OPatch - Oracle 10g/11g Data and Database Management Utilities - page 361

OPatch
Oracle Corporation provides dynamic software which is constantly improving.
Oracle periodically releases software updates by means of Critical Path Updates
( CPU s). Oracle also releases individual patches depending on the circumstances.
These one-off patches can easily be applied using the OPatch tool. Oracle also
releases major maintenance updates known as Patch Sets. A Patch Set is a group of
one-off patches that have been tested and verified to work together. There may be
additional functionality as well as bug fixes included in a Patch Set. When a Patch
Set has been applied, the component-specific release number ( http://download.
oracle.com/docs/cd/B19306_01/server.102/b14231/dba.htm#sthref94 ) is
incremented. Patch Sets are applied with the Oracle Universal Installer included
within the same patchset, and the other kinds of patches are applied using OPatch.
It is strongly suggested to keep your Oracle software updated to the last available
Patch Set level so that known bugs can be avoided and if the database faces an issue
that requires Oracle Support Services it is easier for the analyst to eliminate the
possibility of the issue being caused by a known bug from the beginning. In case of
doubt you should contact Oracle Support Services.
OPatch
OPatch is a Java based utility that requires installation of the Oracle Universal
Installer. Starting Oracle 10g Rel. 2, this tool is included in the Oracle Home. Prior
to this release the DBA had to download a patch from Metalink to install OPatch
( p2617419_10102_GENERIC.zip ). OPatch in 10gRel2 is not compatible with previous
Oracle releases.
Even though OPatch is an executable, it is not located in the ORACLE_HOME/bin
directory. It has its own directory located at ORACLE_HOME/OPatch . The opatch
executable is a shell script that launches the OPatch Java class, the actual
OPatch executable.