killpg - send signal to a process group
int killpg(int pgrp, int sig));
Killpg sends the signal sig to the process group pgrp. See
sigaction(2) for a list of signals. If pgrp is 0, killpg
sends the signal to the sending process's process group.
The sending process and members of the process group must
have the same effective user ID, or the sender must be the
super-user. As a single special case the continue signal
SIGCONT may be sent to any process that is a descendant of
the current process.
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
Sig is not a valid signal number.
No process can be found in the process group specified
The process group was given as 0 but the sending pro-
cess does not have a process group.
The sending process is not the super-user and one or
more of the target processes has an effective user ID
different from that of the sending process.
SVr4, 4.4BSD (The killpg function call first appeared in
kill(2), getpgrp(2), signal(2)