LINUX COMMAND ATLAS · COMMAND GUIDE

Linux uniq command

Report or remove adjacent repeated lines; sort first to group matches.

GNU Coreutils

Syntax

Command form

uniq [OPTION]... [INPUT [OUTPUT]]

6 options

Option	What it does
`-c, --count`	Prefix each output line with its number of occurrences.
`-d, --repeated`	Print only repeated lines.
`-u, --unique`	Print only lines that occur once.
`-i, --ignore-case`	Ignore case when comparing lines.
`-f, --skip-fields=N`	Skip N fields before comparing.
`-s, --skip-chars=N`	Skip N characters before comparing.

2 examples

Report or remove adjacent repeated lines; sort first to group matches.

sort names.txt | uniq -c

Print values that occur more than once.

sort names.txt | uniq -d

uniq only detects adjacent duplicate lines, so sort the input first when duplicates may be separated.