Python:
Reading command line arguments

How to:

Using Python’s sys module, you can snag those command line arguments easily. Here’s how to access them in your script:

import sys

# First argument is always the script name, so we skip it
arguments = sys.argv[1:]

# Do something with the arguments
print("You entered:", arguments)

Run your script like this:

python your_script.py these are your arguments

Sample Output:

You entered: ['these', 'are', 'your', 'arguments']

Deep Dive

Way back when, folks interacted with computers through command lines. That’s why most languages, Python included, have a way to read command line arguments. It’s how scripts were controlled before GUIs came along.

Python’s sys.argv is handy, but for the fancier command-parsing dance, there’s argparse. argparse is a module for when you need more than the basics – like when your arguments need names, types, or default values.

Now, sys.argv is just a list. Everything you pass is a string, no matter what. There’s no magic; if you want numbers, convert them yourself with something like int() or float().

See Also

For more on sys.argv and argparse, check out the Python docs:

• sys.argv: https://docs.python.org/3/library/sys.html#sys.argv
• argparse tutorial: https://docs.python.org/3/howto/argparse.html

And if you really want to dive head-first into command line interfaces:

• Click: https://click.palletsprojects.com/en/7.x/
• docopt: http://docopt.org/

Happy coding!