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add-apt-repository ppa:certbot/certbot
apt-get update
apt-get install certbot

service nginx stop
certbot certonly --standalone -d www.superpig.win

# service nginx start

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/www.superpig.win/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/www.superpig.win/privkey.pem
   Your cert will expire on 2018-01-07. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot
   again. To non-interactively renew *all* of your certificates, run
   "certbot renew"
 - If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le

ssl_certificate /etc/letsencrypt/live/www.superpig.win/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/www.superpig.win/privkey.pem;

15 2 * */2 * certbot renew --pre-hook "service nginx stop" --post-hook "service nginx start"