Nth is the reverse-chronological index in the reflog) or as ref@{timestamp} (with the timestamp for that entry), depending on a few rules:
1. If the starting point is specified as ref@{Nth}, show the index format.
2. If the starting point was specified as ref@{now}, show the timestamp format.
3. If neither was used, but --date was given on the command line, show the timestamp in the format requested by --date.
4. Otherwise, show the index format.
Under --pretty=oneline, the commit message is prefixed with this information on the same line. This option cannot be combined with --reverse. See also git-reflog(1).
Under --pretty=reference, this information will not be shown at all.
--merge After a failed merge, show refs that touch files having a conflict and don’t exist on all heads to merge.
--boundary Output excluded boundary commits. Boundary commits are prefixed with -.
--use-bitmap-index Try to speed up the traversal using the pack bitmap index (if one is available). Note that when traversing with --objects, trees and blobs will not have their associated path printed.
--progress=<header> Show progress reports on stderr as objects are considered. The <header> text will be printed with each progress update.
History Simplification Sometimes you are only interested in parts of the history, for example the commits modifying a particular <path>. But there are two parts of History Simplification, one part is selecting the commits and the other is how to do it, as there are various strategies to simplify the history.
The following options select the commits to be shown:
<paths> Commits modifying the given <paths> are selected.
--simplify-by-decoration Commits that are referred by some branch or tag are selected.
Note that extra commits can be shown to give a meaningful history.
The following options affect the way the simplification is performed:
Default mode Simplifies the history to the simplest history explaining the final state of the tree. Simplest because it prunes some side branches if the end result is the same (i.e. merging branches with the same content)
--show-pulls Include all commits from the default mode, but also any merge commits that are not TREESAME to the first parent but are TREESAME to a later parent. This mode is helpful for showing the merge commits that "first introduced" a change to a branch.
--full-history Same as the default mode, but does not prune some history.
--dense Only the selected commits are shown, plus some to have a meaningful history.
--sparse All commits in the simplified history are shown.
--simplify-merges Additional option to --full-history to remove some needless merges from the resulting history, as there are no selected commits contributing to this merge.
--ancestry-path When given a range of commits to display (e.g.  commit1..commit2 or commit2 ^commit1), only display commits that exist directly on the ancestry chain between the commit1 and commit2, i.e. commits that are both descendants of commit1, and ancestors of commit2.
A more detailed explanation follows.
Suppose you specified foo as the <paths>. We shall call commits that modify foo !TREESAME, and the rest TREESAME. (In a diff filtered for foo, they look different and equal, respectively.)
In the following, we will always refer to the same example history to illustrate the differences between simplification settings. We assume that you are filtering for a file foo in this commit graph:
.-A---M---N---O---P---Q /     /   /   /   /   / I     B   C   D   E   Y \   /   /   /   /   / `-------------'   X
The horizontal line of history A---Q is taken to be the first parent of each merge. The commits are:
•   I is the initial commit, in which foo exists with contents “asdf”, and a file quux exists with contents “quux”. Initial commits are compared to an empty tree, so I is !TREESAME.
•   In A, foo contains just “foo”.
•   B contains the same change as A. Its merge M is trivial and hence TREESAME to all parents.
•   C does not change foo, but its merge N changes it to “foobar”, so it is not TREESAME to any parent.
•   D sets foo to “baz”. Its merge O combines the strings from N and D to “foobarbaz”; i.e., it is not TREESAME to any parent.
•   E changes quux to “xyzzy”, and its merge P combines the strings to “quux xyzzy”.  P is TREESAME to O, but not to E.
•   X is an independent root commit that added a new file side, and Y modified it.  Y is TREESAME to X. Its merge Q added side to P, and Q is TREESAME to P, but not to Y.
rev-list walks backwards through history, including or excluding commits based on whether --full-history and/or parent rewriting (via --parents or --children) are used. The following settings are available.
Default mode Commits are included if they are not TREESAME to any parent (though this can be changed, see --sparse below). If the commit was a merge, and it was TREESAME to one parent, follow only that parent. (Even if there are several TREESAME parents, follow only one of them.) Otherwise, follow all parents.
This results in:
.-A---N---O /     /   / I---------D
Note how the rule to only follow the TREESAME parent, if one is available, removed B from consideration entirely.  C was considered via N, but is TREESAME. Root commits are compared to an empty tree, so I is !TREESAME.
