sys.argv, getopt, argparse

參考資料

• http://www.cyberciti.biz/faq/python-command-line-arguments-argv-example/
• https://docs.python.org/2/howto/argparse.html
• https://docs.python.org/2.7/library/argparse.html
• http://stackoverflow.com/questions/6365601/default-sub-command-or-handling-no-sub-command-with-argparse