GNU bug report logs - #28304
Feature Request - Quit on Non Match

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Message #11 received at 28304 <at> debbugs.gnu.org (full text, mbox):

From: Adam Danischewski <adam.danischewski <at> gmail.com>
To: arnold <at> skeeve.com
Cc: 28304 <at> debbugs.gnu.org
Subject: Re: bug#28304: Feature Request - Quit on Non Match
Date: Thu, 31 Aug 2017 13:50:49 -0400

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Yes, awk can handle it except for maybe very large files. I was trying to
keep it restricted to grep, grep is already counting matches with -m but
maybe GNU views this direction as becoming too programmatic from what the
original vision of grep is?

awk '{if($0~/^[ \t\f#]+/)print $0;else exit}' gen_ent.bsh

Thanks anyway,
 +AMD

On Thu, Aug 31, 2017 at 10:53 AM, <arnold <at> skeeve.com> wrote:

> Adam Danischewski <adam.danischewski <at> gmail.com> wrote:
>
> > I've been writing parsers and it would be really nice if grep could do
> the
> > following:
> >
> > *grep --quit-nm 1 -Pno "^[ \t\f]*#.*$" <(sed -n '2,$p' gen_ent.bsh)*
> >
> > If you:
> > *grep -m 1 -Pno "^[ \t\f]*#.*$" <(sed -n '2,$p' gen_ent.bsh)*
> >
> > Only the first match of the header block gets printed, yet it would be
> nice
> > if grep in O(n), could simply be on the look out for the first failure to
> > match the -o context and quit at --quit-nm non-match occurrences.
>
> I may be misunderstanding what you want, but something like
>
>         awk '/pattern to match/ { print ; continue }
>                 { exit 0}' file
>
> might do what I think you want - exit on first non match.
>
> If gawk can do the same matching you're doing with grep -Pno, that
> is a different question.
>
> HTH,
>
> Arnold
>

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