A great tool is envdir
apt-get install envdir
mkdir /etc/mysite.d/env
echo "postgres://postgres:@localhost:5432/mysite" > /etc/mysite.d/env/DATABASE_URL
echo "s3ce3t K3Y" > /etc/mysite.d/env/SECRET_KEY
echo "/srv/www/mysite/static" > /etc/mysite.d/env/STATIC_ROOT
echo "mysite.settings" > /etc/mysite.d/env/DJANGO_SETTINGS_MODULE