How to prevent open my application more than one time? [duplicate]

Question

This question already has answers here:

Closed 7 years ago.

Possible Duplicate:
What is the correct way to create a single instance application?

How can I define my application to open only one time after click on its exe file over and over?

Answer 1

I've always done this at the application's entry point:

bool onlyInstance = false;

Mutex m = new Mutex(true, "MyUniqueMutextName", out onlyInstance);
if (!onlyInstance)
{
    return;
}

GC.KeepAlive(m);

Answer 2

There are several related questions on Stack Overflow for Single Instance Applications:

This one seems to be the most apropriate: What is the correct way to create a single-instance application?