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From: mouse@mcgill-vision.UUCP (der Mouse)
Newsgroups: comp.unix.questions
Subject: Re: egrep, fgrep, grep
Message-ID: <741@mcgill-vision.UUCP>
Date: Thu, 9-Apr-87 18:51:22 EST
Article-I.D.: mcgill-v.741
Posted: Thu Apr  9 18:51:22 1987
Date-Received: Sun, 19-Apr-87 10:19:16 EST
References: <276@wolf.UUCP>
Organization: McGill University, Montreal
Lines: 27

In article <276@wolf.UUCP>, billw@wolf.UUCP (The Dealy Lama) writes:
> I have always used grep when searching expressions, and gotten along
> fine. So what is the difference between grep, egrep, and fgrep?

The difference is supposed to be:

grep:	workhorse, the "usual" program
fgrep:	fast version, for use when the "expression" is a constant
	  string (no regular expression support)
egrep:	extended version, fancier regular expressions, but slower and
	  chews up more memory.

In fact, of the above three there is no reason to use grep, and use
fgrep only when the string is unknown (such as an argument to a shell
script) and you don't know whether it may contain r.e. metacharacters.
Egrep is usually the fastest and generally best of the three.

The above paragraph is usually true, but if you really care I would
advise doing careful tests on your system to find out which one is
really fastest, smallest, or whatever your criterion for "best" is.

Note that there are readily-available searching programs much better
than any of the above.  Contact your nearest mod.sources archive site.

					der Mouse

				(mouse@mcgill-vision.uucp)