How to obtain a python command line argument if only it's a string

Question

I'm making my own python CLI and i want to pass only String arguments

import sys
import urllib, json
# from .classmodule import MyClass
# from .funcmodule import my_function
def main():

    args = sys.argv[1:]
    #print('count of args :: {}'.format(len(args)))
    #for arg in args:
     #   print('passed argument :: {}'.format(arg))


    #always returns true even if i don't pass the argument as a "String"
    if(isinstance(args[0], str)): 
        print('JSON Body:')
        url = args[0]
        response = urllib.urlopen(url)
        data = json.loads(response.read())
        print(data)

    # my_function('hello world')
    # my_object = MyClass('Thomas')
    # my_object.say_name()
if __name__ == '__main__':
    main()

I execute it by api "url" and this is the correct output:

Although when i'm trying to execute api url without passing it as a String my output is a little odd:

How can i accept only String arguments?

What I've tried so far:

Found this solution here but it didn't work for me (couldn't recognize the join() function)

Your odd output is because of & in the url. More info here unix.stackexchange.com/q/86247 — MePsyDuck
– MePsyDuck, Commented Dec 12, 2019 at 10:56

Jean-François Fabre · Accepted Answer · 2019-12-12 10:57:02Z

3

problem isn't a python issue. It's just that your URL contains a &, and on a linux/unix shell, this asks to run your command in the background (and the data after & is dropped). That explains the [1]+ done output, with your truncated command line.

So you have to quote your argument to avoid it to be interpreted (or use \&). There's no way around this from a Un*x shell (that would work unquoted from a Windows shell for instance)

edited Dec 12, 2019 at 10:57

answered Dec 12, 2019 at 10:54

Jean-François Fabre♦

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3 Comments

Phill Alexakis Over a year ago

there is no way to basically know if the arguments are strings ?

Jean-François Fabre Over a year ago

python doesn't even see the rest of the command line. It's a shell issue. python can't help

bruno desthuilliers Over a year ago

@PhillAlexakis arguments (sys.argv) are ALWAYS strings

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