[apple/xnu.git] / bsd / man / man2 / kill.2

.\"	$NetBSD: kill.2,v 1.7 1995/02/27 12:33:53 cgd Exp $
.\"
.\" Copyright (c) 1980, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)kill.2	8.3 (Berkeley) 4/19/94
.\"
.Dd April 19, 1994
.Dt KILL 2
.Os BSD 4
.Sh NAME
.Nm kill
.Nd send signal to a process
.Sh SYNOPSIS
.Fd #include <signal.h>
.Ft int
.Fo kill
.Fa "pid_t pid"
.Fa "int sig"
.Fc
.Sh DESCRIPTION
The
.Fn kill
function sends the signal specified by
.Fa sig
to
.Fa pid ,
a
process or a group of processes.
Typically,
.Fa Sig
will be one of the signals specified in
.Xr sigaction 2 .
A value of 0, however,
will cause error checking to be performed (with no signal being sent). 
This can be used to check the validity of
.Fa pid .
.Pp
For a process to have permission to send a signal to a process designated
by
.Fa pid ,
the real or effective user ID of the receiving process must match
that of the sending process or the user must have appropriate privileges
(such as given by a set-user-ID program or the user is the super-user).
A single exception is the signal SIGCONT,
which may always be sent to any descendant of the current process.
.Bl -tag -width Ds
.It \&If Fa pid No \&is greater than zero :
.Fa Sig
is sent to the process whose ID is equal to
.Fa pid.
.It \&If Fa pid No \&is zero :
.Fa Sig
is sent to all processes whose group ID is equal
to the process group ID of the sender,
and for which the process has permission;
this is a variant of
.Xr killpg 2 .
.It \&If Fa pid No \&is -1 :
If the user has super-user privileges,
the signal is sent to all processes excluding
system processes and the process sending the signal.
If the user is not the super user,
the signal is sent to all processes with the same uid as the user,
excluding the process sending the signal.
No error is returned if any process could be signaled.
.El
.Pp
For compatibility with System V,
if the process number is negative but not -1,
the signal is sent to all processes whose process group ID
is equal to the absolute value of the process number.
This is a variant of
.Xr killpg 2 .
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.
Otherwise, a value of -1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn Kill
will fail and no signal will be sent if:
.Bl -tag -width Er
.\" ==========
.It Bq Er EINVAL
.Fa Sig
is not a valid, supported signal number.
.\" ==========
.It Bq Er EPERM
The sending process is not the super-user and its effective
user id does not match the effective user-id of the receiving process.
When signaling a process group, this error is returned if any members
of the group could not be signaled.
.\" ==========
.It Bq Er ESRCH
No process or process group can be found
corresponding to that specified by
.Fa pid .
.\" ==========
.It Bq Er ESRCH
The process id was given as 0,
but the sending process does not have a process group.
.El
.Sh SEE ALSO
.Xr getpgrp 2 ,
.Xr getpid 2 ,
.Xr killpg 2 ,
.Xr sigaction 2
.Sh STANDARDS
The
.Fn kill
function is expected to conform to 
.St -p1003.1-88 .
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: kill.2,v 1.7 1995/02/27 12:33:53 cgd Exp $
	2	.\"
	3	.\" Copyright (c) 1980, 1991, 1993
	4	.\" The Regents of the University of California. All rights reserved.
	5	.\"
	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
	34	.\" @(#)kill.2 8.3 (Berkeley) 4/19/94
	35	.\"
	36	.Dd April 19, 1994
	37	.Dt KILL 2
	38	.Os BSD 4
	39	.Sh NAME
	40	.Nm kill
	41	.Nd send signal to a process
	42	.Sh SYNOPSIS
	43	.Fd #include <signal.h>
	44	.Ft int
2d21ac55 A	45	.Fo kill
	46	.Fa "pid_t pid"
	47	.Fa "int sig"
	48	.Fc
9bccf70c A	49	.Sh DESCRIPTION
	50	The
	51	.Fn kill
2d21ac55	52	function sends the signal specified by
9bccf70c A	53	.Fa sig
	54	to
	55	.Fa pid ,
	56	a
	57	process or a group of processes.
2d21ac55	58	Typically,
9bccf70c	59	.Fa Sig
2d21ac55 A	60	will be one of the signals specified in
	61	.Xr sigaction 2 .
	62	A value of 0, however,
	63	will cause error checking to be performed (with no signal being sent).
9bccf70c A	64	This can be used to check the validity of
	65	.Fa pid .
	66	.Pp
	67	For a process to have permission to send a signal to a process designated
	68	by
	69	.Fa pid ,
	70	the real or effective user ID of the receiving process must match
	71	that of the sending process or the user must have appropriate privileges
	72	(such as given by a set-user-ID program or the user is the super-user).
2d21ac55 A	73	A single exception is the signal SIGCONT,
2d21ac55 A	74	which may always be sent to any descendant of the current process.
9bccf70c A	75	.Bl -tag -width Ds
	76	.It \&If Fa pid No \&is greater than zero :
	77	.Fa Sig
	78	is sent to the process whose ID is equal to
	79	.Fa pid.
	80	.It \&If Fa pid No \&is zero :
	81	.Fa Sig
	82	is sent to all processes whose group ID is equal
2d21ac55 A	83	to the process group ID of the sender,
2d21ac55 A	84	and for which the process has permission;
9bccf70c A	85	this is a variant of
	86	.Xr killpg 2 .
	87	.It \&If Fa pid No \&is -1 :
	88	If the user has super-user privileges,
	89	the signal is sent to all processes excluding
	90	system processes and the process sending the signal.
2d21ac55 A	91	If the user is not the super user,
	92	the signal is sent to all processes with the same uid as the user,
	93	excluding the process sending the signal.
9bccf70c A	94	No error is returned if any process could be signaled.
	95	.El
	96	.Pp
	97	For compatibility with System V,
	98	if the process number is negative but not -1,
	99	the signal is sent to all processes whose process group ID
	100	is equal to the absolute value of the process number.
	101	This is a variant of
	102	.Xr killpg 2 .
	103	.Sh RETURN VALUES
	104	Upon successful completion, a value of 0 is returned.
	105	Otherwise, a value of -1 is returned and
	106	.Va errno
	107	is set to indicate the error.
	108	.Sh ERRORS
	109	.Fn Kill
	110	will fail and no signal will be sent if:
	111	.Bl -tag -width Er
2d21ac55	112	.\" ==========
9bccf70c A	113	.It Bq Er EINVAL
9bccf70c A	114	.Fa Sig
2d21ac55 A	115	is not a valid, supported signal number.
2d21ac55 A	116	.\" ==========
9bccf70c A	117	.It Bq Er EPERM
	118	The sending process is not the super-user and its effective
	119	user id does not match the effective user-id of the receiving process.
	120	When signaling a process group, this error is returned if any members
	121	of the group could not be signaled.
2d21ac55 A	122	.\" ==========
	123	.It Bq Er ESRCH
	124	No process or process group can be found
	125	corresponding to that specified by
	126	.Fa pid .
	127	.\" ==========
	128	.It Bq Er ESRCH
	129	The process id was given as 0,
	130	but the sending process does not have a process group.
9bccf70c A	131	.El
9bccf70c A	132	.Sh SEE ALSO
9bccf70c	133	.Xr getpgrp 2 ,
2d21ac55	134	.Xr getpid 2 ,
9bccf70c A	135	.Xr killpg 2 ,
	136	.Xr sigaction 2
	137	.Sh STANDARDS
	138	The
	139	.Fn kill
	140	function is expected to conform to
	141	.St -p1003.1-88 .