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COMM(1)                                  BSD 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 lexically, and produces three text col-umns columns
     umns 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.

     -2      Suppress printing of column 2.

     -3      Suppress printing of column 3.

     -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 characters participate in line com-parisons. comparisons.
     parisons.

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.

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.

BUGS
     Input lines are limited to LINE_MAX (2048) characters in length.

BSD                                           January 26, 2005                                           BSD