ERROR: Environment variable ORACLE_UNQNAME not defined. Please set ORACLE_UNQNAME to database unique name

[oracle@hostname ~]$ emctl status dbconsole

Environment variable ORACLE_UNQNAME not defined. Please set ORACLE_UNQNAME to database unique name.

SQL> SELECT name, db_unique_name FROM v$database;

NAME DB_UNIQUE_NAME

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DB5 db5_db

[oracle@hostname ~]$ export ORACLE_UNQNAME= db5_db