I'm trying to write a perl script that forks off another program and monitors its execution during run time. Something like the following snippet:

    if ( ! defined($kidpid = fork() ) ) {
        # fork returned undef, so failed
        die "Cannot fork: $!";
    } elsif ($pid == 0) {
        # fork returned 0, so this branch is child
        # want to tun program like this:  ( time  exe < stdin > stdout
+ ) >&! stdlog
        exec(   code to run program goes here....   );

        # if exec fails, fall through to the next statement
        die "can't exec date: $!";
    } else {
        # fork returned 0 nor undef so this branch is parent

        # run-time monitoring code goes here....


        waitpid($kidpid, 0);
    }
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I want to use a while(1) loop and wait for the child's pid, so I know when the executable's completed. Any idea on how to do this? I'm able to run the executable in background (using a system call) but w/o run-time monitoring (don't know child pid)? Thanks. E.