From help-octave-request at bevo dot che dot wisc dot edu  Wed Oct 27 08:25:29 1999
Subject: system-question
From: Mats Jansson <mj at networks dot nera dot no>
To: help-octave at bevo dot che dot wisc dot edu
Date: Wed, 27 Oct 1999 15:24:42 +0200

Hi!

I want to start a program in the background from octave. I want to be
able to check if the program is still running and I want to be able to
close the program from octave.

My idea was to start the program (in this case emacs) with

           pid = system("emacs", 1, "async"). 

To check if the program is still running I could use 'system("ps")',
to close the program I could use 'system(["kill ", num2str(pid)])'.

system("emacs", 1, "async") returns a PID to a new octave-process, and
not to the emacs-process, so I don't know the PID to the process to
kill.

Does anybody know how to solve the problem?

Thanks!
Mats

[mj at pctkj ~]$ octave --norc
GNU Octave, version 2.0.14 (i386-redhat-linux-gnu).
Copyright (C) 1996, 1997, 1998, 1999 John W. Eaton.
This is free software with ABSOLUTELY NO WARRANTY.
For details, type `warranty'.

octave:1> system("ps f")
  PID TTY      STAT   TIME COMMAND
24927 pts/7    S      0:00 -csh
24987 pts/7    S      0:00 octave --norc
24988 pts/7    R      0:00  \_ ps f
ans = 0
octave:2> pid=system("emacs",1,"async")
pid = 25024
octave:3> system("ps f")
  PID TTY      STAT   TIME COMMAND
24927 pts/7    S      0:00 -csh
24987 pts/7    S      0:00 octave --norc
25024 pts/7    S      0:00  \_ octave --norc
25025 pts/7    S      0:03  |   \_ emacs
25031 pts/7    R      0:00  \_ ps f
ans = 0
octave:4> ## emacs are closed (ctrl-X ctrl-C)
octave:4> system("ps f")
  PID TTY      STAT   TIME COMMAND
24927 pts/7    S      0:00 -csh
24987 pts/7    S      0:00 octave --norc
25032 pts/7    R      0:00  \_ ps f
ans = 0
octave:5> ## This works fine, I can check if pid is still present
octave:5> pid=system("emacs",1,"async")
pid = 25034
octave:6> system("ps f")
  PID TTY      STAT   TIME COMMAND
24927 pts/7    S      0:00 -csh
24987 pts/7    S      0:00 octave --norc
25034 pts/7    S      0:00  \_ octave --norc
25035 pts/7    S      0:03  |   \_ emacs
25036 pts/7    R      0:00  \_ ps f
ans = 0
octave:7> system("kill -9 25034")
ans = 0
octave:8> system("ps f")
  PID TTY      STAT   TIME COMMAND
24927 pts/7    S      0:00 -csh
24987 pts/7    S      0:00 octave --norc
25038 pts/7    R      0:00  \_ ps f
25035 pts/7    S      0:03 emacs
ans = 0
octave:9> ## Emacs is still there, I want it to disappear!



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