So if your terminal is just a program that lets you issue text-based commands and renders the output of those commands...
...What is the program that runs those commands???
That's a shell.
Shells do a lot of things, but their main job is to interpret the commands you type and execute them.
Shells are often referred to as "REPLs." REPL stands for
This is a fancy way of saying that shells are programs that:
This is a new kind of lesson! You'll simply type your answer into the text box on the right. The only interaction is submitting your answer to be checked.
In your own shell in another window (not the text box on the right), run the following command:
expr 123456 + 7890
If you're on Windows, use your WSL Ubuntu shell for this and all future lessons.
Paste the output of that command into the text box on the right.
If you're confused about prompts vs outputs, here's a quick explanation.
wagslane@MacBook-Pro ~ % echo hello
hello
wagslane@MacBook-Pro ~ %
In the example above, I started with an empty prompt and typed echo hello and pressed enter.
wagslane@MacBook-Pro ~ % echo hello
The shell ran that command, and printed the output:
hello
Finally, it gave me a new prompt to type another command:
wagslane@MacBook-Pro ~ %