# List of POSIX commands

This is a list of POSIX (Portable Operating System Interface) commands as specified by IEEE Std 1003.1-2024, which is part of the Single UNIX Specification (SUS). These commands can be found on Unix operating systems and most Unix-like operating systems.
This is not a comprehensive list of all utilities that existed in the various historic Unix and Unix-like systems, as it excludes utilities that were not mandated by the aforementioned standard.

## List

IEEE Std 1003.1-2024 utilities :
| Name | Category | Status (Option code) | Description | First appeared |
| admin | SCCS | Optional (XSI) | Create and administer SCCS files | PWB UNIX |
| alias | Misc | Mandatory | Define or display aliases | |
| ar | Misc | Mandatory | Create and maintain library archives | Version 1 AT&T UNIX |
| asa | Text processing | Optional (FR) | Interpret carriage-control characters | System V |
| at | Process management | Mandatory | Execute commands at a later time | Version 7 AT&T UNIX |
| awk | Text processing | Mandatory | Pattern scanning and processing language | Version 7 AT&T UNIX |
| basename | Filesystem | Mandatory | Return non-directory portion of a pathname; see also dirname | Version 7 AT&T UNIX |
| batch | Process management | Mandatory | Schedule commands to be executed in a batch queue | |
| bc | Misc | Mandatory | Arbitrary-precision arithmetic language | Version 6 AT&T UNIX |
| bg | Process management | Optional (UP) | Run jobs in the background | |
| cc/c17 | C programming | Optional (CD) | Compile standard C programs | IEEE Std 1003.1-2024 |
| cal | Misc | Optional (XSI) | Print a calendar | Version 5 AT&T UNIX |
| cat | Filesystem | Mandatory | Concatenate and print files | PDP-7 UNIX |
| cd | Filesystem | Mandatory | Change the working directory | Version 6 AT&T UNIX |
| cflow | C programming | Optional (XSI) | Generate a C-language call graph | System V |
| chgrp | Filesystem | Mandatory | Change the file group ownership | PWB UNIX |
| chmod | Filesystem | Mandatory | Change the file modes/attributes/permissions | PDP-7 UNIX |
| chown | Filesystem | Mandatory | Change the file ownership | PDP-7 UNIX |
| cksum | Filesystem | Mandatory | Write file checksums and sizes | 4.4BSD |
| cmp | Filesystem | Mandatory | Compare two files; see also diff | Version 1 AT&T UNIX |
| comm | Text processing | Mandatory | Select or reject lines common to two files | Version 4 AT&T UNIX |
| command | Shell programming | Mandatory | Execute a simple command | |
| compress | Filesystem | Optional (XSI) | Compress data | 4.3BSD |
| cp | Filesystem | Mandatory | Copy files | PDP-7 UNIX |
| crontab | Misc | Mandatory | Schedule periodic background work | System V |
| csplit | Text processing | Mandatory | Split files based on context | PWB UNIX |
| ctags | C programming | Optional (SD) | Create a tags file | 3BSD |
| cut | Text processing | Mandatory | Cut out selected fields of each line of a file | System III |
| cxref | C programming | Optional (XSI) | Generate a C-language program cross-reference table | System V |
| date | Misc | Mandatory | Display the date and time | Version 1 AT&T UNIX |
| dd | Filesystem | Mandatory | Convert and copy a file | Version 5 AT&T UNIX |
| delta | SCCS | Optional (XSI) | Make a delta (change) to an SCCS file | PWB UNIX |
| df | Filesystem | Mandatory | Report free disk space | Version 1 AT&T UNIX |
| diff | Text processing | Mandatory | Compare two files; see also cmp | Version 5 AT&T UNIX |
| dirname | Filesystem | Mandatory | Return the directory portion of a pathname; see also basename | System III |
| du | Filesystem | Mandatory | Estimate file space usage | Version 1 AT&T UNIX |
| echo | Shell programming | Mandatory | Write arguments to standard output | Version 2 AT&T UNIX |
| ed | Text processing | Mandatory | The standard text editor | PDP-7 UNIX |
| env | Misc | Mandatory | Set the environment for command invocation | System III |
| ex | Text processing | Optional (UP) | Text editor | 1BSD |
| expand | Text processing | Mandatory | Convert tabs to spaces | 3BSD |
| expr | Shell programming | Mandatory | Evaluate arguments as an expression | Version 7 AT&T UNIX |
| false | Shell programming | Mandatory | Return false value | Version 7 AT&T UNIX |
| fc | Misc | Optional (UP) | Process the command history list | |
| fg | Process management | Optional (UP) | Run jobs in the foreground | |
| file | Filesystem | Mandatory | Determine file type | Version 4 AT&T UNIX |
| find | Filesystem | Mandatory | Find files | Version 1 AT&T UNIX |
