Name
shutdown — close down the system
Synopsis
shutdown [ −h | −r ] [−fqs] [ now | hh:ss | +mins ]
[message]
reboot [ −h | −r ] [−fqs] [ now | hh:ss | +mins ]
[message]
fastboot [ −h | −r ] [−fqs] [ now | hh:ss | +mins ]
[message]
halt [ −h | −r ] [−fqs] [ now | hh:ss | +mins ]
[message]
fasthalt [ −h | −r ] [−fqs] [ now | hh:ss | +mins ]
[message]
DESCRIPTION
In general, shutdown prepares the system for a
power down or reboot. A absolute or delta time can be given,
and periodic messages will be sent to all users warning of
the shutdown. If no message is specified on the command line,
shutdown will
ask for a message to be sent, unless the −q option is set.
halt is the
same as shutdown -h -q
now
fasthalt is
the same as shutdown -h -q -f
now
reboot is
the same as shutdown -r -q
now
fastboot is
the same as shutdown -r -q -f
now
The default delta time, if none is specified, is 2
minutes.
Five minutes before shutdown (or immediately, if shutdown
is less than five minutes away), the /etc/nologin file is created with a message
stating that the system is going down and that logins are no
longer permitted. The login
(1) program will not allow non-superusers to
login during this period. A message will be sent to all users
at this time.
When the shutdown time arrives, shutdown notifies all users, tells
init(8) not to spawn more
getty(8)'s, writes the shutdown
time into the /var/log/wtmp
file, kills all other processes on the system, sync(2)'s, unmounts all the
disks, sync(2)'s again, waits for
a second, and then either terminates or reboots the
system.
Prior to unmounting all discs, the SIGQUIT signal is sent to the init process, which will in
turn exec shutdown(8). This allows
for clean unmounting, even if the old inode for the
init process was
unlinked. If the current process ID (PID) equals 1, then
shutdown(8) will pause
forever.
OPTIONS
−h-
Halt the system. Do not reboot. This option is used
when powering down the system.
−r-
Reboot the system.
−f-
Fast. When the system is rebooted, the file systems
will not be checked. This is arranged by creating
/fastboot, which
/etc/rc must detect (and
delete).
−q-
Quiet. This uses a default broadcast message, and
does not prompt the user for one.
−s-
Reboot in single user mode. This is arranged by
creating /etc/singleboot,
which simpleinit(8) detects
(and deletes).
CONFIG
The configuration file /etc/shutdown.conf is used to determine the
action to take when halting the machine. The currently
supported file format is extremely primitive. The first line
must contain two strings separated by whitespace. The first
string must be HALT_ACTION and
the second specifies the action you wish to take on halt. The
options allowed are:
- halt
-
This will simply halt the system. This is the
default behaviour. Note also that this is the fallback
if another option fails.
- power_off
-
This will use the kernel power shutdown facility.
This is usually only available on machines with
Advanced Power Management (APM).
programname-
This specifies a command to run to shut down the
power. The first character must be a "/". Bear in mind
that this command will be run with only the root
filesystem mounted (and it will be read-only), and no
daemons running.
BUGS
Unlike the BSD shutdown, users are notified of
shutdown only once or twice, instead of many times, and at
shorter and shorter intervals as "apocalypse approaches."
Some would construe this as a feature.
AUTHOR
This page documents the version of shutdown originally written by
Peter Orbaek (poe@daimi.aau.dk).
Copyright 1992 Rickard E. Faith (faith@cs.unc.edu)
May be distributed under the GNU General Public License
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