The openssl utility can be used to show the details of a certificate, including its ‘Not After’ expiration date in string format. This can be transformed into “how many days till expiration” with a bit of Bash date math. Create test certificate and key Using a line provided by Diego Woitasen for non-interactive self-signed certification … Bash: calculating number of days till certificate expiration using openssl
If you have warning messages coming from apt about an invalid signature verification and EXPKEYSIG, then it is likely that a signing key for one of the remote apt repo has expired. Below is an example coming from an expired podman package at the “download.opensuse.org” repo. W: An error occurred during the signature verification. The … Ubuntu: fixing apt invalid signature warnings
YAML is a popular syntax for configuration, and it is common to have certificate definitions embedded in these files. But since the cert is typically Base64 PEM encoded, it means you can’t easily view its attributes (subject, expiration date, etc) and so you are left with the manual task of copy-pasting it out, saving as … Bash: Examining each certificate in a yaml file using sed and openssl