{"title":"Setting Up Environment","description":"","content":"Before you can run a single line of Python, your machine needs a working Python install, a way to install third-party packages, and an editor that understands the language. By the end of this lesson, `python --version` will print a real version string in your terminal, you'll have `pip` ready to install packages, and an editor open and waiting.\n\nThis chapter only covers setup; here, you just install it.\n\n---\n\n# The Setup Flow\n\nThe whole process is short. Install Python for your operating system, verify it works, learn the `pip` basics, pick an editor, and run something.\n\n\n```mermaid\nflowchart LR\n A[Install Python
for your OS] --> B[Verify with
python --version]\n B --> C[Learn pip
basics]\n C --> D[Install an
editor]\n D --> E[Run Python
code]\n E --> F[Ready to build]\n\n classDef start fill:#00ceff,stroke:#000,color:#000\n classDef step fill:#ffa94d,stroke:#000,color:#000\n classDef verify fill:#38d9a9,stroke:#000,color:#000\n classDef done fill:#69db7c,stroke:#000,color:#000\n\n class A start\n class B verify\n class C,D step\n class E step\n class F done\n```\n\n\nIf you've installed compilers or runtimes for other languages before, none of this will surprise you. Take the steps in order and don't skip the verification one. A lot of \"Python isn't working\" stories turn out to be a terminal that was opened before the installer finished updating `PATH`.\n\n---\n\n# Installing Python\n\nThe Python you want is **Python 3.12 or 3.13** (or whatever the latest stable 3.x release is when you're reading this). Avoid Python 2; it was retired in 2020 and isn't supported anymore. Avoid the very newest release candidate too, because some third-party libraries take a few weeks to catch up to fresh majors.\n\n### macOS\n\nmacOS ships with a Python, but it's there for the operating system, not for you. Don't build projects on top of it. Install a fresh copy instead.\n\n**Option 1: the official installer.** Visit `https://www.python.org/downloads/`, click the macOS download for the latest 3.x release, and run the `.pkg` file. The installer drops `python3` into `/usr/local/bin` (or `/opt/homebrew/bin` on Apple Silicon for Homebrew-managed paths) and updates your `PATH` so a new terminal can find it.\n\n**Option 2: Homebrew.** If you already use Homebrew, this is a one-liner:\n\n\n```shell\nbrew install python\n```\n\n\nThat installs the current stable Python plus `pip`. After it finishes, open a fresh terminal and run:\n\n\n```shell\npython3 --version\n```\n\n\nThe exact patch number (the `.0` part) depends on when you install.\n\n### Windows\n\nOn Windows, head to `https://www.python.org/downloads/`, download the latest 3.x installer for Windows (pick `Windows installer (64-bit)` unless you're on an ARM machine), and run it.\n\nWhen the installer opens, there's one checkbox that matters more than every other option combined:\n\n\n> **INFO**\n>\n> **Add python.exe to PATH**\n\n\nCheck that box before clicking Install. If you don't, the `python` command won't work in PowerShell or Command Prompt, and you'll waste an hour trying to figure out why. Also check **Install pip** if it isn't already ticked.\n\nAfter the installer finishes, close any open PowerShell windows and open a fresh one. Environment variables set by an installer aren't picked up by terminals that were already running. Then verify:\n\n\n```shell\npython --version\n```\n\n\nWindows also ships a small tool called the **`py` launcher**. It comes with the official installer and is the recommended way to run Python on Windows when you have multiple versions installed:\n\n\n```shell\npy --version\npy -3.12 --version\n```\n\n\nThe first command runs the latest Python it can find. The second pins to a specific version. If `python` isn't on your `PATH` for some reason, `py` usually still works, which makes it a handy fallback.\n\n### Linux\n\nMost Linux distributions ship a Python 3, but it may be older than what you want. The system Python also has a quiet job: package managers and parts of the distro itself depend on it. Don't install random packages into the system Python, because you can break tools that ship with your distro.\n\nThe right move is to install a recent Python through your package manager, then do project work inside virtual environments (more on those in a bit).\n\n**Debian or Ubuntu:**\n\n\n```shell\nsudo apt update\nsudo apt install python3 python3-pip python3-venv\n```\n\n\nThe `python3-venv` package matters. Without it, you can't create virtual environments, which you'll want very soon.\n\n**Fedora, RHEL, or CentOS Stream:**\n\n\n```shell\nsudo dnf install python3 python3-pip\n```\n\n\nAfter installing, verify:\n\n\n```shell\npython3 --version\npip3 --version\n```\n\n\nIf your distro's repos are stuck on an older Python (Ubuntu LTS releases sometimes lag a release or two behind), you have two options: live with the older version for now, or use a version manager like `pyenv` to install a newer Python alongside the system one. We'll come back to `pyenv` near the end of this lesson.\n\n---\n\n# Verifying the Install\n\nA few short commands tell you whether everything is wired up correctly.\n\n\n```shell\npython --version\n```\n\n\nIf that prints `command not found`, try:\n\n\n```shell\npython3 --version\n```\n\n\nOn macOS and most Linux distros, the binary is called `python3`, not `python`. We'll talk about why in a moment. For now, whichever one prints a 3.x version is the one you'll use.