brainyron, it sounds like you're missing the "file" rpm.
Is the "file" rpm installed?
open3: exec of file - failed at
This rpm/binary is required by /usr/local/cpanel/bin/register_cpanelplugin. Installing that rpm should then take care of this for you.
This rpm should have been installed by default on a minimal CentOS install; although I have seen some CentOS 6 installations lack this RPM for yet to be determined reasons. A case had since been filed on this matter (Case 51199) to have cPanel ensure this RPM is installed for you just in case your CentOS install lacked it. That's planned for 11.32. But, as mentioned, it's just a matter of installing the missing RPM manually in the interim.