shutdown - close down the system at a given time
shutdown [ -k ] [ -r ] [ -h ] [ -f ] [ -n ] time [ warning-message ... ]
Shutdown provides an automated shutdown procedure which a super-user can use to notify
users nicely when the system is shutting down, saving them from system administrators,
hackers, and gurus, who would otherwise not bother with niceties.
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
and hour:min. The first form brings the system down in number minutes and the second
brings the system down at the time of day indicated (as a 24-hour clock).
At intervals which get closer together as apocalypse approaches, warning messages are dis-
played at the terminals of all users on the system. Five minutes before shutdown, or
immediately if shutdown is in less than 5 minutes, logins are disabled by creating
/etc/nologin and writing a 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
At shutdown time a message is written in the system log, containing the time of shutdown,
who ran shutdown and the reason. Then a terminate signal is sent to init to bring the
system down to single-user state. Alternatively, if -r, -h, or -k was used, then shutdown
will exec reboot(8), halt(8), or avoid shutting the system down (respectively). (If it
isn't obvious, -k is to make people think the system is going down!)
With the -f option, shutdown arranges, in the manner of fastboot(8), that when the system
is rebooted the file systems will not be checked. The -n option prevents the normal
sync(2) before stopping.
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).
/etc/nologin tells login not to let anyone log in
login(1), reboot(8), fastboot(8)
Only allows you to kill the system between now and 23:59 if you use the absolute time for
4th Berkeley Distribution November 16, 1996 SHUTDOWN(8)