Oracle Database 18c: Apply -applyRU Patch before Grid Installation 18.5.0.0.0

With the advent of newer features with Oracle Releases.
One of the good feature of 12c Series is to patch the GI release to latest patch even before the installation.

This has now become possible because of the image based installation, as the zip file is just a "tar ball" of the Grid Home with re-linking required

If you want you can patch to the latest release then after unzipping the home - 

1. Download the Patch
2. Stage it
3. Ensure OPatch is of the version as mentioned in Read me 
4. Apply Patch 

In this example or a one liner I apply patch for 18.5.0.0.0 

$ cd $GRID_HOME
$ ./gridSetup.sh -silent -applyRU /oracle/patch/28828717
Preparing the home to patch...
Applying the patch /images/oracle/28828717...
Successfully applied the patch.
The log can be found at: /opt/oracle/oraInventory/logs/GridSetupActions2019-03-13_05-09-20AM/installerPatchActions_2019-03-13_05-09-20AM.log
Launching Oracle Grid Infrastructure Setup Wizard...

[FATAL] [INS-40426] Grid installation option has not been specified.

   ACTION: Specify the valid installation option.

The last error is ignorable.

If you want to apply one Offs then 
./gridSetup.sh -silent -applyOneOff <unzipped Path of the Patch>