http://www.oracle-base.com/articles/12c/oracle-db-12cr1-installation-on-oracle-linux-6.php
http://www.oracle-base.com/articles/linux/automating-database-startup-and-shutdown-on-linux.php
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RHEL/CentOS 6 64bit How-to Prepare for 12c Database Installation
How-to Install Oracle 12c R1 Database on CentOS 6.X 64bit Step-by-Step Easy Guide