baltpeter

apt-get update # if this is the first boot on e.g. OpenVZ containers
apt-get install language-pack-en
update-locale LANG=en_US.UTF-8
shutdown -rf 0 # reboot to ensure new locale is applied

# when lang is "(undefinded)"; also preferred anyway
export LANGUAGE=en_US.UTF-8
export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8
locale-gen en_US.UTF-8