The sys module provides access to interpreter variables like sys.argv (command-line arguments), sys.path (module search paths), sys.version, sys.exit(), and functions for interacting with the Python runtime environment.
The subprocess module provides subprocess.run(), subprocess.Popen(), and subprocess.PIPE for secure process execution with proper input/output handling, error management, and cross-platform command execution.
The os module provides os.listdir(), os.makedirs(), os.environ, os.path operations, and process management functions for cross-platform system interactions and file operations.
The os module automatically adapts path separators for different operating systems - os.path.join() uses backslashes on Windows and forward slashes on Unix, making your code truly cross-platform without any changes.