debian man page for combine

COMBINE(1)																COMBINE(1)

NAME
       combine - combine sets of lines from two files using boolean operations

SYNOPSIS
       combine file1 and file2

       combine file1 not file2

       combine file1 or file2

       combine file1 xor file2

       _ file1 and file2 _

       _ file1 not file2 _

       _ file1 or file2 _

       _ file1 xor file2 _

DESCRIPTION
       combine combines the lines in two files. Depending on the boolean operation specified, the contents will be combined in different ways:

       and Outputs lines that are in file1 if they are also present in file2.

       not Outputs lines that are in file1 but not in file2.

       or  Outputs lines that are in file1 or file2.

       xor Outputs lines that are in either file1 or file2, but not in both files.

       "-" can be specified for either file to read stdin for that file.

       The input files need not be sorted, and the lines are output in the order they occur in file1 (followed by the order they occur in file2
       for the two "or" operations). Bear in mind that this means that the operations are not commutative; "a and b" will not necessarily be the
       same as "b and a". To obtain commutative behavior sort and uniq the result.

       Note that this program can be installed as "_" to allow for the syntactic sugar shown in the latter half of the synopsis (similar to the
       test/[ command). It is not currently installed as "_" by default, but you can alias it to that if you like.

SEE ALSO
       join(1)

AUTHOR
       Copyright 2006 by Joey Hess <joey@kitenet.net>

       Licensed under the GNU GPL.

moreutils							    2012-04-09								COMBINE(1)