def get_i18n_day_name(day_nb, display='short', ln=None):
    """Get the string representation of a weekday, internationalized

    @param day_nb: number of weekday UNIX like.
                   => 0=Sunday
    @param ln: language for output
    @return: the string representation of the day
    """
    ln = default_ln(ln)
    _ = gettext_set_language(ln)
    if display == 'short':
        days = {0: _("Sun"),
                1: _("Mon"),
                2: _("Tue"),
                3: _("Wed"),
                4: _("Thu"),
                5: _("Fri"),
                6: _("Sat")}
    else:
        days = {0: _("Sunday"),
                1: _("Monday"),
                2: _("Tuesday"),
                3: _("Wednesday"),
                4: _("Thursday"),
                5: _("Friday"),
                6: _("Saturday")}

    return days[day_nb]