Lubuntu - power button doesn't turn off computer,

Solution 1:

Try this. Edit /etc/acpi/powerbtn.sh, and the make sure that the lines below are the last lines in it.

# If all else failed, just initiate a plain shutdown.
/sbin/shutdown -h now "Power button pressed"

also look in /etc/acpi/events/powerbtn, and make sure it matches below, specially the last part.

# /etc/acpi/events/powerbtn
# This is called when the user presses the power button and calls
# /etc/acpi/powerbtn.sh for further processing.

# Optionally you can specify the placeholder %e. It will pass
# through the whole kernel event message to the program you've
# specified.

# We need to react on "button power.*" and "button/power.*" because
# of kernel changes.

event=button[ /]power
action=/etc/acpi/powerbtn.sh

If you make any changes, make sure you run, before you try to see if it works. You may need to reboot.

sudo service acpid restart