linux - Golang exec 进程并否认它

Question

我正在尝试使用我的守护进程来 fork 进程，并试图在我的守护进程崩溃的情况下不承认它们。常规 os/exec 是高级别的，因此我选择了 syscall.ForkExec 并生成了以下代码:

package main

import (
    "fmt"
    "os"
    "os/exec"
    "syscall"
    "time"
)

func main() {

    cmd := "myproc"
    binary, lookErr := exec.LookPath(cmd)
    if lookErr != nil {
        panic(lookErr)
    }
    fmt.Println(binary)

    os.Remove("/tmp/stdin")
    os.Remove("/tmp/stdout")
    os.Remove("/tmp/stderr")

    fstdin, err1 := os.Create("/tmp/stdin")
    fstdout, err2 := os.Create("/tmp/stdout")
    fstderr, err3 := os.Create("/tmp/stderr")
    if err1 != nil || err2 != nil || err3 != nil {
        fmt.Println(err1, err2, err3)
        panic("WOW")
    }

    argv := []string{"hi"}
    procAttr := syscall.ProcAttr{
        Dir:   "/tmp",
        Files: []uintptr{fstdin.Fd(), fstdout.Fd(), fstderr.Fd()},
        Env:   []string{"VAR1=ABC123"},
        Sys: &syscall.SysProcAttr{
            Foreground: false,
        },
    }

    pid, err := syscall.ForkExec(binary, argv, &procAttr)
    fmt.Println("Spawned proc", pid, err)

    time.Sleep(time.Second * 100)
}

我还制作了一个简单的应用程序，它可以休眠并打印 hello world 并将其放到路径中。

#include <stdio.h>

int main(){
    while(1){
        printf("hello world");
        fflush(stdout);
        usleep(300000);
        }
}

它可以工作，但是，进程没有像我预期的那样发送到后台，我的 go 进程仍然拥有 child 。 SysProcAttr 在 Linux 中具有以下值:

type SysProcAttr struct {
    Chroot      string         // Chroot.
    Credential  *Credential    // Credential.
    Ptrace      bool           // Enable tracing.
    Setsid      bool           // Create session.
    Setpgid     bool           // Set process group ID to Pgid, or, if Pgid == 0, to new pid.
    Setctty     bool           // Set controlling terminal to fd Ctty (only meaningful if Setsid is set)
    Noctty      bool           // Detach fd 0 from controlling terminal
    Ctty        int            // Controlling TTY fd
    Foreground  bool           // Place child's process group in foreground. (Implies Setpgid. Uses Ctty as fd of controlling TTY)
    Pgid        int            // Child's process group ID if Setpgid.
    Pdeathsig   Signal         // Signal that the process will get when its parent dies (Linux only)
    Cloneflags  uintptr        // Flags for clone calls (Linux only)
    UidMappings []SysProcIDMap // User ID mappings for user namespaces.
    GidMappings []SysProcIDMap // Group ID mappings for user namespaces.
    // GidMappingsEnableSetgroups enabling setgroups syscall.
    // If false, then setgroups syscall will be disabled for the child process.
    // This parameter is no-op if GidMappings == nil. Otherwise for unprivileged
    // users this should be set to false for mappings work.
    GidMappingsEnableSetgroups bool
}

我也尝试了以下方法，但它导致了错误:

Sys: &syscall.SysProcAttr{
    Setsid:     true,
    Setctty:    true,
    Foreground: false,
 },

Spawned proc 0 inappropriate ioctl for device

还有以下内容:

Sys: &syscall.SysProcAttr{
    Setsid:     true,
    Setctty:    true,
    Foreground: false,
    Noctty:     true,
    Setpgid:    true,
},

Spawned proc 0 operation not permitted (with root privilleges)

我在做什么/假设错了？注意:尽管说 os/exec 是高级别的，但我也尝试了以下方法，但结果相同。

cs := exec.Command(binary)
cs.SysProcAttr = &syscall.SysProcAttr{
    Setctty: true,
}
err := cs.Run()
fmt.Println(err)

Answer 1

使用 Start() 派生的进程即使在其父进程死亡后仍将继续。

func forker() {
    cmd := exec.Command("sleep", "3")
    cmd.Start()
    time.Sleep(2 * time.Second)
    os.Exit(1)
}

这里 sleep 进程会愉快地存活 3 秒，即使父进程只存活 2 秒:

  $ forker &; while true; do ps -f; sleep 1; done

  UID   PID  PPID   C STIME   TTY           TIME CMD
  501 71423 69892   0  3:01PM ttys003    0:00.07 forker
  501 71433 71432   0  3:01PM ttys003    0:00.00 sleep 3

  UID   PID  PPID   C STIME   TTY           TIME CMD
  501 71423 69892   0  3:01PM ttys003    0:00.07 forker
  501 71433 71432   0  3:01PM ttys003    0:00.00 sleep 3

  UID   PID  PPID   C STIME   TTY           TIME CMD
  501 71433     1   0  3:01PM ttys003    0:00.00 sleep 3

注意当父进程71432时sleep进程的父进程ID(PPID)变成1 > 退出。这意味着 sleep 进程已被孤立。