Oracle: do not have sufficient permissions to access the inventory

 Problem:

$./runInstaller
You do not have sufficient permissions to access the inventory '/usr2/app/oracle/product/10.1.2.0.2/ias/inventory'. Installation cannot continue. Make sure that you have read/write permissions to the inventory directory and restart the installer.: Permission denied

Solution:

rename /var/opt/oracle/oraInst.loc to oraInst.loc.backup