Probably the easiest way to install the Oracle database on Linux is to install Oracle Enterprise Linux 6 and before the installation of Oracle do two things:
1. Enable the public yum repository at Oracle:
cd /etc/yum.repos.d wget http://public-yum.oracle.com/public-yum-ol6.repoEdit the file and enable the relevant version by setting enabled=1.
2. Install the package that prepares the server for Oracle database installation:
yum install oracle-rdbms-server-11gR2-preinstallNo need to run any commands after the yum install command. Continue with runInstaller.
With the release of database 12c Oracle has released a new package to prepare Oracle Linux 6 for it.
Get the info from Oracle here. The procedure remains the same as for 11g, only the name of the rpm file changes. I installed it on a fresh new OL6 without any extra configuration of yum repository with:
yum update yum install oracle-rdbms-server-12cR1-preinstall
The outline from Oracle tells you to do step 1 above, but the repo file was included in OL 6.4.