ubuntu长期支持的版本

Before install ubuntu, you should ref following url to make sure which version of ubuntu will be long term support, Then download and install it.

https://wiki.ubuntu.com/LTS

https://wiki.ubuntu.com/Home

https://wiki.ubuntu.com/Releases

Or you can not update your system soon, such as ubuntu 13.04!

14.04 upgrade to 16.04:

# sudo aptitude update

# sudo do-release-upgrade

ref:https://help.ubuntu.com/lts/serverguide/installing-upgrading.html

Or:

图形界面：

# sudo aptitude update

# sudo update-manager