External process launch/terminate

main.go

package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
	"os/exec"
	"sync"
	"syscall"
)

func main() {
	var cmd *exec.Cmd
	var wg sync.WaitGroup
	running := false

	reader := bufio.NewReader(os.Stdin)

	for {
		fmt.Println("Menu:")
		fmt.Println("1. Start Application")
		fmt.Println("2. Stop Application Gracefully (SIGTERM)")
		fmt.Println("3. Stop Application Immediately (Kill)")
		fmt.Println("4. Exit")
		fmt.Print("Enter your choice: ")

		choice, _ := reader.ReadString('\n')
		choice = choice[:len(choice)-1] // Remove newline character

		switch choice {
		case "1":
			if running {
				fmt.Println("Application is already running.")
				continue
			}

			cmd = exec.Command("./simple-hw")
			cmd.Stdout = os.Stdout
			cmd.Stderr = os.Stderr

			wg.Add(1)
			go func() {
				defer wg.Done()
				if err := cmd.Run(); err != nil {
					log.Printf("Error running simple-hw: %v", err)
				}
			}()
			running = true
			fmt.Println("Application started.")

		case "2":
			if !running {
				fmt.Println("Application is not running.")
				continue
			}

			// Send SIGTERM to gracefully stop the application
			if err := cmd.Process.Signal(syscall.SIGTERM); err != nil {
				log.Printf("Error stopping application gracefully: %v", err)
			} else {
				fmt.Println("Application stopped gracefully.")
			}
			wg.Wait()
			running = false

		case "3":
			if !running {
				fmt.Println("Application is not running.")
				continue
			}

			// Kill the application immediately
			if err := cmd.Process.Kill(); err != nil {
				log.Printf("Error stopping application immediately: %v", err)
			} else {
				fmt.Println("Application stopped immediately.")
			}
			wg.Wait()
			running = false

		case "4":
			if running {
				fmt.Println("Stopping running application before exiting...")
				// Kill the application immediately before exiting
				if err := cmd.Process.Kill(); err != nil {
					log.Printf("Error stopping application immediately: %v", err)
				}
				wg.Wait()
			}
			fmt.Println("Exiting program.")
			return

		default:
			fmt.Println("Invalid choice. Please try again.")
		}
	}
}