| fold | Text processing | Mandatory | Filter for folding lines | 1BSD |
| fuser | Process management | Optional (XSI) | List process IDs of all processes that have one or more files open | System V |
| gencat | Misc | Mandatory | Generate a formatted message catalog | |
| get | SCCS | Optional (XSI) | Get a version of an SCCS file | PWB UNIX |
| getconf | Misc | Mandatory | Get configuration values | |
| getopts | Shell programming | Mandatory | Parse utility options | |
| gettext | Misc | Mandatory | Retrieve text string from messages object | |
| grep | Misc | Mandatory | Search text for a pattern | Version 4 AT&T UNIX |
| hash | Misc | Mandatory | Hash database access method | |
| head | Text processing | Mandatory | Copy the first part of files | PWB UNIX |
| iconv | Text processing | Mandatory | Codeset conversion | HP-UX |
| id | Misc | Mandatory | Return user identity | System V |
| ipcrm | Misc | Optional (XSI) | Remove a message queue, semaphore set, or shared memory segment identifier | System V |
| ipcs | Misc | Optional (XSI) | Report interprocess communication facilities status | System V |
| jobs | Process management | Optional (UP) | Display status of jobs in the current session | |
| join | Text processing | Mandatory | Merges two sorted text files based on the presence of a common field | Version 7 AT&T UNIX |
| kill | Process management | Mandatory | Terminate or signal processes | Version 4 AT&T UNIX |
| lex | C programming | Optional (CD) | Generate programs for lexical tasks | Version 7 AT&T UNIX |
| link | Filesystem | Optional (XSI) | Create a hard link to a file | Version 1 AT&T UNIX |
| ln | Filesystem | Mandatory | Link files | Version 1 AT&T UNIX |
| locale | Misc | Mandatory | Get locale-specific information | |
| localedef | Misc | Mandatory | Define locale environment | |
| logger | Shell programming | Mandatory | Log messages | 4.3BSD |
| logname | Misc | Mandatory | Return the user's login name | 4.4BSD |
| lp | Text processing | Mandatory | Send files to a printer | System V |
| ls | Filesystem | Mandatory | List directory contents | Version 1 AT&T UNIX |
| m4 | Misc | Mandatory | Macro processor | PWB UNIX |
| mailx | Misc | Mandatory | Process messages | Version 1 AT&T UNIX |
| make | Programming | Optional (SD) | Maintain, update, and regenerate groups of programs | PWB UNIX |
| man | Misc | Mandatory | Display system documentation | Version 2 AT&T UNIX |
| mesg | Misc | Mandatory | Permit or deny messages | Version 1 AT&T UNIX |
| mkdir | Filesystem | Mandatory | Make directories | Version 1 AT&T UNIX |
| mkfifo | Filesystem | Mandatory | Make FIFO special files | 4.4BSD |
| more | Text processing | Optional (UP) | Display files on a page-by-page basis | 3BSD |
| msgfmt | Misc | Mandatory | Create messages objects from messages object files | |
| mv | Filesystem | Mandatory | Move or rename files | Version 1 AT&T UNIX |
| newgrp | Misc | Mandatory | Change to a new group | Version 6 AT&T UNIX |
| ngettext | Misc | Mandatory | Retrieve text string from messages object with plural form | |
| nice | Process management | Mandatory | Invoke a utility with an altered nice value | Version 4 AT&T UNIX |
| nl | Text processing | Optional (XSI) | Line numbering filter | System III |
| nm | C programming | Optional (SD, XSI) | Write the name list of an object file | Version 1 AT&T UNIX |
| nohup | Process management | Mandatory | Invoke a utility immune to hangups | Version 4 AT&T UNIX |
| od | Misc | Mandatory | Dump files in various formats | Version 1 AT&T UNIX |
| paste | Text processing | Mandatory | Merge corresponding or subsequent lines of files | Version 32V AT&T UNIX |
| patch | Text processing | Mandatory | Apply changes to files | 4.3BSD |
| pathchk | Filesystem | Mandatory | Check pathnames | |
| pax | Misc | Mandatory | Portable archive interchange | 4.4BSD |
| pr | Text processing | Mandatory | Paginate or columnate files for printing | Version 1 AT&T UNIX |
| printf | Shell programming | Mandatory | Write formatted output | 4.3BSD-Reno |
| prs | SCCS | Optional (XSI) | Print an SCCS file | PWB UNIX |
| ps | Process management | Mandatory | Report process status | Version 4 AT&T UNIX |
| pwd | Filesystem | Mandatory | Print working directory | Version 5 AT&T UNIX |
| read | Shell programming | Mandatory | Read a line from standard input | |
| readlink | Filesystem | Mandatory | Print destination of a symbolic link | |
| realpath | Filesystem | Mandatory | Resolve a symbolic link | |
| renice | Process management | Mandatory | Set nice values of running processes | 4BSD |
