uniq
From Wikipedia, the free encyclopedia
- 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. 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. Be careful, uniq expects its input to be already sorted; sometimes sort -u is what you need.
[edit] 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.
- -i Ignore case differences when comparing lines
- -s Skips a number of characters in a line
- -w Specifies the number of characters to compare in lines, after any characters and fields have been skipped
- --help Displays a help message
- --version Displays version number on stdout and exits.
[edit] See also
[edit] External links
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