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1 | .\" Copyright (c) 1980, 1991 Regents of the University of California. |
2 | .\" All rights reserved. | |
3 | .\" | |
4 | .\" Redistribution and use in source and binary forms, with or without | |
5 | .\" modification, are permitted provided that the following conditions | |
6 | .\" are met: | |
7 | .\" 1. Redistributions of source code must retain the above copyright | |
8 | .\" notice, this list of conditions and the following disclaimer. | |
9 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
10 | .\" notice, this list of conditions and the following disclaimer in the | |
11 | .\" documentation and/or other materials provided with the distribution. | |
12 | .\" 3. All advertising materials mentioning features or use of this software | |
13 | .\" must display the following acknowledgement: | |
14 | .\" This product includes software developed by the University of | |
15 | .\" California, Berkeley and its contributors. | |
16 | .\" 4. Neither the name of the University nor the names of its contributors | |
17 | .\" may be used to endorse or promote products derived from this software | |
18 | .\" without specific prior written permission. | |
19 | .\" | |
20 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
21 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
22 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
23 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
24 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
25 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
26 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
27 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
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29 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
30 | .\" SUCH DAMAGE. | |
31 | .\" | |
32 | .\" @(#)kill.2 6.6 (Berkeley) 3/10/91 | |
33 | .\" | |
34 | .Dd March 10, 1991 | |
35 | .Dt KILL 2 | |
36 | .Os BSD 4 | |
37 | .Sh NAME | |
38 | .Nm kill | |
39 | .Nd send signal to a process | |
40 | .Sh SYNOPSIS | |
41 | .Fd #include <sys/signal.h> | |
42 | .Ft int | |
43 | .Fn kill "pid_t pid" "int sig" | |
44 | .Sh DESCRIPTION | |
45 | The | |
46 | .Fn kill | |
47 | function sends the signal given by | |
48 | .Fa sig | |
49 | to | |
50 | .Fa pid , | |
51 | a | |
52 | process or a group of processes. | |
53 | .Fa Sig | |
54 | may be one of the signals specified in | |
55 | .Xr sigaction 2 | |
56 | or it may be 0, in which case | |
57 | error checking is performed but no | |
58 | signal is actually sent. | |
59 | This can be used to check the validity of | |
60 | .Fa pid . | |
61 | .Pp | |
62 | For a process to have permission to send a signal to a process designated | |
63 | by | |
64 | .Fa pid , | |
65 | the real or effective user ID of the receving process must match | |
66 | that of the sending process or the user must have appropriate privileges | |
67 | (such as given by a set-user-ID program or the user is the super-user). | |
68 | A single exception is the signal SIGCONT, which may always be sent | |
69 | to any descendant of the current process. | |
70 | .Bl -tag -width Ds | |
71 | .It \&If Fa pid No \&is greater than zero : | |
72 | .Fa Sig | |
73 | is sent to the process whose ID is equal to | |
74 | .Fa pid. | |
75 | .It \&If Fa pid No \&is zero : | |
76 | .Fa Sig | |
77 | is sent to all processes whose group ID is equal | |
78 | to the process group ID of the sender, and for which the | |
79 | process has permission; | |
80 | this is a variant of | |
81 | .Xr killpg 2 . | |
82 | .It \&If Fa pid No \&is -1 : | |
83 | If the user has super user privileges, | |
84 | the signal is sent to all processes excluding | |
85 | system processes. If the user is not the super user, | |
86 | the signal is sent to all processes with the same uid as the user | |
87 | except the process sending the signal. | |
88 | No error is returned if any process could be signaled. | |
89 | .El | |
90 | .Pp | |
91 | For compatibility with System V, | |
92 | if the process number is negative but not -1, | |
93 | the signal is sent to all processes whose process group ID | |
94 | is equal to the absolute value of the process number. | |
95 | This is a variant of | |
96 | .Xr killpg 2 . | |
97 | .Sh RETURN VALUES | |
98 | Upon successful completion, a value of 0 is returned. | |
99 | Otherwise, a value of -1 is returned and | |
100 | .Va errno | |
101 | is set to indicate the error. | |
102 | .Sh ERRORS | |
103 | .Fn Kill | |
104 | will fail and no signal will be sent if: | |
105 | .Bl -tag -width [EINVAL] | |
106 | .It Bq Er EINVAL | |
107 | .Fa Sig | |
108 | is not a valid signal number. | |
109 | .It Bq Er ESRCH | |
110 | No process can be found corresponding to that specified by | |
111 | .Fa pid . | |
112 | .It Bq Er ESRCH | |
113 | The process id was given as 0 | |
114 | but the sending process does not have a process group. | |
115 | .It Bq Er EPERM | |
116 | The sending process is not the super-user and its effective | |
117 | user id does not match the effective user-id of the receiving process. | |
118 | When signaling a process group, this error is returned if any members | |
119 | of the group could not be signaled. | |
120 | .El | |
121 | .Sh SEE ALSO | |
122 | .Xr getpid 2 , | |
123 | .Xr getpgrp 2 , | |
124 | .Xr killpg 2 , | |
125 | .Xr sigaction 2 | |
126 | .Sh STANDARDS | |
127 | The | |
128 | .Fn kill | |
129 | function is expected to | |
130 | conform to IEEE Std 1003.1-1988 | |
131 | .Pq Dq Tn POSIX . |