locale-gen

To generate

locale-gen en_US.UTF-8

If you get error setlocale: LC_ALL: cannot change locale

echo "LC_ALL=en_US.UTF-8" >> /etc/environment
echo "LANG=en_US.UTF-8" > /etc/locale.conf
echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen
locale-gen en_US.UTF-8

bash: locale-gen: command not found
bash: warning: setlocale: LC_ALL: cannot change locale
language