Uniq

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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.

Switches

-u Print only those lines which are not repeated (unique) in the input.
-d Print only those lines which are repeated in the input.
-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
-f Ignore a number of fields in a line
-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.

External links

v t e Unix command-line interface programs and shell builtins

File system	cat cd chmod chown chgrp cksum cmp cp dd du df file fsck fuser ln ls mkdir mount mv pax pwd rm rmdir size split tee touch type umask

Processes	at bg chroot cron fg kill killall nice pgrep pidof pkill ps pstree time top

User environment	clear env exit finger history id logname mesg passwd su sudo uptime talk tput uname w wall who whoami write

Text processing	awk banner basename comm csplit cut diff dirname ed ex fmt fold head iconv join less more paste sed sort spell strings tail tr uniq vi wc xargs

Shell builtins	alias echo expr printf sleep test true and false unset wait yes

Networking	dig host ifconfig inetd netcat netstat nslookup ping rdate rlogin route ssh traceroute

Searching	find grep locate whatis whereis

Documentation	apropos help man

Miscellaneous	bc dc cal date lp lpr

List of Unix utilities

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Uniq

Switches

See also

External links