bash1

The Terminal and Shell

Simply put, a shell is a program that takes inputs and runs processes or jobs. The user will type a command and expect some sort of output, or side effect. The shell makes it possible to compose commands and programs that can run simple and complicated processes with only one line of code. While it may seem less intuitive than a graphical interface at first glance, it is in fact, much more powerful and scales much better.

Often times, you will have to use a command line in order to interface with other machines, such as supercomputers, servers, or other remote machines. It is also beneficial to know since many projects will have you installing or running things on the command line.

The most popular Unix shell is Bash, and it's the default on most Linux systems. When you open a terminal, you are automatically dropped into a bash shell, where you can begin typing commands right away. You will first be presented with a prompt, most likely represented by the $ symbol. Behind the $ you will may see what user you are logged in as and your current directory.

$

From there you can type any command and press enter

$ ls

And below you will see the output:

$ ls
Desktop     Downloads   Movies      Pictures
Documents   Library     Music       Public

The ls command simply lists all the directories and files inside the directory that you are currently in.

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