compile
protoc --go_out=plugins=grpc:./helloworld/ ./helloworld.proto
Only one pb.go file will be generated, which can be used as client or server.
protoc --go_out=. --go_opt=paths=source_relative --go-grpc_out=. --go-grpc_opt=paths=source_relative ./helloworld.proto
Generate pb.g and grpc.go files in the current directory
proto --go_out=. --go-grpc_out=. helloworld.proto