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.
OPatch 10g Release 2 has five main options. The main options are used to list the contents of the inventory, apply the patch, and retrieve information about the patch and the system to be patched. These options are further detailed in the next section.
lsinventory: This option lists the inventory for a particular Oracle Home. This is used to list the installations that can be found. When launched with no options, this command shows the top level components found for the current Oracle Home.
apply: This option applies an interim patch to an Oracle Home from the current directory. The patch location can be specified using the parameter patch_location...