\n\nAlso check `pip`, the package installer:\n\n\n```shell\npip --version\n```\n\n\nThe `(python 3.13)` part at the end is what you care about. It tells you which Python this `pip` will install packages into. If `pip` says it's tied to Python 3.13 but `python --version` says 3.12, you have two installs and your `PATH` order is mixing them.\n\nIf `pip` isn't found, try `pip3 --version` or `python -m pip --version`. The `-m pip` form runs whichever pip is bundled with the currently active Python, which is the most reliable way to invoke it.\n\n### `python` vs `python3`: Why Both?\n\nFor about a decade, Python had two parallel major versions: Python 2 (released 2000) and Python 3 (released 2008). They were not source-compatible. To keep old scripts from breaking, the convention emerged that `python` referred to Python 2 and `python3` referred to Python 3. Many Linux distros still follow that rule, which is why on Ubuntu the command is `python3` and `python` either doesn't exist or points at Python 2.\n\nPython 2 was officially retired in January 2020. On modern Windows, the official installer maps `python` to Python 3 directly. On macOS with Homebrew, you get `python3` as the primary binary; `python` may or may not be set depending on your install. The portable rule:\n\n- Type `python3` if you want to be safe everywhere.\n- Type `python` if your system has it pointed at Python 3 (Windows usually does; some macOS and Linux setups do too).\n\nYou can always check with `python --version`. If it prints a 3.x number, the short name works. If it prints 2.x or says \"not found\", stick to `python3`.\n\n---\n\n# Working with pip\n\n`pip` is Python's package installer. It pulls libraries from the Python Package Index (**PyPI**), the central registry where the community publishes open-source code. The first time you need to make an HTTP request, parse a CSV, or chart a dataset, you'll reach for a third-party library, and `pip` is how you get it.\n\nThe handful of commands you'll use constantly:\n\n\n```shell\npip install requests\n```\n\n\nThat installs the `requests` library (a popular HTTP client) plus its own dependencies. To see what's installed:\n\n\n```shell\npip list\n```\n\n\nTo see details about one specific package:\n\n\n```shell\npip show requests\n```\n\n\nTo remove a package:\n\n\n```shell\npip uninstall requests\n```\n\n\nTo freeze the current set of installed packages and their versions into a file (the conventional name is `requirements.txt`):\n\n\n```shell\npip freeze > requirements.txt\n```\n\n\nThe output file lists every installed package pinned to an exact version. Someone else can then reproduce your environment by running `pip install -r requirements.txt`.\n\n\n> **INFO**\n>\n> **Tip:** Don't run `pip install` casually on the system Python. Each `install` adds packages to a shared global location, and over time they collide with each other and with the OS's own tools. The clean answer is virtual environments, covered next.\n\n\n---\n\n# Choosing an Editor\n\nA plain text editor plus `python` is enough to write and run code. But an editor with Python support pays for itself within the first hour. It catches typos as you write, autocompletes function names, jumps you to definitions, and runs your code with a keypress.\n\nTwo editors dominate Python work. Here's how they compare:\n\n\n| Criteria | VS Code + Python extension | PyCharm Community |\n|---|---|---|\n| Cost | Free | Free (Community); Pro is paid |\n| Best for | General use, polyglot devs, beginners | Pure Python work, larger projects |\n| Strengths | Lightweight, huge extension ecosystem, great if you already use it for other languages | Deep Python tooling, smart refactoring, built-in debugger and test runner |\n| Weaknesses | Python support is good but needs an extension; settings can feel scattered | Heavier, uses more memory, can feel cluttered until you learn the layout |\n| Recommended for this course? | Yes, especially if you're new | Yes, especially for bigger Python-only projects |\n\n\nIf you don't already have a preference, install **VS Code** with the official **Python extension** from Microsoft. It's free, fast to set up, and the same editor works for the other languages you'll likely touch.\n\n### VS Code Setup\n\nDownload VS Code from `https://code.visualstudio.com/`. Install and launch it. Click the Extensions icon on the left sidebar (or press Cmd+Shift+X / Ctrl+Shift+X), search for **Python**, and install the one published by Microsoft. That single extension pulls in language support, debugging, and integration with the Python interpreter you installed earlier.\n\nTo make sure VS Code is using the right Python, open the Command Palette (Cmd+Shift+P on macOS, Ctrl+Shift+P elsewhere) and run **Python: Select Interpreter**. The list shows every Python it found on your machine. Pick the 3.x install you just verified.\n\n### PyCharm Community Setup\n\nDownload it from `https://www.jetbrains.com/pycharm/download/`. Make sure to grab **Community Edition**, which is free. The paid Professional edition adds support for web frameworks, databases, and remote development, but a beginner doesn't need any of that.