uniq
{{short description|Unix text filtering utility}}
{{about|the command-line utility|other uses|Uniq (disambiguation)}}
{{lowercase title}}
{{Infobox software
| name = uniq
| logo =
| screenshot =
| screenshot size =
| caption =
| author = Ken Thompson
(AT&T Bell Laboratories)
| developer = Various open-source and commercial developers
| released = {{Start date and age|1973|2}}
| latest release version =
| latest release date =
| programming language = C
| operating system = Unix, Unix-like, Plan 9, Inferno, MSX-DOS, IBM i
| platform = Cross-platform
| genre = Command
| license = coreutils: GPLv3+
Plan 9: MIT License
| website = {{URL|http://man7.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
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,{{cite tech report
| first1 = M. D.
| last1 = McIlroy
| authorlink1 = Doug McIlroy
| year = 1987
| url = https://www.cs.dartmouth.edu/~doug/reader.pdf
| title = A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986
| series = CSTR
| number = 139
| institution = Bell Labs}} 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.{{man|cu|uniq|SUS}}
The version bundled in GNU coreutils was written by Richard Stallman and David MacKenzie.{{man|1|uniq|ManKier}}
A uniq command is also part of ASCII's MSX-DOS2 Tools for MSX-DOS version 2.[https://archive.org/details/MSXDOS2TOOLS MSX-DOS2 Tools User's Manual by ASCII Corporation]
The command is available as a separate package for Microsoft Windows as part of the GnuWin32 project[http://gnuwin32.sourceforge.net/packages/coreutils.htm CoreUtils for Windows] and the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.[http://unxutils.sourceforge.net/ Native Win32 ports of some GNU utilities]
The {{Mono|uniq}} command has also been ported to the IBM i operating system.{{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 }}
See also
References
{{Reflist}}
External links
{{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}}
{{Plan 9 commands}}
{{Core Utilities commands}}
Category:Unix text processing utilities
Category:Unix SUS2008 utilities