Nginx.org太坏了，竟然给的apt源是有误。

      其实应该这样添加才行，网站给的老是报错not found   

     vim /etc/apt/sources.list 添加如下

deb http://nginx.org/packages/mainline/debian/ jessie nginx

deb-src http://nginx.org/packages/debian/ jessie nginx

debian系统安装最新版本nginx