1、先查看已安装相关PHP

rpm -qa |grep PHP

2、卸载已安装相关PHP

yum remove PHP

3、添加第三方源

rpm -ivh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

rpm -ivh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

4、编辑[remi.repo]下的enabled选项从0设为1
执行sed -i '/enabled/s/=0/=1/g' /etc/yum.repos.d/remi.repo

5、运行以下命令

yum clean all

yum makecache

6、查看已支持安装的PHP版本

yum list PHP* |grep PHP-devel

7、安装PHP5.6

7.1、yum -y install PHP56PHP56-PHP-fpmPHP56-PHP-MysqL

7.2、如果报错安装运行yum报错解决方法：

Error: Cannot retrieve Metalink for repository: epel. Please verify its path and try again

编辑[epel.repo]下的baseurl前的#号去掉，mirrorlist前添加#号

执行sed 's/#baseurl=/baseurl=/g;s/mirrorlist=/#mirrorlist=/g' /etc/yum.repos.d/epel.repo