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{{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==

*<tt>-u</tt> Print only lines which are not repeated (unique) in the original file
==History==
*<tt>-d</tt> Don't output lines that are not repeated in the input.
First appearing in [[Version 3 Unix]],<ref name="reader">{{cite tech report
*<tt>-c</tt> 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 <tt>-u</tt> and <tt>-d</tt> options are ignored if either or both are also present.
| first1 = M. D.
*<tt>-i</tt> Ignore case differences when comparing lines
| last1 = McIlroy
*<tt>-f</tt> Ignore a number of fields in a line
| authorlink1 = Doug McIlroy
*<tt>-s</tt> Skips a number of characters in a line
| year = 1987
*<tt>-w</tt> Specifies the number of characters to compare in lines, after any characters and fields have been skipped
| url = https://www.cs.dartmouth.edu/~doug/reader.pdf
*<tt>--help</tt> Displays a help message
| title = A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986
*<tt>--version</tt> Displays version number on stdout and exits.
| 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==
==See also==
*[[List of Unix programs]]
* [[List of Unix commands]]

==References==
{{Reflist}}


==External links==
==External links==
{{Wikibooks|Guide to Unix|Commands}}
*[http://www.linuxmanpages.com/man1/uniq.1.php uniq's] [[Linux]] [[manpage]]
* {{man|1|uniq|Linux}}
*[http://sourceforge.net/projects/unxutils/ SourceForge UnxUtils – Port of several GNU utilities to Windows]
* {{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}}
{{Unix commands}}
{{Plan 9 commands}}
{{Core Utilities commands}}


[[Category:Unix text processing utilities]]
[[Category:Unix text processing utilities]]
[[Category:Unix SUS2008 utilities]]
[[Category:Unix SUS2008 utilities]]
[[Category:Plan 9 commands]]

[[Category:Inferno (operating system) commands]]
[[cs:Uniq]]
[[Category:IBM i Qshell commands]]
[[el:Uniq]]
[[fr:Uniq]]
[[ko:Uniq]]
[[it:Uniq]]
[[hu:Uniq]]
[[ja:Uniq]]
[[pl:Uniq]]
[[pt:Uniq]]
[[ru:Uniq]]
[[uk:Uniq]]
[[vi:Uniq (Unix)]]

Latest revision as of 10:09, 25 July 2023

uniq
Original author(s)Ken Thompson
(AT&T Bell Laboratories)
Developer(s)Various open-source and commercial developers
Initial releaseFebruary 1973; 51 years ago (1973-02)
Written inC
Operating systemUnix, Unix-like, Plan 9, Inferno, MSX-DOS, IBM i
PlatformCross-platform
TypeCommand
Licensecoreutils: GPLv3+
Plan 9: MIT License
Websiteman7.org/linux/man-pages/man1/uniq.1.html

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

[edit]

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

[edit]

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]

See also

[edit]

References

[edit]
  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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