Linux Pocket Guide, 2nd Edition

Name

shutdown — stdin  stdout  - file  -- opt  --help  --version

Synopsis

shutdown [options] time [message]

The shutdown command halts or reboots a Linux system; only the superuser may run it. Here’s a command to halt the system in 10 minutes, broadcasting the message “scheduled maintenance” to all users logged in:

# shutdown -h +10 "scheduled maintenance"

The time may be a number of minutes preceded by a plus sign, like +10; an absolute time in hours and minutes, like 16:25; or the word now to mean immediately.

With no options, shutdown puts the system into single-user mode, a special maintenance mode in which only one person is logged in (at the system console), and all nonessential services are off. To exit single-user mode, either perform another shutdown to halt or reboot, or type ^D to bring up the system in normal, multiuser mode.

Useful options

-r	Reboot the system.
-h	Halt the system.
-k	Kidding: don’t really perform a shutdown, just broadcast warning messages to all users as if the system were going down.
-c	Cancel a shutdown in progress (omit the time argument).
-f	On reboot, skip the usual filesystem check performed by the fsck program (described in Disks and Filesystems).
-F	On reboot, require the usual filesystem check.

For technical information about shutdowns, single-user mode, and various system states, see the manpages for init and inittab.