一文搞懂Go Exec 僵尸与孤儿进程

#!/bin/sh
sh sub.sh

#!/bin/sh
n=0
while [ $n -le 100 ]
do
  echo $n
  let n++
  sleep 1
done

ps -j

USER   PID    PPID   PGID   SESS  JOBC  STAT   TT     TIME     COMMAND
root   31758  31346  31758  0     1     S+     s000   0:00.00  /bin/sh ./start.sh
root   31759  31758  31758  0     1     S+     s000   0:00.01  sh sub.sh

kill -9 31758

# 再查看进程组
ps -j

## 返回
USER     PID       PPID  PGID     SESS  JOBC   STAT    TT       TIME     COMMAND
root     31759     1     31758    0      0     S       s000     0:00.03  sh sub.sh

package main

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

func main()  {
	cmd := exec.CommandContext(context.Background(), "./start.sh")

  // 将 start.sh 和 sub.sh 移到当前目录下
	cmd.Dir = "/Go/src/go-code/cmd/"
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	if err := cmd.Start(); err != nil {
		log.Printf("cmd.Start error %+v \n", err)
	}

	for {
		select {
		default:
			log.Println(cmd.Process.Pid)
			time.Sleep(2 * time.Second)
		}
	}
}

go run ./main.go

ps -j

USER   PID    PPID   PGID     SESS  JOBC  STAT   TT      TIME     COMMAND
root   45458  45457  45457    0     0     Ss+    s004    0:00.03  ...___1go_build_go_code_cmd
root   45462  45458  45457    0     0     S+     s004    0:00.01  /bin/sh ./start.sh
root   45463  45462  45457    0     0     S+     s004    0:00.03  sh sub.sh

kill -9 45462

ps -j

USER   PID    PPID   PGID     SESS  JOBC  STAT   TT      TIME     COMMAND
root   45458  45457  45457    0     0     Ss+    s004    0:00.03  ...___1go_build_go_code_cmd
root   45462  1      45457    0     0     S+     s004    0:00.01  (bash)
root   45463  45462  45457    0     0     S+     s004    0:00.03  sh sub.sh

# 列出进程
ps -l

package main

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

func main() {

	ctx := context.Background()
	cmd := exec.CommandContext(ctx, "./start.sh")
  
        // 设置进程组
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setpgid: true,
	}

	cmd.Dir = "/Users/Wilbur/Project/Go/src/go-code/cmd/"
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	if err := cmd.Start(); err != nil {
		log.Printf("cmd.Start error %+v \n", err)
	}

        // 监听进程wait
	errCmdCh := make(chan error, 1)
	go func() {
		errCmdCh <- cmd.Wait()
	}()

	for {
		select {
		case <-ctx.Done():
			log.Println("ctx.done")
			pid := cmd.Process.Pid
			if err := syscall.Kill(-1*pid, syscall.SIGKILL); err != nil {
				return
			}
		case err := <-errCmdCh:
			log.Printf("errCmdCh error %+v \n", err)
			return
		default:
			log.Println(cmd.Process.Pid)
			time.Sleep(2 * time.Second)
		}
	}
}

var (
	status syscall.WaitStatus
	rusage syscall.Rusage
	pid1   int
	e      error
)

for {
	pid1, e = syscall.Wait4(p.Pid, &status, 0, &rusage)
	if e != syscall.EINTR {
		break
	}
}