signals.go

package main

import "fmt"
import "os"
import "os/signal"
import "syscall"

// 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 main() {
	// Go signal notification works by sending os.Signal values on a channel. We’ll create a channel to receive these notifications (we’ll also make one 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")
}

// When we run this program it will block waiting for a signal. By typing ctrl-C (which the terminal shows as ^C) we can send a SIGINT signal, causing the program to print interrupt and then exit.
// $ go run signals.go
// awaiting signal
// ^C
// interrupt
// exiting