.\"	$NetBSD: shutdown.8,v 1.27 2008/02/09 04:09:22 dholland Exp $
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.\"     @(#)shutdown.8	8.2 (Berkeley) 4/27/95
.\"
.Dd February 8, 2008
.Dt SHUTDOWN 8
.Os
.Sh NAME
.Nm shutdown
.Nd close down the system at a given time
.Sh SYNOPSIS
.Nm
.Op Fl b Ar bootstr
.Op Fl Ddfhknpr
.Ar time
.Op Ar message ... | Ar -
.Sh DESCRIPTION
.Nm
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.
.Pp
Available friendlinesses:
.Bl -tag -width bootstr
.It Fl b Ar bootstr
The given
.Ar bootstr
is passed to
.Xr reboot 8
for the benefit of those systems that can pass boot arguments to the
firmware.
Currently, this only affects sun3 and sparc machines.
.It Fl d
.Nm
will pass the
.Fl d
flag to
.Xr reboot 8
or
.Xr halt 8
to request a kernel core dump.
If neither the
.Fl h
or
.Fl r
flags are specified, then
.Fl d
also implies
.Fl r .
.It Fl f
.Nm
arranges, in the manner of
.Xr fastboot 8 ,
for the file systems
.Em not to be
checked on reboot.
.It Fl h
The system is halted at the specified
.Ar time ,
using
.Xr halt 8 .
.It Fl k
Kick everybody off.
The
.Fl k
option
does not actually halt the system, but leaves the
system multi-user with logins disabled (for all but super-user).
.It Fl n
Prevent the normal
.Xr sync 2
before stopping.
.It Fl p
The system is powered down at the specified
.Ar time ,
using
.Xr halt 8 .
If the powerdown fails, or the system does not support software powerdown,
the system will simply halt instead.
.It Fl r
The system is rebooted at the specified
.Ar time ,
using
.Xr reboot 8 .
.It Fl D
Prevents
.Nm
from detaching from the tty with
.Xr fork 2 Ns /
.Xr exit 3 .
.It Ar time
.Ar Time
is the time at which
.Nm
will bring the system down and
may be the word
.Ar now
or a future time in one of two formats:
.Ar +number ,
or
.Ar [[[[[cc]yy]mm]dd]hh]mm ,
where the century, year, month, day, and hour may be defaulted
to the current system values.
The first form brings the system down
.Ar number
minutes from the current time; the second brings the system down at the
absolute time specified.
If the century is not specified, it defaults to 1900 for years between 69
and 99, or 2000 for years between 0 and 68.
A leading zero in the
.Dq yy
value is
.Em not
optional.
.It Ar message ...
Any other arguments comprise the warning message that is broadcast
to users currently logged into the system.
.It Ar -
If
.Ar -
is supplied as the only argument after the time, the warning message is read
from the standard input.
.El
.Sh BEHAVIOR
.Pp
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
.Pa /etc/nologin
and copying the warning message there.
If this file exists when a user attempts to log in,
.Xr login 1
prints its contents and exits.
The file is removed just before
.Nm
exits.
.Pp
At shutdown time, a message is written in the system log containing the
time of shutdown, who initiated the shutdown, and the reason.
Next a message is printed announcing the start of the system shutdown hooks.
Then the shutdown hooks in
.Pa /etc/rc.shutdown
are run, and a message is printed indicating that they have completed.
After a short delay,
.Nm
runs
.Xr halt 8
or
.Xr reboot 8 ,
or sends a terminate
signal to
.Xr init 8
to bring the system down to single-user mode, depending on the choice
of options.
.Pp
The time of the shutdown and the warning message are placed in
.Pa /etc/nologin
and should be used to tell the users why the system is
going down, when it will be back up, and to share any other pertinent
information.
.Sh FILES
.Bl -tag -width /etc/rc.shutdown -compact
.It Pa /etc/nologin
tells
.Xr login 1
not to let anyone log in
.It Pa /fastboot
tells
.Xr rc 8
not to run
.Xr fsck 8
when rebooting
.It Pa /etc/rc.shutdown
System shutdown commands
.El
.Sh SEE ALSO
.Xr login 1 ,
.Xr wall 1 ,
.Xr fastboot 8 ,
.Xr halt 8 ,
.Xr init 8 ,
.Xr poweroff 8 ,
.Xr 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
.Nm
command appeared in
.Bx 4.0 .