Parent/child relations are only visible with --parents, but that does not affect the commits selected in default mode, so we have shown the parent lines.
--full-history without parent rewriting This mode differs from the default in one point: always follow all parents of a merge, even if it is TREESAME to one of them. Even if more than one side of the merge has commits that are included, this does not imply that the merge itself is! In the example, we get
I  A  B  N  D  O  P  Q
M was excluded because it is TREESAME to both parents.  E, C and B were all walked, but only B was !TREESAME, so the others do not appear.
Note that without parent rewriting, it is not really possible to talk about the parent/child relationships between the commits, so we show them disconnected.
--full-history with parent rewriting Ordinary commits are only included if they are !TREESAME (though this can be changed, see --sparse below).
Merges are always included. However, their parent list is rewritten: Along each parent, prune away commits that are not included themselves. This results in
.-A---M---N---O---P---Q /     /   /   /   / I     B   /   D   / \   /   /   /   / `-------------'
Compare to --full-history without rewriting above. Note that E was pruned away because it is TREESAME, but the parent list of P was rewritten to contain E's parent I. The same happened for C and N, and X, Y and Q.
In addition to the above settings, you can change whether TREESAME affects inclusion:
--dense Commits that are walked are included if they are not TREESAME to any parent.
--sparse All commits that are walked are included.
Note that without --full-history, this still simplifies merges: if one of the parents is TREESAME, we follow only that one, so the other sides of the merge are never walked.
--simplify-merges First, build a history graph in the same way that --full-history with parent rewriting does (see above).
Then simplify each commit C to its replacement C' in the final history according to the following rules:
•   Set C' to C.
•   Replace each parent P of C' with its simplification P'. In the process, drop parents that are ancestors of other parents or that are root commits TREESAME to an empty tree, and remove duplicates, but take care to never drop all parents that we are TREESAME to.
•   If after this parent rewriting, C' is a root or merge commit (has zero or >1 parents), a boundary commit, or !TREESAME, it remains. Otherwise, it is replaced with its only parent.
The effect of this is best shown by way of comparing to --full-history with parent rewriting. The example turns into:
.-A---M---N---O /     /       / I     B       D \   /       / `---------'
Note the major differences in N, P, and Q over --full-history:
•   N's parent list had I removed, because it is an ancestor of the other parent M. Still, N remained because it is !TREESAME.
•   P's parent list similarly had I removed.  P was then removed completely, because it had one parent and is TREESAME.
•   Q's parent list had Y simplified to X.  X was then removed, because it was a TREESAME root.  Q was then removed completely, because it had one parent and is TREESAME.
There is another simplification mode available:
--ancestry-path Limit the displayed commits to those directly on the ancestry chain between the “from” and “to” commits in the given commit range. I.e. only display commits that are ancestor of the “to” commit and descendants of the “from” commit.
As an example use case, consider the following commit history:
D---E-------F /     \       \ B---C---G---H---I---J /                     \ A-------K---------------L--M
A regular D..M computes the set of commits that are ancestors of M, but excludes the ones that are ancestors of D. This is useful to see what happened to the history leading to M since D, in the sense that “what does M have that did not exist in D”. The result in this example would be all the commits, except A and B (and D itself, of course).
When we want to find out what commits in M are contaminated with the bug introduced by D and need fixing, however, we might want to view only the subset of D..M that are actually descendants of D, i.e. excluding C and K. This is exactly what the --ancestry-path option does. Applied to the D..M range, it results in:
E-------F \       \ G---H---I---J \ L--M
Before discussing another option, --show-pulls, we need to create a new example history.
A common problem users face when looking at simplified history is that a commit they know changed a file somehow does not appear in the file’s simplified history. Let’s demonstrate a new example and show how options such as --full-history and --simplify-merges works in that case:
.-A---M-----C--N---O---P /     / \  \  \/   /   / I     B   \  R-'`-Z'   / \   /     \/         / \ /      /\        / `---X--'  `---Y--'
For this example, suppose I created file.txt which was modified by A, B, and X in different ways. The single-parent commits C, Z, and Y do not change file.txt. The merge commit M was created by resolving the merge conflict to include both changes from A and B and hence is not TREESAME to either. The merge commit R, however, was created by ignoring the contents of file.txt at M and taking only the contents of file.txt at X. Hence, R is TREESAME to X but not M. Finally, the natural merge resolution to create N is to take the contents of file.txt at R, so N is TREESAME to R but not C. The merge commits O and P are TREESAME to their first parents, but not to their second parents, Z and Y respectively.
