Jump to content

Uniq: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
mNo edit summary
Moaia (talk | contribs)
386 edits
fixed poor tone and style
Line 22: Line 22:


==Overview==
==Overview==
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).
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:

An example: To see the list of lines in a file, sorted by the number of times each occurs:
sort file | uniq -c | sort -n
sort file | uniq -c | sort -n

Using uniq like this is common when building [[pipeline (software)|pipelines]] in [[shell script]]s.
Using <tt>uniq</tt> like this is common when building [[pipeline (software)|pipelines]] in [[shell script]]s.


==History==
==History==
Line 38: Line 37:
| series = CSTR
| series = CSTR
| number = 139
| number = 139
| institution = Bell Labs}}</ref> it is now available for a number of different [[Unix]] and [[Unix-like]] [[operating system]]s
| institution = Bell Labs}}</ref> <tt>uniq</tt> is now available for a number of different [[Unix]] and [[Unix-like]] [[operating system]]s. The version bundled in [[GNU]] [[coreutils]] was written by [[Richard Stallman]] and David MacKenzie.<ref>https://linux.die.net/man/1/uniq</ref> A <tt>uniq</tt> command is also part of [[ASCII Corporation|ASCII]]'s ''MSX-DOS2 Tools'' for [[MSX-DOS]] version 2.<ref>[https://ia902205.us.archive.org/5/items/MSXDOS2TOOLS/MSX-DOS2%20TOOLS.pdf MSX-DOS2 Tools User's Manual by ASCII Corporation]</ref>

The version of <tt>'''uniq'''</tt> bundled in [[GNU]] [[coreutils]] was written by [[Richard Stallman]] and David MacKenzie.<ref>https://linux.die.net/man/1/uniq</ref>

A <tt>'''uniq'''</tt> command is also part of [[ASCII Corporation|ASCII]]'s ''MSX-DOS2 Tools'' for [[MSX-DOS]] version 2.<ref>[https://ia902205.us.archive.org/5/items/MSXDOS2TOOLS/MSX-DOS2%20TOOLS.pdf MSX-DOS2 Tools User's Manual by ASCII Corporation]</ref>


==See also==
==See also==

Revision as of 17:18, 2 February 2020

This article is about the Unix utility. For other uses, see Uniq (disambiguation).


uniq
Original author(s)Ken Thompson
Developer(s)AT&T Bell Laboratories
Initial releaseFebruary 1973; 51 years ago (1973-02)
Operating systemUnix and Unix-like, MSX-DOS
TypeCommand
LicenseGNU GPL v3
Websiteman7.org/linux/man-pages/man1/uniq.1.html

uniq is a Unix utility which, when fed a text file or STDIN, 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. The version bundled in GNU coreutils was written by Richard Stallman and David MacKenzie.[2] A uniq command is also part of ASCII's MSX-DOS2 Tools for MSX-DOS version 2.[3]

See also

References

  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. ^ https://linux.die.net/man/1/uniq
  3. ^ MSX-DOS2 Tools User's Manual by ASCII Corporation
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=Uniq&oldid=938833466"