Review to understand how to use SRVCTL and TNS_ADMIN to manage listeners

To administer Oracle Database 21c local and SCAN listeners using the lsnrctl command, set your ORACLE_HOME environment variable to the path for the Grid home. Do not attempt to use the lsnrctl commands from Oracle home locations for earlier releases, because they cannot be used with Oracle Database 21c.

For listeners not managed by Oracle Clusterware, you can use a non-default location for the listener.ora file by setting the TNS_ADMIN environment variable or registry value to point to the directory that contains the Oracle Net Services configuration files. To use a non-default location for a listener managed by Oracle Clusterware, you must use SRVCTL and the setenv command to modify the value of TNS_ADMIN for each listener.