gistfile1.txt

package main

import (
    "log"
    "os"
    "os/exec"
    "time"
)

func main() {
    if len(os.Args) != 2 {
        log.Fatalf("required: go run test-exec.go docker-exec|nsinit-exec|echo|docker-run")
    }
    switch os.Args[1] {
    case "docker-exec":
        main1()
    case "nsinit-exec":
        main2()
    case "echo":
        main3()
    case "docker-run":
        main4()
    }
}

func main1() {
    exec.Command("docker", "stop", "testing").Run()
    exec.Command("docker", "rm", "testing").Run()
    defer func() {
        exec.Command("docker", "stop", "testing").Run()
        exec.Command("docker", "rm", "testing").Run()
    }()

    exec.Command("docker", "run", "-d", "--name", "testing", "busybox", "top").Run()

    time.Sleep(1 * time.Second)

    cmd := exec.Command("docker", "exec", "-i", "testing", "echo", "hello")
    stdin, err := cmd.StdinPipe()
    if err != nil {
        panic(err)
    }
    defer stdin.Close()

    if err := cmd.Start(); err != nil {
        panic(err)
    }

    time.Sleep(1 * time.Second)
    n, err := stdin.Write([]byte("hello"))
    log.Println(n, err)
}

func main2() {
    cmd := exec.Command("sudo", "nsinit", "exec", "top")
    cmd.Dir = "/busybox"
    if err := cmd.Start(); err != nil {
        panic(err)
    }
    time.Sleep(1 * time.Second)
    defer cmd.Process.Kill()

    exec := exec.Command("sudo", "nsinit", "exec", "true")
    cmd.Dir = "/busybox"
    stdin, err := exec.StdinPipe()
    if err != nil {
        panic(err)
    }
    defer stdin.Close()

    if err := exec.Start(); err != nil {
        panic(err)
    }

    time.Sleep(1 * time.Second)
    n, err := stdin.Write([]byte("hello"))
    log.Println(n, err)
}

func main3() {
    cmd := exec.Command("echo", "hello")
    stdin, err := cmd.StdinPipe()
    if err != nil {
        panic(err)
    }
    defer stdin.Close()

    if err := cmd.Start(); err != nil {
        panic(err)
    }

    time.Sleep(1 * time.Second)
    n, err := stdin.Write([]byte("hello"))
    log.Println(n, err)
}

func main4() {
    cmd := exec.Command("docker", "run", "-i", "--rm", "busybox", "echo", "hello")
    stdin, err := cmd.StdinPipe()
    if err != nil {
        panic(err)
    }
    defer stdin.Close()

    if err := cmd.Start(); err != nil {
        panic(err)
    }

    time.Sleep(1 * time.Second)
    n, err := stdin.Write([]byte("hello"))
    log.Println(n, err)
}