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.
    – nopcorn
    Commented Mar 8, 2013 at 3:05

1 Answer 1


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
    Commented Mar 8, 2013 at 6:19
  • @jordanm ah, I take it wrong, answer updated, thanks for pointing out
    – daisy
    Commented Mar 8, 2013 at 6:26
  • However, all my uses of uniq combine with sort
    – Bernhard
    Commented Mar 8, 2013 at 12:30
  • Downvote removed
    – jordanm
    Commented Mar 8, 2013 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
    Commented Mar 8, 2013 at 17:06

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .