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:''This article is about the Unix utility. For the nightclub, see [[UNIQ]]. For the insurance company, see [http://www.uniqgroup.com/ UNIQ&nbsp;benefit&nbsp;solutions<sup>&reg;</sup>].''
:''This article is about the Unix utility. For the nightclub, see [[UNIQ]]. For the insurance company, see [http://www.uniqgroup.com/ UNIQ&nbsp;benefit&nbsp;solutions<sup>&reg;</sup>]. For the fruit, see [[Ugli fruit]].''


'''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]]. 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).
'''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]]. 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).

Revision as of 13:48, 28 August 2005

This article is about the Unix utility. For the nightclub, see UNIQ. For the insurance company, see UNIQ benefit solutions®. For the fruit, see Ugli fruit.

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. 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).

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

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

Switches

  • -u Print only lines which are not repeated in the original file
  • -d Print one copy only of each repeated line in the input file.
  • -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.