ORACLE - NLS_LANG

SQL> select DECODE(parameter, 'NLS_CHARACTERSET', 'CHARACTER SET',
'NLS_LANGUAGE', 'LANGUAGE',
'NLS_TERRITORY', 'TERRITORY') name,
value from v$nls_parameters
WHERE parameter IN ( 'NLS_CHARACTERSET', 'NLS_LANGUAGE', 'NLS_TERRITORY');

NAME          VALUE
------------- ----------------------------------------------------------------
LANGUAGE      AMERICAN
TERRITORY     AMERICA
CHARACTER SET WE8ISO8859P1

SQL> exit

NLS_LANG=<LANGUAGE>_<TERRITORY>.<CHARACTER SET>

C:\>set NLS_LANG=AMERICAN_AMERICA.WE8ISO8859P1

C:\>echo %NLS_LANG%
AMERICAN_AMERICA.WE8ISO8859P1