[!ABSTRACT] The Terminal (also called Command Line or Shell) is a text-based way to talk to your computer. Instead of clicking icons, you type instructions. It's faster, customisable and more powerful.

[!WARNING]- Prerequisites  You should have completed:  - 11_unix  

1. Opening the Terminal

Before you can time, you need to open the terminal:

• macOS: Press Cmd + Space, type "Terminal" and hit Enter.
• Linux/WSL: Press Ctrl + Alt + T.

2. Navigation

Think of the terminal as a "File Explorer" (Explorer/Finder) without the windows. You are always inside a folder.

• pwd (print working directory): Shows the path to the folder you are currently standing in.
• ls(list): Shows the list of files and folders inside you current location.
• cd <folder>(change directory): Moves into a folder.

[!TIP]- Change Directory Let's say you have the structure Username/Documents/ (this is called a path), and you are currently in username/.

Running cd Documents/ will move you into the Username/Documents/ folder.

To return, you run cd ... ../ describes the path to the mother directory.

3. Managing Files & Folders

• mkdir <name>(make directory): creates a new folder.
• touch <filename>: create a new, empty file.
• rm <filename>(remove): Deletes a file.
• rmdir <folder>: Deletes an empty folder.
• rm -rf <folder: Forces delete of a non-empty folder.

[!DANGER] Remove Commands Running a remove command (rm, rmdiror rm -rf), fully deletes a file or directory. It is not moved to a trash bin, once run it is completely gone. Be very careful!

[!TIP]- Flags If you have noticed, the last command: rm -rf consists of the remove command with an extra component preceded by a minus (-). These are called flags and are used to provide extra information to the command (rm). For example, we will later see how to install dependencies:

pip install SomePackage # this installs a Python package
pip install --upgrade SomePackage # this re-install the lastest version of the package
pip install -U # this flag is the short version of --upgreade (not only 1 '-')

4. Reading and Editing

You don't need to open Notepad or TextEdit to see what's inside a file.

• cat <filename>: Dumps the entire text of a file into your terminal so you can read it.
• nano <filename>: Opens a simple, "old-school" text editor inside the terminal.
  • Press Ctrl+O and Enter to save, and Ctrl + Xto exit.

These text editors are very basic and, especially for beginners, you may consider using a dedicated text editor application (like Visual Studio Code or PyCharm). These are applications that allow you to manage files and edit them more intuitively. They also have a built in terminal (i.e., you can open the terminal from the application itself).

[!TIP]- Pro Text Editing The ultimate command line text editor is Vim or NeoVim. It requires a steep learning curve and some basic understanding of the functioning of computers, thus it is not recommended for beginners. If you want to know more contact @joanalnu (GAMMA PI).

5. Understanding the System

Unix organises files like a tree. Everything starts at the Root (/).

• /: The very top level (there is no mother directory).
• ~: Short-hand for your Home folder (where your personal files live, normally the user folder in the computer)
• sudo (SuperUser Do): Use this before a command if you get a "Permission Denied" error. It's communicates you are the administrator and it will prompt you to enter your password.

6. Beginner Tips

• Tab Completion: Start typing a folder name and hit theTabkey: the terminal finishes the word for you.
• clear: Use this when the screen gets to messy.
• man <command>: If you forget how a command works, type man followed by the command (e.g., man ls, man rm) to see the manual. Press qto quit the manual.

[!SUCCESS] Now that you can move files around, let's learn how to track changes to your code with 13_git.