[HOW TO] Ubuntu Server 12.04 to 14.04 Upgrade

Kurzes How TO um von Ubuntu Server 12.04 LTS auf 14.04 LTS zu wechseln. Von den Ubuntu dev wird es nicht empfohlen!
Anwendung auf eigene Gefahr!

• First you have to upgrade to 12.10 then you can upgrade to 13.04, then you could move to 13.10 (dev version)
• If sudo do-release-upgrade is not working you could use the Debian method, but it is not recommended – it can break your install. I have used it twice for 12.10 to 13.04 with no issues, but your mileage may vary.

1. Use this to upgrade from Precise to Quantal

   sudo sed -i "s/precise/quantal/" /etc/apt/sources.list
   sudo apt-get update
   sudo apt-get dist-upgrade`

2. Then, use this to upgrade from Quantal to Raring

   sudo sed -i "s/quantal/raring/" /etc/apt/sources.list
   sudo apt-get update
   sudo apt-get dist-upgrade
   

3. Then, use this to upgrade from Raring to Saucy

   sudo sed -i "s/raring/saucy/" /etc/apt/sources.list
   sudo apt-get update
   sudo apt-get dist-upgrade