Python argparse unrecognized arguments

Question

I am trying to use argparse to parse command line arguments. Here is my code:

#!/usr/bin/python
# -*- coding: UTF-8 -*-
import argparse

def create_parser():
    parser = argparse.ArgumentParser()
    parser.add_argument('--allow_ips', nargs='*')
    return parser

if __name__ == '__main__':
    parser = create_parser()
    namespace = parser.parse_args()

When the script is executed like this, argparse complains about unrecognized arguments.

./prog.py --allow_ips=192.168.0.10 192.168.0.11 192.168.0.12

But when the script is executed like this, argparse is satisfied.

./prog.py --allow_ips 192.168.0.10 192.168.0.11 192.168.0.12

How should I change my code so '=' can be used in the argument list?

You can't. The relevant docs section: docs.python.org/3/library/argparse.html#option-value-syntax (single command-line argument,) — hpaulj
– hpaulj, Commented Feb 18, 2018 at 7:47
unrelated: to parse the ip addresses you could use ipaddress.IPv4Address — jfs
– jfs, Commented Feb 18, 2018 at 9:32

ndmeiri · Accepted Answer · 2018-02-19 04:13:57Z

4

According to the argparse documentation, passing * in the nargs argument means

All command-line arguments present are gathered into a list.

When you invoke your program without the equal sign, all three IP addresses are considered part of the --allow_ips argument; they will be available to your program in a list.

When you invoke your program with the equal sign, only the first IP address is considered part of the --allow_ips argument. argparse then tries to parse the second and third IP addresses. But it cannot because your program does not take any positional arguments. So argparse raises an exception.

edited Feb 19, 2018 at 4:13

answered Feb 18, 2018 at 6:38

ndmeiri

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1 Comment

Roman Sokolov Over a year ago

Thank you. In my case, the arguments are passed to bash script (entry point). I found that the quotes around the list of IP-addresses are lost. I went through the arguments in the loop, added quotes and wrote it in one line, and then passed it as parameters to my program on the python. Sorry for my english.

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