.\" Copyright (c) 1980, 1991 Regents of the University of California.
.\" All rights reserved.
.\"
.\" SPDX-License-Identifier: BSD-4-Clause-UC
.\"
.\"     @(#)killpg.2	6.5 (Berkeley) 3/10/91
.\"
.\" Modified Fri Jul 23 21:55:01 1993 by Rik Faith <faith@cs.unc.edu>
.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 2004-06-16 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"     Added notes on CAP_KILL
.\" Modified 2004-06-21 by aeb
.\"
.TH killpg 3 2023-03-30 "Linux man-pages 6.05.01"
.SH NAME
killpg \- send signal to a process group
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <signal.h>
.PP
.BI "int killpg(int " pgrp ", int " sig );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR killpg ():
.nf
    _XOPEN_SOURCE >= 500
.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE
.fi
.SH DESCRIPTION
.BR killpg ()
sends the signal
.I sig
to the process group
.IR pgrp .
See
.BR signal (7)
for a list of signals.
.PP
If
.I pgrp
is 0,
.BR killpg ()
sends the signal to the calling process's process group.
(POSIX says: if
.I pgrp
is less than or equal to 1, the behavior is undefined.)
.PP
For the permissions required to send a signal to another process, see
.BR kill (2).
.SH RETURN VALUE
On success, zero is returned.
On error, \-1 is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EINVAL
.I sig
is not a valid signal number.
.TP
.B EPERM
The process does not have permission to send the signal
to any of the target processes.
For the required permissions, see
.BR kill (2).
.TP
.B ESRCH
No process can be found in the process group specified by
.IR pgrp .
.TP
.B ESRCH
The process group was given as 0 but the sending process does not
have a process group.
.SH VERSIONS
There are various differences between the permission checking
in BSD-type systems and System\ V-type systems.
See the POSIX rationale for
.BR kill (3p).
A difference not mentioned by POSIX concerns the return
value
.BR EPERM :
BSD documents that no signal is sent and
.B EPERM
returned when the permission check failed for at least one target process,
while POSIX documents
.B EPERM
only when the permission check failed for all target processes.
.SS C library/kernel differences
On Linux,
.BR killpg ()
is implemented as a library function that makes the call
.IR "kill(\-pgrp,\ sig)" .
.SH STANDARDS
POSIX.1-2008.
.SH HISTORY
POSIX.1-2001, SVr4, 4.4BSD
(first appeared in 4BSD).
.SH SEE ALSO
.BR getpgrp (2),
.BR kill (2),
.BR signal (2),
.BR capabilities (7),
.BR credentials (7)