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

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Message #43 received at 65416 <at> debbugs.gnu.org (full text, mbox):

From: Daniel Green <ddgreen <at> gmail.com>
To: Paul Jackson <pj <at> usa.net>
Cc: arnold <at> skeeve.com, 65416 <at> debbugs.gnu.org
Subject: Re: bug#65416: Feature request: include first line of file in output
Date: Wed, 23 Aug 2023 20:34:46 -0400

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Re Perl's read speed, it's faster when not doing the line number check for
every line. So `perl -ne 'print if (/pattern/)'` is only ~2.60s, compared
to ~3.28s for `perl -ne 'print if ($. == 1 || /pattern/)'`. Doing nothing
in Perl, i.e., `perl -ne ''` is only ~1.38s.

Dan

On Wed, Aug 23, 2023 at 6:22 PM Paul Jackson <pj <at> usa.net> wrote:

> Ah - those times show another reason why one might
> be motivated to keep requesting more options be added
> to grep.
>
> From those timings, and from looking at the source, it's clear
> that the FSF rewrote grep from scratch, sometime back in the
> late 1980's or early 1990's, to have fast reads, whereas sed is
> still using stdio fread in a classical manner, which is a painfully
> slower double copy solution.
>
> If sed were still a widely used command in performance sensitive
> applications, it should have some serious TLC applied to its
> performance.
>
> However, since the pool of Jurassic Park Dinosaurs who can (and
> perhaps do) compose sed commands in their sleep is a nearly
> extinct breed, I see no sufficient interest in accepting such a rewrite
> of sed, even if it showed up as a proposed checkin.
>
> That grep can even seriously beat perl for such raw read performance
> is impressive.  Perl used to be the King of such challenges.
>
> --
>                 Paul Jackson
>                 pj <at> usa.net
>
>
>

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