[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
.Fn kill "pid_t pid" "int sig"
.Sh DESCRIPTION
The
.Fn kill
function sends the signal given by
.Fa sig
to
.Fa pid ,
a
process or a group of processes.
.Fa Sig
may be one of the signals specified in
.Xr sigaction 2
or it may be 0, in which case
error checking is performed but no
signal is actually 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 signal number.
.It Bq Er ESRCH
No process 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.
.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.
.El
.Sh SEE ALSO
.Xr getpid 2 ,
.Xr getpgrp 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
	45	.Fn kill "pid_t pid" "int sig"
	46	.Sh DESCRIPTION
	47	The
	48	.Fn kill
	49	function sends the signal given by
	50	.Fa sig
	51	to
	52	.Fa pid ,
	53	a
	54	process or a group of processes.
	55	.Fa Sig
	56	may be one of the signals specified in
	57	.Xr sigaction 2
	58	or it may be 0, in which case
	59	error checking is performed but no
	60	signal is actually sent.
	61	This can be used to check the validity of
	62	.Fa pid .
	63	.Pp
	64	For a process to have permission to send a signal to a process designated
65	by
66	.Fa pid ,
67	the real or effective user ID of the receiving process must match
68	that of the sending process or the user must have appropriate privileges
69	(such as given by a set-user-ID program or the user is the super-user).
70	A single exception is the signal SIGCONT, which may always be sent
71	to any descendant of the current process.
72	.Bl -tag -width Ds
73	.It \&If Fa pid No \&is greater than zero :
74	.Fa Sig
75	is sent to the process whose ID is equal to
76	.Fa pid.
77	.It \&If Fa pid No \&is zero :
78	.Fa Sig
79	is sent to all processes whose group ID is equal
80	to the process group ID of the sender, and for which the
81	process has permission;
82	this is a variant of
83	.Xr killpg 2 .
84	.It \&If Fa pid No \&is -1 :
85	If the user has super-user privileges,
86	the signal is sent to all processes excluding
87	system processes and the process sending the signal.
88	If the user is not the super user, the signal is sent to all processes
89	with the same uid as the user excluding the process sending the signal.
90	No error is returned if any process could be signaled.
91	.El
92	.Pp
93	For compatibility with System V,
94	if the process number is negative but not -1,
95	the signal is sent to all processes whose process group ID
96	is equal to the absolute value of the process number.
97	This is a variant of
98	.Xr killpg 2 .
99	.Sh RETURN VALUES
100	Upon successful completion, a value of 0 is returned.
101	Otherwise, a value of -1 is returned and
102	.Va errno
103	is set to indicate the error.
104	.Sh ERRORS
105	.Fn Kill
106	will fail and no signal will be sent if:
107	.Bl -tag -width Er
108	.It Bq Er EINVAL
109	.Fa Sig
110	is not a valid signal number.
111	.It Bq Er ESRCH
112	No process can be found corresponding to that specified by
113	.Fa pid .
114	.It Bq Er ESRCH
115	The process id was given as 0
116	but the sending process does not have a process group.
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.
122	.El
123	.Sh SEE ALSO
124	.Xr getpid 2 ,
125	.Xr getpgrp 2 ,
126	.Xr killpg 2 ,
127	.Xr sigaction 2
128	.Sh STANDARDS
129	The
130	.Fn kill
131	function is expected to conform to
132	.St -p1003.1-88 .