使用重定向到文件启动分离命令

Question

I'm trying to start a command in a detached process so that it can continue after go program exits. I need to redirect the output of the command to a file.

What I need is something like this:

func main() {
    command := exec.Command("/tmp/test.sh", ">", "/tmp/out")

    if err := command.Start(); err != nil {
        fmt.Fprintln(os.Stderr, "Command failed.", err)
        os.Exit(1)
    }

    fmt.Println("Process ID:", command.Process.Pid)
}

Obviously such redirect doesn't work. As I immediately exit from the program after starting the long running command, I cannot open a file and bind it to the Stdout.

Is there any way to achieve such a redirect?

Answer 1

Maybe you can try to use this: https://stackoverflow.com/a/28918814/2728768

Opening a file (and os.File implements io.Writer), and then passing it as the command.Stdout could do the trick:

func main() {
    command := exec.Command("./tmp/test.sh")
    f, err := os.OpenFile("/tmp/out", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
    if err != nil {
        fmt.Printf("error opening file: %v", err)
    }
    defer f.Close()
    // On this line you're going to redirect the output to a file
    command.Stdout = f
    if err := command.Start(); err != nil {
        fmt.Fprintln(os.Stderr, "Command failed.", err)
        os.Exit(1)
    }

    fmt.Println("Process ID:", command.Process.Pid)
}

Not sure this could be a viable solution for your case. I've tried it locally and it seems working... remember that your user should be able to create/update the file.