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143 lines
4.7 KiB
Groff
143 lines
4.7 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)kill.2 8.3 (Berkeley) 4/19/94
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.\"
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.TH KILL 2 "16 January 1997" GNO "System Calls"
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.SH NAME
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.BR kill
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\- send signal to a process
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.SH SYNOPSIS
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.br
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#include <signal.h>
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.sp 1
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int
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\fBkill\fR (pid_t \fIpid\fR, int \fIsig\fR);
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.SH DESCRIPTION
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The
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.BR kill
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function sends the signal given by
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.I sig
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to
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.IR pid ,
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a
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process or a group of processes.
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Signals are software interrupts; they act just like hardware interrupts
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and can also be used for basic IPC (inter-process communication).
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.LP
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.I Sig
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may be one of the signals specified in
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.BR signal (2)
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or it may be 0, in which case
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error checking is performed but no
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signal is actually sent.
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This can be used to check the validity of
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.IR pid .
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.LP
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For a process to have permission to send a signal to a process designated
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by
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.IR pid ,
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the real or effective user ID of the receiving process must match
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that of the sending process or the user must have appropriate privileges
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(such as given by a set-user-ID program or the user is the super-user).
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A single exception is the signal SIGCONT, which may always be sent
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to any descendant of the current process.
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.LP
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If
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.IR pid
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is greater than zero,
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.I sig
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is sent to the process whose ID is equal to
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.I pid.
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.LP
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If
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.IR pid
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is zero,
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.I sig
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is sent to all processes whose group ID is equal
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to the process group ID of the sender, and for which the
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process has permission;
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this is a variant of
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.BR killpg (2).
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If
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.IR pid
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is -1, and
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if the user has super-user privileges,
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the signal is sent to all processes excluding
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system processes and the process sending the signal.
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If the user is not the super user, the signal is sent to all processes
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with the same uid as the user excluding the process sending the signal.
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No error is returned if any process could be signaled.
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.LP
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For compatibility with System V,
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if the process number is negative but not -1,
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the signal is sent to all processes whose process group ID
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is equal to the absolute value of the process number.
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This is a variant of
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.BR killpg (2).
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.SH RETURN VALUES
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Upon successful completion, a value of 0 is returned.
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Otherwise, a value of -1 is returned and
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.IR errno
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is set to indicate the error.
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.SH ERRORS
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.BR Kill
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will fail and no signal will be sent if:
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.RS
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.IP \fBEINVAL\fR
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.I Sig
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is not a valid signal number.
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.IP \fBESRCH\fR
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No process can be found corresponding to that specified by
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.RI ( pid )
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.IP \fBESRCH\fR
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The process id was given as 0
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but the sending process does not have a process group.
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.IP \fBEPERM\fR
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The sending process is not the super-user and its effective
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user id does not match the effective user-id of the receiving process.
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When signaling a process group, this error is returned if any members
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of the group could not be signaled.
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.RE
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.SH BUGS
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Do not attempt to send signals from inside a CDA (Classic Desk Accessory)
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or interrupt handler.
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.SH SEE ALSO
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.BR getpid (2),
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.BR getpgrp (2),
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.BR killpg (2),
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.BR signal (2)
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.SH STANDARDS
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The
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.BR kill
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function is expected to
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conform to IEEE Std 1003.1-1988 (POSIX).
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