disable CTRL-ALT-DEL in Ubuntu

I have commented “exec shutdown … ” in /etc/init/control-alt-delete.conf.

# control-alt-delete - emergency keypress handling
#
# This task is run whenever the Control-Alt-Delete key combination is
# pressed, and performs a safe reboot of the machine.

description     "emergency keypress handling"
author          "Scott James Remnant "

start on control-alt-delete

# 110624 prevent restart from command line
# task
# exec shutdown -r now "Control-Alt-Delete pressed"