Print out information about non valid certificates and certificates that will run out in less than 30 days.

show_valid_certs.sh

#!/bin/bash
# Show the validity of certificate files
# If the certificate will run out in less than one month, a warning is shown
# If the certificate is not valid anymore, an error message is shown
# Valid certificates are not printed out

for cert in /etc/nginx/ssl/*.crt; do

    d1=$(date -d "$(openssl x509 -noout -dates -in $cert | grep notAfter | cut -d '=' -f 2)" +%s)
    d2=$(date +%s)

    valid=$(( (d1 - d2) / 86400 ))

    if [ $valid -le 0 ]; then
        echo "[ERRO] $cert is NOT VALID anymore! (since $(( $valid * -1)) days)"
    elif [ $valid -le 30 ]; then
        echo "[WARN] $cert will be run out in less than one month! ($valid days left)"
    fi
done