That's fairly easy to do in a cron job: TARGET="mysite.example.net"; \ RECIPIENT="hostmaster@mysite.example.net"; \ DAYS=7; \ echo "checking if

That's fairly easy to do in a cron job: TARGET="mysite.example.net"; \ RECIPIENT="hostmaster@mysite.example.net"; \ DAYS=7; \ echo "checking if $TARGET expires in less than $DAYS days"; \ expirationdate=$(date -d "$(: | openssl s_client -connect $TARGET:443 -servername $TARGET 2>/dev/null \ | openssl x509 -text \ | grep 'Not After' \ |awk '{print $4,$5,$7}')" '+%s'); \ in7days=$(($(date +%s) + (86400*$DAYS))); \ if [ $in7days -gt $expirationdate ]; then \ echo "KO - Certificate for $TARGET expires in less than $DAYS days, on $(date -d @$expirationdate '+%Y-%m-%d')" \ | mail -s "Certificate expiration warning for $TARGET" $RECIPIENT ; \ else \ echo "OK - Certificate expires on $expirationdate"; \ fi;