Worrking with Command-Line Arguments in Python

The sys module provides access to command-line arguments through the argv list. By default, argv contains a single element - the script name.

Create a script named argument_processor.py:

import sys

for index, arg in enumerate(sys.argv):
    print(f"Argument {index}: {arg}")

Execute the script with additional parameters:

python argument_processor.py param1 param2 param3

The output will display the script name followed by all provided arguments.

Program Termination Control

Use sys.exit() to terminate program execution under specific conditions:

import sys

user_input = input("Enter access code: ")

if user_input != 'valid_code':
    print("Access denied")
    sys.exit(1)
else:
    print("Access granted")

Managing Recursion Limits

Python's interpreter stack depth can be configured using sys functions:

import sys

current_limit = sys.getrecursionlimit()
print(f"Current recursion limit: {current_limit}")

# Set new limit (use caution)
new_limit = 3000
sys.setrecursionlimit(new_limit)
print(f"New recursion limit: {sys.getrecursionlimit()}")

Vertion and Platform Detection

Check interpreter version and platform informaiton for compatibility:

import sys

# Version check
if sys.hexversion >= 0x03080000:
    print("Python 3.8+ features available")
else:
    print("Consider upgrading Python version")

# Platform detection
print(f"Running on: {sys.platform}")

Implementing Cryptographic Hashing with hashlib

Basic SHA-256 Hashing

import hashlib

# Create hash object
hash_processor = hashlib.sha256()

# Add data to hash
hash_processor.update(b'Sample data for hashing')

# Get hexadecimal digest
print(f"Hash result: {hash_processor.hexdigest()}")

Concise Single-Line Hashing

import hashlib

result = hashlib.sha256(b"Complete message in one operation").hexdigest()
print(f"Compact hash: {result}")

Alternative Constructor Method

import hashlib

# Using new() constructor
hash_obj = hashlib.new('sha256', b"initial data")
print(f"Alternative construction: {hash_obj.hexdigest()}")

Hash Object Methods

• update(data): Append data to existing hash
• digest(): Return binary hash value
• hexdigest(): Return hexadecimal string representation
• copy(): Create duplicate hash object

Password Hashing with Salt

import hashlib

# Enhanced security with salt
password_hasher = hashlib.md5()
original_password = "user_password"
secret_salt = "unique_salt_value"

combined = original_password + secret_salt
password_hasher.update(combined.encode())

print(f"Salted hash: {password_hasher.hexdigest()}")