Установка и настройка локали (locale) и языка

К примеру необходима локаль ru_RU.utf8

Проверяем её наличие в системе

# locale -a | grep ru
ru_RU
ru_RU.iso88595
ru_RU.koi8r
ru_RU.utf8
russian
ru_UA
ru_UA.koi8u
ru_UA.utf8

Изменяем

LANG="ru_RU.UTF-8"
SUPPORTED="ru_RU.utf8:ru_RU:ru"
SYSFONT="latarcyrheb-sun16"

# localedef  -i ru_RU -f UTF-8 ru_RU.UTF-8
# export LC_ALL="ru_RU.utf8"

Вернуть локаль

# localedef  -i en_US -f UTF-8 en_US.UTF-8
# export LC_ALL="en_US.UTF-8"

Debian/Ubuntu

apt-get -y install language-pack-en-base language-pack-ru-base
update-locale LANG=ru_RU.UTF-8
locale-gen "ru_RU.UTF-8"

Fedora

Вместо ru_RU.UTF-8 нужно ru_RU.utf8

dnf -y install glibc-langpack-ru
localectl set-locale LANG=ru_RU.UTF-8

dnf -y install \
langpacks-fonts-ru \
langpacks-core-ru \
langpacks-ru \
glibc-langpack-ru