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

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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: bug#65416: Feature request: include first line of file in output
Date: Wed, 23 Aug 2023 10:20:05 -0400

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On the original test machine I timed the sed solution, as well as `(grep
-m1 . 'file' && grep 'pattern' 'file')` and `(mapfile -n1 <'file' && echo
$MAPFILE[0] && grep 'pattern' 'file')` and  `(head -n1 'file' && grep
'pattern' 'file')`. Total table of speeds.

    grep (v2.20):    ~1.15s
    perl (v5.36.1):  ~4.48s
     awk (v4.0.2):  ~10.81s
     sed (v4.2.2):   ~8.15s
     grep && grep:   ~1.15s
  mapfile && grep:   ~1.15s
     head && grep:   ~1.15s

I can write a shell function to make the head+grep version a little easier
to use in practice (i.e., loop over the list of files passed calling
head+grep on each one instead of calling head on the list and then grep on
the list), but I believe it would be difficult to change any options given
to grep. I still think the best combination of speed + output as I imagine
+ ease of integrating with changing grep options used is accomplished by a
new option for grep. But if there's no interest then this feature request
can be closed.

Dan

On Wed, Aug 23, 2023 at 4:23 AM Paul Jackson <pj <at> usa.net> wrote:

> oops - grep slower than awk, not the other way around,
> on these _highly_ inconclusive timings.
>
> --
>                 Paul Jackson
>                 pj <at> usa.net
>

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