package main

import (
	"context"
	"fmt"
	"log"
	"os/exec"
	"time"
)

func main() {
	ctx, cancel := context.WithCancel(context.Background())

	done := make(chan struct{})

	cmd := exec.CommandContext(ctx, "sleep", "300")

	go func() {
		defer close(done)
		err := cmd.Start()
		if err != nil {
			log.Fatal(err)
		}
		err = cmd.Wait()
		if err != nil {
			log.Println("waiting on cmd:", err)
		}
	}()

	select {
	case <-done:
		// cmd.Wait() completed.
	case <-time.After(3 * time.Second):
		fmt.Println("Exit Signal")
		_ = cmd.Process.Kill()
	}

	cancel()
}