GNU bug report logs - #78910
tail does not support -r added by POSIX.1-2024

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Message #17 received at 78910 <at> debbugs.gnu.org (full text, mbox):

From: Collin Funk <collin.funk1 <at> gmail.com>
To: Jim Meyering <jim <at> meyering.net>
Cc: Eric Blake <eblake <at> redhat.com>,
 Pádraig Brady <P <at> draigbrady.com>, 78910 <at> debbugs.gnu.org
Subject: Re: bug#78910: tail does not support -r added by POSIX.1-2024
Date: Fri, 27 Jun 2025 12:16:36 -0700

Hi Jim and Pádraig,

Jim Meyering <jim <at> meyering.net> writes:

>> tail -r comes from the BSDs.
>> Also the BSDs don't have tac(1) which overlaps in functionality quite a bit.
>> I'm a bit surprised -r was added by POSIX, but fair enough.
>
> "Surprised" is putting it lightly. I am disappointed and am tempted to
> push back and to delay encumbering GNU tail with -r.
> That is an option no GNU system needs, since they've all had tac since
> before 1992-era textutils.
>
> I've Cc'd Eric Blake, in case someone wants to propose adding tac to
> POSIX in spite of the fact that the BSDs still lack it.

Thanks for reminding me about 'tac'. For some reason I forgot about it.

That solves my question about how to implement 'tail -r' while avoiding
arbitrary limits. But I agree that duplicating parts of 'tac' into
'tail' does not seem ideal.

Collin

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