Before we add the required repository to our sources, we need to make sure to have the add-apt-repository package available. If you don’t start with step1, otherwise proceed to step2.

Step 1: install the add-apt-repository packages providing the command:

for Ubuntu version <= 12.04

sudo apt-get install python-software-properties

for Ubuntu version >= 12.10

sudo apt-get install software-properties-common

Step2:

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

First the repository is added, then a update to find the new packages is made and finally you’re installing sublime text 3.