cmd

ENV

$ go env

GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/my_name/Library/Caches/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/my_name/workspace/golang"
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
...

Install

go get -u google.golang.org/grpc
go get -u github.com/golang/protobuf/protoc-gen-go