Allow Application Run Only Once

Here is an example to allow software to run only once on a machine.
If the user tries to start the application again, there will ne a notification box and the program will exit.

[file] program.cs in visual studio

using System;
using System.Threading;
using System.Windows.Forms;

namespace myapplicationnamespace
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        ///  Only Once Instance Mode Mutex Variable and Remove IDE Error Message
            #pragma warning disable IDE0052
            private static Mutex mutex = null;
            #pragma warning restore IDE0052
        [STAThread]
        static void Main()
        {
            //
            // Only One Instance Mode
            //
            // One Instance Mode - Disable Warning Message on FailError
            const string appName = "MyApplicationName";
            #pragma warning disable IDE0018
            bool createdNew;
            #pragma warning restore IDE0018

            mutex = new Mutex(true, appName, out createdNew);

            if (!createdNew)
            {
                // App is Running
                MessageBox.Show("Only one instance allowed!");
                return;
            }

            //Default
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new MainForm());
        }
    }
}