问题描述：

[root@Centos ~]# yum install nginx
Loaded plugins: fastestmirror
Repository base is listed more than once in the configuration
Repository updates is listed more than once in the configuration
Repository extras is listed more than once in the configuration
Repository centosplus is listed more than once in the configuration
Repository contrib is listed more than once in the configuration
Loading mirror speeds from cached hostfile
* addons: mirror.bit.edu.cn
* base: mirrors.btte.net
* extras: mirrors.btte.net
* updates: mirror.bit.edu.cn
Setting up Install Process
No package nginx available.
Nothing to do