halt

This command triggers the halt procedure.

Interface

halt [ -h ] [ -a ] [ -f|F ] [ -m message ] [ -t time ] [ -W ] when

This command triggers the halt procedure immediately if when is omitted.

The when provided must be on these formats:

now: triggers the halt sequence immediately. This is the default
mins or +mins : relative time; triggers the halt sequence after mins minutes.
hh:mm : absolute time; triggers the halt sequence when the time hh:mm occurs. If that time has passed for the current day, it will wait for the next day. hh can have 1 or 2 digits; mm must have 2 digits.

-h: print this help.
-a: use access control. The halt sequence will only be launched if one of the users listed in /etc/66/shutdown.allow is currently logged in (as tracked by utmp). /etc/66/shutdown.allow is a text file which accepts one user per line. Lines starting with # are commented out.
-f: do not trigger a clean shutdown procedure; it will just sync the filesystems then tell the kernel to immediately halt. This should be the last step in the lifetime of the machine.
-F: same as -f but do not sync the filesystems.
-m message: replace the default message by message. message is broadcast to all logged in users (as tracked by utmp).
-t time: have a grace time period of time seconds between the SIGTERM and the SIGKILL at the end of the halt sequence when it is time to kill all processes (allows processes to receive SIGTERM to exit cleanly). The default is 3 seconds.
-W: do not send a wall message to users.

Halts the system.

66 halt

Halts a broken system

66 halt -f

Halts the system after 10 minutes

66 halt 10

Sends an "system will be halted in 10 minutes" to connected account and halt the system after 10 minutes

66 halt -m "system will be halted in 10 minutes" 10