I wish to verify if a 3508 has a Gbic installed in a particular slot. The interface is not in use currently. I would expect a CLI comand would be able to determine this, at least for the purpose of identifying the Gbic H'ware. The device is at a remote location.
Yes there is a way.
Do a show interface gi xx and check for media type. It will say media is missing if no gbic installed. If gbic is installed it will say type, SX, LX.
Hope that helps