List of POSIX commands

{{Short description|None}} {{Plain image with caption|POSIX Utilities.pdf|width=600px|Utilities listed in POSIX.1-2017}}

This is a list of the shell commands of the most recent version of the Portable Operating System Interface (POSIX) {{endash}} IEEE Std 1003.1-2024 which is part of the Single UNIX Specification (SUS). These commands are implemented in many shells on modern Unix, Unix-like and other operating systems. This list does not cover commands for all versions of Unix and Unix-like shells nor other versions of POSIX.

As is typical in the context of a POSIX system, the term ''file'' refers to an item of a file system which can be a regular file, a directory or several other more specialized types.

Columns: ; Command: The text one enters to launch the command. ; Category: Functional categorization. ; Optionality: Indicates whether the command is mandatory or optional in order to achieve conformance. If the latter, then a code indicates the optional functionality group to which the command belongs. :; Batch environment (BE): Batch job control. :; C‑language development (CD): For developing software in C. :; FORTRAN development (FD): For developing software in FORTRAN. :; FORTRAN runtime (FR): Runtime‑support for FORTRAN. :; Software development (SD): For developing software; not language specific. :; User portability (UP): Addresses consistency at the user interface level. :; X/Open System Interfaces (XSI): Historically UNIX-like features that were common on System V–style systems. ; Description: Describes what the command does. ; First appeared: Identifies an operating system version in which the command was first provided.

{{Sticky header}} {{Table alignment}} {|class="wikitable sortable sticky-header col3center" |- !scope="col" | Command !scope="col" | Category !scope="col" | Optionality !scope="col" | Description !scope="col" | First appeared |- !scope="row"| admin | SCCS | {{Optional}} (XSI) | Create and administer SCCS files | PWB UNIX |- !scope="row"| alias | Misc | {{needs|Mandatory}} | Manage command aliases | |- !scope="row"| ar | Misc | {{needs|Mandatory}} | Manage library archives | Version 1 AT&T UNIX |- !scope="row"| asa | Text processing | {{Optional}} (FR) | Interpret carriage-control characters | System V |- !scope="row"| at | Process management | {{needs|Mandatory}} | Execute commands at a later time | Version 7 AT&T UNIX |- !scope="row"| awk | Text processing | {{needs|Mandatory}} | Pattern scanning and processing language | Version 7 AT&T UNIX |- !scope="row"| basename | Filesystem | {{needs|Mandatory}} | Report non-directory portion of a pathname | Version 7 AT&T UNIX |- !scope="row"| batch | Process management | {{needs|Mandatory}} | Schedule commands to be executed in a batch queue | |- !scope="row"| bc | Misc | {{needs|Mandatory}} | Arbitrary-precision arithmetic calculator | Version 6 AT&T UNIX |- !scope="row"| bg | Process management | {{Optional}} (UP) | Move jobs to the background | |- !scope="row"| cc | C programming | {{Optional}} (CD) | Compile C source code | IEEE Std 1003.1-2024 |- !scope="row"| cal | Misc | {{Optional}} (XSI) | Print a calendar | Version 5 AT&T UNIX |- !scope="row"| cat | Filesystem | {{needs|Mandatory}} | Concatenate and print files | PDP-7 UNIX |- !scope="row"| cd | Filesystem | {{needs|Mandatory}} | Change the working directory | Version 6 AT&T UNIX |- !scope="row"| cflow | C programming | {{Optional}} (XSI) | Generate a C-language call graph | System V |- !scope="row"| chgrp | Filesystem | {{needs|Mandatory}} | Change file group ownership | PWB UNIX |- !scope="row"| chmod | Filesystem | {{needs|Mandatory}} | Change file modes/attributes/permissions | PDP-7 UNIX |- !scope="row"| chown | Filesystem | {{needs|Mandatory}} | Change file ownership | PDP-7 UNIX |- !scope="row"| cksum | Filesystem | {{needs|Mandatory}} | Report file checksum and size | 4.4BSD |- !scope="row"| cmp | Filesystem | {{needs|Mandatory}} | Compare