The following commands will install redis on a server running CentOS 6.4.

First, install the epel repo

sudo rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm  

Next, install the remi repo

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

Now, you should be able to install redis using the yum package manager.

yum install redis -y  

You should now be able to start redis using the following command

redis-server