How to do it…

1. Open the console and create the folder chapter01/recipe11.
2. Navigate to the directory.
3. Create the main.go file with the following content:

        package main

        import (
          "fmt"
          "io"
          "log"
          "os"
          "os/signal"
          "syscall"
          "time"
        )

        var writer *os.File

        func main() {

          // The file is opened as
          // a log file to write into.
          // This way we represent the resources
          // allocation.
          var err error
          writer, err = os.OpenFile(fmt.Sprintf("test_%d.log",
                time.Now().Unix()), os.O_RDWR|os.O_CREATE, os.ModePerm)
          if err != nil {
            panic(err)
          }

          // The code is running in a goroutine
          // independently. So in case the program is
          // terminated from outside, we need to
          // let the goroutine know via the closeChan
          closeChan := make(chan bool)
          go func() {
            for {
              time.Sleep(time.Second)
              select {
                case <-closeChan:
                  log.Println("Goroutine closing")
                  return
                default:
                  log.Println("Writing to log")
                  io.WriteString(writer, fmt.Sprintf("Logging access
                                 %s\n", time.Now().String()))
              }  

            }
          }()

          sigChan := make(chan os.Signal, 1)
          signal.Notify(sigChan,
            syscall.SIGTERM,
            syscall.SIGQUIT,
            syscall.SIGINT)

          // This is blocking read from
          // sigChan where the Notify function sends
          // the signal.
          <-sigChan

          // After the signal is received
          // all the code behind the read from channel could be
          // considered as a cleanup.
          // CLEANUP SECTION
          close(closeChan)
          releaseAllResources()
          fmt.Println("The application shut down gracefully")
        }

        func releaseAllResources() {
          io.WriteString(writer, "Application releasing 
                         all resources\n")
          writer.Close()
        }

1. Run the code by executing go run main.go.
2. Press CTRL + C to send a SIGINT signal.
3. Wait until the Terminal output looks like this:

1. The recipe11 folder should also contain a file called test_XXXX.log, which contains lines like this: