80. Python's sys Module

Here are 10 Python code snippets that demonstrate different use cases of Python's sys module:

1. Accessing Command-Line Arguments

This example shows how to retrieve command-line arguments using sys.argv.

import sys

if __name__ == "__main__":
    print("Command-line arguments:")
    for arg in sys.argv:
        print(arg)

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2. Exiting a Program with sys.exit()

You can use sys.exit() to exit a program gracefully, optionally providing an exit status.

import sys

def main():
    print("This is an example of sys.exit()")
    sys.exit(0)

if __name__ == "__main__":
    main()

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3. Redirecting Output Using sys.stdout

This example demonstrates redirecting standard output to a file.

import sys

with open('output.txt', 'w') as f:
    sys.stdout = f
    print("This will be written to output.txt")
    
sys.stdout = sys.__stdout__  # Resetting stdout

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4. Checking the Python Version with sys.version

You can check the version of Python being used with sys.version.

import sys

print(f"Python version: {sys.version}")

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5. Working with sys.path for Importing Modules

This example shows how to manipulate sys.path to control module search paths.

import sys

# Print current sys.path
print("Before modifying sys.path:", sys.path)

# Add a new path
sys.path.append('/path/to/directory')

# Print updated sys.path
print("After modifying sys.path:", sys.path)

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6. Getting the Size of an Object with sys.getsizeof()

This example shows how to use sys.getsizeof() to get the size of an object in bytes.

import sys

a = [1, 2, 3]
size = sys.getsizeof(a)
print(f"Size of list 'a': {size} bytes")

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7. Handling Standard Error Output with sys.stderr

This example shows how to write error messages to sys.stderr.

import sys

print("This is a normal message.")
print("This is an error message.", file=sys.stderr)

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8. Getting the Recursion Limit with sys.getrecursionlimit()

You can check and set the recursion limit using sys.getrecursionlimit() and sys.setrecursionlimit().

import sys

print(f"Current recursion limit: {sys.getrecursionlimit()}")
sys.setrecursionlimit(2000)
print(f"Updated recursion limit: {sys.getrecursionlimit()}")

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9. Using sys.stdin for User Input

This example uses sys.stdin to read user input.

import sys

print("Please enter your name:")
name = sys.stdin.readline().strip()
print(f"Hello, {name}!")

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10. Exiting with an Error Code Using sys.exit()

This snippet shows how to exit a program with a specific error code.

import sys

print("Something went wrong.")
sys.exit(1)  # Exit with error code 1

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These examples demonstrate how to use the sys module for interacting with the interpreter, handling input/output, working with command-line arguments, and managing program behavior. The sys module is essential for low-level system interactions in Python.