How do you get command line arguments in Python

In the command line shell of the operating system, the arguments that are given after the name of the program are known as Command Line Arguments. We know that Python Command line arguments are input parameter passed to the script when executing them in sequence. In this programming world mostly all programming language provide support for command line arguments function. 

 Python language provides various ways of dealing with these types of arguments.

command line arguments in python

There are some options to read python command line arguments.  In this article we are seeing the three most common ones are:

1. Using sys.argv
2. Using getopt module
3. Using argparse module

Let’s look through simple program to learn how to read and use python command line arguments.

#  program for command line arguments in python

import sys

print(type(sys.argv))

print('Example of command line arguments are:')

for i in sys.argv:

    print(i)

import sys 

# Passed total arguments 

n = len(sys.argv) 

print("Passed total arguments:", n) 

# Arguments passed 

print("\nname of script:", sys.argv[0]) 

print("\narguments passed:", end = " ") 

for i in range(1, n): 

	print(sys.argv[i], end = " ") 

# Add. of numbers 

Sum = 0

Using argparse module 

for i in range(1, n): 

	Sum += int(sys.argv[i]) 	

print("\nresult:", Sum) 

OUTPUT:

name of script: pythonslearning.py

arguments passed:  4 5 3 2 

result: 14

Python getopt module

Python getopt module is like as the C getopt() function.This module for parsing command-line parameter where we want user to enter some options too it.

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Let’s see at a simple example to understand this.

import getopt

import sys

argv = sys.argv[1:]

try:

    opts, args = getopt.getopt(argv, 'hm:d', ['help', 'my_file='])

    print(opts)

    print(args)

except getopt.GetoptError:

    # Print a message or do something useful

    print('Something went wrong happen!')

    sys.exit(2)

In this above example getopt module will automatically parse the option value and map them. 

Python argparse module :

This module is the one way to parse command line arguments. It provides a lot of more option such as default value for arguments, help message,  positional arguments, specifying data type of argument etc.  we can use python argparse module like below.

import argparse

parser = argparse.ArgumentParser()

parser.parse_args()

Python argparse module provide a lot many features like that.

So finally we are take one more example : Python script for adding two numbers and the numbers are passed as command-line arguments.

Some FAQ about command line arguments in python :

conclusion :

In this article we saw the different types of argument in Python like 1. keyword arguments.
2. positional arguments.
3. arbitrary positional arguments.
4. arbitrary keyword arguments.
5. default arguments.

so about this section you have any query then please comment below.

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