I have a script that launches various external processes to perform tasks in a 3rd party software product. Unfortunately, these tasks will sometimes hang, and so the entire script will hang.

This is running in Perl 5.6 on AIX, and I am not permitted to install any additional modules. The solution I have come up with is shown below.

This seems to work OK, but I would like to know if there is a more clever way to do this. Also, this code doesn't cope well if the spawned process completes within the time limit. I'm guessing I should be able to use waitpid() to check see if the child has completed running; is that a sensible way to do it?

One final thing to note is that I need to work with any output returned from the spawned process. At present I am using code such as this:

my $rc = `/usr/bin/somecommand param1 param2`;

How might I get this output back into the parent process?

#!/usr/bin/perl -w

use strict;

if (!defined(my $pid = fork)) {
    print "Failed to fork.\n";
    exit -1;
} else {
    if ($pid == 0) {
        print "PID variable is zero; I am the child.\n";

        # This is where we would execute the external process
        # Replaced this with a sleep loop to simulate a long-running p
+rocess
        for (my $x = 0; $x < 10; $x++) {
            print "Sleeping iteration $x.\n";
            sleep 1;
        }
        print "Child process has finished.\n";
        exit 0;
    } else {
        print "I am the parent. Child PID is $pid.\n";
        my $timer = 0;
        while ($timer < 5) {
            sleep 1;
            $timer++;
        }
        # After 5 seconds, kill the child
        print "Killing the child process.\n";
        kill 1, $pid;
        print "Parent process finishing.\n";
    }
}
print "End of the forked code block.\n";
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