// Ensure only one instance of this application is running.
bool alone = false;
Mutex m = new Mutex(true, "<name>", out alone);
 
if (!alone)
{
    Console.WriteLine("Another instance is already running.");
    Console.ReadKey();
    return;
}
 
Console.WriteLine("Running...\n");
Console.ReadKey();
 
// Needed to ensure only one instance is running.
GC.KeepAlive(m);