April 15, 2014, 2:07 PM — Here's how you can use the terminal to upgrade Ubuntu 12.10 to Ubuntu 14.04.
1. Open a terminal window.
2. Type in the following commands then hit Enter after each.
sudo apt-get install update-manager-core
As you may know, Ubuntu 12.10 Quantal Quetzal is a non-LTS system and so, it will reach EOL in April 2014. The final date for the Ubuntu 12.10 EOL hasn’t been set yet, but it will probably be after the big April 17 launch of Ubuntu 14.04 LTS.