gno/sbin/shutdown/shutdown.8

.\" Copyright (c) 1988, 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.
.\"
.\"     @(#)shutdown.8	8.1 (Berkeley) 6/5/93
.\"
.TH SHUTDOWN 8 "4 October 1997" GNO "System Administration"
.SH NAME
.BR shutdown
\- close down the system at a given time
.SH SYNOPSIS
.BR shutdown
[
.B -
] [
.BR -hkrn
]
.I time
.I "warning-message ..."
.SH DESCRIPTION
.BR Shutdown
provides an automated shutdown procedure for super-users
to nicely notify users when the system is shutting down,
saving them from system administrators, hackers, and gurus, who
would otherwise not bother with such niceties.
.LP
Available friendlinesses:
.RS
.IP \fBh\fR
The system is halted at the specified
.BR time
when
.BR shutdown
execs
.BR halt (8).
.IP \fBk\fR
Kick every body off.
The
.B k
option
does not actually halt the system, but leaves the
system multi-user with logins disabled (for all but super-user).
.IP \fBn\fR
Prevent the normal
.BR sync (2)
before stopping.
.IP \fBr\fR
.BR Shutdown
execs
.BR reboot (8)
at the specified
.BR time .
.IP \fItime\fR
.BR Time
is the time at which
.BR shutdown
will bring the system down and
may be the word
.BR now
(indicating an immediate shutdown) or
specify a future time in one of two formats:
.BR +number ,
or
.BR yymmddhhmm ,
where the year, month, and day may be defaulted
to the current system values.  The first form brings the system down in
.BR number
minutes and the second at the absolute time specified.
.IP \fIwarning-message\fR
Any other arguments comprise the warning message that is broadcast
to users currently logged into the system.
.IP \fB-\fR
If
.BR -
is supplied as an option, the warning message is read from the standard
input.
.RE
.LP
At intervals, becoming more frequent as apocalypse approaches
and starting at ten hours before shutdown, warning messages are displayed
on the terminals of all users logged in.  Five minutes before
shutdown, or immediately if shutdown is in less than 5 minutes,
logins are disabled by creating
.B /etc/nologin
and copying the
warning message there.  If this file exists when a user attempts to
log in,
.BR login (1)
prints its contents and exits.  The file is
removed just before
.BR shutdown
exits.
.LP
At shutdown time a message is written in the system log, containing the
time of shutdown, who initiated the shutdown and the reason.
A terminate
signal is then sent to
.BR init 
to bring the system down to single-user state (depending on above
options).
The time of the shutdown and the warning message
are placed in
.B /etc/nologin
and should be used to
inform the users about when the system will be back up
and why it is going down (or anything else).
.SH FILES
.IP \fB/etc/nologin\fR
tells login not to let anyone log in
.SH SEE ALSO
.BR login (1),
.BR wall (1),
.BR halt (8),
.BR reboot (8)
.SH BACKWARD COMPATIBILITY
The hours and minutes in the second time format may be separated by
a colon (``:'') for backward compatibility.
.SH HISTORY
The
.BR shutdown
command appeared in 4.0BSD.