How to check your CentOS version
Most Red Hat-based distributions, like CentOS, should have a file called redhat-release which will contain the CentOS version.
# cat /etc/redhat-release CentOS release 5.5 (Final)
or
# rpm -q centos-release centos-release-5-5.el5.centos.1
and finally
# lsb_release -i Distributor ID: CentOS # lsb_release -r Release: 5.5 # lsb_release -d Description: CentOS release 5.5 (Final)