1. 配置yum源
查看yum源的链接是不是有效的。可以参考此链接 https://webtatic.com/projects/yum-repository/
# rpm -Uvh http://ftp.iij.ad.jp/pub/linux/fedora/epel/7/x86_64/e/epel-release-7-5.noarch.rpm # rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-7.rpm
2. 确认安装的php版本
# yum list --enablerepo=remi --enablerepo=remi-php56 | grep php
3. 安装php5.6
# yum install --enablerepo=remi --enablerepo=remi-php56 php php-opcache php-pecl-apcu php-devel php-mbstring php-mcrypt php-mysqlnd php-phpunit-PHPUnit php-pecl-xdebug php-pecl-xhprof php-pdo php-pear php-fpm php-cli php-xml php-bcmath php-process php-gd php-common
原文：http://www.cnblogs.com/liujiaq/p/5901116.html