00 Quiz: Terminal and CLI Foundations

A terminal is a text-based interface – essentially a text conversation with your computer. You type commands, and the computer responds with text output. While terminals were originally physical devices (option B) in the 1960s-70s, today they are software programs called “terminal emulators” that simulate that same text-based interaction. They are not graphical browsers (C), and while some browsers have developer consoles, a terminal is a standalone application (D).

The terminal application is the window (handling text display, colors, fonts, scrolling). The shell is the program running inside that window that interprets your commands and communicates with the operating system. The lecture uses an analogy: the terminal is the phone (the device), and the shell is the language you speak on the phone. Option C reverses the correct definitions, and option A ignores a distinction that matters when troubleshooting or configuring your environment.

Since macOS Catalina (2019), the default shell is zsh. Before that, macOS used bash. Linux distributions typically default to bash, and Windows defaults to PowerShell. Command Prompt (cmd.exe) is not a shell in the Unix sense.

Git Bash is recommended because it provides a bash shell on Windows, so commands like ls, cd, cat, grep work the same as on Linux and macOS. The vast majority of tutorials and documentation use bash syntax. WSL (C) is an advanced option not needed for this course. PowerShell (B) uses different syntax, and Command Prompt (A) is legacy.

Every option in the VS Code terminal dropdown opens the same terminal window but with a different shell running inside it. This is the terminal vs. shell distinction in action – the VS Code terminal is the terminal application, and you choose which shell runs inside it. You can even have multiple tabs open, each running a different shell.

Bash and zsh are both Unix shells that understand the same core commands: cd, ls, mkdir, rm, cat, echo, grep, and hundreds more. If you learn bash, you effectively know zsh too for everyday use. The differences (zsh has better tab completion, spelling correction, and customization) only matter for advanced usage. The lecture advises: “do not spend time choosing a shell right now.”

The $ at the beginning is the prompt – it indicates that the terminal is ready for your next command. You do not type it yourself. You only type git status and press Enter. Different shells use different prompt symbols ($ for bash, % for zsh, > for PowerShell), but they all serve the same purpose: “I am ready for your next command.”

The ~ (tilde) is a shortcut for your home directory (/home/user on Linux, /Users/user on macOS, C:\Users\user on Windows). The root directory is /, the parent directory is .., and the current directory is ..

In the command structure git commit -m "Add README file", -m is a flag (also called an option) that modifies the command’s behavior. Specifically, -m tells commit that the next value is the commit message. Without -m, git would open a text editor for you to write the message. git is the program (D), commit is the subcommand (A), and "Add README file" is the argument (B).

Most flags have two forms: a short form (single dash + one letter, like -m) and a long form (double dash + a word, like --message). They do exactly the same thing. Short flags are faster to type; long flags are easier to read. This pattern is consistent across most CLI tools, not just git.

The PATH is an environment variable that contains a list of folders. When you type a command like git, the shell searches through these folders in order until it finds a program with that name. The lecture compares it to a phone book: the shell looks up the name you typed in a list of known addresses. If the program’s folder is not in PATH, you get “command not found.”

“Command not found” does not mean the program does not exist in general – it means the shell cannot find it. The most common causes are: (1) the program is not installed, or (2) the program’s installation folder is not in your PATH. A third common cause is that you installed the program but did not restart the terminal – many installers add to PATH, but the change only takes effect in new terminal windows.

A program is simply a file on your hard drive that contains instructions your computer can execute. Installing a program means copying files to your hard drive and typically adding the program’s folder to your PATH so the shell can find it. Running a program means the operating system reads the file and follows the instructions inside. There is no magic involved – no kernel compilation (B), no recompilation on each run (C), and no internet streaming (D).

Git is a compiled program – its source code was translated into machine code once by a compiler, producing a standalone executable file. The computer runs it directly. Python scripts are interpreted – the source code is read and executed line by line by another program called an interpreter. The .py file is not an executable on its own; you need the Python interpreter installed to run it: python my_script.py means “tell the Python interpreter to read and run this file.”

The program (e.g., python, ruff, git) is the actual tool that does the work in the terminal. The IDE extension is a bridge between VS Code and the program – it calls the program behind the scenes and displays the results inside VS Code (syntax highlighting, error underlining, autocomplete). The extension does not contain a Python interpreter (C); it talks to the installed program. If you install the extension but forget the program, VS Code will show an error saying it cannot find a Python interpreter.

The key advantage of scripts is repeatability and maintainability. A script does exactly what you did manually, but faster, without typos, and repeatably. If you need to change the process, you edit one file instead of remembering a sequence of commands. This principle underlies all modern automation: pre-commit hooks, CI/CD pipelines, test runners, and linters. Scripts do not bypass the shell (A) or prevent all errors (B).