$ zt
cmd running: 18859
killing cmd: 18859
It's alive!!!!! (No such process)
It's alive!!!!! (No such process)
It's alive!!!!! (No such process)

$ ps aux
...
alan     18858  1.0  0.4   5660  1932 pts/2    S+   20:30   0:00 /usr/bin/perl ./zt
alan     18859  0.0  0.1   3184   492 pts/2    S+   20:30   0:00 sleep 10