Running Python Scripts

Beginner Satellite

Running Python Scripts

Move beyond the REPL by running `.py` files, passing CLI arguments, and making scripts executable.

Use python CLI flagsAdd arguments

Basic execution

python hello.py
python3 hello.py   # macOS/Linux when both versions installed

Use absolute or relative paths. Activate your virtual environment first (source .venv/bin/activate).

Passing arguments

python greet.py --name "Ada" --times 3

Inside your script, parse them with argparse:

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('--name', default='Developer')
args = parser.parse_args()

Shebang for executables

#!/usr/bin/env python3
print("Hello")

1. Add shebang as the first line.
2. Make file executable: chmod +x script.py
3. Run ./script.py

Helpful flags

Flag	Purpose
-m module	Run a module as a script (python -m venv .venv)
-i	Drop into interactive mode after running
-O	Optimize bytecode (removes asserts)

Next up in your learning path

Use the REPL

Switch to interactive mode when experimenting.

Companion

Bundle scripts into packages

Organize code for distribution.

Next step

Automate tasks

Hook scripts into cron/CI once reliable.

Project