How to apply a Patch in Apps

Patching is the most basic thing that an Oracle Apps Dba is expected to know.A patch is applied either to fix a bug or to add some new functionality.
Here are the steps for patching in Apps 11i
1 First check that the patch is already not applied.
select * from ad_bugs where bug_number='patchnumber';
Now if the patch is not applied then go through the read me of the patch on Metalink. Check for pre-reqs and download the patch.
1 Stop the apps services
./adstpall.sh apps/password
2 Bounce the database(This is not mandatory but it kills any hanging process)
./addbctl.sh stop immediate
./addlnctl.sh stop listnername
./addlnctl.sh start listnername
./addbctl.sh start
3 Put the system in Maintenance mode
Run adadmin--Goto step 5-Change Maintenance mode-step 1 Enable Maintenance mode
4 Goto the patch directory where you downloaded the patch.Unzip the patch as applmgr user(application owner).It will create a directory with the patch number.
5 Goto the directory with the patch number and run
adpatch
It will ask for patch log file,apps,system password,driver name(c,d,g,u),number of workers.
6 go through the patch log file and check that there is no error
7 Disable maintenance mode
Run adadmin--Goto step 5-Change Maintenance mode-step 2 Dis-able Maintenance mode
8 Bounce the database again
9 Start the apps services
./adstartal.sh apps/password