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From: Leo Butler <leo.butler@umanitoba.ca>
To: Olivier Dion via General Guile related discussions <guile-user@gnu.org>
Subject: Re: Shell commands with output to string
Date: Tue, 22 Feb 2022 10:00:00 -0600	[thread overview]
Message-ID: <87y222lwn3.fsf@t14.reltub.ca> (raw)
In-Reply-To: <87o82z5636.fsf@laura> (Olivier Dion via General Guile related discussions's message of "Tue, 22 Feb 2022 09:27:57 -0500")

Olivier Dion via General Guile related discussions <guile-user@gnu.org>
writes:

> On Tue, 22 Feb 2022, Zelphir Kaltstahl <zelphirkaltstahl@posteo.de> wrote:
>> Hello Guile users!
>>
>> How would I run a shell command from inside Guile and get its output
>> as a string, instead of the output being outputted directly? (Guile
>> 3.0.8)
>
> I use the following:
>
> (define-module (shell utils)
>   #:use-module (ice-9 format)
>   #:use-module (ice-9 popen)
>   #:use-module (ice-9 textual-ports))
>
> (define (shell% proc fmt . args)
>   (let* ((port (open-input-pipe (format #f "~?" fmt args)))
>          (output (proc port)))
>     (close-pipe port)
>     output))

You probably want to inspect the exit value of the shell process, so
that you can handle/throw the error. This is what I use (similar to your
`shell'):

(define* (shell-command-to-string cmd)
  (catch 'shell-command-error
    ;; thunk                                                                                                                                                                                                                        
    (lambda ()
      (let* ((port (open-pipe cmd OPEN_READ))
             (str (read-string port))
             (wtpd (close-pipe port))
             (xval (status:exit-val wtpd)))
        (if (or (eqv? xval #f) (> xval 0)) (throw 'shell-command-error cmd str))
        str))
    ;; handler                                                                                                                                                                                                                      
    (lambda (key cmd str)
      (simple-format #t "ERROR: in command ~a\nstring: ~a\n" cmd str)
      (throw 'error-in-shell-command-to-string cmd str))))

>
> (define-public (shell . args)
>   (apply shell% (cons get-string-all args)))
>
> (define-public (shell$ . args)
>   (apply shell% (cons get-line args)))
>
> Then
> (shell "ls" "-l")
>
> The $ variant is to get a single line in the output.

I wonder why there is no module already in ice-9 which does this stuff?
It seems like a lot of people are re-inventing the wheel.

Leo



  reply	other threads:[~2022-02-22 16:00 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-22  9:29 Shell commands with output to string Zelphir Kaltstahl
2022-02-22  9:38 ` Zelphir Kaltstahl
2022-02-22 10:20   ` Alex Sassmannshausen
2022-02-22 10:43     ` post
2022-02-23 14:01       ` Josselin Poiret
2022-03-08 23:12         ` Zelphir Kaltstahl
2022-03-09 14:14           ` Josselin Poiret
2022-02-22 11:20     ` Neil Jerram
2022-02-23  1:28       ` Zelphir Kaltstahl
2022-02-23  1:29     ` Zelphir Kaltstahl
2022-02-22 10:21   ` tomas
2022-02-22 14:27 ` Olivier Dion via General Guile related discussions
2022-02-22 16:00   ` Leo Butler [this message]
2022-02-22 16:33     ` Olivier Dion via General Guile related discussions
2022-02-23  1:26       ` Zelphir Kaltstahl
2022-02-23 14:13         ` Olivier Dion via General Guile related discussions
2022-02-26  0:32           ` Zelphir Kaltstahl
  -- strict thread matches above, loose matches on Subject: below --
2022-02-23 17:48 Blake Shaw
2022-02-23 18:25 ` Olivier Dion via General Guile related discussions

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