How to easily check whether the certificate has expired or not.
My bash command
You can use, all dates (creating and expiring):
openssl x509 -enddate -noout -in /etc/pki/tls/certs/localhost.crt
You can use, only expiring date:
openssl x509 -dates -noout -in /etc/pki/tls/certs/localhost.crt
Bash script to list multiple certificates in order of their expiration, most recently expiring first:
for pem in /etc/pki/tls/certs/*.crt; do printf '%s: %s\n' \ "$(date --date="$(openssl x509 -enddate -noout -in "$pem"|cut -d= -f 2)" --iso-8601)" \ "$pem" done | sort