This articles explains how you can upgrade to CentOS 6.4 from any previous CentOS 6.x versions, which includes CentOS 6.0, 6.1, 6.2 and 6.3
Backup all important data (optional)
- Backup all your personal files if you need them
- Backup /etc directory
- Backup logs /var/log
- Backup MySQL databases
- Backup web server configurations and sites
Upgrade Process
List the packages that are going to be upgraded
yum list updates
Start the Upgrade
yum update
Reboot
reboot
Check the updated CentOS version
cat /etc/redhat-release
Output
CentOS release 6.4 (Final)
Now you have the most updated version of CentOS running on you system.