The Terminal and Shell

When you use a computer, you usually point and click: you open apps from a menu, drag files into folders, and type in word processors. But there is another way to work—by typing text commands into a terminal. The terminal is the window or application where you type those commands. The shell is the program that reads what you type, interprets it, and runs the right actions. Think of the terminal as the keyboard and screen you use to talk to the computer, and the shell as the “translator” that turns your words into things the computer does. Learning to use the terminal and shell will give you more control and is essential for programming, working on servers, and using many development tools.

Terminal vs. Shell: What's the Difference?

It's easy to mix these up, but they refer to different parts of the same workflow:

When you "open a terminal," you're really opening an app that runs a shell. You type a command, press Enter, and the shell runs it and shows you the result.

Why Use the Terminal?

You might use the terminal when:

• You need to run programming tools (compilers, interpreters, package managers)
• You're working on a remote server or a lab machine that has no graphical interface
• You want to automate tasks with scripts
• You need more power or precision than point-and-click interfaces provide

The Command Line and the Prompt

When you open a terminal, you see a line of text that usually ends with a symbol such as $ or %. That line is called the prompt. It means "the shell is ready for your next command." You type a command and press Enter to run it.

$ pwd
/home/student
$

Here, pwd is the command (it prints your current folder). The line below is the output, and then you get a new prompt. Everything happens one command at a time.

Prompt Format

Prompts can look different on different systems. Common patterns:

In this course we'll often show just $ before a command. You type only what comes after the $; don't type the $ itself.

Common Shells

Different shells have slightly different features and syntax. The ideas in this course apply to all of them; we'll use Bash-style examples.

To see which shell you're using, you can run:

echo $SHELL

Output might be /bin/bash or /bin/zsh, for example.

Basic Interaction

Every time you use the terminal, you're doing the same basic loop:

1. Read the prompt.
2. Type a command (and any options or arguments).
3. Press Enter.
4. Read the output (or any error message).
5. Repeat.

# Show current directory
pwd

# List files and folders here
ls

# Show which shell is running
echo $SHELL

Tips for Success

• Type carefully: Commands and file names are case-sensitive (File.txt and file.txt are different).
• Use Tab completion: Type part of a command or path and press Tab; the shell often fills in the rest or shows options.
• Read error messages: They usually say what went wrong (e.g. “No such file or directory”).
• One command per line: Press Enter after each command.
• Don't type the prompt: Only type the command that comes after $ or %.

Common Mistakes to Avoid

• Typing the $ or % as part of the command
• Forgetting that spaces matter (e.g. putting a space in a file name when the name has no space)
• Confusing the terminal (the window) with the shell (the program running inside it)
• Ignoring error messages instead of reading them to fix the problem