Path: utzoo!attcan!uunet!ogicse!uwm.edu!zaphod.mps.ohio-state.edu!usc!apple!mips!daver!lynx!m5
From: m5@lynx.uucp (Mike McNally)
Newsgroups: comp.unix.wizards
Subject: Re: serious awk bug
Keywords: awk
Message-ID: <7232@lynx.UUCP>
Date: 14 Mar 90 15:25:00 GMT
References: <702@chem.ucsd.EDU>
Organization: Lynx Real-Time Systems, Inc., Campbell CA
Lines: 52

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 }
>'

>When given the following input

>b
>ab

>It produces the following output

>2: b
>1: ab
>2: ab

>Basically, the line "ab" should match only rule 2 . . .


I disagree:

    a*[^b] => <null>[^b] => <null>a

The a* is matching the empty string, and the [^b] is matching the a.


















-- 
Mike McNally                                    Lynx Real-Time Systems
uucp: {voder,athsys}!lynx!m5                    phone: 408 370 2233

            Where equal mind and contest equal, go.