Uniq: Difference between revisions

uniq
Original author(s)	Ken Thompson; (AT&T Bell Laboratories)
Developer(s)	Various open-source and commercial developers
Initial release	February 1973; 51 years ago
Written in	C
Operating system	Unix, Unix-like, Plan 9, Inferno, MSX-DOS, IBM i
Platform	Cross-platform
Type	Command
License	coreutils: GPLv3+; Plan 9: MIT License
Website	man7.org/linux/man-pages/man1/uniq.1.html

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uniq is a utility command on Unix, Plan 9, Inferno, and Unix-like operating systems which, when fed a text file or standard input, outputs the text with adjacent identical lines collapsed to one, unique line of text.

Overview

The command is a kind of filter program. Typically it is used after sort. It can also output only the duplicate lines (with the -d option), or add the number of occurrences of each line (with the -c option). For example, the following command lists the unique lines in a file, sorted by the number of times each occurs:

$ sort file | uniq -c | sort -n

Using uniq like this is common when building pipelines in shell scripts.

History

First appearing in Version 3 Unix,^[1] uniq is now available for a number of different Unix and Unix-like operating systems. It is part of the X/Open Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX and the Single Unix Specification.^[2]

The version bundled in GNU coreutils was written by Richard Stallman and David MacKenzie.^[3]

A uniq command is also part of ASCII's MSX-DOS2 Tools for MSX-DOS version 2.^[4]

The command is available as a separate package for Microsoft Windows as part of the GnuWin32 project^[5] and the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.^[6]

The uniq command has also been ported to the IBM i operating system.^[7]

References

^ McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 (PDF) (Technical report). CSTR. Bell Labs. 139.
^ uniq – Shell and Utilities Reference, The Single UNIX Specification, Version 4 from The Open Group
^ uniq(1) – Linux General Commands Manual
^ MSX-DOS2 Tools User's Manual by ASCII Corporation
^ CoreUtils for Windows
^ Native Win32 ports of some GNU utilities
^ IBM. "IBM System i Version 7.2 Programming Qshell" (PDF). IBM. Retrieved 2020-09-05.

External links

uniq(1) – Linux User Manual – User Commands
uniq(1) – Plan 9 Programmer's Manual, Volume 1
uniq(1) – Inferno General commands Manual
SourceForge UnxUtils – Port of several GNU utilities to Windows

[reader-1] McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 (PDF) (Technical report). CSTR. Bell Labs. 139.

[2] uniq – Shell and Utilities Reference, The Single UNIX Specification, Version 4 from The Open Group

[3] uniq(1) – Linux General Commands Manual

[4] MSX-DOS2 Tools User's Manual by ASCII Corporation

[5] CoreUtils for Windows

[6] Native Win32 ports of some GNU utilities

[7] IBM. "IBM System i Version 7.2 Programming Qshell" (PDF). IBM. Retrieved 2020-09-05.

