Installing sublime text through command line is very easy. First you have to adds a PPA to your list of sources, so that Ubuntu knows to look for updates from that PPA as well as from the official Ubuntu sources. If you do not add this ppa then you will get less recent version of any application. Then, you need to the update the local database to know what package can be installed and from where to install. Then, third process is to install. This  searches the package in its database or download it from the PPA and install on the local machine.

For sublime-text-2:

sudo add-apt-repository ppa:webupd8team/sublime-text-2
sudo apt-get update
sudo apt-get install sublime-text

For Sublime-text-3:

sudo add-apt-repository ppa:webupd8team/sublime-text-3
sudo apt-get update
sudo apt-get install sublime-text-installer