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Command: shutdown | Section: 8 | Source: Digital UNIX | File: shutdown.8.gz
shutdown(8) System Manager's Manual shutdown(8)
NAME
shutdown - Ends system operation
SYNOPSIS
/usr/sbin/shutdown [-bfhknr] time [warning-message ...]
DESCRIPTION
The shutdown command provides an automated shutdown procedure. You
must be root to use this command.
The time argument specifies when shutdown will bring the system down.
You can use the word now (indicating an immediate shutdown) or specify
a future time in one of two formats: +number or hhmm. The first form
brings the system down in number minutes. The second form brings the
system down at the hours and minutes specified. The hours and minutes
in the second time format may be separated by a colon (:) for backward
compatibility.
Any other arguments comprise the warning message that is broadcast to
users currently logged into the system. Prior to shutdown, warning
messages are displayed at the terminals of all users on the system.
Messages are sent at intervals which get closer together as shutdown
approaches.
Five minutes before shutdown (or immediately, if shutdown is in less
than five minutes) logins are disabled by creating the /etc/nologin
file and copying the warning message there. If this file exists when a
user attempts to log in, the login program prints its contents and ex-
its. The nologin file is removed just before shutdown exits. If the
shutdown is canceled or aborted, the nologin file may remain, and then
must then be removed by the superuser after determining that the system
is safe for users. If you cancel the shutdown during the grace period
by using the kill shutdown_process_id command, the shutdown is can-
celled and the nologin file is removed. A shutdown process should not
be aborted once the grace period ends and shutdown actually begins.
At shutdown time a message is written in the system log, containing the
time of shutdown, who ran shutdown and the reason. A terminate signal
is then sent to init to bring the system down to the single-user state.
Alternatively, if you invoke shutdown with the -r, -h, or -k flag, the
command executes the reboot command or the halt command, or avoids
shutting the system down. Note that the -h and -r flags use a broad-
cast kill signal and not the run level transition scripts. To use the
run level transition scripts, execute the shutdown command without the
-h or -r flag. This will bring the system down to single user mode.
From single user mode, execute shutdown with the -h or -r flag. Alter-
natively, you can execute init 0 which will bring the system from level
3 to the console prompt.
If you invoke the command with the -f flag, shutdown shuts down the
system quickly (in the manner of the fastboot or the fasthalt program);
the system halts or reboots without checking the file systems. For ex-
ample, the shutdown -f time command brings the system to single user
and creates the /fastboot file; when the system reboots to multiuser,
it does not invoke fsck. The shutdown -f -r time command causes the
system to shut down, create the /fastboot file, then immediately re-
boot. The shutdown -f -h time command causes the system to halt and
create the /fastboot file.
The -n flag prevents the normal syncing of disks before stopping the
system. The -n and -f flags together on the command line are incompat-
ible.
The time of the shutdown and the warning message are placed in the
nologin file and can be used to inform the users about when the system
will be back up and why it is going down.
FLAGS
Sends a shutdown message to the rwalld daemon on all remote client
hosts that have NFS file systems mounted from this system. Causes a
fast shutdown, bypassing the messages to other users and bringing the
system down as quickly as possible. Causes the system to shutdown and
halt using a broadcast kill signal. Causes shutdown messages to be
sent to users, warning them of an impending shutdown. The system does
not actually shut down. The /etc/nologin file is not created. Causes
a shutdown without syncing the disks. Causes the system to shutdown
using a broadcast kill signal and automatically reboot.
FILES
Specifies the command path Location of the nologin file.
RELATED INFORMATION
Commands: login(1), wall(1), fastboot(8), fasthalt(8), halt(8), re-
boot(8) delim off
shutdown(8)