How do I SET the GOPATH environment variable on Ubuntu? What file must I edit?

I am trying to do a `go get`: go get github.com/go-sql-driver/mysql and it fails with the following error: package github.com/go-sql-driver/mysql: cannot download, $GOPATH not set. For more details see: go help gopath when I do a `go env` , a list of Go values is shown as below: ubuntu@ip-xxx-x-xx-x:~$ go env GOARCH="amd64" GOBIN="" GOCHAR="6" GOEXE="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOOS="linux" GOPATH="" GORACE="" GOROOT="/usr/lib/go" GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64" CC="gcc" GOGCCFLAGS="-g -O2 -fPIC -m64 -pthread" CGO_ENABLED="1" clearly the GOPATH is not set, how and where do I set it? I see many threads that mention this error but none that provide an answer to my question, which file needs to be edited to provide a value for this path?