hello everyone, I wrote a very simple python script to pipe into aircrack-ng. My question is how can i enter a variable on commencement?

or how can i make this work:

$ python3 script.py -p /usr/file/document.txt

so that the script can use the path i've entered.
I looked around a bit with google already but i could think of how to pose my question without this whole explanation.

-thanks much