1. (optional) under xubuntu – install seahorse
  2. generate gpg key
  3. publish key: hkp://keyserver.ubuntu.com — https://launchpad.net/+help-registry/openpgp-keys.html#publish
  4. add the key to launchpad: https://launchpad.net/~nixin/+editpgpkeys
  5. sign https://launchpad.net/codeofconduct
  6. prepare the new package:

I used the 3.8 kernel on Ubuntu Server and after a crash I couldn’t boot anymore.…

Source: http://askubuntu.com/questions/250733/can-i-do-a-silent-or-unattended-release-upgrade