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@@ Line 1: / Line 1: @@
+{{short description|Unix text filtering utility}}
-{{lowercase|title=uniq}}
-{{about|the Unix utility|other uses|Uniq (disambiguation)}}
+{{about|the command-line utility|other uses|Uniq (disambiguation)}}
+{{lowercase title}}
-'''uniq''' is a [[Unix]] utility which, when fed a text file, outputs the file with adjacent identical lines collapsed to one.  It is a kind of [[filter program]]. Typically it is used after [[Sort (Unix)|sort]]. It can also output only the duplicate lines (with the <tt>-d</tt> option), or add the number of occurrences of each line (with the <tt>-c</tt> option).
+{{Infobox software
+| name                   = uniq
+| logo                   =
+| screenshot             =
+| screenshot size        =
+| caption                =
+| author                 = [[Ken Thompson]]<br />([[AT&T Bell Laboratories]])
+| developer              = Various [[open-source software|open-source]] and [[commercial software|commercial]] developers
+| released               = {{Start date and age|1973|2}}
+| latest release version =
+| latest release date    =
+| programming language   = [[C (programming language)|C]]
+| operating system       = [[Unix]], [[Unix-like]], [[Plan 9 from Bell Labs|Plan 9]], [[Inferno (operating system)|Inferno]], [[MSX-DOS]], [[IBM i]]
+| platform               = [[Cross-platform]]
+| genre                  = [[Command (computing)|Command]]
+| license                = [[coreutils]]: [[GPLv3+]]<br />Plan 9: [[MIT License]]
+| website                = {{URL|http://man7.org/linux/man-pages/man1/uniq.1.html}}
+}}
+<code>'''uniq'''</code> is a utility [[command (computing)|command]] on [[Unix]], [[Plan 9 from Bell Labs|Plan 9]], [[Inferno (operating system)|Inferno]], and [[Unix-like]] [[operating system]]s which, when fed a [[text file]] or [[Standard streams#Standard input (stdin)|standard input]], outputs the text with adjacent identical lines collapsed to one, unique line of text.
+==Overview==
-An example: To see the list of lines in a file, sorted by the number of times each occurs:
+The command is a kind of [[filter program]]. Typically it is used after [[Sort (Unix)|<code>sort</code>]]. It can also output only the duplicate lines (with the <code>-d</code> option), or add the number of occurrences of each line (with the <code>-c</code> option). For example, the following command lists the unique lines in a file, sorted by the number of times each occurs:
-:<tt>sort file | uniq -c | sort -n</tt>
+<syntaxhighlight lang="sh">
-Using uniq like this is common when building [[pipeline (software)|pipelines]] in [[shell script]]s.
+$ sort file | uniq -c | sort -n
+</syntaxhighlight>
+Using <code>uniq</code> like this is common when building [[pipeline (software)|pipelines]] in [[shell script]]s.
-==Switches==
-*-u   Print only lines which are not repeated (unique) in the original file
+==History==
-*-d   Don't output lines that are not repeated in the input.
+First appearing in [[Version 3 Unix]],<ref name="reader">{{cite tech report
-*-c   Generate an output report in default style except that each line is preceded by a count of the number of times it occurred.  If this option is specified, the -u and -d options are ignored if either or both are also present.
+ | first1      = M. D.
-*-i   Ignore case differences when comparing lines
+ | last1       = McIlroy
-*-s   Skips a number of characters in a line
+ | authorlink1 = Doug McIlroy
-*-w   Specifies the number of characters to compare in lines, after any characters and fields have been skipped
+ | year        = 1987
-*--help    Displays a help message
+ | url         = https://www.cs.dartmouth.edu/~doug/reader.pdf
-*--version Displays version number on stdout and exits.
+ | title       = A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986
+ | series      = CSTR
+ | number      = 139
+ | institution = Bell Labs}}</ref> <code>uniq</code> is now available for a number of different [[Unix]] and [[Unix-like]] [[operating system]]s. It is part of the [[X/Open]] Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX and the [[Single Unix Specification]].<ref>{{man|cu|uniq|SUS}}</ref>
+The version bundled in [[GNU]] [[coreutils]] was written by [[Richard Stallman]] and David MacKenzie.<ref>{{man|1|uniq|ManKier}}</ref>
+A <code>uniq</code> command is also part of [[ASCII Corporation|ASCII]]'s ''MSX-DOS2 Tools'' for [[MSX-DOS]] version 2.<ref>[https://archive.org/details/MSXDOS2TOOLS MSX-DOS2 Tools User's Manual by ASCII Corporation]</ref>
+The command is available as a separate package for [[Microsoft Windows]] as part of the [[GnuWin32]] project<ref>[http://gnuwin32.sourceforge.net/packages/coreutils.htm CoreUtils for Windows]</ref> and the [[UnxUtils]] collection of [[Native (computing)|native]] [[Windows API|Win32]] [[porting|ports]] of common GNU Unix-like utilities.<ref>[http://unxutils.sourceforge.net/ Native Win32 ports of some GNU utilities]</ref>
+The {{Mono|uniq}} command has also been ported to the [[IBM i]] operating system.<ref>{{cite web |title=IBM System i Version 7.2 Programming Qshell |language=en |author=IBM |website=[[IBM]] |author-link=IBM |url=https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_74/rzahz/rzahzpdf.pdf?view=kc |access-date=2020-09-05 }}</ref>
 ==See also==
-*[[List of Unix programs]]
+* [[List of Unix commands]]
-==External links==
+==References==
+{{Reflist}}
-*[http://www.linuxmanpages.com/man1/uniq.1.php uniq's] [[Linux]] [[manpage]]
-*[http://sourceforge.net/projects/unxutils/ SourceForge UnxUtils – Port of the most important GNU utilities to Windows]
+==External links==
-{{unix commands}}
+{{Wikibooks|Guide to Unix|Commands}}
+* {{man|1|uniq|Linux}}
+* {{man|1|uniq|Plan 9}}
+* {{man|1|uniq|Inferno}}
+* [https://sourceforge.net/projects/unxutils/ SourceForge UnxUtils – Port of several GNU utilities to Windows]
+{{Unix commands}}
-[[Category:Unix software]]
+{{Plan 9 commands}}
+{{Core Utilities commands}}
+[[Category:Unix text processing utilities]]
-[[fr:Uniq]]
+[[Category:Unix SUS2008 utilities]]
-[[ko:Uniq]]
+[[Category:Plan 9 commands]]
-[[it:Uniq]]
+[[Category:Inferno (operating system) commands]]
-[[hu:Uniq]]
+[[Category:IBM i Qshell commands]]
-[[ja:Uniq]]
-[[pl:Uniq]]
-[[pt:Uniq]]
-[[ru:Uniq]]
-[[uk:Uniq]]

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
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Miscellaneous	bc cal expr lp od sleep true and false
Categories Standard Unix programs Unix SUS2008 utilities List

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File system	chmod chgrp cmp cp dd du file gzip ls mkdir pwd rm split tee touch
Processes	kill ps
User environment	passwd who
Text processing	awk basename comm diff ed eqn join sed sort spell strings tail tr troff uniq wc
Shell builtins	echo test
Networking	ip/ipconfig ip/ping netstat
Searching	grep
Software development	ar hoc lex nm strip yacc
Miscellaneous	bc cal fortune sleep
Category

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