GNU bug report logs - #65416
Feature request: include first line of file in output

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Message #17 received at 65416 <at> debbugs.gnu.org (full text, mbox):

From: Daniel Green <ddgreen <at> gmail.com>
To: arnold <at> skeeve.com
Cc: 65416 <at> debbugs.gnu.org
Subject: Re: bug#65416: Feature request: include first line of file in output
Date: Mon, 21 Aug 2023 14:03:11 -0400

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That works, as well as the Perl version I've been using:

    perl -ne 'print if ($. == 1 || /pattern/)'

But timings for a real-life example (3GB file with ~16m lines, CentOS 7)
show the problem:

    grep (v2.20):    ~1.15s
    perl (v5.36.1):  ~4.48s
     awk (v4.0.2):  ~10.81s

Admittedly grep is just searching in those timings, but I suspect it could
accomplish the full task with a minimal decrease in speed.

Dan

On Mon, Aug 21, 2023 at 12:57 PM <arnold <at> skeeve.com> wrote:

> Daniel Green <ddgreen <at> gmail.com> wrote:
>
> > I'm frequently searching CSV files with 20-30 columns, and when there's a
> > hit it can be hard to know what the columns are. An option to also print
> > the first line of a file (either always, or only if that file had a match
> > to the pattern) in addition to any hits would be nice.
> >
> > Thanks,
> > Dan
>
> It sounds like awk would be a better tool:
>
>         awk 'FNR == 1 || /pattern/' files ...
>
> should do the trick.
>
> HTH,
>
> Arnold
>

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