Hello Linux Geeksters. In order not to loose all you data when upgrading from Ubuntu Touch based on Ubuntu 13.10, to Ubuntu Touch based on Ubuntu 14.04, there are two things you can do:
One: Use the above command:
$ adb shell system-image-cli -c trusty -b 0 -v
Two: Add the ppa:phablet-team/tools PPA to your system, update the local repository index and install the phablet-tools package, to get the latest phablet tools version available:
$ sudo add-apt-repository ppa:phablet-team/tools
$ sudo apt-get update
$ sudo apt-get install phablet-tools
Next, follow the instructions from this article.
As you may know, the first stable version of Ubuntu Touch (based on Ubuntu 13.10) has been released in October 2013. The developers have already started work for the next Ubuntu Touch version, which is now based on Ubuntu 14.04, a system that should bring a full mobile-desktop convergence, and make Mark Shuttleworth very happy. Despite the fact that it is not mature enough to compete with Android, Ubuntu Touch has good chances of becoming a popular mobile OS, at least among the Linux enthuriasts.