When using the default mode, N and R both have a TREESAME parent, so those edges are walked and the others are ignored. The resulting history graph is:
I---X
When using --full-history, Git walks every edge. This will discover the commits A and B and the merge M, but also will reveal the merge commits O and P. With parent rewriting, the resulting graph is:
.-A---M--------N---O---P /     / \  \  \/   /   / I     B   \  R-'`--'   / \   /     \/         / \ /      /\        / `---X--'  `------'
Here, the merge commits O and P contribute extra noise, as they did not actually contribute a change to file.txt. They only merged a topic that was based on an older version of file.txt. This is a common issue in repositories using a workflow where many contributors work in parallel and merge their topic branches along a single trunk: manu unrelated merges appear in the --full-history results.
When using the --simplify-merges option, the commits O and P disappear from the results. This is because the rewritten second parents of O and P are reachable from their first parents. Those edges are removed and then the commits look like single-parent commits that are TREESAME to their parent. This also happens to the commit N, resulting in a history view as follows:
.-A---M--. /     /    \ I     B      R \   /      / \ /      / `---X--'
In this view, we see all of the important single-parent changes from A, B, and X. We also see the carefully-resolved merge M and the not-so-carefully-resolved merge R. This is usually enough information to determine why the commits A and B "disappeared" from history in the default view. However, there are a few issues with this approach.
The first issue is performance. Unlike any previous option, the --simplify-merges option requires walking the entire commit history before returning a single result. This can make the option difficult to use for very large repositories.
The second issue is one of auditing. When many contributors are working on the same repository, it is important which merge commits introduced a change into an important branch. The problematic merge R above is not likely to be the merge commit that was used to merge into an important branch. Instead, the merge N was used to merge R and X into the important branch. This commit may have information about why the change X came to override the changes from A and B in its commit message.
--show-pulls In addition to the commits shown in the default history, show each merge commit that is not TREESAME to its first parent but is TREESAME to a later parent.
When a merge commit is included by --show-pulls, the merge is treated as if it "pulled" the change from another branch. When using --show-pulls on this example (and no other options) the resulting graph is:
I---X---R---N
Here, the merge commits R and N are included because they pulled the commits X and R into the base branch, respectively. These merges are the reason the commits A and B do not appear in the default history.
When --show-pulls is paired with --simplify-merges, the graph includes all of the necessary information:
.-A---M--.   N /     /    \ / I     B      R \   /      / \ /      / `---X--'
Notice that since M is reachable from R, the edge from N to M was simplified away. However, N still appears in the history as an important commit because it "pulled" the change R into the main branch.
The --simplify-by-decoration option allows you to view only the big picture of the topology of the history, by omitting commits that are not referenced by tags. Commits are marked as !TREESAME (in other words, kept after history simplification rules described above) if (1) they are referenced by tags, or (2) they change the contents of the paths given on the command line. All other commits are marked as TREESAME (subject to be simplified away).
Bisection Helpers --bisect Limit output to the one commit object which is roughly halfway between included and excluded commits. Note that the bad bisection ref refs/bisect/bad is added to the included commits (if it exists) and the good bisection refs refs/bisect/good-* are added to the excluded commits (if they exist). Thus, supposing there are no refs in refs/bisect/, if
$ git rev-list --bisect foo ^bar ^baz
outputs midpoint, the output of the two commands
$ git rev-list foo ^midpoint $ git rev-list midpoint ^bar ^baz
would be of roughly the same length. Finding the change which introduces a regression is thus reduced to a binary search: repeatedly generate and test new 'midpoint’s until the commit chain is of length one.
--bisect-vars This calculates the same as --bisect, except that refs in refs/bisect/ are not used, and except that this outputs text ready to be eval’ed by the shell. These lines will assign the name of the midpoint revision to the variable bisect_rev, and the expected number of commits to be tested after bisect_rev is tested to bisect_nr, the expected number of commits to be tested if bisect_rev turns out to be good to bisect_good, the expected number of commits to be tested if bisect_rev turns out to be bad to bisect_bad, and the number of commits we are bisecting right now to bisect_all.
--bisect-all This outputs all the commit objects between the included and excluded commits, ordered by their distance to the included and excluded commits. Refs in refs/bisect/ are not used. The farthest from them is displayed first. (This is the only one displayed by --bisect.)
