Time in days remaining for SSL certs, for use by monitoring systems.

ssl_time_left.sh

#!/bin/bash
host=$1
port=$2
#This is a little bit nasty with all the piping and all
cert_expire=`echo | openssl s_client -showcerts -connect $host:$port 2>/dev/null |sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' | openssl x509 -noout -subject -dates | grep notAfter | awk -F= '{print $2}'`
cert_expire_unix=`date --date="$cert_expire" +%s`
current_time_unix=`date +%s`

timediff_days=$((($cert_expire_unix - $current_time_unix) / 86400))

#For monitoring systems
echo $timediff_days

#More output when running manually
if [[ -t "0" || -p /dev/stdin ]]
then
    echo "Cert for $host expires on $cert_expire" >&2
    echo "Current (local) time is `date`" >&2
fi