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Re: Shell commands with output to string
From: |
Josselin Poiret |
Subject: |
Re: Shell commands with output to string |
Date: |
Wed, 23 Feb 2022 15:01:46 +0100 |
Hello,
post@thomasdanckaert.be writes:
> Hi,
>
> to throw in an example: I once used a function like the one below to
> handle stdout and stderr from external commands (from
> https://github.com/tdanckaert/jobview/blob/master/jobtools.scm#L38 ).
> Probably far from perfect (my first and only scheme project...), but
> hopefully it gives you an idea.
Just chiming in to say that [1] isn't fixed yet, so you may run into
issues if you try to redirect out and err to the same port. In Guix, we
use the following workaround for now ([2]):
--8<---------------cut here---------------start------------->8---
(match-let (((input . output) (pipe)))
;; Hack to work around Guile bug 52835
(define dup-output (duplicate-port output "w"))
;; Void pipe, but holds the pid for close-pipe.
(define dummy-pipe
(with-input-from-file "/dev/null"
(lambda ()
(with-output-to-port output
(lambda ()
(with-error-to-port dup-output
(lambda ()
(apply open-pipe* (cons "" command)))))))))
(close-port output)
(close-port dup-output)
(handler input)
(close-port input)
(close-pipe dummy-pipe))
--8<---------------cut here---------------end--------------->8---
[1] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=52835
[2]
https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/installer/utils.scm?id=c0bc08d82c73e464a419f213d5ae5545bc67e2bf#n87
Best,
--
Josselin Poiret
Re: Shell commands with output to string, Olivier Dion, 2022/02/22