active single instance only

[reza assar]

hi i want to develop an application that , user could not execute more than one instance at a time for example my application name is: "APP" . if some one click APP icon it will be run if there is no another instance running at the current machine what should i do? thanks in advance!

[N a v a n e e t h]

Take a look at Mutex[^] class.

Best wishes, Navaneeth

[anishkannan]

try this code.... this is for just check ur Exe application name is currently running or not [DllImport("user32.dll", EntryPoint = "SetForegroundWindow")] static extern IntPtr SetForegroundWindow(IntPtr hWnd); private static bool AppIsAlreadyRunning() { Process c = Process.GetCurrentProcess(); foreach (Process p in Process.GetProcessesByName(c.ProcessName)) { if (p.Id != c.Id) { if (p.MainModule.FileName.ToLower().Equals(c.MainModule.FileName.ToLower())) { SetForegroundWindow(p.MainWindowHandle); return true; } } } return false; }

[Lost User]

You need to be very careful when you are using globally available mutexes running on limited OS accounts. Maybe finding all processes with the same name like the current will be better and safer solution because doesn't require any special permissions.

Life is a stage and we are all actors!

[N a v a n e e t h]

Hristo Bojilov wrote:

You need to be very careful when you are using globally available mutexes running on limited OS accounts

What problems are you seeing?

Best wishes, Navaneeth

[Lost User]

The method System.Threading.Mutex.OpenExisting could throw UnauthorizedAccessException for sample.Will this method work when the current account doesn't have the desired access and cannot acquire it?I've used this mutexes method for my current project but after discovering this exception is thrown to often when running on limited accounts I had removed it and used just simple scan for the running processes which queries Windows performance counter API.

Life is a stage and we are all actors!

[Luc Pattyn]

Hi, I haven't used the managed mutex class yet, however it seems to me the MutexSecurity parameter in one of the constructors should be the key to solving the problems you've had. Anyway, relying on GetProcessesByName() does not seem right as: 1. when a user renames an EXE, the resulting process would also be getting a different name; 2. I expect the Process methods also can fail when you have insufficient rights. :)

Luc Pattyn

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I only read code that is properly indented, and rendered in a non-proportional font; hint: use PRE tags in forum messages

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[vtchris peterson]

I've implemented a few ways of doing this, each with various limitations. Then, I came across this solution which works great: http://dotnetperls.com/single-instance-windows-form[^]

[reza assar]

thanks for your attention but the link is not refer correctly please to fix it!

[vtchris peterson]

Link works fine for me. Google C# Single-Instance Windows Form by Sam Allen.