foreach $row ( @{$ref} ) {
     my $pid = $pm->start(@$row->[0]) and next;
     system 'alert_main.pl', '-h', $row->[0], '-p', $passId;
     print "\n";
     $pm->finish($row);
}

##</code><code>##

foreach $row ( @{$ref} ) {
     my $pid = $pm->start(@$row->[0]) and next;
     exec 'alert_main.pl', '-h', $row->[0], '-p', $passId;
     $pm->finish($row);  # In case exec fails.
}