Re: Graphics in forked subprocess

[Mike Miller]

On Sun, May 19, 2019 at 21:52:39 +0200, Pavel Hofman wrote:
> Thanks a lot for your help. I did use exec. But exec creates two child
> processes:  A) octave which runs B)
> /usr/lib/x86_64-linux-gnu/octave/4.2.2/exec/x86_64-pc-linux-gnu/octave-gui.
> B) runs the actual script while PID of A) is returned by exec().

Are you sure the process IDs of A and B are different? In my testing
they are the same. The intent is for the process ID to remain the same.

> I need to
> have a way to stop the child process from my control script. I wanted to
> stop the child process by sending kill(pid) - for that I need pid of B) -
> sending kill to A) does not stop B). I have to be able to check B) has
> finished/died to restart if needed

Sure.

> That is why I skipped the exec call and sourced octave code directly after
> forking.
> 
> Please what is the best practice for this kind of control? I know I can use
> a side channel, but I want to be able to kill the child reliably (kill -15
> ?) even if it  gets stuck.

That sounds like a fine approach. Keep in mind there is at least one
known bug with ending an Octave process with SIGTERM in Octave 4.4 and
later versions.

  https://savannah.gnu.org/bugs/?54444)

Feel free to ask for help or report bugs if you run into other problems
starting or controlling Octave subprocesses.

-- 
mike

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