Checking if my Windows application is running

Question

How do I check if my C# Windows application is running ?

I know that I can check the process name but the name can be changed if the exe changes.

Is there any way to have a hash key or something to make my application unique?

Answer 1

public partial class App : System.Windows.Application
{
    public bool IsProcessOpen(string name)
    {
        foreach (Process clsProcess in Process.GetProcesses()) 
        {
            if (clsProcess.ProcessName.Contains(name))
            {
                return true;
            }
        }

        return false;
    }

    protected override void OnStartup(StartupEventArgs e)
    {
        // Get Reference to the current Process
        Process thisProc = Process.GetCurrentProcess();

        if (IsProcessOpen("name of application.exe") == false)
        {
            //System.Windows.MessageBox.Show("Application not open!");
            //System.Windows.Application.Current.Shutdown();
        }
        else
        {
            // Check how many total processes have the same name as the current one
            if (Process.GetProcessesByName(thisProc.ProcessName).Length > 1)
            {
                // If ther is more than one, than it is already running.
                System.Windows.MessageBox.Show("Application is already running.");
                System.Windows.Application.Current.Shutdown();
                return;
            }

            base.OnStartup(e);
        }
    }

Answer 2

The recommended way is to use a Mutex. You can check out a sample here : http://www.codeproject.com/KB/cs/singleinstance.aspx

In specific the code:

        /// 
        /// check if given exe alread running or not
        /// 
        /// returns true if already running
        private static bool IsAlreadyRunning()
        {
            string strLoc = Assembly.GetExecutingAssembly().Location;
            FileSystemInfo fileInfo = new FileInfo(strLoc);
            string sExeName = fileInfo.Name;
            bool bCreatedNew;

            Mutex mutex = new Mutex(true, "Global\\"+sExeName, out bCreatedNew);
            if (bCreatedNew)
                mutex.ReleaseMutex();

            return !bCreatedNew;
        }

Answer 3

For my WPF application i've defined global app id and use semaphore to handle it.

public partial class App : Application
{      
    private const string AppId = "c1d3cdb1-51ad-4c3a-bdb2-686f7dd10155";

    //Passing name associates this sempahore system wide with this name
    private readonly Semaphore instancesAllowed = new Semaphore(1, 1, AppId);

    private bool WasRunning { set; get; }

    private void OnExit(object sender, ExitEventArgs e)
    {
        //Decrement the count if app was running
        if (this.WasRunning)
        {
            this.instancesAllowed.Release();
        }
    }

    private void OnStartup(object sender, StartupEventArgs e)
    {
        //See if application is already running on the system
        if (this.instancesAllowed.WaitOne(1000))
        {
            new MainWindow().Show();
            this.WasRunning = true;
            return;
        }

        //Display
        MessageBox.Show("An instance is already running");

        //Exit out otherwise
        this.Shutdown();
    }
}

Answer 4

Checkout: What is a good pattern for using a Global Mutex in C#?

// unique id for global mutex - Global prefix means it is global to the machine
const string mutex_id = "Global\\{B1E7934A-F688-417f-8FCB-65C3985E9E27}";

static void Main(string[] args)
{
    using (var mutex = new Mutex(false, mutex_id))
    {
        // edited by Jeremy Wiebe to add example of setting up security for multi-user usage
        // edited by 'Marc' to work also on localized systems (don't use just "Everyone") 
        var allowEveryoneRule = new MutexAccessRule(new SecurityIdentifier(WellKnownSidType.WorldSid, null), MutexRights.FullControl, AccessControlType.Allow);
        var securitySettings = new MutexSecurity();
        securitySettings.AddAccessRule(allowEveryoneRule);
        mutex.SetAccessControl(securitySettings);

        //edited by acidzombie24
        var hasHandle = false;
        try
        {
            try
            {
                // note, you may want to time out here instead of waiting forever
                //edited by acidzombie24
                //mutex.WaitOne(Timeout.Infinite, false);
                hasHandle = mutex.WaitOne(5000, false);
                if (hasHandle == false) return;//another instance exist
            }
            catch (AbandonedMutexException)
            {
                // Log the fact the mutex was abandoned in another process, it will still get aquired
            }

            // Perform your work here.
        }
        finally
        {
            //edit by acidzombie24, added if statemnet
            if (hasHandle)
                mutex.ReleaseMutex();
        }
    }
}

Answer 5

you need a way to say that "i am running" from the app,

1) open a WCF ping service 2) write to registry/file on startup and delete on shutdown 3) create a Mutex

... i prefer the WCF part because you may not clean up file/registry correctly and Mutex seems to have its own issues

Answer 6

Mutex and Semaphore didn't work in my case (I tried them as suggested, but it didn't do the trick in the application I developed). The answer abramlimpin provided worked for me, after I made a slight modification.

This is how I got it working finally. First, I created some helper functions:

public static class Ext
{
   private static string AssemblyFileName(this Assembly myAssembly)
    {
        string strLoc = myAssembly.Location;
        FileSystemInfo fileInfo = new FileInfo(strLoc);
        string sExeName = fileInfo.Name;
        return sExeName;
    }

    private static int HowManyTimesIsProcessRunning(string name)
    {
        int count = 0;
        name = name.ToLowerInvariant().Trim().Replace(".exe", "");
        foreach (Process clsProcess in Process.GetProcesses())
        {
            var processName = clsProcess.ProcessName.ToLowerInvariant().Trim();
            // System.Diagnostics.Debug.WriteLine(processName);
            if (processName.Contains(name))
            {
                count++;
            };
        };
        return count;
    }

    public static int HowManyTimesIsAssemblyRunning(this Assembly myAssembly)
    {
        var fileName = AssemblyFileName(myAssembly);
        return HowManyTimesIsProcessRunning(fileName);
    }
}

Then, I added the following to the main method:

[STAThread]
static void Main()
{
    const string appName = "Name of your app";

    // Check number of instances running:
    // If more than 1 instance, cancel this one.
    // Additionally, if it is the 2nd invocation, show a message and exit.
    var numberOfAppInstances = Assembly.GetExecutingAssembly().HowManyTimesIsAssemblyRunning();
    if (numberOfAppInstances == 2)
    {
       MessageBox.Show("The application is already running!
        +"\nClick OK to close this dialog, then switch to the application by using WIN + TAB keys.",
        appName, MessageBoxButtons.OK, MessageBoxIcon.Warning);
    };
    if (numberOfAppInstances >= 2)
    {
        return;
    };
}

If you invoke the application a 3rd, 4th ... time, it does not show the warning any more and just exits immediately.

Answer 7

I really simplistic way I guess would be, for every exe that is running, you could create/open a file on disk in a known location (c:\temp) with a special name "yourapp.lock" and then just count how many of those there are.

A harder way, would be to open up some inter-process communication, or sockets, so with the process list you could interrogate each process to see if it was your application.

Answer 8

Enter a guid in your assembly data. Add this guid to the registry. Enter a reg key where the application read it's own name and add the name as value there.

The other task watcher read the reg key and knows the app name.

Answer 9

you can simply use varialbles and one file to check for running your program. when open the file contain a value and when program closes changes this value to another one.