[EMAIL PROTECTED] wrote:
> Hi there
>
> I'm stuck with system(). According to some posts, system() is passing
> SIGINT and SIGQUIT to it's child, yet this doesn't seem to work.
No, I don't think that's correct. A terminal driver will catch ^C and ^\ and
send the appropriate signals to all the processes in the foreground process
group, but that has nothing to do with system().
> I've
> boiled the code down to the following lines. (Please note that
> 'alsaplayer' is a console soundfile player that honors SIGINT and
> SIGQUIT by immediately quitting.)
>
> sub controler
> {
> my $pid = fork;
> if (!$pid) { &player(); }
(Lose the & char)
Note that after player returns, the child will execute the code below. The
child should exit() when it's finished.
> while (!-e "stop") { sleep(10); }
> kill('QUIT', $pid);
Why use SIGQUIT? Do you want the core dump? SIGTERM would be the typical
use. Also, $pid is the PID of your child, not the PID of alsaplayer. You
kill a process group to send the signal to both, but if you exec()
alsaplayer (see below), you don't have to fool with that.
perldoc -f kill
perldoc -f getpgrp
> }
>
> sub player
> {
> system("alsaplayer -q song.mp3");
> sleep;
Why should the child wait here? If it finishes, why not exit? Also, why not
just use exec() instead of system()? That would make:
sub player { exec 'alsaplayer -q song.mp3' }
> }
>
> The controler forks off the player child which
> system()-implicitly forks
> again and runs alsaplayer in the child. So the sound's playing. I
> 'touch stop' and the controler signals SIGQUIT to the player child.
> This works as I can see when I catch SIGQUIT there. Still, the
> SIGQUIT is not forwarded to the child running alsaplayer the way it
> is supposed to do
> - at least according
> to my literature.
I don't think that literature is correct.
>
> Am I missing something here? Any idea how I could do this differently?
sub controller {
defined(my $pid = fork) or die "Couldn't fork: $!";
exec('alsaplayer -q song.mp3') unless $pid;
sleep 1 while !-e 'stop';
kill 'TERM', $pid;
}
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