Template - 新增唯讀的全域變數

靈感來自 http://www.kfirlavi.com/blog/2012/11/14/defensive-bash-programming/

Signed-off-by: Ｖ字龍(Vdragon) <pika1021@gmail.com>
新增程式進入點 main()

from http://www.kfirlavi.com/blog/2012/11/14/defensive-bash-programming/
Signed-off-by: Ｖ字龍(Vdragon) <pika1021@gmail.com>