If certbot (or letsencrypt) is packaged for your Unix OS (visit
certbot.eff.org to find out), you can install it
from there, and run it by typing certbot (or letsencrypt). Because
not all operating systems have packages yet, we provide a temporary solution
via the certbot-auto wrapper script, which obtains some dependencies from
your OS and puts others in a python virtual environment:
user@webserver:~$ wget https://dl.eff.org/certbot-auto
user@webserver:~$ chmod a+x ./certbot-auto
user@webserver:~$ ./certbot-auto --help
Hint
The certbot-auto download is protected by HTTPS, which is pretty good, but if you’d like to
double check the integrity of the certbot-auto script, you can use these steps for verification before running it:
user@server:~$ wget -N https://dl.eff.org/certbot-auto.asc
user@server:~$ gpg2 --recv-key A2CFB51FA275A7286234E7B24D17C995CD9775F2
user@server:~$ gpg2 --trusted-key 4D17C995CD9775F2 --verify certbot-auto.asc certbot-auto
And for full command line help, you can type:
./certbot-auto --help all
certbot-auto updates to the latest client release automatically. And
since certbot-auto is a wrapper to certbot, it accepts exactly
the same command line flags and arguments. More details about this script and
other installation methods can be found in the User Guide.