List of POSIX commands

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) – 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.

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	Sets or displays 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^{[citation needed]}
`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^{[dubious – discuss]}
`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^{[citation needed]}
`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^{[citation needed]}
`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	Display elapsed, system and kernel time used by the current shell or designated process.	Version 3 AT&T UNIX^[1]
`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