.TH COMM 1 
.SH NAME
comm \- select or reject lines common to two sorted files
.SH SYNOPSIS
.B comm
[
.B \-123
] file1 file2
.SH DESCRIPTION
.I comm
reads
.I file1
and
.I file2,
which should be ordered in ASCII collating sequence,
and produces a three column output: lines only in
.I file1;
lines only in
.I file2;
and lines in both files.
The filename `\-' means the standard input.
.PP
Flags 1, 2, or 3 suppress printing of the corresponding
column.
Thus
.B comm
.B \-12
prints only the lines common to the two files;
.B comm
.B \-23
prints only lines in the first file but not in the second;
.B comm
.B \-123
is a no-op.
.PP
.SH "SEE ALSO"
cmp(1), diff(1), uniq(1)