I have just installed Python on my Windows machine, but I’m struggling to run my .py files. When I double-click the file, a window flashes and closes immediately. Could someone explain the proper steps to execute a script via the CLI? I specifically need to know how to navigate to my project folder using 'cd' and whether I should be using the 'python' or 'py' command to ensure my script runs in the correct environment.
3 answers
To run a script properly on Windows, you should avoid double-clicking the file. Instead, open the Command Prompt (CMD) and use the cd command to navigate to your folder, such as cd Documents\PythonProjects. Once there, the most reliable way to execute your code is by typing py script_name.py. The py command refers to the Python Launcher for Windows, which automatically detects the latest version of Python installed on your system. This method is much better because it keeps the console window open, allowing you to see any output or traceback errors that occur during execution. This is a fundamental workflow for anyone starting in software development or automation.
That is a great explanation of the Python Launcher! However, what happens if a user has multiple versions of Python installed, like 3.8 and 3.11? Is there a specific flag or argument we can add to the py command to ensure the script runs with a specific version instead of just the default one, especially if certain libraries aren't compatible with the newest release?
If you want to run your script by double-clicking without the window closing, just add input("Press Enter to exit") at the very end of your Python code. This pauses the execution until you interact with it.
I agree with Joseph, that's a handy "quick fix" for beginners. However, I’d still encourage learning the CMD method as Thomas and Michelle described. As you move into more complex areas like Data Science or DevOps, you'll find that running scripts via the command line offers far more control over arguments and environment variables than double-clicking ever could.
Robert, you can easily handle that by adding a version flag. You would type py -3.8 script_name.py to force it to use that specific version. This is incredibly helpful when managing legacy code. Also, if you are using virtual environments—which is a best practice in professional software development—you should activate the environment first; then, simply typing python will automatically point to the interpreter located inside that specific environment folder.