Monitor that uses openssl for OCSP

Thanks for both answers, I had essentially each component you have in the above script except I used a few more variables for the openssl command like this:

openssl ocsp -url http://$IP:$PORT -issuer $CERTFILE -no_cert_verify -resp_text -serial $SERIAL | grep $QUERYSTRING | cut -d " " -f2 > /dev/null

where $QUERYSTRING was "$SERIAL: " since I only want to test if the OSCP responder is processing requests, I don't really care if the response is "good" or "unknown" as long as it's a non error response. Both responses were helpful but I gave credit to Kevin since he spent more time on a full explanation.