Linux and Unix comm command

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About comm
Syntax
Examples
Related commands
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About comm

Compare two sorted files line-by-line.

Syntax

comm [OPTION]... FILE1 FILE2

Description

Compare sorted files FILE1 and FILE2 line-by-line.

With no options, comm produces 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. Each of these columns can be suppressed individually with options.

Options

-1 suppress column 1 (lines unique to FILE1)
-2 suppress column 2 (lines unique to FILE2)
-3 suppress column 3 (lines that appear in both files)
--check-order check that the input is correctly sorted, even if all input lines are pairable
--nocheck-order do not check that the input is correctly sorted
--output-delimiter=STR separate columns with string STR
--help display a help message, and exit.
--version output version information, and exit.

Examples

comm -12 myfile1.txt myfile2.txt

Print only the lines present in both myfile1.txt and myfile2.txt.

comm -3 myfile1.txt myfile2.txt

Print only the lines that are present in myfile1.txt and not myfile2.txt, and vice versa.

Related commands

cmp
diff
join
sort
uniq