Enable hibernation in Xubuntu 14.04

Hibernation is disabled by default in all Ubuntu-based distributions because of problems in some laptops. However, it works fine on my Thinkpad. I do not use hibernation much, but sometimes I want to switch batteries without closing all my applications.

Before enabling hibernation, test that it works on your machine by running the following code.
sudo pm-hibernate

If hibernation works, enable it permanently by opening, with sudo,
/var/lib/polkit-1/localauthority/10-vendor.d/com.ubuntu.desktop.pkla

Then find the two sections below,
[Disable hibernate by default in upower]
[Disable hibernate by default in logind]

Finally, change
“ResultActive=no” to “ResultActive=yes” in both cases.

Restart your computer and you should be able to hibernate your computer from the power menu.