$job = "/usr/bin/qsub pbs_job.sh";

$status = system($job);    #it submits the job here and
                           #exits perl code

If ($status == 0) {

do something

}


##</code><code>##

$job = "/usr/bin/qsub pbs_job.sh";

open(my $status, "-|", $job)
   or die "couldn't launch qsub job: $!/$?\n";

for (<$status>) {
       print "$_";
}
close $status;