two files | Version 1 AT&T UNIX |- !scope="row"| comm | Text processing | {{needs|Mandatory}} | Select or reject lines common to two files | Version 4 AT&T UNIX |- !scope="row"| command | Shell programming | {{needs|Mandatory}} | Execute a simple command | |- !scope="row"| compress | Filesystem | {{Optional}} (XSI) | Compress data | 4.3BSD |- !scope="row"| cp | Filesystem | {{needs|Mandatory}} | Copy files | PDP-7 UNIX |- !scope="row"| cron | Misc | {{needs|Mandatory}} | Schedule periodic background work | System V |- !scope="row"| csplit | Text processing | {{needs|Mandatory}} | Split files based on context | PWB UNIX |- !scope="row"| ctags | C programming | {{Optional}} (SD) | Create a tags file | 3BSD |- !scope="row"| cut | Text processing | {{needs|Mandatory}} | Cut out selected fields of each line of a file | System III |- !scope="row"| cxref | C programming | {{Optional}} (XSI) | Generate a C-language program cross-reference table | System V |- !scope="row"| date | Misc | {{needs|Mandatory}} | Report or change system date and time | Version 1 AT&T UNIX |- !scope="row"| dd | Filesystem | {{needs|Mandatory}} | Convert and copy files | Version 5 AT&T UNIX |- !scope="row"| delta | SCCS | {{Optional}} (XSI) | Make a delta (change) to an SCCS file | PWB UNIX |- !scope="row"| df | Filesystem | {{needs|Mandatory}} | Report free storage space | Version 1 AT&T UNIX |- !scope="row"| diff | Text processing | {{needs|Mandatory}} | Compare two files | Version 5 AT&T UNIX |- !scope="row"| dirname | Filesystem | {{needs|Mandatory}} | Report the directory portion of a pathname | System III |- !scope="row"| du | Filesystem | {{needs|Mandatory}} | Estimate file space usage | Version 1 AT&T UNIX |- !scope="row"| echo | Shell programming | {{needs|Mandatory}} | Write to standard output | Version 2 AT&T UNIX |- !scope="row"| ed | Text processing | {{needs|Mandatory}} | The standard text editor | PDP-7 UNIX |- !scope="row"| env | Misc | {{needs|Mandatory}} | Set the environment for command invocation | System III |- !scope="row"| ex | Text processing | {{Optional}} (UP) | Text editor | 1BSD |- !scope="row"| expand | Text processing | {{needs|Mandatory}} | Convert tabs to spaces | 3BSD |- !scope="row"| expr | Shell programming | {{needs|Mandatory}} | Evaluate arguments as an expression | Version 7 AT&T UNIX |- !scope="row"| false | Shell programming | {{needs|Mandatory}} | Exit immediately with status 1 | Version 7 AT&T UNIX |- !scope="row"| fc | Misc | {{Optional}} (UP) | Process the command history list | |- !scope="row"| fg | Process management | {{Optional}} (UP) | Move a job to the foreground | |- !scope="row"| file | Filesystem | {{needs|Mandatory}} | Report type of files | Version 4 AT&T UNIX |- !scope="row"| find | Filesystem | {{needs|Mandatory}} | Find files | Version 1 AT&T UNIX |- !scope="row"| fold | Text processing | {{needs|Mandatory}} | Filter for folding lines | 1BSD |- !scope="row"| fuser | Process management | {{Optional}} (XSI) | List process IDs of all processes that have one or more files open | System V |- !scope="row"| gencat | Misc | {{needs|Mandatory}} | Generate a formatted message catalog | |- !scope="row"| get | SCCS | {{Optional}} (XSI) | Get a version of an SCCS file | PWB UNIX |- !scope="row"| getconf | Misc | {{needs|Mandatory}} | Get configuration values | |- !scope="row"| getopts | Shell programming | {{needs|Mandatory}} | Parse utility options | |- !scope="row"| gettext | Misc | {{needs|Mandatory}} | Retrieve text string from messages object | |- !scope="row"| grep | Misc | {{needs|Mandatory}} | Search text for a pattern | Version 4 AT&T UNIX |- !scope="row"| hash | Misc | {{needs|Mandatory}} | Hash database access method | |- !scope="row"| head | Text processing | {{needs|Mandatory}} | Copy the first part of files | PWB UNIX{{citation needed|date=May 2009}} |- !scope="row"| iconv | Text processing | {{needs|Mandatory}} | Codeset conversion | HP-UX |- !scope="row"| id | Misc | {{needs|Mandatory}} | Report user identity | System V |- !scope="row"| ipcrm | Misc | {{Optional}} (XSI) | Remove a message queue, semaphore set, or shared memory segment identifier | System V |- !scope="row"| ipcs | Misc | {{Optional}} (XSI) | Report interprocess communication facilities status | System V |- !scope="row"| jobs | Process management | {{Optional}} (UP) | Report background jobs | |- !scope="row"| join | Text processing | {{needs|Mandatory}} | Merges two sorted text files based on the presence of a common field | Version 7 AT&T UNIX |- !scope="row"| kill | Process management | {{needs|Mandatory}} | Terminate or signal processes | Version 4 AT&T UNIX |- !scope="row"| lex | C programming | {{Optional}} (CD) | Generate programs for lexical tasks | Version 7 AT&T UNIX |- !scope="row"| link | Filesystem | {{Optional}} (XSI) | Create a hard link to a file | Version 1 AT&T UNIX |- !scope="row"| ln | Filesystem | {{needs|Mandatory}} | Link files | Version 1 AT&T UNIX |- !scope="row"| locale | Misc | {{needs|Mandatory}} | Get locale-specific information | |- !scope="row"| localedef | Misc | {{needs|Mandatory}} | Define locale environment | |- !scope="row"| logger | Shell programming | {{needs|Mandatory}} | Log messages | 4.3BSD |- !scope="row"| logname | Misc | {{needs|Mandatory}} | Report the user's login name | 4.4BSD |- !scope="row"| lp | Text processing | {{needs|Mandatory}} | Send files to a printer | System V |- !scope="row"| ls | Filesystem | {{needs|Mandatory}} | List directory contents | Version 1 AT&T UNIX |- !scope="row"| m4 | Misc | {{needs|Mandatory}} | Macro processor | PWB UNIX |- !scope="row"| mailx | Misc | {{needs|Mandatory}} | Process messages | Version 1 AT&T UNIX |- !scope="row"| make | Programming | {{Optional}} (SD) | Maintain, update, and regenerate groups of programs | PWB UNIX |- !scope="row"| man | Misc | {{needs|Mandatory}} | Display system documentation | Version 2 AT&T UNIX |- !scope="row"| mesg | Misc | {{needs|Mandatory}} | Permit or deny messages | Version 1 AT&T UNIX |- !scope="row"| mkdir | Filesystem | {{needs|Mandatory}} | Make directories | Version 1 AT&T UNIX |- !scope="row"| mkfifo | Filesystem | {{needs|Mandatory}} | Make FIFO special files | 4.4BSD{{dubious|mkfifo|date=April 2014}} |- !scope="row"| more | Text processing | {{Optional}} (UP) | Display files on a page-by-page basis | 3BSD |- !scope="row"| msgfmt | Misc | {{needs|Mandatory}} | Create messages objects from messages object files | |- !scope="row"| mv | Filesystem | {{needs|Mandatory}} | Move or rename files | Version 1 AT&T UNIX |- !scope="row"| newgrp | Misc | {{needs|Mandatory}} | Change to a new group | Version 6 AT&T UNIX |- !scope="row"| ngettext | Misc | {{needs|Mandatory}} | Retrieve text string from messages object with plural form | |- !scope="row"| nice | Process management | {{needs|Mandatory}} | Invoke a utility with an altered nice value | Version 4 AT&T UNIX |- !scope="row"| nl | Text processing | {{Optional}} (XSI) | Line numbering filter | System III |- !scope="row"| nm | C programming | {{Optional}} (SD, XSI) | Write the name list of an object file | Version 1 AT&T UNIX |- !scope="row"| nohup | Process management | {{needs|Mandatory}} | Invoke a utility immune to hangups | Version 4 AT&T UNIX |- !scope="row"| od | Misc | {{needs|Mandatory}} | Dump files in various formats | Version 1 AT&T UNIX |- !scope="row"| paste | Text processing | {{needs|Mandatory}} | Merge corresponding or subsequent lines of files | Version 32V AT&T UNIX |- !scope="row"| patch | Text processing | {{needs|Mandatory}} | Apply changes to files | 4.3BSD |- !scope="row"| pathchk | Filesystem | {{needs|Mandatory}} | Check pathnames | |- !scope="row"| pax | Misc | {{needs|Mandatory}} | Portable archive interchange | 4.4BSD{{citation needed|date=December 2014}} |- !scope="row"| pr | Text processing | {{needs|Mandatory}} | Paginate or columnate files for printing | Version 1 AT&T UNIX |- !scope="row"| printf | Shell programming | {{needs|Mandatory}} | Write formatted output | 4.3BSD-Reno |- !scope="row"| prs | SCCS | {{Optional}} (XSI) | Print an SCCS file | PWB UNIX |- !scope="row"| ps | Process management | {{needs|Mandatory}} | Report process status | Version 4 AT&T UNIX |- !scope="row"| pwd | Filesystem | {{needs|Mandatory}} | Print working directory | Version 5 AT&T UNIX |- !scope="row"| read | Shell programming | {{needs|Mandatory}} | Read a line from standard input | |- !scope="row"| readlink | Filesystem | {{needs|Mandatory}} | Print destination of a symbolic link | |- !scope="row"| realpath | Filesystem | {{needs|Mandatory}} | Report the fully qualified path of a file | XPG4<ref name="realpath">{{Cite web|author=IEEE Computer Society|author-link=IEEE Computer Society|date=2008-12-01|title=POSIX.1-2008 System Interfaces: realpath()|website=The Open Group|url=https://pubs.opengroup.org/onlinepubs/9699919799.orig/functions/realpath.html|url-status=dead|archive-url=https://web.archive.org/web/20240918051049/https://pubs.opengroup.org/onlinepubs/9699919799.orig/functions/realpath.html|archive-date=2024-09-18|series=Base Specifications (Issue 7)|doi=10.1109/IEEESTD.2008.4694976|isbn=978-0-7381-4048-3|access-date=2025-10-27|df=mdy-all|quote=First released in CAE Specification: System Interface Definitions (XBD), Issue 4, Version 2 (August 1994).}}</ref> |- !scope="row"| renice | Process management | {{needs|Mandatory}} | Set nice values of running processes | 4BSD |- !scope="row"| rm | Filesystem | {{needs|Mandatory}} | Remove file(s) | Version 1 AT&T UNIX |- !scope="row"| rmdel | SCCS | {{Optional}} (XSI) | Remove a delta from an SCCS file | PWB UNIX |- !scope="row"| rmdir | Filesystem | {{needs|Mandatory}} | Remove empty directory(ies) | Version 1 AT&T UNIX |- !scope="row"| sact | SCCS | {{Optional}} (XSI) | Print current SCCS file-editing activity | System III |- !scope="row"| sccs | SCCS | {{Optional}} (XSI) | Front end for the SCCS subsystem | 4.3BSD |- !scope="row"| sed | Text processing | {{needs|Mandatory}} | Stream editor | Version 7 AT&T UNIX |- !scope="row"| sh | Shell programming | {{needs|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) |- !scope="row"| sleep | Shell programming | {{needs|Mandatory}} | Suspend execution for an interval | Version 4 AT&T UNIX |- !scope="row"| sort | Text processing | {{needs|Mandatory}} | Sort, merge, or sequence check text files | Version 1 AT&T UNIX |- !scope="row"| split | Misc | {{needs|Mandatory}} | Split files into pieces | Version 3 AT&T UNIX |- !scope="row"| strings | C programming | {{needs|Mandatory}} | Find printable strings in files | 2BSD |- !scope="row"| strip | C programming | {{Optional}} (SD) | Remove unnecessary information from executable files | Version 1 AT&T UNIX |- !scope="row"| stty | Misc | {{needs|Mandatory}} | Set the options for a terminal | Version 2 AT&T UNIX |- !scope="row"| tabs | Misc | {{needs|Mandatory}} | Set terminal tabs | PWB UNIX |- !scope="row"| tail | Text processing | {{needs|Mandatory}} | Copy the last part of a file | PWB UNIX{{citation needed|date=May 2009}} |- !scope="row"| talk | Misc | {{Optional}} (UP) | Talk to another user | 4.2BSD |- !scope="row"| tee | Shell programming | {{needs|Mandatory}} | Duplicate the standard output | Version 5 AT&T UNIX |- !scope="row"| test | Shell programming | {{needs|Mandatory}} | Evaluate expression | Version 7 AT&T UNIX |- !scope="row"| time | Process management | {{needs|Mandatory}} | Display elapsed, system and kernel time used by the current shell or designated process. | Version 3 AT&T UNIX<ref>{{cite web |author= |date=July 7, 2020 |title=FreeBSD Manual Pages: time |url=https://man.freebsd.org/cgi/man.cgi?query=time |website=man.freebsd.org|access-date=Mar 23, 2025}} </ref> |- !scope="row"| timeout | Process management | {{needs|Mandatory}} | Run command with a time limit | Version 3 AT&T UNIX |- !scope="row"| touch | Filesystem | {{needs|Mandatory}} | Change file access and modification