shutdown.8

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)shutdown.8	8.1	9/11/90
.TH shutdown 8
.SH Name
shutdown \- close down the system at a given time
.SH Syntax
.B /etc/shutdown
[
.B \-k
] [
.B \-r
] [
.B \-h
] [
.B \-o
]
.I time [ warning-message ... ]
.SH Description
.NXR "shutdown command"
.NXR "system" "shutting down"
The
.PN shutdown
command
provides an automated shutdown procedure that a superuser
can use to notify users
when the system is shutting down.
.PP
The
.I time
is the time at which
.PN shutdown
will bring the system down. 
It may be the word
`now',
indicating an immediate shutdown,
or specify a future time in one of two formats:
.I + number
or
.I hour : min.
The first form brings the system down in
.I number
minutes.
The second brings the system down at the time of day indicated,
using a 24\-hour clock format.
.PP
At intervals which get shorter as shutdown nears,
warning messages are displayed at the terminals of all users on the
system. 
Warning messages are also sent to
users who are logged in to a remote system that has
mounted a file system or directory from the local system using NFS.
Five minutes before shutdown, or immediately if
shutdown is timed for less than five minutes, logins 
are disabled by creating
.PN /etc/nologin
and writing a message there.
If this file exists when a user attempts to log in,
.MS login 1 
prints its contents
and exits.
The file is removed just before
.PN shutdown
exits.
.PP
At shutdown time, a
message is written in the file 
.PN /usr/adm/shutdownlog . 
This message contains the  
time of shutdown, who ran shutdown, and the reason.
Then, a terminate signal is sent at
.PN init
to bring the system to single-user state.
.PP
If the
.PN \-r ,
.PN \-h ,
or
.PN \-k
options are used,
then
.PN shutdown
executes
.MS reboot 8 ,
.MS halt 8 ,
or avoids shutting the system down (respectively).
The
.PN \-o
option is for use by 
.PN opser 
only.  It indicates to
.PN shutdown
that it is being called by
.PN opser
and not to return to the user.
.PP
You should place the time of the shutdown and the warning message
in 
.PN /etc/nologin .  
.NXR "nologin file" "contents"
Use the message to
inform the users about when the system will be back up
and why it is going down. 
.SH Restrictions
You can kill the system only between now and 23:59, if
you use the absolute time for shutdown.
.SH Files
.TP 15
.PN /etc/nologin
Tells login not to let anyone log in
.TP
.PN /usr/adm/shutdownlog
Log file for successful shutdowns
.SH See Also
login(1), wall(1), halt(8), opser(8), reboot(8), rwalld(8c)