# certbot > The Let's Encrypt Agent for automatically obtaining and renewing TLS certificates. > Successor to `letsencrypt`. > More information: . - Obtain a new certificate via webroot authorization, but do not install it automatically: `sudo certbot certonly --webroot --webroot-path {{path/to/webroot}} --domain {{subdomain.example.com}}` - Obtain a new certificate via nginx authorization, installing the new certificate automatically: `sudo certbot --nginx --domain {{subdomain.example.com}}` - Obtain a new certificate via apache authorization, installing the new certificate automatically: `sudo certbot --apache --domain {{subdomain.example.com}}` - Renew all Let's Encrypt certificates that expire in 30 days or less (don't forget to restart any servers that use them afterwards): `sudo certbot renew` - Simulate the obtaining of a new certificate, but don't actually save any new certificates to disk: `sudo certbot --webroot --webroot-path {{path/to/webroot}} --domain {{subdomain.example.com}} --dry-run` - Obtain an untrusted test certificate instead: `sudo certbot --webroot --webroot-path {{path/to/webroot}} --domain {{subdomain.example.com}} --test-cert`