The clearos-base package performs a small set of required tasks:
Before you can install this package, you may need to change the distroverpkg parameter in /etc/yum.conf to clearos-release. You should also upgrade to the latest version:
yum-config-manager --enable clearos-centos,clearos-centos-updates yum --nogpgcheck upgrade
The yum-config-manager command is used to enable the clearos-centos and clearos-centos-updates repositories. By default, ClearOS uses a tight subset of the upstream packages as opposed to the whole package set. For example, the Thunderbird desktop e-mail client is provided in upstream sources, but it doesn't make much sense to include such a package on a ClearOS server. However, the clearos-centos/clearos-centos-updates repositories do include a rebuild of all the upstream packages, but this repository may be disabled by default. Since your CentOS install may contain packages from clearos-centos/clearos-centos-updates, it is a good idea to enable these repositories.
The software keys are part of the app-base package, but that is a future step. Until then, the –nogpgcheck flag is required.
Now it's time to install clearos-base:
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-* yum install clearos-base
Again, not much will happen when installing clearos-base. You may see a small number of dependencies installed, but for the vast majority of cases the dependencies are already installed. Also, you should now see a few entries in the /var/log/system log file.