如果已经安装过php，先删除之。编译安装直接删掉目录即可，yum源安装yum remove php。
更新centos7yum源
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
如果和系统自带的php冲突
yum list installed | grep php | gerp 5.4
列出系统php老版本，删除
yum remove php-common.x86_64
再安装
yum -y install php72w php72w-cli php72w-common php72w-devel php72w-embedded php72w-fpm php72w-gd php72w-mbstring php72w-mysqlnd php72w-opcache php72w-pdo php72w-xml php72w-bcmath