How to add the Universe & Multiverse repositories from the command line

Enabling the Universe & Multiverse repositories will give you access to tons of software that your Ubuntu system doesn’t give you access to by default. Here is how to enable them.

Open a Terminal. Applications > Accessories > Terminal
Type in:

sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak

This makes a copy of the file we’re going to modify, in case [...]