Skip to main content

Python Setup and First Run

Launchpad taught you to save and locate files. This bridge adds the interpreter that executes a Python file. Do it inside the first lesson's 3–5 hours, not as a new Launchpad gate. If installation needs longer, record setup repair separately and reforecast; installation trouble does not show inability to program.

1. Check before installing​

Use one terminal/environment for the lesson. On macOS, Linux or inside WSL, run:

python3 --version

In Windows PowerShell, use:

py -3 --version

A version line confirms an interpreter can start; it does not run your file yet. The supplied lab uses Python 3.10-compatible syntax or newer. For a new installation choose a currently supported stable Python 3 release, not an old version merely because it meets the syntax floor. Check the official release list rather than treating a version written in this course as permanently supported.

If the Windows launcher is unavailable but python --version reports a suitable Python 3 runtime, use python consistently for the commands below. Record the command and version that actually work. If a command opens a store prompt or reports “not found,” installation/command discovery is unresolved; it is not an error in your future program.

2. If an interpreter is missing​

  • Windows: follow the official Windows installation guidance, including its troubleshooting section for command aliases or existing installations. Reopen your terminal and repeat the version check.
  • macOS: use the installer and instructions linked from Python's macOS guide. Reopen Terminal and check python3.
  • Linux or WSL: inspect your distribution's supported Python package instructions using the official Unix overview as context. WSL is its own Linux environment; a Windows installation does not by itself establish that python3 is available inside it.

Do not build Python from source for this beginner lesson. No third-party Python package, API key, paid editor or account is required. On a managed computer, record the restriction and use its supported installation/help route instead of guessing administrator commands.

Git Bash and PowerShell have different command/path conventions. If you use native Windows Python, follow the PowerShell route for this lesson. If you choose WSL, keep the interpreter, terminal and saved file in that environment. Switching environments mid-task can explain “file not found”; write down which one you used.

3. Connect editor, file and interpreter​

Open the Values lesson and save its first program as plain text named first.py in your practice folder. Use your editor to confirm the exact folder and filename, including the extension; avoid an accidental first.py.txt.

In your chosen terminal, navigate to that folder using Launchpad's file-location skills. On macOS/Linux/WSL, inspect pwd and ls; in PowerShell, Get-Location and Get-ChildItem. Quote a folder path if it contains spaces. Predict the lesson's output before execution, then run:

python3 first.py

For the Windows launcher route use py -3 first.py; for the checked python route use python first.py. These are alternatives, not three required runs. The lesson explains why the first example prints 40 and then 2515.

4. Diagnose one boundary at a time​

  • Command not found: the shell cannot locate the interpreter. Return to the version check and installation guidance.
  • Cannot open file: an interpreter started, but the named file is not at the supplied location. Inspect folder, filename, extension and saved content before reinstalling anything.
  • Syntax error or traceback: the interpreter opened Python source and reports a problem with it. Preserve the message and compare the saved lines with the lesson.
  • Old output: check the saved file rather than only the editor buffer. Confirm you ran the intended copy before changing logic.
  • A >>> prompt: you opened Python's interactive mode rather than executing a filename. Type exit() to return to the shell, then run the saved file there.

Record OS/shell, command/version, saved path, prediction, observed output and any help in your existing record. A correct copied output is only setup evidence. Continue the Values lesson's independent predictions and changed examples to demonstrate understanding.

Sources and limits​

The linked Python Software Foundation documentation supplies installation/platform guidance; this bridge's sequence and assessment boundaries are curriculum design decisions. Author execution verifies the available host's first script, not every supported Windows/Linux/macOS installation. Do not claim another platform was tested without an actual observation.