How to programmatically restart windows explorer process

Question

I'm working on a windows shell extension, and unfortunately, when making changes to the DLL, I must restart windows explorer (since it keeps the DLL in memory).

I found this program from Dino Esposito, but it doesn't work for me.

void SHShellRestart(void)
{
    HWND hwnd;
    hwnd = FindWindow("Progman", NULL );
    PostMessage(hwnd, WM_QUIT, 0, 0 );
    ShellExecute(NULL, NULL, "explorer.exe", NULL, NULL, SW_SHOW );
    return;
}

Does any one have something they can share to do this?

P.S. I realize that I can go to task manager and kill the explorer process, but I just want to do it the lazy way. Besides, this enables automation.

P.P.S I am using .NET for the development, but the shell restart functionality could be in C, C++ or a .NET language. It will simply be a small stand-alone executable.

Answer 1

A fool-proof solution:

foreach (Process p in Process.GetProcesses())
{
    // In case we get Access Denied
    try
    {
        if (p.MainModule.FileName.ToLower().EndsWith(":\\windows\\explorer.exe"))
        {
            p.Kill();
            break;
        }
    }
    catch
    { }
}
Process.Start("explorer.exe");

Answer 2

After parsing some of the earlier answers and doing a bit of research, I've created a little complete example in C#. This closes the explorer shell then waits for it to completely shut down and restarts it. Hope this helps, there's a lot of interesting info in this thread.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Threading;

namespace RestartExplorer
{
class Program
{
    [DllImport("user32.dll", SetLastError = true)]
    static extern bool PostMessage(IntPtr hWnd, [MarshalAs(UnmanagedType.U4)] uint Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", SetLastError = true)]
    static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

    const int WM_USER = 0x0400; //http://msdn.microsoft.com/en-us/library/windows/desktop/ms644931(v=vs.85).aspx

    static void Main(string[] args)
    {
        try
        {
            var ptr = FindWindow("Shell_TrayWnd", null);
            Console.WriteLine("INIT PTR: {0}", ptr.ToInt32());
            PostMessage(ptr, WM_USER + 436, (IntPtr)0, (IntPtr)0);

            do
            {
                ptr = FindWindow("Shell_TrayWnd", null);
                Console.WriteLine("PTR: {0}", ptr.ToInt32());

                if (ptr.ToInt32() == 0)
                {
                    Console.WriteLine("Success. Breaking out of loop.");
                    break;
                }

                Thread.Sleep(1000);
            } while (true);
        }
        catch (Exception ex)
        {
            Console.WriteLine("{0} {1}", ex.Message, ex.StackTrace);
        }
        Console.WriteLine("Restarting the shell.");
        string explorer = string.Format("{0}\\{1}", Environment.GetEnvironmentVariable("WINDIR"), "explorer.exe");
        Process process = new Process();           
        process.StartInfo.FileName = explorer;
        process.StartInfo.UseShellExecute = true;
        process.Start();

        Console.ReadLine();

    }
}
}

Answer 3

I noticed no one addressed the issue of starting explorer.exe as the shell, rather than it just opening an explorer window. Took me a while to figure this out, turns out it was something simple:

string explorer = string.Format("{0}\\{1}", Environment.GetEnvironmentVariable("WINDIR"), "explorer.exe");
        Process process = new Process();
        process.StartInfo.FileName = explorer;
        process.StartInfo.UseShellExecute = true;
        process.Start();

You have to set the StartInfo.UseshellExecute as true to get it to restart as the shell.

Answer 4

After FindWindow use GetWindowThreadProcessId, then OpenProcess, then TerminateProcess.

Answer 5

After some more googling, I came up with the following C# solution:

using System.Diagnostics;
...
static public void RestartExplorer()
{
    foreach(Process p in Process.GetProcesses())  {
       if(p.MainModule.ModuleName.contains("explorer") == true)
         p.Kill();
    }
    Process.Start("explorer.exe");
}

Answer 6

This works for me on Vista:

DWORD dwPID;
HANDLE hExp;
HWND hSysTray = ::FindWindow (TEXT("Shell_TrayWnd"), NULL) ;
GetWindowThreadProcessId (hSysTray, &dwPID);
hExp = OpenProcess (PROCESS_TERMINATE, FALSE, dwPID);

if (hExp)
{
   TerminateProcess (hExp, 0);
}
Sleep (2000);
ShellExecute (NULL, NULL, TEXT("explorer.exe"), NULL, NULL, SW_HIDE);

But I can't find any way to suppress the explore window that opens (I tried, hence the SW_HIDE). On Vista, running explorer.exe without parameters seems to be the same as running "explorer.exe /e" on earlier systems. You'll have to try it for yourself on XP, I don't have it here.

Note: Using TerminateProcess does seem extreme, but posting a WM_CLOSE to explorer provokes a windows shutdown dialog.

Answer 7

This is for Windows 7/8 (and need testing, maybe even works on Vista).

Since there is a proper way to close Explorer (progman) included in Windows 7 & 8 - by right clicking the taskbar (Shell_TrayWnd in Win8 or StartMenu on Win7) while pressing Ctrl-Shift, it shows in the popup menu a hidden option to close Explorer, and digging it using Spy++ it is triggered by message WM_USER+436.

So I tested and doing the following it works great.

PostMessage(FindWindow('Shell_TrayWnd'),nil),WM_USER+436,0,0);

It closes Explorer, with all the opened instances. And to relaunch explorer, use the methods provided above.

So, please confirm in comments if this works on 32bit/64bit editions of your windows vista/7/8 or any other.

Answer 8

A C# solution that provides more certainty that the "right" explorer processes get killed.

using System;
using System.Diagnostics;

...............

public static void RestartExplorer()
 {
 const string explorer = "explorer.exe";
 string explorerPath = string.Format("{0}\\{1}", Environment.GetEnvironmentVariable("WINDIR"), explorer);
 foreach (Process process in Process.GetProcesses())
  {
  // In case we get Access Denied
  try
   {
   if (string.Compare(process.MainModule.FileName, explorerPath, StringComparison.OrdinalIgnoreCase) == 0)
    {
    process.Kill();
    }
   }
  catch
   {
   }
  }
 Process.Start(explorer);
 }