The shell is a program that lets you issue commands directly to your computer. Mastering the shell is an absolutely essential skill for anyone who works with computers, including web developers. It gives you the ability to install and manage programs, do sophisticated management of your filesystem, and much more.
(readwrite.com)
A basic introduction to why the command line is important to learn, with some basic commands you will use regularly.
(askubuntu.com)
There are a lot of different terms thrown around about what the shell is. You may have also heard of terms like Terminal, bash, command line, and others. Read this question and answer about the difference between these terms to clear it up.
(www.youtube.com)
This crash course gives you a full overview of the basics of bash, the terminal, and shell. It condenses an enormous amount of information into just over an hour of video.
(jilles.me)
You can take your terminal to the next level to the next level by following the tips in this tutorial. There are many ways to customize and extend your terminal to become far more powerful than the standard program.