Want to check TLS/SSL certificate expiration date from #[0], macOS or UNIX command line? Try:

DOM="your-www-domain-name-here"

PORT="443"

echo | openssl s_client -servername "$DOM" -connect "$DOM:$PORT" | openssl x509 -noout -dates

See https://www.cyberciti.biz/faq/find-check-tls-ssl-certificate-expiry-date-from-linux-unix/ for more info.