How to apply Critical Patch Update using Opatch

1. Download interim patch to /home/patchnumber (ftp updates.oracle.com with metalink user id and password)

2. Shutdown the databases and listener

3. Set env variables

setenv ORACLE_HOME /oracle/10.2.0
setenv LD_LIBRARY_PATH ${ORACLE_HOME}/lib
setenv TNS_ADMIN ${ORACLE_HOME}/network/admin
set filec
setenv PATH .:/usr/sbin:/usr/bin:$ORACLE_HOME/Opatch:$ORACLE_HOME/bin

4. Install patch

cd /home/4567866
opatch apply

5. Start the affected database and complete the post installation steps

cd $ORACLE_HOME/cpu/CPUOct2005
sqlplus "/as sysdba"
sql> startup
sql> @catcpu.sql
SQL> @?/rdbms/admin/utlrp.sql
6. Start listener

Patch Deinstallation Instructions
To de-install the patch, set your current directory to the directory where the patch is located and then run opatch by entering the following command:

cd 4567866
opatch rollback -id 4567866

Start up all database instances running out of the ORACLE_HOME being patched.For each database instance running out of the ORACLE_HOME being patched, connect to the database using Sqlplus as sysdba and run catcpu_rollback.sql as follows -

cd $ORACLE_HOME/cpu/CPUOct2005
sqlplus /nolog
SQL> connect / as sysdba
SQL> STARTUP
SQL> @catcpu_rollback.sql
SQL> QUIT

Inspect the logfile and utlrplog files for any errors.
If catcpu.sql reports any Invalid Objects, Oracle recommends that you compile the invalid objects using the following;

cd $ORACLE_HOME/rdbms/admin
sqlplus /nolog
SQL> connect / as sysdba
SQL> @utlrp.sql
SQL> QUIT

You can check for any invalid objects by executing following statement;
select OBJECT_NAME from DBA_OBJECTS where status = 'INVALID';

Functions within Opatch

If you type opatch -h you will get a helplist over commands that can be used in opatch.
Here are some of them :

opatch apply -- Used to apply a patch

opatch apply -force --Used to apply patch even if there is a conflict due to previous applied interim patch. This will deinstall the previous one and install this one.

opatch lsinventory --Used to list the inventory for a particular $ORACLE_HOME or display all installations that can be found.

Opatch version Used to provide the version of the opatch utility.

If applying -report to any command everything will be printed on screen without executing the actions
To every command there is a number of arguments that can be used. To see the arguments issue the command -help along with the command to display the options.
Ex. opatch apply -help