[go-nuts] Starting detached child process

On 17 Jul 2014, at 18:15, Shawn Milochik wrote:

It looks like exec.Start() does what you want.

http://golang.org/pkg/os/exec/#Cmd.Start


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On Thu, Jul 17, 2014 at 9:56 PM, Hein Meling wrote:

No, because if the go program (the parent) is killed, the children also
gets killed.

Hein :)

On Thursday, July 17, 2014 7:04:25 PM UTC-7, Shawn Milochik wrote:

On Thu, Jul 17, 2014 at 9:56 PM, Hein Meling <hein....@gmail.com
<javascript:>> wrote:
That doesn't seem to be the case.

package main

import (
"os/exec"
)

func main() {
cmd := exec.Command("/tmp/monkey.sh")
cmd.Start()
}

When I run that, with monkey.sh being a program that just appends text
to a file, it keeps running after the Go program exits. I can even run the
Go program multiple times and multiple instances of monkey.sh are running.

On Thu, Jul 17, 2014 at 8:12 PM, Hein Meling wrote:

Your solution seems to work when then parent process exits cleanly. But if
you do:

func main() {
cmd := exec.Command("sleep", "15")
cmd.Start()
time.Sleep(20 * time.Second)
}

And CTRL-C the parent process before it exits cleanly, then also the sleep
process goes away. Does the same happen to your monkey.sh process?

Moreover, my use case is actually somewhat more involved. That is, I would
like to do cmd.Wait() (from different goroutines), in order to monitor the
child processes, but I don't want the child processes to fail if the parent
fails.

:) Hein

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On Thu, Jul 17, 2014 at 8:12 PM, Hein Meling wrote:
Your solution seems to work when then parent process exits cleanly. But if
you do:

func main() {
cmd := exec.Command("sleep", "15")
cmd.Start()
time.Sleep(20 * time.Second)
}

And CTRL-C the parent process before it exits cleanly, then also the sleep
process goes away. Does the same happen to your monkey.sh process?

Moreover, my use case is actually somewhat more involved. That is, I would
like to do cmd.Wait() (from different goroutines), in order to monitor the
child processes, but I don't want the child processes to fail if the parent
fails.

On Friday, July 18, 2014 1:07:44 AM UTC-7, Ian Lance Taylor wrote:


^C kills all the processes because on Unix typing ^C on the terminal
sends a signal to every process in the process group. So you want to
have a child process that is in a different process group. You do
that by setting Setpgid to true in the Cmd.SysProcAttr field.

Ian

On Friday, July 18, 2014 at 11:07:44 AM UTC+3, Ian Lance Taylor wrote:

On Thu, Jul 17, 2014 at 8:12 PM, Hein Meling <hein....@gmail.com
<javascript:>> wrote:
^C kills all the processes because on Unix typing ^C on the terminal
sends a signal to every process in the process group. So you want to
have a child process that is in a different process group. You do
that by setting Setpgid to true in the Cmd.SysProcAttr field.

Ian