In this article I will show you how to add the Hibernate Button in the Shutdown Menu, in Ubuntu 12.10 Quantal Quetzal. (The same thing can be done in Ubuntu 12.04, read this article to find out how)
When your computer goes to hibernate, the system sends all the aplications running in the RAM memory, to the swap memory (which is a file or a partition located on the hard drive).
The command for sending your system to hibernation is: sudo pm-hibernate
But if you are used to sending your computer to hibernation, you may want the old Hibernate button in the Shutdown menu. All that you have to do is to paste some codelines in a file.
Paste the following code to the /etc/polkit-1/localauthority/50-local.d/com.ubuntu.enable-hibernate.pkla file (if you don’t have this file on your system, create it):
[Re-enable hibernate by default]
Identity=unix-user:*
Action=org.freedesktop.upower.hibernate
ResultActive=yes