CODEWITHSUNDEEP
pythonpython-3.x
shaboinkin
shaboinkin

Reputation: 183

Command line argument shows up as an empty string

I'm attempting to pass in an argument to my script but for some reason if I specify -t for my time value, it shows up in the script as an empty string. If I specify --time, I get the correct value. Why?

import sys, getopt, time


def main(argv):
    inputfile = ''
    outputfile = ''
    sleeptime = 6

    if len(sys.argv) == 1:
        print("No arguments supplied")
        print('Usage: test.py -i <inputfile> -o <outputfile> -t <1-24>')
        sys.exit()

    try:
        opts, arg = getopt.getopt(argv, "i:o:t", ["ifile=", "ofile=", "time="])
    except getopt.GetoptError:
        print('Incorrect options.')
        print('Usage: test.py -i <inputfile> -o <outputfile> -t <1-24>')
        sys.exit()

    for opt, arg in opts:
        if opt in ("-i", "--ifile"):
            inputfile = arg
        elif opt in ("-o", "--ofile"):
            outputfile = arg
        elif opt in ("-t", "--time"):
            print("time = ", arg)
            sleeptime = int(arg)
        else:
            print("Unknown arg")
            sys.exit()

    print(sleeptime)

if __name__ == "__main__":
    main(sys.argv[1:])

I pretty much ripped the code from here: https://www.tutorialspoint.com/python/python_command_line_arguments.htm

Upvotes: 2

Views: 1894

Answers (2)

deif
deif

Reputation: 1389

To answer your question, i think you forgot the trailing colon for the t option (since t requires an argument), try changing it to "i:o:t:", see https://docs.python.org/3/library/getopt.html#getopt.getopt.

The whole line should look like this:

opts, arg = getopt.getopt(argv, "i:o:t:", ["ifile=", "ofile=", "time="])

In general i agree with the comments above though, i would recommend to use https://docs.python.org/3/library/argparse.html for command line argument parsing :).

Upvotes: 5

wim
wim

Reputation: 363486

In the docs:

shortopts is the string of option letters that the script wants to recognize, with options that require an argument followed by a colon

You missed the colon on the t. Modify like this, and it works:

opts, arg = getopt.getopt(argv, "i:o:t:", ["ifile=", "ofile=", "time="])

Upvotes: 2

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