SHUTDOWN(8) BSD System Manager's Manual SHUTDOWN(8)
shutdown -- close down the system at a given time
shutdown [-] [-h | -p | -r | -k] [-o [-n]] time [warning-message ...]
The shutdown utility 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.
The following options are available:
-h The system is halted at the specified time.
-p The system is halted and the power is turned off (hardware sup-
port required) at the specified time.
-r The system is rebooted at the specified time.
-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 super-user).
-o If one of the -h, -p or -r is specified, shutdown will execute
halt(8) or reboot(8) instead of sending signal to init(8).
-n If the -o is specified, prevent the file system cache from being
flushed by passing -n option to halt(8) or reboot(8). This
option should probably not be used.
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.
Any other arguments comprise the warning message that is broad-
cast 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 start-
ing at ten hours before shutdown, warning messages are displayed on the
terminals of all users logged in. Five minutes before shutdown, or imme-
diately if shutdown is in less than 5 minutes, logins are disabled by
creating /var/run/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 to the system log, containing the
time of shutdown, the person who initiated the shutdown and the reason.
Corresponding signal is then sent to init(8) to respectively halt, reboot
or bring the system down to single-user state (depending on the above
options). The time of the shutdown and the warning message are placed in
/var/run/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).
A scheduled shutdown can be canceled by killing the shutdown process (a
SIGTERM should suffice). The /var/run/nologin file that shutdown created
will be removed automatically.
/var/run/nologin tells login not to let anyone log in
kill(1), login(1), wall(1), nologin(5), halt(8), init(8), reboot(8)
The hours and minutes in the second time format may be separated by a
colon (``:'') for backward compatibility.
The shutdown utility appeared in 4.0BSD.
BSD December 11, 1998 BSD