Handle Ctrl-C (SIGINT) in a Go Program with NotifyContext

A long-running Go program should shut down cleanly when it receives an interrupt.

package main

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

func main() {
	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	go func() {
		time.Sleep(200 * time.Millisecond)
		syscall.Kill(os.Getpid(), syscall.SIGINT)
	}()

	select {
	case <-ctx.Done():
		fmt.Println("interrupted:", ctx.Err())
	case <-time.After(5 * time.Second):
		fmt.Println("no signal")
	}
	stop()
	fmt.Println("default handling is back; a second Ctrl-C would now kill the process")
}

interrupted: context canceled
default handling is back; a second Ctrl-C would now kill the process

signal.NotifyContext(parent, signals...) returns a derived context that is canceled when one of the signals arrives, so the same select on ctx.Done() that handles timeouts also handles Ctrl-C. The program sends itself SIGINT after 200 milliseconds and the output shows interrupted: context canceled. Calling stop() unregisters the handler, and from then on a second signal ends the process in the usual way. See signal.NotifyContext.

syscall.Kill is Unix only; on Windows only os.Interrupt is delivered. The context says that a signal arrived, not which one, so use signal.Notify with a channel when the signal number matters. Always call stop, or the handler stays registered for the life of the process.