I know we can retrieve the SSL cert with openssl s_client -connect host:port command. Is there any way to find out the file system location of the cert that was used by the process handling the SSL traffic? Am I being very unreasonable?
Finding SSL cert location by connecting to the port
openssl;ssl;certificates
No, you can't get that information. It's none of the TLS client's business. It's purely up to the server how and where it loads its certificate (and private key) from. It might not even come from a file on a filesystem but from, say, an HSM.