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From: edhall%rand-unix@sri-unix.UUCP
Newsgroups: net.unix-wizards
Subject: Re:  the many greps
Message-ID: <13610@sri-arpa.UUCP>
Date: Fri, 11-Nov-83 03:01:00 EST
Article-I.D.: sri-arpa.13610
Posted: Fri Nov 11 03:01:00 1983
Date-Received: Tue, 15-Nov-83 02:51:09 EST
Lines: 30

There are definitely still enough differences to require 3 greps.
For example, try comparing:

  egrep '....................................................................'

with:

  grep '....................................................................'

The grep will be much faster than the egrep.  This seems to be true for any
regular expression with a lot of wild card characters (i.e. `.''s).

Also, when you are looking for matches with a long list of words, you'll
find:

  fgrep -f list

much faster than:

  egrep -f list

(Alas, in both cases the maximum number of strings in `list' has a fairly
small limit--about 400 for fgrep, and substantially less for egrep.)

So, though I use egrep in about 85% of cases, I still find some use for
fgrep and plain ol' grep.

		-Ed Hall
		edhall@rand-unix        (ARPA)
		decvax!randvax!edhall   (UUCP)