in reply to Re: Re: Signals and subprocesses using fork, and system or exec.
in thread Signals and subprocesses using fork, and system or exec.

I suggest that you use a second fork(), and then exec in the child process of that fork. Something like this in setupProcess: 
#!/usr/bin/perl -w

use strict;


my $sshpid = fork();
defined($sshpid)
  or die "fork error: $!";
if ($sshpid)
{
  print "Parent PID is $$\n";
  # Parent
  $SIG{HUP} = sub { 
                    warn "Aborting ssh pid $sshpid\n"; 
                    kill 'ABRT', $sshpid;
                    exit(1);
                  };
  wait;
  exit(0);
}
else
{
  # Child
  exec '/bin/sleep 6'
    or die "exec error: $!";
}

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I'm using an ABRT signal because that's what you used; I still don't think it's the right signal for this purpose, although I'm not sure what is if you can't use TERM.

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Re: Re: Re: Re: Signals and subprocesses using fork, and system or exec.
by exussum0 (Vicar) on Aug 26, 2003 at 11:08 UTC
    I'm not quite sure what you are accomplishing by second fork.
    --
    Play that funky music white boy..
[reply]

      The second fork lets you have two processes: one to run ssh, and the other to catch a HUP signal and do whatever it likes to the ssh server. The problem with your existing code is that when you run exec, the signal handler is cleared; using fork too lets you have one process with a signal handler of your choice, and a second process running ssh.

      I'm not sure that this has an advantage over not doing the second fork and just keeping the PID's that ran exec in %PIDPOOL.

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        Well, here's an interesting note. If i fork off only one child, this code works. Doing 2 or more, it won't.

        Note: I'm not managing sshd servers. I'm managing the ssh clients. I can prove that my child gets the signal but doesn't propogate outward properly.

        All in all, I guess ssh is ignoring me :( I've done it via pipe, open (popen), system, exec.. ssh just doesn't like me :\
        ----
        Play that funky music white boy..

[reply]

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