Re: occasional checking process is alive

From: Erick Gallesio <>
Date: Thu, 16 Sep 1999 22:08:47 +0200 (CEST) writes:

> Please excuse this newbie question:

No problem
> Preamble:
> I have a simple-minded STk GUI which creates input for a
> process. When the data are in an appropriate form, the STk
> program writes it to a file and starts a subprocess (which may
> or may not fail horribly).
> What I would like to do is every-so-often check to see if the
> process is still alive (pressumbably using (process-alive?
> *process-num*)). If it is not then do some action (such as
> (my-popup "Job terminated")). It would be good if I could check
> the exit status of the program and I could change the popup
> message appropriately. I'm guessing I need some sort of (after
> ..) or (tkwait ..) thing - but I don't see how to do it...
Yes you can do this using a procedure which re-launch itself if
the process is not terminated. Something like the following code
should do the job.

     (require "process")

     (define (check-process p)
       (format #t "Checking process ~S\n" p)
       (if (process-alive? p)
           (after 1000 (lambda () (check-process p)))
           ;; Process has finished
           (let ((status (process-exit-status p)))
             (format #t "Process exit with status ~S\n" status))))

     (define p (run-process "emacs"))
     (check-process p)

Hope it helps.

                -- Erick
Received on Thu Sep 16 1999 - 22:27:03 CEST

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