实战经验：Ubuntu 16.04 apt-get设置HTTP代理

新建文件/etc/apt/apt.conf.d/95proxies，添加以下内容到文件：
Acquire::http::proxy “http://UserName:Password@ProxyIP:ProxyPort/”;
Acquire::ftp::proxy “http://UserName:Password@ProxyIP:ProxyPort/”;
Acquire::https::proxy “http://UserName:Password@ProxyIP:ProxyPort/”;