How to check if another instance of the application is running [duplicate]

Answer 1

You can try this

Process[] processes = Process.GetProcessesByName("processname");
foreach (Process p in processes)
{
    IntPtr pFoundWindow = p.MainWindowHandle;
    // Do something with the handle...
    //
}

Answer 2

It's not sure what you mean with 'the program', but if you want to limit your application to one instance then you can use a Mutex to make sure that your application isn't already running.

[STAThread]
static void Main()
{
    Mutex mutex = new System.Threading.Mutex(false, "MyUniqueMutexName");
    try
    {
        if (mutex.WaitOne(0, false))
        {
            // Run the application
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new MainForm());
        }
        else
        {
            MessageBox.Show("An instance of the application is already running.");
        }
    }
    finally
    {
        if (mutex != null)
        {
            mutex.Close();
            mutex = null;
        }
    }
}

Answer 3

Want some serious code? Here it is.

var exists = System.Diagnostics.Process.GetProcessesByName(System.IO.Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetEntryAssembly().Location)).Count() > 1;

This works for any application (any name) and will become true if there is another instance running of the same application.

Edit: To fix your needs you can use either of these:

if (System.Diagnostics.Process.GetProcessesByName(System.IO.Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetEntryAssembly().Location)).Count() > 1) return;

from your Main method to quit the method... OR

if (System.Diagnostics.Process.GetProcessesByName(System.IO.Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetEntryAssembly().Location)).Count() > 1) System.Diagnostics.Process.GetCurrentProcess().Kill();

which will kill the currently loading process instantly.

---

You need to add a reference to System.Core.dll for the .Count() extension method. Alternatively, you can use the .Length property.

Answer 4

Here are some good sample applications. Below is one possible way.

public static Process RunningInstance() 
{ 
    Process current = Process.GetCurrentProcess(); 
    Process[] processes = Process.GetProcessesByName (current.ProcessName); 

    //Loop through the running processes in with the same name 
    foreach (Process process in processes) 
    { 
        //Ignore the current process 
        if (process.Id != current.Id) 
        { 
            //Make sure that the process is running from the exe file. 
            if (Assembly.GetExecutingAssembly().Location.
                 Replace("/", "\\") == current.MainModule.FileName) 

            {  
                //Return the other process instance.  
                return process; 

            }  
        }  
    } 
    //No other instance was found, return null.  
    return null;  
}


if (MainForm.RunningInstance() != null)
{
    MessageBox.Show("Duplicate Instance");
    //TODO:
    //Your application logic for duplicate 
    //instances would go here.
}

Many other possible ways. See the examples for alternatives.

First one.

Second One.

Third One

EDIT 1: Just saw your comment that you have got a console application. That is discussed in the second sample.

Answer 5

The Process static class has a method GetProcessesByName() which you can use to search through running processes. Just search for any other process with the same executable name.