如果exec.Start（）创建的进程的父进程被SIGINT杀死，为什么会退出呢？

Question

I found a strange problem in golang.The program executed by exec.Start() will quit if the parent program is interrupt by the signal os.Interrupt,while the child program will NOT quit if the parent program exit normally.What's the difference between that two conditions? For examples:

package main

import "fmt"
import "os"
import "time"
import "os/exec"

func main(){
    cmd := exec.Command("sleep", "100000")
    cmd.Env = os.Environ()
    fmt.Println(cmd.Env)
    cmd.Start()

    time.Sleep(1e9*20)
    return
} 

In the later condition the parent of sleep 100000 will be the init process after 20s if we didn't interrupt the main program.

Answer 1

What's happening is that if you send a process SIGINT (as e.g. os.Interrupt does), all proceses in the same process group will also get that signal (which includes child processes) - SIGINT will by default terminate a process.

If however a parent process exits normally, not because of SIGINT or similar, a process in the same process group does not get any signal - it will continue to run, but be adopted by the init process. This is not specific to Go.