On CentOS/RHEL/Scientific Linux 7 x86_64:
wget http://rpms.famillecollet.com/enterprise/remi-release-7.rpm
rpm -Uvh remi-release-7.rpm

On CentOS/RHEL/Scientific Linux 6 i386 or x86_64:
wget http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
rpm -Uvh remi-release-6.rpm

## for RHEL only
rhn-channel –add –channel=rhel-$(uname -i)-server-optional-6
On CentOS/RHEL/Scientific Linux 5 i386 or x86_64:

wget http://rpms.famillecollet.com/enterprise/remi-release-5.rpm
rpm -Uvh remi-release-5.rpminstall