If the negative of a pid is passed to kill, the signal is sent to all processes with process group id equal to that pid.

Suppose process 60604 is running and is creating multiple children, willy, nilly. You can terminate them all by:

        kill(9, -60604);
     

Note you can also do this at the prompt with the kill program, which just calls the kill function.

        $ kill -9 -60604