Uniq

uniq is a Unix utility which, when fed a text file, outputs the file with adjacent identical lines collapsed to one.

Contents

• mv uniq eoeo
• mv uniq luv again
• References

First appearing in Version 3 Unix, 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:

Using uniq like this is common when building pipelines in shell scripts.