64_signals.go

package gobyexample

import (
	"fmt"
	"os"
	"os/signal"
	"syscall"
)

// SignalsDemo - Sometimes we'd like our Go programs to intelligently handle Unix signals.
// For example, we might want a server to gracefully shutdown when it receives a SIGTERM,
// or a command-line tool to stop processing input if it receives a SIGINT. Here's how to
// handle signals in Go with channels.
func SignalsDemo() {
	// Go signal notification works by sending os.Signal values on a channel.
	// We'll create a channel to receive these notifications, and also create another
	// channel to notify us when the program can exit.
	sigs := make(chan os.Signal, 1)
	done := make(chan bool, 1)

	// signal.Notify registers the given channel to receive notifications of the
	// specified signals.
	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)

	// This goroutine executes a blocking receive for signals. When it gets one
	// it'll print it out and then notify the program that it can finish.
	go func() {
		sig := <-sigs
		fmt.Println()
		fmt.Println(sig)
		done <- true
	}()

	// The program will wait here until it gets the expected signal (as indicated
	// by the goroutine above sending a value on `done`) and then exit.
	fmt.Println("awaiting signal")
	<-done
	fmt.Println("exiting")
}