Check out example codes for "webmin lets encrypt renewal failed". It will help you in understanding the concepts better.

Code Example 1

mv /usr/share/webmin/webmin/acme_tiny.py /root/acme_tiny.py && wget -O /usr/share/webmin/webmin/acme_tiny.py https://raw.githubusercontent.com/diafygi/acme-tiny/master/acme_tiny.py

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