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Re: portability of xargs


From: Nick Bowler
Subject: Re: portability of xargs
Date: Tue, 15 Feb 2022 16:01:24 -0500

On 2022-02-14, Mike Frysinger <vapier@gentoo.org> wrote:
> context: https://bugs.gnu.org/53340
>
> how portable is xargs ?  like, beyond POSIX, as autoconf & automake both
> support non-POSIX compliant systems.  i want to use it in its simplest
> form: `echo $var | xargs rm -f`.

As far as I can tell xargs was introduced in the original System V UNIX
(ca. 1983).  This utility subsequently made its way back into V10 UNIX
(ca. 1989) and subsequently 4.3BSD-Reno (ca. 1990) and from there to
basically everywhere.  The original implementation from System V
supports the "-x", "-l", "-i", "-t", "-e", "-s", "-n" and "-p" options.
Of these, POSIX only chose to standardize "-x", "-t", "-s", "-n" and
"-p" suggesting possible incompatibilities with other options.

HP-UX 11 xargs expects the last filename to be followed by a white-space
character, or it will be ignored:

  gnu% printf 'no blank at the end' | xargs printf '[%s]'; echo
  [no][blank][at][the][end]

  hpux11% printf 'no blank at the end' | xargs printf '[%s]'; echo
  [no][blank][at][the]

The HP-UX 11 behaviour is also observed on Ultrix 4.5, but not on
4.3BSD-Reno.  Since xargs input typically ends with a newline, this is
not a serious practical problem.

Cheers,
 Nick



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