How to use opatch utility? or how to apply oracle patch

set OPatch patch first:

$> export PATH=$PATH:/ora02/app/oracle/product/11.2.0.3/OPatch

to check opatch version:

$> opatch version (Note: always read the readme file for patch, see which version of opatch you should use)

Then find out whether this patch already has been applied or not?

$> opatch lsinventory

Note: will give list off all the applied patch

then goto patch directory then type

$> cd <patch number>
$> opatch apply