\n\nOn first launch, PyCharm asks if you want to create a new project. Click **New Project**. PyCharm wants to know which Python to use; the dropdown should auto-detect the one you installed. If it doesn't, click the gear icon and point it at the path that `python --version` runs (find it with `which python3` on macOS/Linux or `where python` on Windows).\n\nPyCharm creates a project folder and, by default, a virtual environment inside it. You don't need to understand that fully yet; it's the same `python -m venv` idea you'll see in a moment, just wired up for you.\n\n---\n\n# Running Python Code\n\nThere are three ways to actually run Python, and you'll use all of them at different times.\n\n**1. The REPL (interactive shell).** Type `python` (or `python3`) with no arguments:\n\n\n```shell\npython3\n```\n\n\nThe `>>>` prompt is the **REPL**, which stands for Read-Eval-Print Loop. You type one expression, hit Enter, and Python prints the result. Try it:\n\n\n```python\n>>> 2 + 2\n4\n>>> \"shopping cart\".upper()\n'SHOPPING CART'\n>>> exit()\n```\n\n\n`exit()` (or Ctrl+D on macOS/Linux, Ctrl+Z then Enter on Windows) leaves the REPL. The REPL is perfect for trying out a one-liner, checking what a function returns, or remembering how a method works.\n\n**2. Running a `.py` file.** Save a file called `cart.py` with this content:\n\n\n```python\nitems = [\"shirt\", \"shoes\", \"hat\"]\nprint(f\"Your cart has {len(items)} items.\")\n```\n\n\nThen run it from the same directory:\n\n\n```shell\npython3 cart.py\n```\n\n\nThis is how you'll run almost every program you write.\n\n**3. One-liners with `-c`.** Sometimes you want to run a single expression without opening the REPL or creating a file:\n\n\n```shell\npython3 -c \"print('cart total:', 29.99 * 3)\"\n```\n\n\nHandy in shell scripts and CI pipelines, or just to check something quickly.\n\n---\n\n# Virtual Environments (Preview)\n\nThere's one more piece you should know exists, even though we'll only sketch it here. A **virtual environment** is an isolated copy of Python and its installed packages, attached to a single project. Instead of installing `requests` globally, you create a virtual environment for your project and install `requests` into that. Two projects on the same machine can then depend on different versions of the same library without colliding.\n\nPython ships with a tool called `venv` for this. Inside a project folder:\n\n\n```shell\npython3 -m venv .venv\n```\n\n\nThat creates a folder called `.venv` containing its own Python and an empty package list. To start using it, you **activate** it. The exact command depends on your shell:\n\n\n```shell\n# macOS / Linux (bash, zsh)\nsource .venv/bin/activate\n\n# Windows (PowerShell)\n.venv\\Scripts\\Activate.ps1\n\n# Windows (Command Prompt)\n.venv\\Scripts\\activate.bat\n```\n\n\nOnce activated, your shell prompt usually shows the venv name in parentheses, and any `pip install` you run goes into this venv, not into the system Python. To leave, run `deactivate`.\n\nThat's enough to know for now.\n\n---\n\n# Other Tools (uv, pyenv): Brief Mention\n\nThe Python tooling space has moved fast in the last few years, and two newer tools come up a lot:\n\n- **`uv`** is a fast Python package installer and project manager written in Rust. It can install packages 10 to 100 times faster than `pip` and is increasingly the default in modern Python projects. For now, sticking with `pip` is fine.\n- **`pyenv`** is a Python version manager. It lets you install multiple Python versions side by side and switch between them per-project. Useful if your distro's Python is too old, or if you maintain projects pinned to different Python versions.\n\nYou don't need either to follow this course. Mentioning them here so the names aren't a mystery the first time you see them in a tutorial or job description.\n\n---\n\n# Summary\n\n- Install a recent **Python 3** (3.12 or 3.13 at the time of writing). On macOS use the python.org installer or `brew install python`. On Windows, run the installer and check **Add python.exe to PATH**. On Linux, use `apt` or `dnf`, and don't build projects on the system Python.\n- Verify with `python --version` (or `python3 --version` on macOS/Linux) and `pip --version`. Both should agree on which Python you're using.\n- The `python` vs `python3` split is leftover from the Python 2 retirement. On Windows, `python` usually works; on macOS and most Linux distros, use `python3` to be safe.\n- The core `pip` commands: `pip install `, `pip list`, `pip show `, `pip uninstall `, `pip freeze > requirements.txt`. Running `python -m pip` instead of plain `pip` is the most reliable form when multiple Pythons are installed.\n- Pick an editor: **VS Code with the Microsoft Python extension** is the easiest start, especially if you already use it. **PyCharm Community** is free and excellent for pure-Python work.\n- Run Python three ways: the REPL (`python`), a file (`python script.py`), and a one-liner (`python -c \"...\"`).\n- A **virtual environment** (`python -m venv .venv` plus activation) gives each project its own package directory and keeps the system Python clean.\n- Modern tools like **`uv`** (fast installer) and **`pyenv`** (Python version manager) exist alongside the standard tooling.\n\nYour environment is ready. In the next lesson, First Python Program, you'll write, save, and run your first piece of Python code using the install you just verified.","pageType":"python"}

Setting Up Environment

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