视频地址：
https://www.bilibili.com/video/av55251610?p=65
卸载不干净的环境：
rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm
yum -y install php72w php72w-cli php72w-common php72w-devel php72w-fpm php72w-gd php72w-mbstring php72w-opcache php72w-mysqlnd php72w-pdo php72w-xml php72w-xmlrpc php72w-pecl-imagick