Question

I want to open a web browser:

c, err := exec.Command("http://localhost:4001").Output()
if err != nil {
    fmt.Printf("ERROR: %v, %v\n",err,c)
} else {
    fmt.Printf("OK:%v\n",c)
}

and I get the error

ERROR: exec: "http://localhost:4001": file does not exist

Edit: What I want to achieve is the same as in Windows and C# when you do:

Process.Start("http://localhost:4001")

With it a new instance of your default browser will launch showing the URL

Answer 1

"http://localhost:4001/" is a URL, it can not be executed, but you can execute a web browser (e.g. firefox) and pass the URL as first argument.

On Windows, OS X, and Linux helper programs exist which can be used to start the default web browser. I guess there is a similar thing for FreeBSD and Android, but I am not sure about it. The following snippet should work on Windows, OS X, and most Linux distros:

var err error
switch runtime.GOOS {
case "linux":
    err = exec.Command("xdg-open", "http://localhost:4001/").Start()
case "windows", "darwin":
    err = exec.Command("open", "http://localhost:4001/").Start()
default:
    err = fmt.Errorf("unsupported platform")
}