How to see ORACLE_HOME OR ORACLE_BASE OR ORACLE_SID from command prompt?

On windows

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1)

C:\>echo %ORACLE_HOME%

%ORACLE_HOME%

C:\>

C:\>SET ORACLE_HOME=G:\oracle\product\10.2.0\db_1

C:\>

C:\>echo %ORACLE_HOME%

G:\oracle\product\10.2.0\db_1

C:\>

C:\>

C:\>

C:\>

C:\>SET ORACLE_SID=+ASMHALIM

C:\>echo %ORACLE_SID%

+ASMHALIM

C:\>

C:\>

C:\>echo %ORACLE_HOME%

G:\oracle\product\10.2.0\db_1

C:\>

C:\>

C:\>SQLPLUS /NOLOG

SQL*Plus: Release 10.2.0.1.0 - Production on Mon Oct 10 16:15:19 2011

Copyright (c) 1982, 2005, Oracle. All rights reserved.

SQL>

2)

RUN----->CMD----->regedit------>

HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE

HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\HOMEID

HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\ALL_HOMES

ON LINUX/UNIX

================

1) $env | grep ORACLE_HOME

$env | grep ORACLE_BASE

#env | grep ORACLE_SID

2) $ echo $ORACLE_HOME

for setting ORACLE_HOME

$ export ORACLE_HOME=