shutdown - close down the system at a given time
shutdown [-] [-dfhkrnp] time [warning-message ...]
shutdown provides an automated shutdown procedure for superusers 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. When the shutdown command is issued without
options the
system is placed in single user mode at the indicated time
after shutting
down all system services.
The options are as follows:
-d When used with -h or -r causes system to perform a
dump. This
option is useful for debugging system dump procedures or capturing
the state of a corrupted or misbehaving system.
See
savecore(8) for information on how to recover this
dump.
-f Create the file /fastboot so that the file systems
will not be
checked by fsck(8) during the next boot. (See
rc(8)).
-h The system is halted at the specified time when
shutdown execs
halt(8).
-k Kick everybody off. The -k option does not actually
halt the
system, but leaves the system multi-user with logins
disabled
(for all but superuser).
-n When used with -h or -r prevents the normal sync(2)
before stopping
the system.
-r shutdown execs reboot(8) at the specified time.
-p The -p flag is passed on to halt(8), causing machines which support
automatic power down to do so after halting.
(Currently
supported on some i386, mac68k, macppc, sparc and
sparc64 platforms.)
time time is the time at which shutdown will bring the
system down and
may be the word now (indicating an immediate shutdown) or specify
a future time in one of two formats: +number, or
yymmddhhmm,
where the year, month, and day may be defaulted to
the current
system values. The first form brings the system
down in number
minutes and the second at the absolute time specified.
warning-message
Any other arguments comprise the warning message
that is broadcast
to users currently logged into the system.
- If `-' is supplied as an option, the warning message
is read from
the standard input.
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 /etc/nologin and copying the warning message there.
If this
file exists when a user attempts to log in, login(1) prints
its contents
and exits. The file is removed just before shutdown exits.
At shutdown time a message is written in the system log,
containing the
time of shutdown, who initiated the shutdown and the reason.
A terminate
signal is then sent to init to bring the system down to single-user state
(depending on above options). The time of the shutdown and
the warning
message are placed in /etc/nologin and should be used to inform the users
about when the system will be back up and why it is going
down (or anything
else).
You can cancel a scheduled shutdown with the kill(1) command
by killing
the shutdown process.
/etc/nologin tells login not to let anyone log in
/fastboot tells rc(8) not to run fsck(8) during the
next boot
/etc/rc.shutdown run by rc(8) before the system is shutdown
kill(1), login(1), wall(1), halt(8), rc.shutdown(8), reboot(8)
The hours and minutes in the second time format may be separated by a
colon (`:') for backward compatibility.
The shutdown command appeared in 4.0BSD.
OpenBSD 3.6 June 5, 1993
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