1，配置CentOs8的yum源

vim /etc/yum.repos.d/CentOS-AppStream.repo

[AppStream]

name=CentOS-$releasever - AppStream

baseurl=http://mirrors.aliyun.com/centos/$releasever/AppStream/$basearch/os/

gpgcheck=1

enabled=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

vim /etc/yum.repos.d/CentOS-Base.repo

[BaseOS]

name=CentOS-$releasever - Base

baseurl=http://mirrors.aliyun.com/centos/$releasever/BaseOS/$basearch/os/

gpgcheck=1

enabled=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

vim /etc/yum.repos.d/CentOS-Epel.repo

[epel]

name=CentOS-$releasever - Epel

baseurl=http://mirrors.aliyun.com/epel/8/Everything/$basearch

enabled=1

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-8

2，yum源配置成功后

yum clean all　　#命令清除yum缓存元数据

3，yum makecache 　　#重新建立yum缓存

4，安装epel存储库

sudo dnf -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

5，确认epel库是否安装成功

rpm -qa | grep epel

6，安装remi存储库

dnf install https://rpms.remirepo.net/enterprise/remi-release-8.rpm

7，确认remi存储库是否安装成功

8，成功添加EPEL和Remi存储库后，执行以下命令以获取可用PHP模块流的列表

dnf module list php

9，dnf module reset php 　　#重置php模块

10，根据第八步中的php流模块，启用对应php版本的流模块，这里我们安装的是php7.4的版本，所以启用remi-7.4版本的流

dnf module enable php:remi-7.4 　　

11，安装PHP，此命令还安装许多其他软件包

dnf install php php-cli php-common

12，查看php是否安装成功