How to create a "sage program" with command line input

edit

I am completely new to Sage and Pyhton, so this is probably a very trivial question, but I am not able to find any answer. I have a file script.sage

N=10
sage_command1
sage_command2
sage_command3
print(result)

I use this script via sage script.sage and it does what I want. How can I modify this so that I can pass the variable N in the command line? Something like sage script.sage 10 and then it prints the result.

Thank you!