While shutdown –h does the trick of shutting down a server just fine, occasionally I’d prefer the haptic version. While I’ve never had problems getting the powerbutton to work with Ubuntu desktop versions, it didn’t work out of the box on my AMD Athlon XP.
Fortunately the solution seems to be quite simple:
sudo apt-get install apmd sudo apt-get install acpid
I also had to edit /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="acpi=force acpi_osi=Linux"
and
sudo update-grub
George's Techblog 