On Tue, 22 Feb 2022, Leo Butler <leo.but...@umanitoba.ca> wrote: > Olivier Dion via General Guile related discussions <guile-user@gnu.org> > writes: > >> On Tue, 22 Feb 2022, Zelphir Kaltstahl <zelphirkaltst...@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
