LANG=ru_RU LANGUAGE=ru_RU:ru LC_ALL=ru_RU.CP1251 LC_MESSAGES=ru_RU.CP1251 perl  -e 'open my $f, "<", "notafile" or print $!'

##</code><code>##

LANG=ru_RU LANGUAGE=ru_RU:ru LC_ALL=ru_RU.utf8 perl  -e 'open my $f, "<", "notafile" or print $!'

##</code><code>##

my $errno = decode("SOMEENCODING", $!)