killpg - send signal to all members of a process group.
int killpg(pid_t pidgrp, int signal));
The killpg() function causes signal signal to be sent to all
the processes in the process group pidgrp or to the
processes' own process group if pidgrp is equal to zero.
It is equivalent to
The value returned is -1 on error, or 0 for success.
Errors are returned in errno and can be one of the follow-
for an invalid signal,
for a process group which does not exist, and
if the userid of the calling process is not equal to
that of the process the signal is sent to, and the
userid is not that of the superuser.
kill(2), signal(2), signal(7)