sys

• sys provides access to some variables used or maintained by the interpreter and to functions that interact strongly with the interpreter.

sys.argv

• The list of command line arguments passed to a Python script.
• argv[0] is the script name.

sys.exit([arg])

• It is used to exit from the Python script. It raises a SystemExit exception signalling an intention to exit the interpreter.
• The optional arg can be an integer giving the exit status (default: 0).
  • sys.exit(0) exits without errors.
  • sys.exit(1) exits because of an error.

sys.path

• It provides a list of strings that specifies the search path for modules.

sys.stdin, sys.stdout, sys.stderr

• They are standard I/O streams provided by python.

sys.platform

• It specifies the platform on which Python is running.
  • Linux, win32, etc.

sys.version

• It specifies the version of python you are using.

sys.modules

• It is a dictionary of all the modules that have been imported in this Python instance.
  • keys: module names as strings
  • values: module objects themselves

sys.modules['<module_name>']