在終端機升級ubuntu版本

Network Upgrade for Ubuntu Servers (Recommended)

1. Install update-manager-core if it is not already installed:

   sudo apt-get install update-manager-core

2. Edit /etc/update-manager/release-upgrades and set:
   
   nano /etc/update-manager/release-upgrades
   
   Prompt=lts改為
   
   Prompt=normal
   

3. Launch the upgrade tool:

   sudo do-release-upgrade

4. Follow the on-screen instructions.

參考：http://www.ubuntu.com/getubuntu/upgrading