Linux Commands Examples

A great documentation place for Linux commands


compare two sorted files line by line

see also : join - uniq


comm [OPTION]... FILE1 FILE2

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comm -12 file1 file2

Print only lines present in both file1 and file2.

comm -3 file1 file2

Print lines in file1 not in file2, and vice versa.


Compare sorted files FILE1 and FILE2 line by line.

With no options, produce three-column output. Column one contains lines unique to FILE1, column two contains lines unique to FILE2, and column three contains lines common to both files.


suppress column 1 (lines unique to FILE1)


suppress column 2 (lines unique to FILE2)


suppress column 3 (lines that appear in both files)


check that the input is correctly sorted, even if all input lines are pairable


do not check that the input is correctly sorted


separate columns with STR


display this help and exit


output version information and exit

Note, comparisons honor the rules specified by ’LC_COLLATE’.


Copyright © 2012 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

reporting bugs

Report comm bugs to bug-coreutils[:at:]gnu[:dot:]org
GNU coreutils home page: <>
General help using GNU software: <>
Report comm translation bugs to <>

see also

join , uniq

The full documentation for comm is maintained as a Texinfo manual. If the info and comm programs are properly installed at your site, the command

info coreutils 'comm invocation'

should give you access to the complete manual.


Written by Richard M. Stallman and David MacKenzie.

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