Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!mcsun!isgate!krafla!magnus
From: magnus@rhi.hi.is (Magnus Gislason)
Newsgroups: comp.unix.wizards
Subject: Re: serious awk bug
Keywords: awk
Message-ID: <1579@krafla.rhi.hi.is>
Date: 14 Mar 90 16:36:43 GMT
References: <702@chem.ucsd.EDU>
Organization: University of Iceland
Lines: 16

tps@chem.ucsd.edu (Tom Stockfisch) writes:
>The following awk script doesn't behave properly:
>#! /bin/sh
>awk '/^a*[^b]/	{  print "1:", $0 }
>/^a*b/ 	{ print "2:", $0 }
>'
[stuff deleted]
>Basically, the line "ab" should match only rule 2, but it matches both
>rules.  The following script:

In Regular Expressions `a*' meens 0 or more occurrencies of `a' and
`[^b]' meens any character except `b'.  In this case `a*[^b]' matches
0 `a's followed by a character that is not `b' (in this case `a').

I tried this with grep, egrep, sed and vi and they all behaved like awk
so I suppose it's the correct way.