OPatch - Oracle 10g/11g Data and Database Management Utilities - page 364

6. When working in RAC environments, make sure the user equivalence

between hosts is correctly set.

7. Verify the Oracle Inventory is valid, you can check this by issuing the

command OPatch lsinventory -detail . This command displays the
software installed on the target Oracle Home. If this command returns no
information or it shows an error message, it means that the Inventory within
the Oracle Home is either missing or corrupt.

OPatch syntax
The opatch executable can be found at <Oracle Home>/OPatch directory and it has
this syntax:

<Oracle Home>/OPatch/opatch option [-arguments]

You should be aware that the OPatch for 10g Release 1 was a Perl script and
it had a different syntax. For more information, refer to the Metalink note 242993.1
OPatch FAQ.