When it comes to the Linux shell, it's important to understand what exactly this pertains to. We've been using the command-line repeatedly throughout the book, but we haven't yet had any formal discussion about the actual interface through which our commands are entered.
Essentially, we've been entering our commands into a command interpreter known as the Bourne-Again Shell, or simply Bash. Bash is just one of many different shells that you can use to enter commands. There are other options, such as Zsh, Fish, ksh, and so on. Bash is the default command shell for pretty much every Linux distribution in existence. It's possible there's a Linux distribution I have yet to try that defaults to another shell, but Bash is definitely the most common. In fact, it's even available on macOS in its Terminal, and in Windows...