yum配置
执行命令下载、安装yum源，当前是针对Centos6并且64位版本的源：

[root@T_249 yum.repos.d]# rpm -ivh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
[root@T_249 yum.repos.d]# rpm -ivh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

编辑[remi.repo]下的enabled选项从0设为1

[root@T_249 yum.repos.d]# sed -i '/enabled/s/=0/=1/g' /etc/yum.repos.d/remi.repo 

运行如下命令

[root@T_249 yum.repos.d]# yum clean all
[root@T_249 yum.repos.d]# yum makecache 

安装PHP5.4

[root@T_249 yum.repos.d]# yum install PHP54 PHP54-PHP-devel PHP54-PHP-MysqL* PHP54-PHP-gd PHP54-PHP-fpm PHP54-PHP-mbstring

如果安装PHP5.5

[root@T_249 yum.repos.d]# yum install PHP55 PHP55-PHP-devel PHP55-PHP-MysqL* PHP55-PHP-gd PHP55-PHP-fpm PHP55-PHP-mbstring

目前可以安装到PHP7.0
查看所有支持版本

[root@T_249 yum.repos.d]# yum list PHP* |grep PHP-devel
PHP-devel.x86_64                          5.3.3-46.el6_6          @updates      
PHP54-PHP-devel.x86_64                    5.4.45-2.el6.remi       @remi         
PHP-devel.x86_64                          5.6.15-1.el6.remi       remi-PHP56    
PHP55-PHP-devel.x86_64                    5.5.30-1.el6.remi       remi          
PHP56-PHP-devel.x86_64                    5.6.16-0.1.RC1.el6.remi remi-test     
PHP70-PHP-devel.x86_64                    7.0.0-0.25.RC8.el6.remi remi        

运行如下命令[yum update PHP*],则直接升级到PHP5.6

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

[root@T_249 yum.repos.d]# sed 's/#baseurl=/baseurl=/g;s/mirrorlist=/#mirrorlist=/g' /etc/yum.repos.d/epel.repo