How to use the LSNRCTL utility to confirm the ENV for a DB Instance?

It is possible, using the LSNRCTL utility, to check the ENV settings for instances that are dynamically registered to the VIP or standalone listener.
It is also possible to check the ENV for an instance that is statically defined in the listener.ora file.

Here's how:

Launch LSNRCTL:

./lsnrctl

LSNRCTL>set current_listener <listener name here>

LSNRCTL>set displaymode verbose

LSNRCTL>services

Service "ORCL.oracle.com" has 1 instance(s).
    Instance "ORCL", status READY, has 1 handler(s) for this service...
      Handler(s):
      "DEDICATED" established:2 refused:0 state:ready
      LOCAL SERVER
      (ADDRESS=(PROTOCOL=BEQ)(PROGRAM=/app/oracle/db_home112/bin/oracle)(ARGV0=oracleORCL)(ARGS='(LOCAL=NO)')