times | Version 7 AT&T UNIX |- !scope="row"| tput | Misc | {{needs|Mandatory}} | Change terminal characteristics | System V |- !scope="row"| tr | Text processing | {{needs|Mandatory}} | Translate characters | Version 4 AT&T UNIX |- !scope="row"| true | Shell programming | {{needs|Mandatory}} | Exit immediately with status 0 | Version 7 AT&T UNIX |- !scope="row"| tsort | Text processing | {{needs|Mandatory}} | Topological sort | Version 7 AT&T UNIX |- !scope="row"| tty | Misc | {{needs|Mandatory}} | Report user's terminal name | Version 1 AT&T UNIX |- !scope="row"| type | Misc | {{Optional}} (XSI) | Displays how a name would be interpreted if used as a command | |- !scope="row"| ulimit | Misc | {{Optional}} (XSI) | Set or report file size limit | |- !scope="row"| umask | Misc | {{needs|Mandatory}} | Get or set file mode creation mask | System III |- !scope="row"| unalias | Misc | {{needs|Mandatory}} | Remove alias definitions | |- !scope="row"| uname | Misc | {{needs|Mandatory}} | Report system name | PWB UNIX |- !scope="row"| uncompress | Misc | {{Optional}} (XSI) | Expand compressed data | 4.3BSD |- !scope="row"| unexpand | Text processing | {{needs|Mandatory}} | Convert spaces to tabs | 3BSD |- !scope="row"| unget | SCCS | {{Optional}} (XSI) | Undo a previous get of an SCCS file | System III |- !scope="row"| uniq | Text processing | {{needs|Mandatory}} | Report or filter out repeated lines in a file | Version 3 AT&T UNIX |- !scope="row"| unlink | Filesystem | {{Optional}} (XSI) | Call the unlink function | Version 1 AT&T UNIX |- !scope="row"| uucp | Network | {{Optional}} (UU) | System-to-system copy | Version 7 AT&T UNIX |- !scope="row"| uudecode | Network | {{needs|Mandatory}} | Decode a binary file | 4BSD |- !scope="row"| uuencode | Network | {{needs|Mandatory}} | Encode a binary file | 4BSD |- !scope="row"| uustat | Network | {{Optional}} (UU) | uucp status inquiry and job control | System III |- !scope="row"| uux | Process management | {{Optional}} (UU) | Remote command execution | Version 7 AT&T UNIX |- !scope="row"| val | SCCS | {{Optional}} (XSI) | Validate SCCS files | System III |- !scope="row"| vi | Text processing | {{Optional}} (UP) | Screen-oriented (visual) display editor | 1BSD |- !scope="row"| wait | Process management | {{needs|Mandatory}} | Await process completion | Version 4 AT&T UNIX |- !scope="row"| wc | Text processing | {{needs|Mandatory}} | Line, word and byte or character count | Version 1 AT&T UNIX |- !scope="row"| what | SCCS | {{Optional}} (XSI) | Identify SCCS files | PWB UNIX |- !scope="row"| who | System administration | {{Optional}} (XSI) | Display who is on the system | Version 1 AT&T UNIX |- !scope="row"| write | Misc | {{needs|Mandatory}} | Write to another user's terminal | Version 1 AT&T UNIX |- !scope="row"| xargs | Shell programming | {{needs|Mandatory}} | Construct argument lists and invoke utility | PWB UNIX |- !scope="row"| xgettext | C programming | {{Optional}} (CD) | Extract gettext calls from C source code strings | IEEE Std 1003.1-2024 |- !scope="row"| yacc | C programming | {{Optional}} (CD) | Yet another compiler compiler | PWB UNIX |- !scope="row"| zcat | Text processing | {{Optional}} (XSI) | Expand and concatenate compressed data | 4.3BSD |- |}

==References== {{Reflist}}

==External links== {{wikibooks|Guide to UNIX|Commands}} {{Commons category|Unix reference cards}} * [https://pubs.opengroup.org/onlinepubs/000095399/ IEEE Std 1003.1,2004 specifications] * [https://pubs.opengroup.org/onlinepubs/9699919799/ IEEE Std 1003.1,2008 specifications] * [https://pubs.opengroup.org/onlinepubs/9799919799/ IEEE Std 1003.1,2024 specifications] * [https://bhami.com/rosetta.html Rosetta Stone For *Nix] – configurable list of equivalent programs for *nix systems. * [http://roesler-ac.de/wolfram/acro/Cmd.htm The Unix Acronym List: Unix Commands] – explains the names of many Unix commands.

Unix programs Category:System administration Category:Unix SUS2008 utilities