查看系统版本命令

[lihuabing@mariadb ~]$ cat /etc/centos-release
CentOS Linux release 7.5.1804 (Core)

若之前安装过其他版本PHP，先删除

yum remove php*

rpm安装PHP7相应的yum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

CentOS/RHEL 6.x:

rpm -Uvh https://mirror.webtatic.com/yum/el6/latest.rpm

yum安装PHP7

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

安装完毕，测试是否安装成功

php -v