Hello Linux Geeksters. In this article I will show you how to install the F.lux indicator on Ubuntu 13.04 Raring Ringtail via command line interface.

Actually, it is very simple, all you have to do is this:
Step 1. Add these lines to your /etc/apt/sources.list:
deb http://ppa.launchpad.net/kilian/f.lux/ubuntu raring main
deb-src http://ppa.launchpad.net/kilian/f.lux/ubuntu raring main
Step 2. Update the repository index:
$ sudo apt-get update
Step 3. Install F.lux:
$ sudo apt-get install fluxgui
This is it. Enjoy.