Enable Hibernate in Ubuntu 12.04

In Ubuntu 12.04 and newer, hibernation has been disabled by default in policykit. To enable hibernation, you can follow official documentation here.

 Before enabling hibernation, please try to test whether it works correctly by running pm-hibernate in a terminal. The system will try to hibernate. If you are able to start the system again then you are more or less safe to add an override.

To do so, start editing:

sudo gedit /etc/polkit-1/localauthority/50-local.d/com.ubuntu.enable-hibernate.pkla

Paste the following lines:

[Re-enable hibernate by default]
Identity=unix-user:*
Action=org.freedesktop.upower.hibernate
ResultActive=yes

Save and exit gedit.

Restart and hibernation is back!

Or run the following code to just reset the menu:

killall unity-panel-service

Source: How to enable hibernation?

AUTHOR: OBSCURE