How to read from device when stdin is pipe - go

Question

So I have a Go program that reads from STDIN as such below. I want the username and password to be entered from keyboard or device but the string slice can be passed using pipe. If I run the command as below:
echo "Hello World" | go run main.go
os.Stdin will be set to read from pipes and never the keyboard. Is there a way that I can change os.Stdin FileMode as such that it will be reading from device, i.e. keyboard for username and password?
I tried using os.Stdin.Chmod(FileMode) but received this error:
chmod /dev/stdin: invalid argument
func main() {
var n = []string{}
scanner := bufio.NewScanner(os.Stdin)
fmt.Println("Please type anything with Newline Separated, empty line signals termination")
for scanner.Scan() {
h := scanner.Text()
if h == "" {
break
}
n = append(n, h)
}
if err := scanner.Err(); err != nil {
fmt.Printf("Error in reading from STDIN: %v\n", err)
}
reader := bufio.NewReader(os.Stdin)
os.Stdout.WriteString("Username: ")
username, err := reader.ReadString('\n')
if err != nil {
fmt.Printf("Unable to read username: %v\n", err)
}
username = strings.TrimSpace(username)
os.Stdout.WriteString("Password: ")
bytePassword, _ := terminal.ReadPassword(int(os.Stdin.Fd()))
password := string(bytePassword)
os.Stdout.WriteString("\n")
}

Answer 1

Probably scanf could help, check this example:
https://play.golang.org/p/tteQNl0trJp
package main
import (
"fmt"
)
func main() {
fmt.Println("Enter your name")
var name string
fmt.Scanf("%s", &name)
fmt.Printf("name = %s\n", name)
}
Something a little more elaborated to check if there is something to read from stdin and if not prompt the user:
https://play.golang.org/p/7qeAQ5UNhdQ
package main
import (
"bufio"
"fmt"
"log"
"os"
)
func main() {
// check if there is somethinig to read on STDIN
stat, _ := os.Stdin.Stat()
if (stat.Mode() & os.ModeCharDevice) == 0 {
var stdin []byte
scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
stdin = append(stdin, scanner.Bytes()...)
}
if err := scanner.Err(); err != nil {
log.Fatal(err)
}
fmt.Printf("stdin = %s\n", stdin)
} else {
fmt.Println("Enter your name")
var name string
fmt.Scanf("%s", &name)
fmt.Printf("name = %s\n", name)
}
}

Answer 2

You can instead read from /dev/tty as this is always the terminal (if the program runs on a terminal). This is portable only to Unix-like systems (Linux, BSD, macOS, etc) and won't work on Windows.
// +build !windows
tty, err := os.Open("/dev/tty")
if err != nil {
log.Fatalf("can't open /dev/tty: %s", err)
}
scanner := bufio.NewScanner(tty)
// as you were ...