comm --
select or reject lines common to two sorted files
Syntax
comm [ -123 ] file1file2
Description
comm reads file1 and file2, which
should be ordered
according to the collating sequence defined by the current locale
(see
sort(C)),
and produces a three-column output: lines only in file1;
lines only in file2; and lines in both files. The filename
``-'' means the standard input.
Flags 1, 2, or 3 suppress printing of the corresponding column. Thus
comm -12 prints only the lines common to the two files;
comm -23 prints only lines in the first file but not in
the second; comm -123 is a no-op (does nothing).
comm understands the -- option delimiter.
Exit values
comm returns the following values:
0
all input files were successfully output as specified