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 following:
- 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.