Certbot

certbot^[1] is a fully-featured, extensible client for the Let’s Encrypt CA (or any other CA that speaks the ACME protocol defined in 2015-2016) that can automate the tasks of obtaining certificates and configuring webservers to use them. This client runs on Unix-based operating systems.

Ubuntu:

Binaries: certbot and letscrypt
Renewals configuration: /etc/cron.d/certbot

Examples

To request a certificate:

certbot certonly --standalone --preferred-challenges http -d YOUR_DOMAIN_NAME.com

certonly --standalone

certbot --nginx
Saving debug log to /var/log/letsencrypt/letsencrypt.log
The requested nginx plugin does not appear to be installed

certbot certificates
Saving debug log to /var/log/letsencrypt/letsencrypt.log

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No certs found.
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certbot renew
Saving debug log to /var/log/letsencrypt/letsencrypt.log

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No renewals were attempted.
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Changing a Certificdate's Domain^[2]: certbot certonly --cert-name example.com -d example.org,www.example.org
Automated renewals: systemctl list-timers