The killpg() function sends the signal sig to the process group pgrp. See signal(3HEAD) for a list of signals.

The real or effective user ID of the sending process must match the real or saved set-user ID of the receiving process, unless the effective user ID of the sending process is the privileged user. A single exception is the signal SIGCONT, which may always be sent to any descendant of the current process.

Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

The killpg() function will fail and no signal will be sent if:

EINVAL

The sig argument is not a valid signal number.

EPERM

The effective user ID of the sending process is not privileged user, and neither its real nor effective user ID matches the real or saved set-user ID of one or more of the target processes.

ESRCH

No processes were found in the specified process group.

See attributes(5) for descriptions of the following attributes:

kill(2), setpgrp(2), sigaction(2), signal(3HEAD), attributes(5)