package main import ( "os" "time" ) func main() { // Open the file in append mode, create it if it doesn't exist file, err := os.OpenFile("output.txt", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644) if err != nil { panic(err) } defer file.Close() // Define the byte to be written data := []byte("A") // Replace 'A' with any byte you wish to write // Loop to write the byte every 3 seconds for { _, err := file.Write(data) if err != nil { panic(err) } // Flush writes to stable storage err = file.Sync() if err != nil { panic(err) } // Wait for 3 seconds time.Sleep(3 * time.Second) } }