Awk scans input files for specified patterns and can perform an associated
action when a line of the file matches the pattern.

This is the One True version of awk described in "The AWK Programming Language"
by Al Aho, Brian Kernighan, and Peter Weinberger
(Addison-Wesley, 1988, ISBN 0-201-07981-X).

WWW: http://cm.bell-labs.com/cm/cs/awkbook/index.html