check certificate expiration

Here’s the openssl command to find out if a cert is expired.

$ openssl s_client -connect yourdomain.com:443 -servername yourdomain.com 2> /dev/null | openssl x509 -noout -dates

Result

notBefore=Apr  9 00:00:00 2020 GMT
notAfter=Apr  9 23:59:59 2022 GMT