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.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Modified by Michael Haardt (michael@moria.de)
.\" Modified by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
.\" Modified Fri Jul 23 21:51:36 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Sun Jul 25 10:53:24 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Wed Nov 01 18:56:43 1995 by Michael Haardt
.\" (michael@cantor.informatik.rwth-aachen.de)
.\" Modified Sun Apr 14 17:04:32 1996 by Andries Brouwer (aeb@cwi.nl)
.\" [added some polishing contributed by Mike Battersby (mib@deakin.edu.au)]
.\" Modified Sun Jul 21 21:25:26 1996 by Andries Brouwer (aeb@cwi.nl)
.\" Modified Fri Jan 17 23:49:46 1997 by Andries Brouwer (aeb@cwi.nl)
.\"
.TH KILL 2 "14 September 1997" "Linux 2.0.30" "Linux Programmer's Manual"
.SH NAME
kill \- send signal to a process
.SH SYNOPSIS
.nf
.B #include <sys/types.h>
.br
.B #include <signal.h>
.sp
.BI "int kill(pid_t " pid ", int " sig );
.fi
.SH DESCRIPTION
The
.B kill
system call
can be used to send any signal to any process group or process.
.PP
If \fIpid\fP is positive, then signal \fIsig\fP is sent to \fIpid\fP.
.PP
If \fIpid\fP equals 0, then \fIsig\fP is sent to every process in the
process group of the current process.
.PP
If \fIpid\fP equals \-1, then \fIsig\fP is sent to every process except
for the first one, from higher numbers in the process table to lower.
.PP
If \fIpid\fP is less than \-1, then \fIsig\fP is sent to every process
in the process group \fI\-pid\fP.
.PP
If \fIsig\fP is 0, then no signal is sent, but error checking is still
performed.
.SH "RETURN VALUE"
On success, zero is returned. On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EINVAL
An invalid signal was specified.
.TP
.B ESRCH
The pid or process group does not exist.
Note that an existing process might be a zombie,
a process which already committed termination, but
has not yet been \fBwait()\fPed for.
.TP
.B EPERM
The process does not have permission to send the signal
to any of the receiving processes.
For a process to have permission to send a signal to process
.I pid
it must either have root privileges, or the real or effective
user ID of the sending process must equal the real or
saved set-user-ID of the receiving process.
.SH "BUGS"
It is impossible to send a signal to task number one, the init process, for
which it has not installed a signal handler. This is done to assure the
system is not brought down accidentally.
.SH "CONFORMING TO"
SVr4, SVID, POSIX.1, X/OPEN, BSD 4.3
.SH "SEE ALSO"
.BR _exit (2),
.BR exit (3),
.BR signal (2),
.BR signal (7)
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