# cd /root/letsencrypt
# ./letsencrypt-auto --config /etc/letsencrypt/configs/example.com.conf certonly
Updating letsencrypt and virtual environment dependencies.......
Running with virtualenv: /root/.local/share/letsencrypt/bin/letsencrypt --config /etc/letsencrypt/configs/mydomain.conf certonly

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at
   /etc/letsencrypt/live/www.example.com/fullchain.pem. Your cert will
   expire on 2016-02-05. To obtain a new version of the certificate in
   the future, simply run Let's Encrypt again.