Re: How to capture pid of (system process?

[Timothy Sample <samplet@ngyro.com>]

Hi Jacob,

Jacob Hrbek <kreyren@rixotstudio.cz> writes:

>> If you want to do things asynchronuously, you can look at
>> open-pipe. It should also be possible to build anything you want with
>> the lower-level fork, execl, dup->fdes, ... primitives (assuming
>> things are single-threaded).
>
> Can you elaborate? (I am noob in guile atm)

If you want to dig into it, the GNU manual is not half bad:

https://www.gnu.org/software/libc/manual/html_node/Processes.html

Guile just wraps those same C functions, so that description applies
quite well to Guile.  Here’s the Guile reference for the procedures
you’d need:

https://www.gnu.org/software/guile/manual/html_node/Processes.html

Alternatively, if you are feeling adventurous – you must be if you are
using Potato Make :) – you could try and use Gash, too.  You would end
up with a very Scheme-y Make experience indeed!

Gash’s interface is laser focused on shell semantics so far, so it’s a
little wonky as a Scheme library, but here’s an example:

    (use-modules (gash environment)
                 (gash shell))

    (sh:async
     (lambda ()
       (execlp "emacs")))
    (display "waiting a bit...\n")
    (sleep 5)
    (let ((emacs-pid (get-last-job)))
      (display "sending SIGTERM to ")
      (display emacs-pid)
      (newline)
      (kill emacs-pid SIGTERM))

Gash is very much experimental software when used like this, though.
The latest release does not have ‘sh:async’, so you would have to build
it from Git.  It might not be super practical, but it would be fun!  :)


-- Tim