Passing argument to function from command line

Python Help
1

My son wrote a command line program in ruby for me. I want to convert it to python. To run the program he has done this on the command line; “./myProgram.rb ‘argument’”. Then the 'argument ’ is passed into the program to be processed. I want to do the same in python. I am not asking that someone write the code for me, rather give me a hint where I can get the info to do that. Oh yes, I am sort of a nub when it comes to programming.

2

Depending on the complexity of your program, you’re likely looking for either sys.argv (a list of all of the command-line arguments as strings) or argparse (a module in the standard library for building user friendly command-line interfaces).

One of the following templates may help you get started:

#!/usr/bin/env python3

import sys

def print_uppercase(s):
    print(f"uppercase: {s.upper()}")

if len(sys.argv) < 2:
    print("too few arguments")
    sys.exit(1)
print_uppercase(sys.argv[1])

#!/usr/bin/env python3

import argparse

def print_uppercase(s):
    print(f"uppercase: {s.upper()}")

parser = argparse.ArgumentParser()
parser.add_argument("my_argument")
args = parser.parse_args()

print_uppercase(args.my_argument)
3

Hello,

so you want to run the Python script from the command line including passing arguments:

This tutorial should be what you are looking for:

4

Thanks everyone, that looks as though it will get me started down the right path.

Mel…

5

Let me add this. In his ruby script he used ‘ARGV’ so that looks familiar. The script is small. It is used to read lines from a data file and any line that contains the argument is printed to std out. The data file is just a list of family birthdays so the argument will be a month. I am going to have it print to a file on my desktop so I can see who has birthdays that month. Not very earth shattering!

Mel…

6

Yes, likely the sys.argv approach is best because your needs are simple. You have to run import sys first and then sys.argv is a Python list that contains the strings of the script filename and any arguments after it.

7

OK, looking for opinions here. What Python reference book do you have close at hand?

Mel…

8

The official documentation, particularly the library reference.

9

Thanks ND. Have bookmarked it and will use it I’m sure. I have the program working though I changed it some what from my original idea. Now you don’t have to put the month on the command line. I used “datetime” to get the month and have months set up in a dictionary. Also writing the output to a file on desktop.