1.\" Copyright (c) 1989, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the Institute of Electrical and Electronics Engineers, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" From: @(#)comm.1 8.1 (Berkeley) 6/6/93 36.\" $FreeBSD$ 37.\" 38.Dd July 3, 2004 39.Os 40.Dt COMM 1 41.Sh NAME 42.Nm comm 43.Nd select or reject lines common to two files 44.Sh SYNOPSIS 45.Nm 46.Op Fl 123i 47.Ar file1 file2 48.Sh DESCRIPTION 49The 50.Nm 51utility reads 52.Ar file1 53and 54.Ar file2 , 55which should be 56sorted lexically, and produces three text 57columns as output: lines only in 58.Ar file1 ; 59lines only in 60.Ar file2 ; 61and lines in both files. 62.Pp 63The filename ``-'' means the standard input. 64.Pp 65The following options are available: 66.Bl -tag -width indent 67.It Fl 1 68Suppress printing of column 1. 69.It Fl 2 70Suppress printing of column 2. 71.It Fl 3 72Suppress printing of column 3. 73.It Fl i 74Case insensitive comparison of lines. 75.El 76.Pp 77Each column will have a number of tab characters prepended to it 78equal to the number of lower numbered columns that are being printed. 79For example, if column number two is being suppressed, lines printed 80in column number one will not have any tabs preceding them, and lines 81printed in column number three will have one. 82.Pp 83The 84.Nm 85utility assumes that the files are lexically sorted; all characters 86participate in line comparisons. 87.Sh ENVIRONMENT 88The 89.Ev LANG , 90.Ev LC_ALL , 91.Ev LC_COLLATE , 92and 93.Ev LC_CTYPE 94environment variables affect the execution of 95.Nm 96as described in 97.Xr environ 7 . 98.Sh DIAGNOSTICS 99.Ex -std 100.Sh SEE ALSO 101.Xr cmp 1 , 102.Xr diff 1 , 103.Xr sort 1 , 104.Xr uniq 1 105.Sh STANDARDS 106The 107.Nm 108utility conforms to 109.St -p1003.2-92 . 110.Pp 111The 112.Fl i 113option is an extension to the 114.Tn POSIX 115standard. 116.Sh HISTORY 117A 118.Nm 119command appeared in 120.At v4 . 121