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From: flee@cs.psu.edu (Felix Lee)
Newsgroups: comp.unix.wizards,comp.lang.perl
Subject: Re: Word-oriented GREP
Message-ID: <b08Gc5!p1@cs.psu.edu>
Date: 15 Apr 91 15:12:09 GMT
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(from comp.unix.questions)
| When I use the command "grep V\[0-9\]\[0-9\]\[0-9\] fred.c" it returns
| 	#define VERSION "V002"
|   or somesuch.  What I would really like is just the string of characters
|   which matched:
| 	V002

I've wanted an "xgrep" tool for a while.  It would scan an input
stream for a pattern and print any part of the stream that matches.

Randal Schwartz offers a Perl solution, but you can't escape line
boundaries.  Consider the pattern
	^(.*\n){0,3}.*Able.*(\n.*){0,3}$
which means, print three lines of context around any line that
contains "Able".  Generalized context grep.  You can write patterns
for any type of simple context.

(You can actually do this in Perl, but it becomes extremely
inefficient for large files, because you can only apply patterns to
strings, not streams.)
--
Felix Lee	flee@cs.psu.edu