Date: Thu, 23 Jan 2014 15:44:56 -0800 From: <dteske@FreeBSD.org> To: "'Warren Block'" <wblock@wonkity.com>, "'Devin Teske'" <dteske@FreeBSD.org> Cc: 'RW' <rwmaillists@googlemail.com>, freebsd-questions@freebsd.org Subject: RE: awk programming question Message-ID: <04d201cf1895$20956890$61c039b0$@FreeBSD.org> In-Reply-To: <alpine.BSF.2.00.1401231537260.80613@wonkity.com> References: <F01EB9CE742DEB17DB6B51C7@localhost> <alpine.BSF.2.00.1401230900270.76961@wonkity.com> <20140123185604.4cbd7611@gumby.homeunix.com> <04a201cf1878$8ebce540$ac36afc0$@FreeBSD.org> <alpine.BSF.2.00.1401231346520.80613@wonkity.com> <04aa01cf187e$cfcf9ef0$6f6edcd0$@FreeBSD.org> <alpine.BSF.2.00.1401231537260.80613@wonkity.com>
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> -----Original Message-----
> From: Warren Block [mailto:wblock@wonkity.com]
> Sent: Thursday, January 23, 2014 2:42 PM
> To: 'Devin Teske'
> Cc: 'RW'; freebsd-questions@freebsd.org
> Subject: RE: awk programming question
>
> On Thu, 23 Jan 2014, dteske@FreeBSD.org wrote:
>
> >
> >
> >> -----Original Message-----
> >> From: Warren Block [mailto:wblock@wonkity.com]
> >> Sent: Thursday, January 23, 2014 12:57 PM
> >> To: 'Devin Teske'
> >> Cc: 'RW'; freebsd-questions@freebsd.org
> >> Subject: RE: awk programming question
> >>
> >> On Thu, 23 Jan 2014, dteske@FreeBSD.org wrote:
> >>
> >>>> From: RW [mailto:rwmaillists@googlemail.com]
> >>>> Note that awk supports +, but not newfangled things like *.
> >>>
> >>> With respect to regex, what awk really needs is the quantifier
syntax...
> >>>
> >>> * = {0,} = zero or more
> >>> + = {1,} = one or more
> >>> {x,y} = any quantity from x inclusively up to y {x,} = any quantity
> >>> from x or more
> >>
> >> I think RW meant to type that awk did not have the newfangled "?" for
> >> non- greedy matches.
> >
> > But that one is supported. Tested on 9.2-R and 10.0-R...
> >
> > echo abbb | awk '{sub(/a?bbb/, ""); print}' # produces NULL output
> > echo bbb | awk '{sub(/a?bbb/, ""); print}' # similarly produces NULL
> > output
> >
> > Seems to be supported. But I'd really like to see {x,y} (the ? is
> > equivalent to {0,1}).
>
> No, the non-greedy modifier to a standard quantifier:
>
> echo "abczabczabcz" | perl -ne '/(a.*z)/; print "$1\n"'
> abczabczabcz
>
> echo "abczabczabcz" | perl -ne '/(a.*?z)/; print "$1\n"'
> abcz
Craziness! Wonder when that crept in.
I'm not entirely sure how I feel about that -- in terms of
readability, I'm not sure if the following is more readable:
/(a[^z]*z)/
--
Devin
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