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killpg() - Unix, Linux System Call
killpg - send signal to a process group
int killpg(int pgrp, int sig);
killpg() sends the signal
sig to the process group
for a list of signals.
pgrp is 0,
killpg() sends the signal to the sending processs process group.
(POSIX says: If
pgrp is less than or equal to 1, the behaviour is undefined.)
For a process to have permission to send a signal
it must either be privileged (under Linux: have the
CAP_KILL capability), or the real or effective
user ID of the sending process must equal the real or
saved set-user-ID of the target process.
In the case of SIGCONT it suffices when the sending and receiving
processes belong to the same session.
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
Sig is not a valid signal number.
The process does not have permission to send the signal
to any of the target processes.
No process can be found in the process group specified by
The process group was given as 0 but the sending process does not
have a process group.
There are various differences between the permission checking
in BSD-type systems and System V-type systems. See the POSIX rationale
kill(). A difference not mentioned by POSIX concerns the return
value EPERM: BSD documents that no signal is sent and EPERM returned
when the permission check failed for at least one target process,
while POSIX documents EPERM only when the permission check failed
for all target processes.
SVr4, 4.4BSD (The
killpg() function call first appeared in 4BSD), POSIX.1-2001.