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From: bamford@ihuxp.UUCP (Bamford)
Newsgroups: net.micro.att
Subject: Re: UNIX PC command surprises...
Message-ID: <1247@ihuxp.UUCP>
Date: Mon, 24-Mar-86 17:55:32 EST
Article-I.D.: ihuxp.1247
Posted: Mon Mar 24 17:55:32 1986
Date-Received: Mon, 21-Apr-86 01:19:50 EST
References: <351@hropus.UUCP> <888@kitty.UUCP>
Organization: AT&T Bell Laboratories
Lines: 29

> In article <351@hropus.UUCP>, jrw@hropus.UUCP (Jim Webb) writes:
> > 	Has anyone else out there noticed that on the "7300" the
> > 	grep, egrep, and fgrep commands are IDENTICAL.  The other
> > 	day I did an egrep "nproc|NPROC" or some such thing and
> > 	it failed!  A quick cmp of grep and egrep yielded no 
> > 	differences, in fact, grep and fgrep are linked together.
> 
> 	Aw, come on!  *THINK*  I'm suprised that you haven't discovered that
> ``edit'', ``ex'', and ``vi'' are also identical and are linked together. Does
> that mean they are the same?
> 	In case you still don't know the answer...  In an program, argv[0] is
> the NAME by which the program was invoked.  Since the source code for grep &
> egrep is very similar, the same compiled program is used, with the argv[0]
> being used to switch the internal program logic.  The same situation is also
> used for the above editors.

It is true, and it is reasonable, that some programs modify their
behavior according to the name by which they are called.  However, the
original comment above was to the effect that "egrep" was not behaving
as advertised, and it appears to be because it is the same as "grep". 
egrep, grep, and fgrep use radically different methods and do not
normally share source, so seeing them linked together IS a surprise.
-- 

				Harold Bamford
				AT&T Bell Labs
				(cornet) 8-367-5744
				Naperville, Ill
				(312) 979-5744