How to read/process command line arguments?

Question

I am originally a C programmer. I have seen numerous tricks and "hacks" to read many different arguments.

What are some of the ways Python programmers can do this?

Related

• What’s the best way to grab/parse command line arguments passed to a Python script?
• Implementing a “[command] [action] [parameter]” style command-line interfaces?
• How can I process command line arguments in Python?
• How do I format positional argument help using Python’s optparse?

Answer 1

There is also argparse stdlib module (an "impovement" on stdlib's optparse module). Example from the introduction to argparse:

# script.py
import argparse

if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument(
        'integers', metavar='int', type=int, choices=range(10),
         nargs='+', help='an integer in the range 0..9')
    parser.add_argument(
        '--sum', dest='accumulate', action='store_const', const=sum,
        default=max, help='sum the integers (default: find the max)')

    args = parser.parse_args()
    print(args.accumulate(args.integers))

Usage:

$ script.py 1 2 3 4
4

$ script.py --sum 1 2 3 4
10

Answer 2

If you need something fast and not very flexible

main.py:

import sys

first_name = sys.argv[1]
last_name = sys.argv[2]
print("Hello " + first_name + " " + last_name)

Then run python main.py James Smith

to produce the following output:

Hello James Smith

Answer 3

import sys

print("\n".join(sys.argv))

sys.argv is a list that contains all the arguments passed to the script on the command line.

Basically,

import sys
print(sys.argv[1:])

Answer 4

Pocoo's click is more intuitive, requires less boilerplate, and is at least as powerful as argparse.

The only weakness I've encountered so far is that you can't do much customization to help pages, but that usually isn't a requirement and docopt seems like the clear choice when it is.

Answer 5

You may be interested in a little Python module I wrote to make handling of command line arguments even easier (open source and free to use) - Commando