[Oracle]How to find the ORACLE_HOME path in Oracle Database?

In 9i:

SELECT substr(file_spec,1,instr(file_spec,'lib')-2) ORACLE_HOME FROM dba_libraries
WHERE library_name='DBMS_SUMADV_LIB';

In 10g:

SQL > var OHM varchar2(100);
SQL > EXEC dbms_system.get_env('ORACLE_HOME', :OHM) ;
SQL > PRINT OHM

Linux/Unix:

echo $ORACLE_HOME

Windows:

start - run - regedit (enter) - HKEY_LOCAL_MACHINE - SOFTWARE - ORACLE


Type the below command at prompt if the environment variable is defined for ORACLE_HOME

c:\> set oracle_home (ENTER)