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COMM(1)			    General Commands Manual		       COMM(1)

NAME
       comm -- select or reject	lines common to	two files

SYNOPSIS
       comm [-123i] file1 file2

DESCRIPTION
       The  comm  utility  reads file1 and file2, which	should be sorted lexi-
       cally, and produces three text columns as output: lines only in	file1;
       lines only in file2; and	lines in both files.

       The filename ``-'' means	the standard input.

       The following options are available:

       -1      Suppress	printing of column 1, lines only in file1.

       -2      Suppress	printing of column 2, lines only in file2.

       -3      Suppress	printing of column 3, lines common to both.

       -i      Case insensitive	comparison of lines.

       Each  column will have a	number of tab characters prepended to it equal
       to the number of	lower numbered columns that are	 being	printed.   For
       example,	 if  column  number  two is being suppressed, lines printed in
       column number one will not have any  tabs  preceding  them,  and	 lines
       printed in column number	three will have	one.

       The comm	utility	assumes	that the files are lexically sorted; all char-
       acters participate in line comparisons.

ENVIRONMENT
       The LANG, LC_ALL, LC_COLLATE, and LC_CTYPE environment variables	affect
       the execution of	comm as	described in environ(7).

EXIT STATUS
       The comm	utility	exits 0	on success, and	>0 if an error occurs.

EXAMPLES
       Assuming	a file named example.txt with the following contents:

	     a
	     b
	     c
	     d

       Show lines only in example.txt, lines only in stdin and common lines:

	     $ echo -e "B\nc" |	comm example.txt -
		     B
	     a
	     b
			     c
	     d

       Show only common	lines doing case insensitive comparisons:

	     $ echo -e "B\nc" |	comm -1	-2 -i example.txt -
	     b
	     c

SEE ALSO
       cmp(1), diff(1),	sort(1), uniq(1)

STANDARDS
       The comm	utility	conforms to IEEE Std 1003.2-1992 ("POSIX.2").

       The -i option is	an extension to	the POSIX standard.

HISTORY
       A comm command appeared in Version 4 AT&T UNIX.

FreeBSD	14.3			 July 27, 2020			       COMM(1)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=comm&sektion=1&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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