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	Manage command aliases
`ar`	Misc	Mandatory	Manage 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	Report non-directory portion of a pathname	Version 7 AT&T UNIX
`batch`	Process management	Mandatory	Schedule commands to be executed in a batch queue
`bc`	Misc	Mandatory	Arbitrary-precision arithmetic calculator	Version 6 AT&T UNIX
`bg`	Process management	Optional (UP)	Move jobs to the background
`cc`	C programming	Optional (CD)	Compile C source code	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 file group ownership	PWB UNIX
`chmod`	Filesystem	Mandatory	Change file modes/attributes/permissions	PDP-7 UNIX
`chown`	Filesystem	Mandatory	Change file ownership	PDP-7 UNIX
`cksum`	Filesystem	Mandatory	Report file checksum and size	4.4BSD
`cmp`	Filesystem	Mandatory	Compare two files	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
`cron`	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	Report or change system date and time	Version 1 AT&T UNIX
`dd`	Filesystem	Mandatory	Convert and copy files	Version 5 AT&T UNIX
`delta`	SCCS	Optional (XSI)	Make a delta (change) to an SCCS file	PWB UNIX
`df`	Filesystem	Mandatory	Report free storage space	Version 1 AT&T UNIX
`diff`	Text processing	Mandatory	Compare two files	Version 5 AT&T UNIX
`dirname`	Filesystem	Mandatory	Report the directory portion of a pathname	System III
`du`	Filesystem	Mandatory	Estimate file space usage	Version 1 AT&T UNIX
`echo`	Shell programming	Mandatory	Write 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	Exit immediately with status 1	Version 7 AT&T UNIX
`fc`	Misc	Optional (UP)	Process the command history list
`fg`	Process management	Optional (UP)	Move a job to the foreground
`file`	Filesystem	Mandatory	Report type of files	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	Report 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)	Report background jobs
`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	Report 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 absolute (canonical) location of file or directory	XPG4^[1]
`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^[2]
`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	Exit immediately with status 0	Version 7 AT&T UNIX
`tsort`	Text processing	Mandatory	Topological sort	Version 7 AT&T UNIX
`tty`	Misc	Mandatory	Report 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 file mode creation mask	System III
`unalias`	Misc	Mandatory	Remove alias definitions
`uname`	Misc	Mandatory	Report 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 compressed data	4.3BSD

References

^ IEEE Computer Society (December 1, 2008). "POSIX.1-2008 System Interfaces: realpath()". The Open Group. Base Specifications (Issue 7). doi:10.1109/IEEESTD.2008.4694976. ISBN 978-0-7381-4048-3. Archived from the original on September 18, 2024. Retrieved October 27, 2025. First released in CAE Specification: System Interface Definitions (XBD), Issue 4, Version 2 (August 1994).
^ "FreeBSD Manual Pages: time". man.freebsd.org. July 7, 202. Retrieved Mar 23, 2025.

External links

IEEE Std 1003.1,2004 specifications
IEEE Std 1003.1,2008 specifications
IEEE Std 1003.1,2024 specifications
Rosetta Stone For *Nix – configurable list of equivalent programs for *nix systems.
The Unix Acronym List: Unix Commands – explains the names of many Unix commands.

[realpath-1] IEEE Computer Society (December 1, 2008). "POSIX.1-2008 System Interfaces: realpath()". The Open Group. Base Specifications (Issue 7). doi:10.1109/IEEESTD.2008.4694976. ISBN 978-0-7381-4048-3. Archived from the original on September 18, 2024. Retrieved October 27, 2025. First released in CAE Specification: System Interface Definitions (XBD), Issue 4, Version 2 (August 1994).

[2] "FreeBSD Manual Pages: time". man.freebsd.org. July 7, 202. Retrieved Mar 23, 2025.

[1]

[2]

v t e Unix command-line interface programs and shell builtins
File system	cat chattr chmod chown chgrp cksum cmp cp dd du df file fuser ln ls mkdir mv pax pwd rm rmdir split tee touch type umask
Processes	at bg crontab fg kill nice ps time
User environment	env exit logname mesg talk tput uname who write
Text processing	awk basename comm csplit cut diff dirname ed ex fold head iconv join m4 more nl paste patch printf read sed sort strings tail tr troff uniq vi wc xargs
Shell builtins	alias cd echo test unset wait
Searching	find grep
Documentation	man
Software development	ar ctags lex make nm strip yacc
Miscellaneous	bc cal expr lp od sleep true and false
Categories Standard Unix programs Unix SUS2008 utilities List

See also

References

External links