| 1 | .\" Copyright (c) 1980 Regents of the University of California.
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| 2 | .\" All rights reserved. The Berkeley software License Agreement
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| 3 | .\" specifies the terms and conditions for redistribution.
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| 4 | .\"
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| 5 | .\" @(#)kill.2 6.5 (Berkeley) 5/14/86
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| 6 | .\"
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| 7 | .TH KILL 2 "May 14, 1986"
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| 8 | .UC 4
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| 9 | .SH NAME
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| 10 | kill \- send signal to a process
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| 11 | .SH SYNOPSIS
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| 12 | .nf
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| 13 | .ft B
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| 14 | #include <sys/types.h>
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| 15 | #include <signal.h>
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| 16 |
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| 17 | int kill(pid_t \fIpid\fP, int \fIsig\fP)
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| 18 | .ft R
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| 19 | .fi
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| 20 | .SH DESCRIPTION
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| 21 | .B Kill
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| 22 | sends the signal \fIsig\fP
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| 23 | to a process, specified by the process number
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| 24 | .IR pid .
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| 25 | .I Sig
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| 26 | may be one of the signals specified in
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| 27 | .BR sigaction (2),
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| 28 | or it may be 0, in which case
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| 29 | error checking is performed but no
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| 30 | signal is actually sent.
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| 31 | This can be used to check the validity of
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| 32 | .IR pid .
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| 33 | .PP
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| 34 | The sending and receiving processes must
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| 35 | have the same effective user ID, otherwise
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| 36 | this call is restricted to the super-user.
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| 37 | .ig
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| 38 | A single exception is the signal SIGCONT, which may always be sent
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| 39 | to any descendant of the current process.
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| 40 | ..
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| 41 | .PP
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| 42 | If the process number is 0,
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| 43 | the signal is sent to all processes in the
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| 44 | sender's process group.
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| 45 | .PP
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| 46 | If the process number is \-1
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| 47 | and the user is the super-user,
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| 48 | the signal is broadcast universally
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| 49 | except to
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| 50 | .B init
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| 51 | and the process sending the signal.
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| 52 | If the process number is \-1
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| 53 | and the user is not the super-user,
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| 54 | the signal is broadcast universally to
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| 55 | all processes with the same uid as the user
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| 56 | except the process sending the signal.
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| 57 | No error is returned if any process could be signaled.
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| 58 | .PP
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| 59 | If the process number is negative but not \-1,
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| 60 | the signal is sent to all processes whose process group ID
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| 61 | is equal to the absolute value of the process number.
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| 62 | .PP
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| 63 | Processes may send signals to themselves.
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| 64 | .SH "RETURN VALUE
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| 65 | Upon successful completion, a value of 0 is returned.
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| 66 | Otherwise, a value of \-1 is returned and
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| 67 | .B errno
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| 68 | is set to indicate the error.
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| 69 | .SH "ERRORS
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| 70 | .B Kill
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| 71 | will fail and no signal will be sent if any of the following
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| 72 | occur:
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| 73 | .TP 15
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| 74 | [EINVAL]
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| 75 | \fISig\fP is not a valid signal number.
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| 76 | .TP 15
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| 77 | [ESRCH]
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| 78 | No process can be found corresponding to that specified by \fIpid\fP.
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| 79 | .TP 15
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| 80 | [ESRCH]
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| 81 | The process id was given as 0
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| 82 | but the sending process does not have a process group.
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| 83 | .TP 15
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| 84 | [EPERM]
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| 85 | The sending process is not the super-user and its effective
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| 86 | user id does not match the effective user-id of the receiving process.
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| 87 | When signaling a process group, this error was returned if any members
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| 88 | of the group could not be signaled.
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| 89 | .SH "SEE ALSO"
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| 90 | .BR getpid (2),
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| 91 | .BR getpgrp (2),
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| 92 | .BR sigaction (2),
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| 93 | .BR raise (3).
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