package main import (	"flag"	"github.com/ftrvxmtrx/fd"	"log"	"net"	"os") var (	filename string	socket   string) func init() {	flag.StringVar(&filename, "f", "", "filename")	flag.StringVar(&socket, "s", "/tmp/sendfd.sock", "socket")} func main() {	flag.Parse() 	if !flag.Parsed() || filename == "" || socket == "" {		flag.Usage()		os.Exit(1)	} 	f, err := os.Open(filename)	if err != nil {		log.Fatal(err)	}	defer f.Close() 	l, err := net.Listen("unix", socket)	if err != nil {		log.Fatal(err)	}	defer l.Close() 	var a net.Conn	a, err = l.Accept()	if err != nil {		log.Fatal(err)	}	defer a.Close() 	listenConn := a.(*net.UnixConn)	if err = fd.Put(listenConn, f); err != nil {		log.Fatal(err)	}}