NAME

comm − select or reject lines common to two sorted files

SYNOPSIS

comm [− [123]] file1 file2

DESCRIPTION

comm reads file1 and file2, which should be ordered in increasing collating sequence (see sort(1) and Environment Variables below), and produces a three-column output: lines only in file1; lines only in file2; and lines in both files. The file name − 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. 

EXTERNAL INFLUENCES

Environment Variables

LC_COLLATE determines the collating sequence comm expects from the input files. 

LANG determines the language in which messages are displayed. 

If LC_COLLATE is not specified in the environment or is set to the empty string, the value of LANG is used as a default.  If LANG is not specified or is set to the empty string, a default of “C” (see lang(5)) is used instead of LANG.  If any internationalization variable contains an invalid setting, comm behaves as if all internationalization variables are set to “C”.  See environ(5).

International Code Set Support

Single- and multi-byte character code sets are supported with the exception that multi-byte character file names are not supported. 

EXAMPLES

The following command prints all lines common to the files green and yellow:

comm -12 green yellow

It is assumed that the contents of green and yellow have been ordered in the collating sequence defined by the LC_COLLATE or LANG environment variable. 

SEE ALSO

cmp(1), diff(1), sdiff(1), sort(1), uniq(1). 

STANDARDS CONFORMANCE

comm: SVID2, XPG2, XPG3

Hewlett-Packard Company  —  HP-UX Release 8.05: June 1991