get.acme.sh

1. Install from web: https://get.acme.sh

Install https://github.com/acmesh-official/acme.sh

curl https://get.acme.sh | sh -s email=my@example.com

or

wget -O -  https://get.acme.sh | sh -s email=my@example.com

2. What the installer does

The script at https://get.acme.sh only downloads acme.sh from GitHub and runs its installer (--install-online) with the email you pass. You can read it first: index.html. The install:

1. Where: everything goes to ~/.acme.sh/ -- the acme.sh script, configs, and the certs you issue. An acme.sh alias is added to your shell profile. Nothing else on the system is touched. Uninstall with acme.sh --uninstall.
2. Email: the ACME account email registered with the CA. The CA uses it for expiry notices, and ZeroSSL (the default CA) uses it to auto-obtain the required EAB credentials. It is not used for anything else.
3. Cron: a daily cron job runs acme.sh --cron to renew your certs before they expire. Certificates are 90 days or shorter, so unattended renewal is the point. If you do not want the cron job, use the advanced install with --nocron, then renewals are up to you.

3. Advanced Installation:

https://github.com/acmesh-official/acme.sh/wiki/How-to-install