Python argparse: "unrecognized arguments"

Question

I am trying to use my program with command line option. Here is my code:

import argparse

def main():

    parser = argparse.ArgumentParser()
    parser.add_argument("-u","--upgrade", help="fully automatized upgrade")
    args = parser.parse_args()

    if args.upgrade:
        print "Starting with upgrade procedure"
main()

When I try to run my program from terminal (python script.py -u), I expect to get the message Starting with upgrade procedure, but instead I get the error message unrecognized arguments -u.

I am not seeing any error message and I am getting your expecpted output; I think it could be because of space, tab in your program Please verify that [viswesn.viswesn-PC] ➤ python script.py -u 10 Starting with upgrade procedure [viswesn.viswesn-PC] ➤ python script.py -u usage: script.py [-h] [-u UPGRADE] script.py: error: argument -u/--upgrade: expected one argument — Viswesn
– Viswesn, Commented Jul 17, 2015 at 6:51
The only issue here, is that -u will expect a value or some sort. try doing python myscript.py -u True — Torxed
– Torxed, Commented Jul 17, 2015 at 6:57

Rakholiya Jenish · Accepted Answer · 2015-07-17 07:01:37Z

24

The error you are getting is because -u is expecting a some value after it. If you use python script.py -h you will find it in usage statement saying [-u UPGRADE].

If you want to use it as boolean or flag (true if -u is used), add an additional parameter action:

parser.add_argument("-u","--upgrade", help="fully automatized upgrade", action="store_true")

action - The basic type of action to be taken when this argument is encountered at the command line

With action="store_true", if the option -u is specified, the value True is assigned to args.upgrade. Not specifying it implies False.

Source: Python argparse documentation

edited Jul 17, 2015 at 7:01

answered Jul 17, 2015 at 6:54

Rakholiya Jenish

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Anand S Kumar · Accepted Answer · 2015-07-17 06:55:02Z

3

Currently, your argument requires a value to be passed in for it as well.

If you want -u as an option instead, Use the action='store_true' for arguments that do not need a value.

Example -

parser.add_argument("-u","--upgrade", help="fully automatized upgrade", action='store_true')

answered Jul 17, 2015 at 6:55

Anand S Kumar

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Nitesh Patel · Accepted Answer · 2015-07-17 06:59:48Z

3

For Boolean arguments use action="store_true":

parser.add_argument("-u","--upgrade", help="fully automatized upgrade", action="store_true")

See: https://docs.python.org/2/howto/argparse.html#introducing-optional-arguments

answered Jul 17, 2015 at 6:59

Nitesh Patel

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