Next: 1.4.21 su
Up: 1.4 Man Pages
Previous: 1.4.19 rmdir
Contents
- NAME
-
shutdown - bring the system down
- SYNOPSIS
-
/sbin/shutdown [-t sec] [-rkhncfF] time [warning-message]
- DESCRIPTION
-
shutdown brings the system down in a secure way. All logged-in users
are notified that the system is going down, and login(1) is blocked.
It is possible to shut the system down immediately or after a specified
delay. All processes are first notified that the system is going down
by the signal SIGTERM. This gives programs like vi(1) the time to
save the file being edited, mail and news processing programs a chance
to exit cleanly, etc. shutdown does its job by signalling the init
process, asking it to change the runlevel. Runlevel 0 is used to halt
the system, runlevel 6 is used to reboot the system, and runlevel
1 is used to put to system into a state where administrative tasks
can be performed; this is the default if neither the -h or -r flag
is given to shutdown. To see which actions are taken on halt or reboot
see the appropriate entries for these runlevels in the file /etc/inittab.
- OPTIONS
-
- -t
- sec Tell init(8) to wait sec seconds between sending processes
the warning and the kill signal, before changing to another runlevel.
- -k
- Don't really shutdown; only send the warning messages to everybody.
- -r
- Reboot after shutdown.
- -h
- Halt after shutdown.
- -n
- [DEPRECATED] Don't call init(8) to do the shutdown but do
it ourself. The use of this option is discouraged, and its results
are not always what you'd expect.
- -f
- Skip fsck on reboot.
- -F
- Force fsck on reboot.
- -c
- Cancel an already running shutdown. With this option it is of
course not possible to give the time argument, but you can enter a
explanatory message on the command line that will be sent to all users.
- time
- When to shutdown.
- warning-message
- Message to send to all users.
The time argument can have different formats. First, it can be an
absolute time in the format hh:mm, in which hh is the hour (1 or 2
digits) and mm is the minute of the hour (in two digits). Second,
it can be in the format +m, in which m is the number of minutes to
wait. The word now is an alias for +0.
The -f flag means `reboot fast'. This only creates an advisory file
/fastboot which can be tested by the system when it comes up again.
The boot rc file can test if this file is present, and decide not
to run fsck(1) since the system has been shut down in the proper way.
After that, the boot process should remove /fast- boot.
The -F flag means `force fsck'. This only creates an advisory file
/forcefsck which can be tested by the system when it comes up again.
The boot rc file can test if this file is present, and decide to run
fsck(1) with a special `force' flag so that even properly unmounted
filesystems get checked. After that, the boot process should remove
/forcefsck.
The -n flag causes shutdown not to call init, but to kill all running
processes itself. shutdown will then turn off quota, accounting, and
swapping and unmount all filesystems.
- ACCESS CONTROL
-
shutdown can be called from init(8) when the magic keys CTRL-ALT-
DEL are pressed, by creating an appropriate entry in /etc/inittab.
This means that everyone who has physical access to the console keyboard
can shut the system down. To prevent this, shutdown can check to see
if an authorized user is logged in on one of the virtual consoles.
If shutdown is called from init(8), it checks to see if the file /etc/shutdown.allow
is present. It then compares the login names in that file with the
list of people that are logged in on a virtual console (from /var/run/utmp).
Only if one of those authorized users or root is logged in, it will
proceed. Otherwise it will write the message shutdown: no authorized
users logged in to the (physical) system console. The format of /etc/shutdown.allow
is one user name per line. Empty lines and comment lines (prefixed
by a #) are allowed. Currently there is a limit of 32 users in this
file.
- FILES
-
/fastboot /etc/inittab /etc/init.d/halt /etc/init.d/reboot /etc/shutdown.allow
- BUGS
-
Not really a bug, but most users forget to give the time argument
and are then puzzled by the error message shutdown produces. The time
argument is mandatory; in 90 percent of all cases this argument will
be the word now.
- AUTHOR
-
Miquel van Smoorenburg, miquels@cistron.nl
- SEE ALSO
-
fsck(8), init(1), halt(8), reboot(8)
- EXAMPLES
-
Next: 1.4.21 su
Up: 1.4 Man Pages
Previous: 1.4.19 rmdir
Contents
