Proof of concept for deamons

fork2.go

package main

import (
    "os"
    "log"
    "time"
    "syscall"
)

func main() {
    tm := 15
    args := os.Args
    dir, _ := os.Getwd()
    attrs := os.ProcAttr{Dir: dir, Env: os.Environ(), Files: []*os.File{nil, nil, os.Stderr}}

    if len(args) == 1 {
	log.Printf("First instance; PID: %d\n", os.Getpid())
	args = []string{args[0], "second"}
	tm = 10
    } else if args[1] == "second" {
	log.Printf("Second instance; PID: %d\n", os.Getpid())
	args = []string{args[0], "third"}
	tm = 5
	sysattr := syscall.SysProcAttr{Setsid: true}
	attrs.Sys = &sysattr
    } else if args[1] == "third" {
	log.Printf("Third instance; PID: %d\n", os.Getpid())
	log.Printf("Process %d running for another %d seconds\n", os.Getpid(), tm)
	time.Sleep(time.Duration(tm) * 1e9)
	log.Printf("Process %d exiting\n", os.Getpid())
	os.Exit(0)
    }

    proc, err := os.StartProcess("fork2", args, &attrs)

    if err != nil {
	log.Printf("Unable to start process (my PID: %d)\n", os.Getpid());
    }

    proc.Release()
    log.Printf("Process %d running for another %d seconds\n", os.Getpid(), tm)
    time.Sleep(time.Duration(tm) * 1e9)

    log.Printf("Process %d exiting\n", os.Getpid())
    os.Exit(0)
}