centos7系統庫中默認是沒有nginx的rpm包的，所以我們自己需要先更新下rpm依賴庫
(1)使用yum安裝nginx需要包括Nginx的庫，安裝Nginx的庫
#rpm -Uvh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm
(2)使用下面命令安裝nginx
#yum install nginx
(3)啓動Nginx
#service nginx start
或
#systemctl start nginx.service
本文轉自：http://www.cnblogs.com/Robert-huge/p/6003934.html