GNU bug report logs - #48330
The xargs -r, --no-run-if-empty Option Is Ignored When a Delimiter Is Passed

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Kurt von Laven <kurt.von.laven <at> gmail.com>
To: bug-coreutils <at> gnu.org
Subject: Re: The xargs -r, --no-run-if-empty Option Is Ignored When a
 Delimiter Is Passed
Date: Sun, 9 May 2021 23:07:18 -0700

[Message part 1 (text/plain, inline)]

P.S. Apologies, the || in that last command should be a &&. Here is the
corrected command:

[[ $input = *[![:space:]]* ]] && xargs --null -I str echo str <<< "$input"

El dom, 9 may 2021 a las 23:04, Kurt von Laven (<kurt.von.laven <at> gmail.com>)
escribió:

> Hello,
>
> When the -r, --no-run-if-empty option is combined with the -d, --delimiter
> or -0, --null options, the -r, --no-run-if-empty option does not
> take effect. The manual describes the intended behavior of the -r,
> --no-run-if-empty option: "If the standard input does not contain any
> nonblanks, do not run the command.  Normally, the command is run once even
> if there is no input.  This option is a GNU extension."
>
> The following command correctly outputs nothing.
> xargs --no-run-if-empty -I str echo str <<< ""
>
> The following command incorrectly outputs 1 empty line.
> xargs --no-run-if-empty --delimiter="\n" -I str echo str <<< ""
>
> The following command incorrectly outputs 2 empty lines.
> xargs --no-run-if-empty --null -I str echo str <<< ""
>
> As a workaround according to this Stack Overflow answer
> <https://stackoverflow.com/a/17287097/3866835>, the following commands
> output nothing when the input consists only of whitespace.
> [[ $input = *[![:space:]]* ]] && xargs --delimiter="\n" -I str echo str
> <<< "$input"
> [[ $input = *[![:space:]]* ]] || xargs --null -I str echo str <<< "$input"
>
> Be well,
> Kurt von Laven
>

[Message part 2 (text/html, inline)]

Message #8 received at 48330 <at> debbugs.gnu.org (full text, mbox):

From: Bernhard Voelker <mail <at> bernhard-voelker.de>
To: Kurt von Laven <kurt.von.laven <at> gmail.com>, 48330 <at> debbugs.gnu.org
Subject: Re: bug#48330: The xargs -r, --no-run-if-empty Option Is Ignored When
 a Delimiter Is Passed
Date: Mon, 10 May 2021 14:55:47 +0200

tag 48330 notabug
close 48330
stop

On 5/10/21 8:07 AM, Kurt von Laven wrote:
> [[ $input = *[![:space:]]* ]] && xargs --null -I str echo str <<< "$input"

You have reached the GNU coreutils mailing list, and 'xargs' is not part
of the coreutils [1].

[1] https://www.gnu.org/software/coreutils/

Instead, 'xargs' is part of the 'findutils' package, so you're better off asking
on their mailing list or bug tracker.

  $ xargs --help | tail -n4
  You can report (and track progress on fixing) bugs in the "xargs"
  program via the GNU findutils bug-reporting page at
  https://savannah.gnu.org/bugs/?group=findutils or, if
  you have no web access, by sending email to <bug-findutils <at> gnu.org>.

I'm therefore marking this as "not a bug" + "closed" in the coreutils bug tracker.

Have a nice day,
Berny

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