问题
nginx启动或者重启提示信息如下：
nginx: [emerg] unknown "connection_upgrade" variable
nginx: configuration file /www/server/nginx/conf/nginx.conf test failed
解决方法
在nginx配置文件http标签下添加如下几行：
map $http_upgrade $connection_upgrade { default upgrade; '' close; }
Ps：主配置文件yum安装默认路径为/etc/nginx/conf/nginx.conf
