Since Oracle 12cR2 RU(Release Update) and RUR (Release Update Revision) was introduced by Oracle for patching every quarter.

The following is the guide in how to apply RU to Oracle 18c release, as you might know Oracle introduced 18c on-premise with 18.3 release….here i am applying January 2019 Oracle Security Patch release which is 18.5.

its worth pointing out that you might face patching issues…..check the below helpful references i blogged about it before:

https://geodatamaster.com/2018/07/19/oracle-psu-july-2018-error-ora-20001-latest-xml-inventory-is-not-loaded-into-table/

https://geodatamaster.com/2018/11/04/oracle-ojvm-psu-error/

download the latest RU patch and place it in a directory accessible by your database server:

cd /oracle-app/linux/18c_RU/18.5_DB/28822489

/$ORACLE_HOME/OPatch/opatch apply

sqlplus / as sysdba

SQL> STARTUP

exit

cd $ORACLE_HOME/OPatch

./datapatch -verbose

*** Post-Patch verification:

sqlplus / as sysdba
SQL> @?/rdbms/admin/utlrp.sql
//check your database components

SQL> select COMP_NAME,STATUS from dba_registry;
// query to list applied patches on the database instance:

SQL > select * from dba_registry_sqlpatch;

so the database has been successfully patched with full release number 18.5.0.0190115

if your database has “java” component, you need to download the java patch (OJVM) and repeat the above steps….except that you will startup the database in upgrade mode before running the data-patch.

I hope this is helpful……have a nice day.