CentOS 7 yum Loaded plugins: fastestmirror, langpacks Loading mirror speeds from cached hostfile

yum install nginx
Loaded plugins: fastestmirror, ovl
Loading mirror speeds from cached hostfile
.....
No package nginx available.
Error: Nothing to do

可能缺epel EPEL (Extra Packages for Enterprise Linux)是基于Fedora的一个项目，为“红帽系”的操作系统提供额外的软件包，适用于RHEL、CentOS和Scientific Linux.

# 这个可以不执行主要是为了国内镜像
wget -O /etc/yum.repos.d/epel-7.repo http://mirrors.aliyun.com/repo/epel-7.repo

yum install epel-release

清理并生成缓存

yum clean all 
yum makecache