Add a namespace prefix to the output of a subprocess

cmd-namespaced.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"log"
	"os/exec"
)

func main() {
	pr, pw := io.Pipe()
	go do(pw)
	
	scanner := bufio.NewScanner(pr)
	for scanner.Scan() {
		fmt.Printf("subprocess-1 | %s\n", scanner.Text())
	}
}

func do(w io.Writer) {
	cmd := exec.Command("ping", "google.com")
	cmd.Stdout = w
	if err := cmd.Start(); err != nil {
		log.Fatal(err)
	}
	if err := cmd.Wait(); err != nil {
		log.Fatal(err)
	}
}