The LANG variable have a form ll_CC.coding where ll is the
language and CC is the area. (It is even more complicated,
but we can forget about that rignt now.) When looking for
message catalogs, the locale function tries shortened
versions of this if it can't find longer. So if there is a
catalog for "sv" it will be found if I set my LANG to
sv_SE.iso8859-1, for example.
But rpm unfortunately rpm doesn't seem to use the same
algorithm when selecting a description and summary. So even
though I added a Swedish description to a package, I get the
English default description unless I set LANG to precisely
Try rpm-3.0.3-0.19 from Raw Hide. This problem should be fixed there.
Otherwise, you should be able to do something like
which should work in other versions of rpm-3.0.x