killpg — send signal to a process group
killpg() sends the signal
sig to the process
signal(7) for a list of
pgrp is 0,
killpg() sends the signal to
the calling process's process group. (POSIX says: If
pgrp is less than or
equal to 1, the behavior 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
On success, zero is returned. On error, −1 is
errno is set
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
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 for
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.
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(#)killpg.2 6.5 (Berkeley) 3/10/91
Modified Fri Jul 23 21:55:01 1993 by Rik Faith <faithcs.unc.edu>
Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esrthyrsus.com>
Modified 2004-06-16 by Michael Kerrisk <mtk.manpagesgmail.com>
Added notes on CAP_KILL
Modified 2004-06-21 by aeb