system("sleep 1234 &");
my ( $pid ) =
    qx{ pgrep -f sleep | xargs ps | grep "1234" | grep -v grep }
    =~ /(\d+)/;

print "Check me\n\tps $pid\n";

# kill 9 => $$; # Leaves sleep process alive.

# kill -9 => $$; # Kills sleep process.

kill 9 => -$$; # Also kills sleep process.