Command Line is a text-based application that allows for viewing, handling, and manipulating files on your computer.
Usually, people work with programs that use Graphical User Interfaces (GUIs). GUIs use buttons and icons to complete certain tasks on the computer. Command Line also completes tasks, except it uses commands that must be typed into a Command Line Interface (CLI).
GUIs and CLIs both allow you to interact with your computer. However, CLI can be faster and more powerful to navigate with. That’s why most programmers prefer it.
To access the CLI, we can use Unix shell. Shell is a program where people can type their commands in the CLI. Bash is the most popular shell used.
By using shell, users are able to complete repetitive tasks on their computer in a timely manner with minimal errors. Since shell uses commands, you must know the commands that are needed to achieve a specific task. Just knowing a few commands can bring one a long way in the world of shell because the commands used are universal. Shell is also able to read and execute a series of commands within a shell script, allowing users to execute numerous commands in an efficient manner.
Bash (Bourne Again SHell) is the default shell for many Unix systems. While the commands for shell are universal, the commands used in bash are specific to bash.
Software Carpentry ‘The Unix Shell’ is a course that will help you get started with learning how to use the CLI in shell. The course can be accessed here.
For a quick start into shell, focus on the lessons below.
For more advanced skills, take the remaining lessons.
Codecademy ‘The Command Line’ is an interactive course that can be used to further strengthen your skills. There is a free and pro version. To access the free version, click here.
CMD Challenge is a resource that uses fun exercises to test your CLI knowledge. There are also user submitted solutions you can take a look at if needed. To access CMD Challenge, click here.
Unix Cheat Sheet has a list of commands that are great for a quick reference. To access it, click here.
Bash Hackers Wiki is a resource that has helpful descriptions of many commands that are used in Bash. To access the wiki page, click here.
There are also many games you can play to test and strengthen your Bash skills. To access the list of games available, click here.
It is important to note that the latest version of macOS (Catalina)
uses Z Shell (zsh) instead of Bash. It is very similar to Bash, but
there are some minor differences. For example, .bashrc or
.bash_profile are under different files names in your home
directory. Thus, any information you have on these files such as aliases
would have to be migrated over to the zsh files .zshrc and
.zprofile. More about the differences can be found here
Bash is essential for efficient usage of High Performance Computing (HPC). Even if a user chooses to log in using OnDemand, one would still need to know how to create a basic shell script to submit jobs to Slurm. To help you get started with Cheaha, click here. To access OnDemand, click here.