Oracle pre-install rpm is used to automate the setting and checking of per-requistes at the OS for the installation of Oracle RDBMS. All you have to is to install it and after that you can go ahead and install Oracle 12c. pre-install rpm can be downloaded from the YUM among some other sources:

Step 1: Configure YUM (For Oracle Linux 6)

 With root user:

cd /etc/yum.repos.d
wget http://public-yum.oracle.com/public-yum-ol6.repo

Optionally you can check for latest yum updates:

yum update

Step 2: Install the pre-install rpm from YUM

yum install oracle-rdbms-server-12cR1-preinstall

That's about it. This pre-install will check for all the dependent rpms, will create Oracle user with proper privileges and security settings.

YUM is yummy for sure, just like an Aussie bbq.