select or reject lines common to two
comm utility reads
file1 and file2, which should be
sorted lexically, and produces three text columns as output: lines only in
file1; lines only in file2; and
lines in both files.
The filename ‘-’ means the standard input.
The options are as follows:
- Suppress printing of column 1.
- Suppress printing of column 2.
- Suppress printing of column 3.
- Fold case in line comparisons.
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.
comm assumes that the files are lexically
sorted; all characters participate in line comparisons.
comm utility exits 0 on
success, and >0 if an error occurs.
cmp(1), diff(1), sort(1), uniq(1)
comm utility conforms to
IEEE Std 1003.1-2008 (“POSIX.1”).
The flag [
-f] is an extension to that
comm command appeared in
Version 4 AT&T UNIX.