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Module 001: Setting Up Your Dev Environment (Python, VS Code, Terminal)

Phase: 0. Orientation | Estimated time: 2 hours | Milestone Project: No

Prerequisites

Learning Objectives

By the end of this module, you will be able to:

  • Verify Python 3.12 is installed on your system
  • Navigate the filesystem using basic terminal commands (pwd, ls, cd)
  • Open and use VS Code for editing Python files
  • Run a Python script both from the terminal and from within VS Code
  • Create your first .py file

Why This Matters

You can't write Python without a working environment. A properly configured setup — terminal, editor, and Python interpreter — is the foundation every developer builds on. Spending time here saves hours of frustration later.

Concept Explanation

Installing Python 3.12

Python does not come pre-installed on all systems, or it may ship with Python 2 (macOS). You need Python 3.12 specifically.

Windows

  1. Go to python.org/downloads
  2. Download the Python 3.12 installer for Windows
  3. Important: Check "Add Python to PATH" during installation
  4. Open Command Prompt and type python --version

macOS

  1. Install Homebrew from brew.sh if you don't have it
  2. Run brew install python@3.12
  3. Verify with python3 --version

Linux (Ubuntu/Debian)

  1. Run sudo apt update && sudo apt install python3.12
  2. Verify with python3.12 --version

Terminal Basics

The terminal (also called shell or command line) is a text-based interface to your computer. You will use it constantly as a developer.

Command What it does Example
pwd Print Working Directory — shows where you are /home/student
ls List files in the current directory ls
cd Change Directory — move somewhere else cd Desktop
cd .. Go up one directory cd ..
mkdir Make a new directory mkdir myproject
clear Clear the terminal screen clear

VS Code

VS Code is a free, lightweight code editor by Microsoft. It has excellent Python support through extensions.

  1. Download from code.visualstudio.com
  2. Install the Python extension by Microsoft (search Extensions panel)
  3. Open a folder: File → Open Folder
  4. Create a new file: File → New File → save as hello.py

Running Python

There are two main ways to run Python:

Interactive mode (REPL):

$ python3
>>> print("Hello!")
Hello!
>>> exit()

Script mode (run a .py file):

$ python3 hello.py
Hello!

The REPL is great for experimenting. Script mode is for real programs.

Your First .py File

Create a file called hello.py and add:

print("Hello, World!")

Save it, then run:

$ python3 hello.py
Hello, World!

Common Pitfalls

  1. "Python is not recognized" on Windows: You forgot to check "Add Python to PATH". Re-run the installer and check the box.
  2. Using python instead of python3 on macOS/Linux: On these systems, python often points to Python 2. Always use python3.
  3. Typos in terminal commands: cd requires a space between the command and the directory name.
  4. Forgetting to save before running: If you edit your .py file but don't save, you will run the old version.
  5. Running from the wrong directory: Use pwd and ls to confirm you are where you think you are.

Hands-On Walkthrough

Follow along step by step:

  1. Open your terminal.
  2. Type python3 --version (or python --version on Windows). You should see something like Python 3.12.x.
  3. Create a project folder: 
    mkdir ~/python-intro
cd ~/python-intro
  4. Open VS Code from the terminal: code . (the dot means "current directory").
  5. Create a new file called hello.py and write: 
    print("Welcome to Python 3.12!")
  6. Save the file (Ctrl+S / Cmd+S).
  7. Back in the terminal, run: 
    python3 hello.py
  8. You should see Welcome to Python 3.12! printed.

Key Takeaways

  • Always use Python 3 (check with python3 --version or python --version).
  • pwd — where am I? ls — what's here? cd — take me somewhere else.
  • VS Code with the Python extension is a great editor for beginners.
  • Python runs in two modes: interactive REPL and script mode.
  • A .py file is just a text file with Python code inside.
  • Save your file before running it.
  • Use exit() or Ctrl+D to leave the REPL.

Further Reading

Next Module

Let's write real code! Module 002: Your First Python Program teaches the print() function and basic program structure.