There is nothing wrong, you have started the server, it is running and listening on port 27017. Now you can start to interact with the server, for example just open a new terminal tab and run mongo ,which will open mongo’s interactive console and connects to the default server(localhost:27017)
If you want to run mongod as a background process (to get back the console) you can use –fork command option. This requires you to use some sort of logging.
Eg. mongod --dbpath /path/to/my/mongodata --fork --logpath /path/to/my/mongod.log
If you want to restore a bsonexport you will probably use the mongorestore command