⊕ Usage

comm [ options ... ] file1 file2

⊕ Purpose

 

To indicate which lines in the two input files are unique or common.

⊕ Major options

 

-1

 

Do not print column one (lines unique to file1).

 

Do not print column two (lines unique to file2).

 

Do not print column three (lines common to both files).

⊕ Behavior

 

Read the two files line by line. The input files must be sorted. Produce three columns of output: lines that are only in file1, lines that are only in file2, and lines that are in both files. Either filename can be -, in which case comm reads standard input.

⊕ Caveats

 

The options are not intuitive; it is hard to remember to add an option in order to remove an output column!