Uniq

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

uniq is a Unix utility which, when fed a text file, outputs the file with adjacent identical lines collapsed to one.

First appearing in Version 3 Unix, 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.

See also

• List of Unix programs

External links

• uniq's Linux manpage
• SourceForge UnxUtils – Port of several GNU utilities to Windows