test_write.go

package main

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

func main() {
	console, err := os.OpenFile("/dev/console", os.O_RDWR, 0)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Fprintln(console, "write before dup /dev/null to stdio")
	makeNullStdio()
	fmt.Fprintln(console, "write after dup /dev/null to stdio")
	console.Close()

	logf, _ := os.Create("/tmp/logfile")
	for {
		console, err = os.OpenFile("/dev/console", os.O_RDWR, 0)
		if err != nil {
			fmt.Fprint(logf, err)
			os.Exit(1)
		}
		fmt.Fprintln(console, "open, write to console, and close")
		console.Close()
		time.Sleep(time.Second)
	}
}

func makeNullStdio() {
	nullFd, _ := os.OpenFile("/dev/null", os.O_RDWR, 0)
	defer nullFd.Close()
	fd := int(nullFd.Fd())
	syscall.Dup2(fd, 0)
	syscall.Dup2(fd, 1)
	syscall.Dup2(fd, 2)
}