A script to return the number of days before a SSL certificate expires. Visit https://sbcode.net/zabbix/system-run/ for instructions

checkssl.sh

data=`echo | openssl s_client -servername $1 -connect $1:443 2>/dev/null | openssl x509 -noout -enddate | sed -e 's#notAfter=##'`

ssldate=`date -d "${data}" '+%s'`
nowdate=`date '+%s'`
diff="$((${ssldate}-${nowdate}))"

echo $((${diff}/86400))

Thanks, works like a charm.
Particularly useful if we have some protected hosts and public check of SSL expiration is not possible. Script is doing it locally on own host, nice.
All the best