Hitting CTRL-ALT-DELETE on most Linux distributions will start the soft reboot process. Normally I prefer to disable this (at least on production systems) because someone might make a mistake and reboot the system, specially those who are used to administrate Windows servers. Also what I don’t like about this shortcut is that you don’t need to be logged in (no user/password needed – but only console access) to reboot the system.
To disable this behavior, open the /etc/init/control-alt-delete.conf configuration file in a text editor such as vi or nano.
Then replace the actual shutdown action with a less harmful one:
# control-alt-delete - emergency keypress handling
# This task is run whenever the Control-Alt-Delete key combination is
# pressed. Usually used to shut down the machine.
start on control-alt-delete
#exec /sbin/shutdown -r now "Control-Alt-Delete pressed"
exec echo "CONTROL-ALT-DELETE DISABLED BY ADMIN"
The init daemon should automagically reload this change, but just to be sure run this command: