question about perl's exec

danfou · 11-05-2006, 09:56 PM

Here's part of my perl program:

if (my $pid = fork) {
waitpid($pid, 0);
print "end exec\n";
}
else {
defined($pid) or die "fork: $!";
print "start exec\n";
exec "ssh -f $opt_s ping -c 10 $opt_d > pingout";
}

I want to do other things after the ping ends.
But it turns out that the parent proc continue to do the following command while ping is still running.

Can you tell me how to write the correct program to such thing?
Thanks a lot.

chrism01 · 11-05-2006, 10:57 PM

From the Camel book:
exec: This fn terminates the currently running Perl script by executing another proggram in place of itself (!)
My exclamation...
Once you've forked, you now have 2 perl procs. You don't need to actually invoke exec.
If you want to run an external prog, try the system() fn in the child proc.

See here http://perldoc.perl.org/functions/fork.html & http://perldoc.perl.org/functions/exec.html