| rm | Filesystem | Mandatory | Remove directory entries | Version 1 AT&T UNIX |
| rmdel | SCCS | Optional (XSI) | Remove a delta from an SCCS file | PWB UNIX |
| rmdir | Filesystem | Mandatory | Remove directories, if they are empty. | Version 1 AT&T UNIX |
| sact | SCCS | Optional (XSI) | Print current SCCS file-editing activity | System III |
| sccs | SCCS | Optional (XSI) | Front end for the SCCS subsystem | 4.3BSD |
| sed | Text processing | Mandatory | Stream editor | Version 7 AT&T UNIX |
| sh | Shell programming | Mandatory | Shell, the standard command language interpreter | Version 7 AT&T UNIX (in earlier versions, sh was either the Thompson shell or the PWB shell) |
| sleep | Shell programming | Mandatory | Suspend execution for an interval | Version 4 AT&T UNIX |
| sort | Text processing | Mandatory | Sort, merge, or sequence check text files | Version 1 AT&T UNIX |
| split | Misc | Mandatory | Split files into pieces | Version 3 AT&T UNIX |
| strings | C programming | Mandatory | Find printable strings in files | 2BSD |
| strip | C programming | Optional (SD) | Remove unnecessary information from executable files | Version 1 AT&T UNIX |
| stty | Misc | Mandatory | Set the options for a terminal | Version 2 AT&T UNIX |
| tabs | Misc | Mandatory | Set terminal tabs | PWB UNIX |
| tail | Text processing | Mandatory | Copy the last part of a file | PWB UNIX |
| talk | Misc | Optional (UP) | Talk to another user | 4.2BSD |
| tee | Shell programming | Mandatory | Duplicate the standard output | Version 5 AT&T UNIX |
| test | Shell programming | Mandatory | Evaluate expression | Version 7 AT&T UNIX |
| time | Process management | Mandatory | Retrieve and format time and date | Version 3 AT&T UNIX |
| timeout | Process management | Mandatory | Run command with a time limit | Version 3 AT&T UNIX |
| touch | Filesystem | Mandatory | Change file access and modification times | Version 7 AT&T UNIX |
| tput | Misc | Mandatory | Change terminal characteristics | System V |
| tr | Text processing | Mandatory | Translate characters | Version 4 AT&T UNIX |
| true | Shell programming | Mandatory | Return true value | Version 7 AT&T UNIX |
| tsort | Text processing | Mandatory | Topological sort | Version 7 AT&T UNIX |
| tty | Misc | Mandatory | Return user's terminal name | Version 1 AT&T UNIX |
| type | Misc | Optional (XSI) | Displays how a name would be interpreted if used as a command | |
| ulimit | Misc | Optional (XSI) | Set or report file size limit | |
| umask | Misc | Mandatory | Get or set the file mode creation mask | System III |
| unalias | Misc | Mandatory | Remove alias definitions | |
| uname | Misc | Mandatory | Return system name | PWB UNIX |
| uncompress | Misc | Optional (XSI) | Expand compressed data | 4.3BSD |
| unexpand | Text processing | Mandatory | Convert spaces to tabs | 3BSD |
| unget | SCCS | Optional (XSI) | Undo a previous get of an SCCS file | System III |
| uniq | Text processing | Mandatory | Report or filter out repeated lines in a file | Version 3 AT&T UNIX |
| unlink | Filesystem | Optional (XSI) | Call the unlink function | Version 1 AT&T UNIX |
| uucp | Network | Optional (UU) | System-to-system copy | Version 7 AT&T UNIX |
| uudecode | Network | Mandatory | Decode a binary file | 4BSD |
| uuencode | Network | Mandatory | Encode a binary file | 4BSD |
| uustat | Network | Optional (UU) | uucp status inquiry and job control | System III |
| uux | Process management | Optional (UU) | Remote command execution | Version 7 AT&T UNIX |
| val | SCCS | Optional (XSI) | Validate SCCS files | System III |
| vi | Text processing | Optional (UP) | Screen-oriented (visual) display editor | 1BSD |
| wait | Process management | Mandatory | Await process completion | Version 4 AT&T UNIX |
| wc | Text processing | Mandatory | Line, word and byte or character count | Version 1 AT&T UNIX |
| what | SCCS | Optional (XSI) | Identify SCCS files | PWB UNIX |
| who | System administration | Optional (XSI) | Display who is on the system | Version 1 AT&T UNIX |
| write | Misc | Mandatory | Write to another user's terminal | Version 1 AT&T UNIX |
| xargs | Shell programming | Mandatory | Construct argument lists and invoke utility | PWB UNIX |
| xgettext | C programming | Optional (CD) | Extract gettext calls from C source code strings | IEEE Std 1003.1-2024 |
| yacc | C programming | Optional (CD) | Yet another compiler compiler | PWB UNIX |
| zcat | Text processing | Optional (XSI) | Expand and concatenate data | 4.3BSD |