由于CentOS的默认的php安装源版本都是5.4以下的，如果你的项目对php版本有要求或者想升级折腾的可以参考此文升级方法，新项目新环境个人更推荐使用更牛x地php7。

了解php5.6的新特性可参考：

PHP5.6 New Features：http://php.net/manual/en/migration56.new-features.php
PHP5.6正式版新特性、新功能介紹：http://www.arefly.com/php-5-6-new-feature/

本教程适用的linux发行版：CentOS/RHEL 7、CentOS/RHEL 6、CentOS/RHEL 5，提供PHP5.4升级至PHP5.6的方法。

首先查看你的php版本：

php -v

PHP 5.4.35 (cli) (built: Nov 14 2014 07:04:10)
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend Technologies
    with Zend OPcache v7.0.4-dev, Copyright (c) 1999-2015, by Zend Technologies

安装rpm升级包

注意：请选择符合你的系统版本的命令

CentOS/RHEL 7:

rpm -Uvh https://mirror.webtatic.com/yum/el7/epel-release.rpm
rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm

CentOS/RHEL 6:

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

CentOS/RHEL 5:

rpm -Uvh http://mirror.webtatic.com/yum/el5/latest.rpm

安装完之后我们要删除旧版php模块

# yum remove php-common

Dependencies Resolved

===================================================================================
 Package             Arch          Version                      Repository    Size
===================================================================================
Removing:
 php-common          x86_64        5.4.39-1.el6.remi            @remi        7.0 M
Removing for dependencies:
 php                 x86_64        5.4.39-1.el6.remi            @remi        9.1 M
 php-cli             x86_64        5.4.39-1.el6.remi            @remi         12 M
 php-devel           x86_64        5.4.39-1.el6.remi            @remi        8.1 M
 php-gd              x86_64        5.4.39-1.el6.remi            @remi        665 k
 php-ldap            x86_64        5.4.39-1.el6.remi            @remi        119 k
 php-mbstring        x86_64        5.4.39-1.el6.remi            @remi        2.5 M
 php-mcrypt          x86_64        5.4.39-1.el6.remi            @remi         86 k
 php-mysql           x86_64        5.4.39-1.el6.remi            @remi        452 k
 php-pdo             x86_64        5.4.39-1.el6.remi            @remi        348 k
 php-pear            noarch        1:1.9.5-9.el6.remi           @remi        2.0 M
 php-process         x86_64        5.4.39-1.el6.remi            @remi        128 k
 php-snmp            x86_64        5.4.39-1.el6.remi            @remi        107 k
 php-xml             x86_64        5.4.39-1.el6.remi            @remi        626 k

Transaction Summary
===================================================================================
Remove       14 Package(s)

Installed size: 43 M

开始安装PHP5.6

# yum install -y php56w php56w-opcache php56w-xml php56w-mcrypt php56w-gd php56w-devel php56w-mysql php56w-intl php56w-mbstring

安装完成后重启Apache

# /etc/init.d/httpd restart

再次查看php版本

# php -v

PHP 5.6.8 (cli) (built: Apr 17 2015 22:49:36)
Copyright (c) 1997-2015 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend Technologies
    with Zend OPcache v7.0.4-dev, Copyright (c) 1999-2015, by Zend Technologies

至此，大功告成！