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From: lyda@acsu.buffalo.edu (kevin lyda)
Newsgroups: comp.unix.wizards
Subject: Re: Word-oriented GREP
Message-ID: <73515@eerie.acsu.Buffalo.EDU>
Date: 28 Apr 91 17:08:59 GMT
References: <1991Apr15.014626.28903@berlioz.nsc.com> <1991Apr15.044312.27326@iwarp.intel.com> <b08Gc5!p1@cs.psu.edu>
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In article <b08Gc5!p1@cs.psu.edu> flee@cs.psu.edu (Felix Lee) writes:
.(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

.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.)

why not cut down your search space by using grep to find the lines with
the matching patterns and then using perl, or some other unix tool to grab
the pattern.... from the previous example you could do:

grep V\[0-9\]\[0-9\]\[0-9\] fred.c | tr ' ' \012 | grep V\[0-9\]\[0-9\]\[0-9\]

of course that assumes that your field separators are spaces.

	a non-wizard,
		kevin