This is useful because it makes it easy to choose a good commit to test when you want to avoid to test some of them for some reason (they may not compile for example).
This option can be used along with --bisect-vars, in this case, after all the sorted commit objects, there will be the same text as if --bisect-vars had been used alone.
Commit Ordering By default, the commits are shown in reverse chronological order.
--date-order Show no parents before all of its children are shown, but otherwise show commits in the commit timestamp order.
--author-date-order Show no parents before all of its children are shown, but otherwise show commits in the author timestamp order.
--topo-order Show no parents before all of its children are shown, and avoid showing commits on multiple lines of history intermixed.
For example, in a commit history like this:
---1----2----4----7 \              \ 3----5----6----8---
where the numbers denote the order of commit timestamps, git rev-list and friends with --date-order show the commits in the timestamp order: 8 7 6 5 4 3 2 1.
With --topo-order, they would show 8 6 5 3 7 4 2 1 (or 8 7 4 2 6 5 3 1); some older commits are shown before newer ones in order to avoid showing the commits from two parallel development track mixed together.
--reverse Output the commits chosen to be shown (see Commit Limiting section above) in reverse order. Cannot be combined with --walk-reflogs.
Object Traversal These options are mostly targeted for packing of Git repositories.
--objects Print the object IDs of any object referenced by the listed commits. --objects foo ^bar thus means “send me all object IDs which I need to download if I have the commit object bar but not foo”.
--in-commit-order Print tree and blob ids in order of the commits. The tree and blob ids are printed after they are first referenced by a commit.
--objects-edge Similar to --objects, but also print the IDs of excluded commits prefixed with a “-” character. This is used by git-pack-objects(1) to build a “thin” pack, which records objects in deltified form based on objects contained in these excluded commits to reduce network traffic.
--objects-edge-aggressive Similar to --objects-edge, but it tries harder to find excluded commits at the cost of increased time. This is used instead of --objects-edge to build “thin” packs for shallow repositories.
--indexed-objects Pretend as if all trees and blobs used by the index are listed on the command line. Note that you probably want to use --objects, too.
--unpacked Only useful with --objects; print the object IDs that are not in packs.
--object-names Only useful with --objects; print the names of the object IDs that are found. This is the default behavior.
--no-object-names Only useful with --objects; does not print the names of the object IDs that are found. This inverts --object-names. This flag allows the output to be more easily parsed by commands such as git-cat-file(1).
--filter=<filter-spec> Only useful with one of the --objects*; omits objects (usually blobs) from the list of printed objects. The <filter-spec> may be one of the following:
The form --filter=blob:none omits all blobs.
The form --filter=blob:limit=<n>[kmg] omits blobs larger than n bytes or units. n may be zero. The suffixes k, m, and g can be used to name units in KiB, MiB, or GiB. For example, blob:limit=1k is the same as blob:limit=1024.
The form --filter=object:type=(tag|commit|tree|blob) omits all objects which are not of the requested type.
The form --filter=sparse:oid=<blob-ish> uses a sparse-checkout specification contained in the blob (or blob-expression) <blob-ish> to omit blobs that would not be required for a sparse checkout on the requested refs.
The form --filter=tree:<depth> omits all blobs and trees whose depth from the root tree is >= <depth> (minimum depth if an object is located at multiple depths in the commits traversed). <depth>=0 will not include any trees or blobs unless included explicitly in the command-line (or standard input when --stdin is used). <depth>=1 will include only the tree and blobs which are referenced directly by a commit reachable from <commit> or an explicitly-given object. <depth>=2 is like <depth>=1 while also including trees and blobs one more level removed from an explicitly-given commit or tree.
Note that the form --filter=sparse:path=<path> that wants to read from an arbitrary path on the filesystem has been dropped for security reasons.
Multiple --filter= flags can be specified to combine filters. Only objects which are accepted by every filter are included.
The form --filter=combine:<filter1>+<filter2>+...<filterN> can also be used to combined several filters, but this is harder than just repeating the --filter flag and is usually not necessary. Filters are joined by + and individual filters are %-encoded (i.e. URL-encoded). Besides the + and % characters, the following characters are reserved and also must be encoded: ~!@#$^&*()[]{}\;",<>?'` as well as all characters with ASCII code <= 0x20, which includes space and newline.