Concept: The sys module

Function / attribute	Description	Example
sys.argv	List of command-line arguments; sys.argv[0] is the script name.	./backup.py /data → sys.argv[1] is '/data'
sys.exit(code)	Stops the script with an exit code (0 = success, anything else = error).	sys.exit(1)
sys.stdin	The standard input stream; useful for reading piped input.	for line in sys.stdin:
sys.stdout	The standard output stream.	sys.stdout.write("OK\n")
sys.stderr	The standard error stream; use it for error messages.	print("Error!", file=sys.stderr)
sys.platform	Identifies the platform: 'linux', 'win32', 'darwin', ...	if sys.platform == "linux":
sys.version	String with the version of the Python interpreter.	sys.version → '3.14.0 (main, ...)'
sys.version_info	Version as a tuple-like object; handy for checking a minimum version.	if sys.version_info < (3, 10):
sys.executable	Absolute path of the Python interpreter running the script.	sys.executable → '/usr/bin/python3'
sys.path	List of directories Python searches when importing modules.	print(sys.path)