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From: @(#)comm.1 8.1 (Berkeley) 6/6/93
$FreeBSD$
.Dd December 12, 2009 .Dt COMM 1 .Os .Sh NAME .Nm comm .Nd select or reject lines common to two files .Sh SYNOPSIS .Nm .Op Fl 123i .Ar file1 file2 .Sh DESCRIPTION The .Nm utility reads .Ar file1 and .Ar file2 , which should be sorted lexically, and produces three text columns as output: lines only in .Ar file1 ; lines only in .Ar file2 ; and lines in both files.
p The filename ``-'' means the standard input.
p The following options are available: l -tag -width indent t Fl 1 Suppress printing of column 1, lines only in .Ar file1 . t Fl 2 Suppress printing of column 2, lines only in .Ar file2 . t Fl 3 Suppress printing of column 3, lines common to both. t Fl i Case insensitive comparison of lines. .El
p 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.
p The .Nm utility assumes that the files are lexically sorted; all characters participate in line comparisons. .Sh ENVIRONMENT The .Ev LANG , .Ev LC_ALL , .Ev LC_COLLATE , and .Ev LC_CTYPE environment variables affect the execution of .Nm as described in .Xr environ 7 . .Sh EXIT STATUS .Ex -std .Sh SEE ALSO .Xr cmp 1 , .Xr diff 1 , .Xr sort 1 , .Xr uniq 1 .Sh STANDARDS The .Nm utility conforms to .St -p1003.2-92 .
p The .Fl i option is an extension to the .Tn POSIX standard. .Sh HISTORY A .Nm command appeared in .At v4 .