How to install and update sublime text in ubuntu from the command line
To install sublime text 3 do the following
sudo add-apt-repository ppa:webupd8team/sublime-text-3
sudo apt-get update
sudo apt-get install sublime-text-installer
To upgrade sublime text 3, do the following
sudo apt-get update
sudo apt-get install --only-upgrade sublime-text-installer
References
http://www.ubuntuupdates.org/ppa/sublime_text_3
http://askubuntu.com/questions/44122/how-to-upgrade-a-single-package-using-apt-get