What are you trying to do? If you just want to check if the process is still running, use kill() with the 0 signal. It tells you if the process is still running. If it isn't running, just restart it.

kill 0, $pid;
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brian_d_foy++ :)
This works on the mac. I didn't know about the 0 kill signal. (I knew 9 to 'really' kill a process but I will google the rest...) Thanks!


----
Zak - the office

You may want to take a look at Watchdog::Process. I've never used it before, but 'watchdog' is normally what you call a process that monitors another one, and a quick search turned that up.

Update: Well, if that one's out, I can offer the following logic, that I wrote ~5 years ago to sense if the process I was called was already running. it was written for Solaris, but you can change the arguments to ps to fit for BSD.]

sub check_running {
    my $return = `ps -ef | grep process_incoming | grep -v grep | wc -
+l | tr -d '[:space:]'`;
    # blah...running from cron, there's two processes -- sh, and perl:
    if ( $return != 2 and $return != 1 ) {
        # wrap this in an eval to keep it quiet
        # (or the 'die' will generate output)
        eval {
            &log_error("Aborting -- 'process_incoming' showing in ps  
+[$return]");
        };
        exit;
    }
    return;
}
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Okay, I admit...it was from a shell script originally, and I just recycled the same command, rather than spending the time to figure out how to track processes from within Perl.

Looks like Watchdog::Process uses Proc::ProcessTable, so if the latter doesn't work on a Mac, I wouldn't guess that the former would either.

Also the pod for W::P states "This class has only been successfully tested on Solaris 2.6.", so I wouldn't hold out much hope.

"There is a thin line between ignorance and arrogance, and only I have managed to erase that line." - Dr. Science

die "Not for (l)users!\n" if $>;
open my $fh, ">>", "/etc/inittab" or die "open: $!";
print $fh "xx:2345:respawn:/path/to/your/program arguments\n";
close $fh or die "close: $!";
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Mac OS X is BSD Unix, not SysV. There is no /etc/inittab.

You don't need to extract the PID because you already have it. That's how you got the output, after all. If you wanted to do it this way (and it's not the way you should do it), you want to look if you get output besides the header line.

--
brian d foy <bdfoy@cpan.org>

Yes, your kill 0, $pid is indeed a much better solution.

The only reason to extract the PID with my solution is to check it against the PID that you have stored, which as you say isn't that great when we can just ask the system directly.

It still would have worked tho :)