From the console, either a remote SSH session or from in front of the machine you also have access to the following commands:
shutdown poweroff
The second command will take no arguments and immediately begin shutting down the machine, simply run as root :
poweroff
The shutdown command is more configurable, it allows you to specify whether you wish to reboot or shutdown, and will also allow you to schedule the action for later. Generally the usage is:
shutdown -r now
Here “-r” means to reboot, and “now” is the time to carry that activity out. If you wished to shutdown your machine at 8pm you could instead run:
shutdown 20:00
This will pause until 8pm and then shutdown – pressing Ctrl + C will cancel the shutdown, as will running another copy of shutdown with the “cancel” flag:
shutdown -c
Debian machines are typically setup so that if you press the three-fingered-salute “Ctrl + Alt + Delete” they will reboot. This is specified by the following line in the file “/etc/inittab“.
# What to do when CTRL-ALT-DEL is pressed. ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now
This command can be changed to anything else you desire such as:
# Poweroff on Ctrl + Alt + Del ca:12345:ctrlaltdel:/sbin/poweroff
# Ignore it completley ca:12345:ctrlaltdel:/bin/echo "Three Finger Salute Ignored"