An example that you could use via bash script would be this:
curl --data '{"jsonrpc":"2.0","method":"cmdb.object.create","params":{"type":"C__OBJTYPE__SERVER","title":"My little server","apikey":"c1ia5q"},"id":1}' --header "Content-Type: application/json" https://demo.i-doit.com/src/jsonrpc.php