To check current locale just run:
:~# locale
LANG=C
So current locale is 'C'.
To add support of another locale we should change /var/lib/locales/supported.d/locale or create it if it doesn't exist. For example, to add US English UTF-8 locale we need to add following line:
en_US.UTF-8 UTF-8
(You can see supported locales at /usr/share/i18n/SUPPORTED ( Read more... )