uniq command tutorial in linux/unix with examples and use cases

linux uniq command – report or omit repeated lines.

Linux uniq command, which usually requires sorted input, compares and ranks only on adjacent lines.




  • -c, –count
    prefix lines by the number of occurrences
  • -d, –repeated
    only print duplicate lines, one for each group
  • -D
    print all duplicate lines
  • -f, –skip-fields=N
    avoid comparing the first N fields
  • –group[=METHOD]
    show all items, separating groups with an empty line;
  • -i, –ignore-case
    ignore differences in case when comparing
  • -s, –skip-chars=N
    avoid comparing the first N characters
  • -u, –unique
    only print unique lines
  • -z, –zero-terminated
    line delimiter is NUL, not newline
  • -w, –check-chars=N
    compare no more than N characters in lines


Remove adjacent duplicates using uniq command

➜ uniq test.log

Remove duplicates using sort and uniq commands

➜ sort test.log | uniq

Remove duplicates and count duplicates

➜ sort test.log | uniq -c
      3 hello 99
      5 test 73
      2 ylspirit 78

Show only duplicate rows

➜  uniq sort test.log | uniq -d

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