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Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: comp.bugs.4bsd,comp.bugs.sys5
Subject: egrep botch
Message-ID: <8759@utzoo.UUCP>
Date: Tue, 13-Oct-87 13:35:01 EDT
Article-I.D.: utzoo.8759
Posted: Tue Oct 13 13:35:01 1987
Date-Received: Tue, 13-Oct-87 13:35:01 EDT
Organization: U of Toronto Zoology
Lines: 21

The following bug appears to be present in egrep (the Bell/AT&T one, not
the comp.sources.unix one) on all extant versions of Unix.  Certainly it
is present in V7, 4.2BSD, Sunnix 3.2, and 386 System V Release 3.

	% echo 0 >foo
	% egrep '0.' foo
	% egrep '^0.' foo
	0
	%

Adding the "^" seems to convince egrep that "." can legitimately match
newline.  Changing "." to "[^x]" does not change the behavior.  Some quick
tests suggest that "$" does not produce a similar anomaly.  I can find no
statement in any manual that gives even a shred of legitimacy to this.

Unfortunately, I lack the time to root around in the somewhat obscure
innards of egrep to discover the exact cause and fix.  Anybody out there
feeling ambitious? :-)
-- 
"Mir" means "peace", as in           |  Henry Spencer @ U of Toronto Zoology
"the war is over; we've won".        | {allegra,ihnp4,decvax,utai}!utzoo!henry