Added the sample of a daemon

sample/sample.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"flag"
+	"github.com/sevlyar/go-daemon"
+	"log"
+	"os"
+	"syscall"
+	"time"
+)
+
+var (
+	signal = flag.String("s", "", `send signal to the daemon
+		quit — graceful shutdown
+		stop — fast shutdown
+		reload — reloading the configuration file`)
+)
+
+func main() {
+	flag.Parse()
+	daemon.AddCommand(daemon.StringFlag(signal, "quit"), syscall.SIGQUIT, termHandler)
+	daemon.AddCommand(daemon.StringFlag(signal, "stop"), syscall.SIGTERM, termHandler)
+	daemon.AddCommand(daemon.StringFlag(signal, "reload"), syscall.SIGHUP, reloadHandler)
+
+	cntxt := &daemon.Context{
+		PidFileName: "pid",
+		PidFilePerm: 0644,
+		LogFileName: "log",
+		LogFilePerm: 0640,
+		WorkDir:     "./",
+		Umask:       027,
+		Args:        []string{"[go-daemon sample]"},
+	}
+
+	if len(daemon.ActiveFlags()) > 0 {
+		d, err := cntxt.Search()
+		if err != nil {
+			log.Fatalln("Unable send signal to the daemon:", err)
+		}
+		daemon.SendCommands(d)
+		return
+	}
+
+	d, err := cntxt.Reborn()
+	if err != nil {
+		log.Fatalln(err)
+	}
+	if d != nil {
+		return
+	}
+	defer cntxt.Release()
+
+	log.Println("- - - - - - - - - - - - - - -")
+	log.Println("daemon started")
+
+	go worker()
+
+	err = daemon.ServeSignals()
+	if err != nil {
+		log.Println("Error:", err)
+	}
+	log.Println("daemon terminated")
+}
+
+var (
+	stop = make(chan struct{})
+	done = make(chan struct{})
+)
+
+func worker() {
+	for {
+		time.Sleep(time.Second)
+		if _, ok := <-stop; ok {
+			break
+		}
+	}
+	done <- struct{}{}
+}
+
+func termHandler(sig os.Signal) error {
+	log.Println("terminating...")
+	stop <- struct{}{}
+	if sig == syscall.SIGQUIT {
+		<-done
+	}
+	return daemon.ErrStop
+}
+
+func reloadHandler(sig os.Signal) error {
+	log.Println("configuration reloaded")
+	return nil
+}