TO FIND ORACLE HOME WITH FROM SQL PROMPT

1ST WAY

SQL> select file_spec from dba_libraries where library_name='ORDIMLIBS';

FILE_SPEC
------------------------------------------------------------
/u01/app/oracle/product/1110/dbhome/lib/libordim11.so



2ND WAY

SQL> host echo $ORACLE_HOME
/opt/oracle/product/10.2.0/db_1