This is a how-to of install php 5.3 an dphp 5.5 on one server, CentOS and use them simultaneously. It is based on CentOS 6.5, 64bit for Apache only. 1) Enable rpmforge and epel yum repository   2) Install php 5.3 CentOS has php 5.3 built-in-box, simply install it with yum 3) Compile and install