Strange behavoir : characterset conversion

Question

there is a strange behavior related to character set conversion under windows. Please take a look at the example below and give me you comment :
-- Under Windows 2000 box
SQL> @.[%NLS_LANG%]
SP2-0310: impossible d'ouvrir le fichier ".[French_France.US7ASCII]"
SQL> desc test_nls
Nom NULL ? Type
C1 VARCHAR2(5)
SQL> select * from nls_database_parameters where parameter='NLS_CHARACTERSET';
PARAMETER VALUE
NLS_CHARACTERSET WE8ISO8859P1
SQL> insert into test_nls values('éàèôï');
1 ligne créée.
SQL> commit;
Validation effectuée.
SQL> col dmp for a40
SQL> select C1, dump(C1) dmp from test_nls;
C1 DMP
éàèôï Typ=1 Len=5: 233,224,232,244,239
-- Under Unix box
SQL> ! echo $NLS_LANG
French_France.US7ASCII
SQL> desc test_nls
Name Null? Type
C1 VARCHAR2(5)
SQL> select * from test_nls;
C1
eaeoi
SQL> é
SQL> col dmp for a40
select C1, dump(C1) dmp from test_nls;SQL>
C1 DMP
eaeoi Typ=1 Len=5: 233,224,232,244,239
SQL> ! export NLS_LANG=French_France.WE8ISO8859P1
SQL> ! echo $NLS_LANG
French_France.US7ASCII
SQL> select * from nls_database_parameters where parameter='NLS_CHARACTERSET';
PARAMETER VALUE
NLS_CHARACTERSET WE8ISO8859P1
SQL> insert into test_nls values('éàèôï');
1 row created.
SQL> commit;
Commit complete.
SQL> col dmp for a40
select C1, dump(C1) dmp from test_nls;SQL>
C1 DMP
eaeoi Typ=1 Len=5: 233,224,232,244,239
i`hto Typ=1 Len=5: 105,96,104,116,111
Under MS-Dos (windows cmd CLI)
SQL> host echo %NLS_LANG%
French_France.US7ASCII
SQL> select dump(convert('é','WE8ISO8859P1','US7ASCII')) from dual;
DUMP(CONVERT('☻','WE8ISO8859P1
Typ=1 Len=1: 2
SQL>
--- Under Unix (Aix 5.2)
SQL> ! echo $NLS_LANG
French_France.US7ASCII
SQL> select dump(convert('é','WE8ISO8859P1','US7ASCII')) from dual;
DUMP(CONVERT('I','WE8ISO8859P1
Typ=1 Len=1: 105

Answer 1

This does seem like strange behaviour, are your windows and Unix clients perhaps of different versions? All I can do is echo Barry's comments, if your database is WE8MSWIN1252 and you want to provide WE8MSWIN1252 data from the client, NLS_LANG must be set to French_France.WE8MSWIN1252.
Note that this must occur before you start SQL*Plus otherwise the setting will not take effect.