Currently I have Ubuntu 14.04 in my laptop and now I want to update it to 15.04. I have Windows 8 and Kali Linux along with my Ubuntu. How should I update my Ubuntu to 15.04 without losing my other operating systems. I was thinking of downloading Ubuntu 15.04 and then installing it over Ubuntu 14.04, instead of updating Ubuntu 14.04 via terminal or update manager. Will that be a good option?
(Moreover I cannot update my Ubuntu via terminal or update manager as I use internet through a proxy server which requires authentication. I asked about it in my previous question and none of the techniques given by others worked)
Thanks in advance 🙂