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Re: Shell commands with output to string
From: |
Olivier Dion |
Subject: |
Re: Shell commands with output to string |
Date: |
Tue, 22 Feb 2022 11:33:49 -0500 |
On Tue, 22 Feb 2022, Leo Butler <leo.butler@umanitoba.ca> wrote:
> 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'):
You're absolutely right. It would also probably a good idea to use
dynamic-wind for close-pipe in case an exception is thrown in
read-string I think.
>
> (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.
There's ton of missing stuffs in the standard library IMO. On top of my
head, filesystem paths manipulation (e.g. path-join) is also one that is
probably getting re-invented a lots.
I believe that the successful story of Python is not just about its
pretty syntax, but also dues to its very large standard library.
--
Olivier Dion
Polymtl
- Re: Shell commands with output to string, (continued)
Re: Shell commands with output to string, Olivier Dion, 2022/02/22
Re: Shell commands with output to string, Blake Shaw, 2022/02/23