Understanding Python Command Line Arguments

Command line arguments allow users to pass information to a Python script during execution, significantly enhancing the script's flexibility and usability.

Key Concepts

• Command Line Arguments: Inputs provided to a Python script at execution time, accessible through the sys module.
• sys.argv: A list in Python containing the command line arguments passed to the script. The first element (sys.argv[0]) refers to the script name, followed by any additional arguments.

How to Use Command Line Arguments

• sys.argv[0] = 'example.py'
• sys.argv[1] = 'arg1'
• sys.argv[2] = 'arg2'
• sys.argv[3] = 'arg3'

Example of Running a Script:
For a script named example.py, run it from the command line as follows:

python example.py arg1 arg2 arg3

In this case, sys.argv would be:

Accessing Arguments:
After importing sys, command line arguments can be accessed using sys.argv.

# Example: Accessing command line arguments
print("Script name:", sys.argv[0])
print("Number of arguments:", len(sys.argv))
print("Arguments:", sys.argv[1:])

Import the sys Module:
You need to import the sys module to utilize sys.argv.

import sys

Practical Example

Below is a simple example demonstrating how to print the command line arguments:

import sys

# Check if any arguments were provided
if len(sys.argv) > 1:
    print("You provided the following arguments:")
    for arg in sys.argv[1:]:
        print(arg)
else:
    print("No arguments were provided.")

Running the Example

• Save the script as args_example.py.

Output:

You provided the following arguments:
Hello
World

Execute it in the terminal with arguments:

python args_example.py Hello World

Conclusion

Utilizing command line arguments in Python scripts enables dynamic input and enhances user interaction. By leveraging sys.argv, scripts can be made more versatile and user-friendly.