http://www.linux.com/print.pl?sid=06/05/19/1920231
grep changes quick reference
-Cx prints context lines before and after matches and must have argument x.
--color outputs matches in color (default red).
-D action specifies an action to take on device files (the default is "read").
--exclude= filespec excludes files matching filespec.
--include= filespec only searches through files matching filespec.
--label= name makes name the new label for stdin.
--line-buffered turns on line buffering.
-m X stops searching input after finding X matched lines.
-o outputs only matched patterns, not entire lines.
-P uses Perl-style regular expressions.
