golang 中创建daemon的方法

https://github.com/takama/daemon

https://github.com/immortal/immortal/blob/master/fork.go                  这个是比较原始的最接近c语言的实现，它里面还有很多原始c语言的东西的golang实现：

// fork.go
package immortal

import (
    "os"
    "os/exec"
    "syscall"
)

// Fork crete a new process
func Fork() (int, error) {
    args := os.Args[1:]
    cmd := exec.Command(os.Args[0], args...)
    cmd.Env = os.Environ()
    cmd.Stdin = nil
    cmd.Stdout = nil
    cmd.Stderr = nil
    cmd.ExtraFiles = nil
    cmd.SysProcAttr = &syscall.SysProcAttr{
        // Setsid is used to detach the process from the parent (normally a shell)
        //
        // The disowning of a child process is accomplished by executing the system call
        // setpgrp() or setsid(), (both of which have the same functionality) as soon as
        // the child is forked. These calls create a new process session group, make the
        // child process the session leader, and set the process group ID to the process
        // ID of the child. https://bsdmag.org/unix-kernel-system-calls/
        Setsid: true,
    }
    if err := cmd.Start(); err != nil {
        return 0, err
    }
    return cmd.Process.Pid, nil
}