Correct NLS_LANG for exports

It's important to set the right NLS_LANG environment variable when doing exports/imports.
The following query makes it easy getting the syntax and values right.

set heading off
set feedback off
select 'export NLS_LANG=' || lan.value || '_' || ter.value || '.' || chr.value
from v$nls_parameters lan,
v$nls_parameters ter,
v$nls_parameters chr
where lan.parameter='NLS_LANGUAGE'
and ter.parameter='NLS_TERRITORY'
and chr.parameter='NLS_CHARACTERSET';
set heading on
set feedback on

This gives the line (e.g.)
export NLS_LANG=AMERICAN_AMERICA.WE8ISO8859P15

which can easily be copied before the imp/exp is run.
For windows environments, you would need to replace 'export' by 'set' in the query.