First, be root
sudo -i
Copy the example
cp /usr/share/doc/gdm/examples/custom.conf /etc/gdm/
Edit it with your favourite editor
vim /etc/gdm/custom.conf
Add lines like these under [daemon]
[daemon]
AutomaticLoginEnable=true
AutomaticLogin=username
Update 14. Oct. 2010: Works in Ubuntu 10.10 as well.
To poweroff only if the power button is pressed twice – change /etc/acpi/powerbtn.sh like this:
#!/bin/sh
# /etc/acpi/powerbtn.sh
# Initiates a shutdown when the power putton has been
# pressed.
# you need to double 'click' the power button to shutdown
( if ! [ $(pidof -x powerbtn.sh | wc -w) -eq 3 ]; then
sleep .4
exit
else
poweroff
fi
) &
It won’t ask silly questions either – just shutdown now.
Now remove the wire from the reset button to make it more kid proof.