I'm confused on the use of the uniq command. Can anyone explain this command and how to use it?

How can I use uniq without specifying any option? Any example would be helped and appreciated.

  • 8
    Have you tried reading the man page for uniq? man uniq. – n0pe Mar 8 '13 at 3:05

uniq read file line-by-line, and only consider a duplicate when the current line is exactly the same as the last line,

i.e for a input file like this,


You'll get an output like this,


To use it, you can either run it though a pipe, i.e

command | uniq

Or get the input from a file like this,

uniq < input > output

  • I have to downvote this because it doesn't appear to answer the question at all. The question is about uniq, not sort. Data does need to be sorted for uniq to work, but that is not included here. – jordanm Mar 8 '13 at 6:19
  • @jordanm ah, I take it wrong, answer updated, thanks for pointing out – daisy Mar 8 '13 at 6:26
  • However, all my uses of uniq combine with sort – Bernhard Mar 8 '13 at 12:30
  • Downvote removed – jordanm Mar 8 '13 at 15:37
  • For completeness, I'd suggest including a demonstration of how uniq and sort work together; I agree that uniq is most useful when combined with sort. – davidcl Mar 8 '13 at 17:06

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