Re: Shell commands with output to string

[Zelphir Kaltstahl <zelphirkaltstahl@posteo.de>]

Hi Alex!

On 2/22/22 11:20, Alex Sassmannshausen wrote:
> Hi Zelphir,
>
> I think you want to be using the popen / pipe procedures for this. See
> https://www.gnu.org/software/guile/docs/docs-2.2/guile-ref/Pipes.html
> for the chapter in the manual.
>
> Hope this helps :)
>
> Alex
>
> Zelphir Kaltstahl <zelphirkaltstahl@posteo.de> writes:
>
>> Corrections below.
>>
>> On 2/22/22 10:29, Zelphir Kaltstahl 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)
>>>
>>> So far I have found
>>>
>>> ~~~~
>>> (system ...)
>>> ~~~~
>>>
>>> which I tried to use with
>>>
>>> ~~~~
>>> scheme@(guile-user)> (with-output-to-string
>>>    (system "ls -al"))
>>>
>>> ;; lots of output immediately shown and not stored in variable
>>>
>>> ice-9/boot-9.scm:1685:16: In procedure raise-exception:
>>> Wrong type to apply: 0
>>>
>>> Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
>>> scheme@(guile-user) [1]> ,bt
>>> In ice-9/ports.scm:
>>>      476:4  2 (with-output-to-string 0)
>>> While executing meta-command:
>>> In procedure frame-local-ref: Argument 2 out of range: 1
>>> ~~~~
>>>
>>> But this does not give me a string back.
>>>
>>> I also tried with
>>>
>>> ~~~~
>>> scheme@(guile-user)> (call-with-values (lambda () (system "ls -al"))
>>> ... (lambda (exit-code output) output))
>>>
>>> ;; lots of output immediately shown
>>>
>>> ice-9/boot-9.scm:1685:16: In procedure raise-exception:
>>> Wrong number of values returned to continuation (expected 2)
>>>
>>> Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
>>>
>>> scheme@(guile-user) [1]> ,bt
>>> In current input:
>>>      10:29  1 (_)
>>> In ice-9/boot-9.scm:
>>>    1685:16  0 (raise-exception _ #:continuable? _)
>>> ~~~~
>>>
>>> Is there another function I should be using?
>>>
>>> I would like to have the exit code and the output of a command.
>>>
>>> Best regards,
>>> Zelphir
>> Of course I should use `with-output-to-string` correctly:
>>
>> ~~~~
>> scheme@(guile-user)> (with-output-to-string
>>    (lambda () (system "ls -al")))
>> ;; directly outputted stuff
>> $1 = ""
>> ~~~~
>>
>> But still not a win.
>>
>> Regards,
>> Zelphir

Thanks for that!

Regards,
Zelphir

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