Your computer can be driven with text
Every computer runs an operating system (OS): the master program (Linux, macOS, Windows) that manages files, memory, and every app you open. You usually control it by clicking. There is a second way: typing commands.
Why learn it? Three concrete reasons. Most servers — the machines that run websites, databases, and AI models — have no screen or desktop at all, so a text connection is the only way in. Typed commands can be saved and replayed, which turns a 40-click chore into one line you rerun tomorrow. And nearly every developer tool (git, compilers, package managers) is built terminal-first, with graphical wrappers added later — the terminal is where the full feature set lives.
Three words you need, defined once:
- Terminal: the window you type into. It just displays text.
- Shell: the program running inside the terminal that reads what you type and acts on it. The most common shell is called bash, and it is what this course teaches.
- Command: one instruction you type, like
echo hello. Press Enter and the shell runs it, prints any output, and waits for the next one.
So the loop is: you type a command → the shell asks the OS to do it → the result is printed back to you.
Your first command: echo
echo is the simplest command there is: it prints back whatever you give it. That makes it perfect for experimenting safely, because it cannot break anything.
echo Hello, terminal!One detail: the shell treats spaces as separators. If you want text kept exactly as written, extra spaces and all, wrap it in double quotes: echo "like this". Try both in the runnable example below. Press Run and compare the output.
Code exercise · bash
Run this example. The first echo prints a plain message. The second uses quotes so the extra spaces survive.
Quiz
Which program actually reads your command and decides what to do with it?
Code exercise · bash
Your turn. Use echo twice to print exactly these two lines: ``` Hello, world I am learning bash ```