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How can you ensure an executable is opened via another executable?

There's a neat little trick that you can use to never have the OS hold a lock on the .dll's / .exe's an .exe needs to run.
Let's say our directory looks like this:
>opener.exe
>actualProgram.exe
>dependency.dll
As a basic example, we could do this:
namespace Opener
{
class Program
{
static void Main(string[] args)
{
AppDomain domain = AppDomain.CurrentDomain;
AppDomain newDomain = AppDomain.CreateDomain(
domain.FriendlyName,
domain.Evidence,
domain.BaseDirectory,
domain.RelativeSearchPath,
true, // "shadow copy" files: copy rather than lock
domain.SetupInformation.AppDomainInitializer,
domain.SetupInformation.AppDomainInitializerArguments
);
string assembly =
System.Reflection.Assembly.GetExecutingAssembly().Location
+ "\\..\\actualProgram.exe";
newDomain.ExecuteAssembly(assembly, args);
}
}
}
We could also put more logic in there, which we could use to actually replace/update actualProgram.exe despite an instance of the process being opened. Try it: you'll be able to delete/modify/replace dependencies and the "actual" program when it's loaded via the "opener". Obviously this has its benefits, namely making updates a lot easier.
But in your "actual.exe", how can you be sure that it was loaded via another executable, and know that it was loaded without having a lock taken on the .exe? If someone is to just load the "actual.exe", i.e. not via the "opener", I want to make sure that the process immediately exits.
Hints?

Pass a command line parameter to actualProgram.exe that lets it know it was launched by the launcher. (Also suggested in a comment on the OP by oleksii)
Set an environment variable in the launcher that can be inherited by the child process.
Use one of the documented methods for getting the parent process id, and use that to get information about the launching process. (Of course if the parent process terminates, Windows is free to re-assign the PID to a new process.)
Create a memory-mapped file/named pipe/etc. in the launcher that can be used to pass information to the child.
Manually load and unload the library references in the child. If they are .Net assemblies, you can use the AssemblyResolve event, loading the file from disk into a byte array and using the Assembly.Load(byte[], byte[]) overload.
Note: As long as all of your assemblies are loaded manually or by the runtime before you modify/move/delete them, you're probably ok. Also, changing the DLL after it's been loaded will probably have no effect on the running process. I say probably in both cases, because it's generally a good idea to leave the libraries alone at runtime, especially if you aren't loading them manually.
See Also:
Run-Time Dynamic Linking # MSDN
How can a Win32 process get the pid of its parent?
Assembly.Load Method (Byte[], Byte[])

How about sending a custom message to the application after it is launched? The code to launch would be something like this:
private void LaunchApplication()
{
ProcessStartInfo start = new ProcessStartInfo();
//you could pass in arguments here if you wanted
start.Arguments = string.Empty;
//your EXE name
start.FileName = #"c:\your_program.exe";
start.WindowStyle = ProcessWindowStyle.Normal;
start.CreateNoWindow = true;
Process p = Process.Start(start);
while (0 == (int)p.MainWindowHandle)
{
System.Threading.Thread.Sleep(100);
}
processHandle = p.MainWindowHandle;
label1.Text = processHandle.ToString();
//the launched program will receive this message as a signal that it can continue
SendNotifyMessage(processHandle, 99999, UIntPtr.Zero, IntPtr.Zero);
}
and the application you are running would need a short custom windows message handler to watch out for the "stay-alive" signal.
private bool allowedToLive = false;
//how long will we wait for the signal? should arrive in < 1 second
private int TimeoutSeconds = 1;
private DateTime appStartTime = DateTime.Now;
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
//receiving the special message means we are allowed to live.
if(!allowedToLive)
{
allowedToLive = (m.Msg == 99999);
if (!allowedToLive && (TimeoutSeconds <= DateTime.Now.Subtract(appStartTime).Seconds))
{
//times up. quit.
Application.Exit();
}
}
}
If you don't want to rely on the timing of windows messages, you could alter your target program to launch, but not actually begin doing anything until it receives the custom message.

Why does closing a console that was started with AllocConsole cause my whole application to exit? Can I change this behavior?

What I want to have happen is that the console window just goes away, or better yet that it is hidden, but I want my application to keep running. Is that possible? I want to be able to use Console.WriteLine and have the console serve as an output window. I want to be able to hide and show it, and I don't want the whole app to die just because the console was closed.
EDIT
Code:
internal class SomeClass {
[DllImport("kernel32")]
private static extern bool AllocConsole();
private static void Main() {
AllocConsole();
while(true) continue;
}
}
EDIT 2
I tried the accepted solution here [ Capture console exit C# ], per the suggestion in the comments on this question. The example code is bugged in that the DLLImport needs to be "kernel32.dll" or "kernel32", not "Kernel32". After making that change, I'm getting a message to my handler for CTRL_CLOSE_EVENT when I click the X on the console window. However, calling FreeConsole and/or returning true doesn't prevent the application from terminating.

Ah, yes, this is one of the caveats of using the Windows console subsystem. When the user closes the console window (regardless of how the console was allocated), all of the processes that are attached to the console are terminated. That behavior makes obvious sense for console applications (i.e., those that specifically target the console subsystem, as opposed to standard Windows applications), but it can be a major pain in cases like yours.
The only workaround that I know of is to use the SetConsoleCtrlHandler function, which allows you to register a handler function for Ctrl+C and Ctrl+Break signals, as well as system events like the user closing the console window, the user logging off, or the system shutting down. The documentation says that if you're only interested in ignoring these events, you can pass null for the first argument. For example:
[DllImport("kernel32")]
static extern bool SetConsoleCtrlHandler(HandlerRoutine HandlerRoutine, bool Add);
delegate bool HandlerRoutine(uint dwControlType);
static void Main()
{
AllocConsole();
SetConsoleCtrlHandler(null, true);
while (true) continue;
}
That works perfectly for Ctrl+C and Ctrl+Break signals (which would have otherwise caused your application to terminate as well), but it doesn't work for the one you're asking about, which is the CTRL_CLOSE_EVENT, generated by the system when the user closes the console window.
Honestly, I don't know how to prevent that. Even the sample in the SDK doesn't actually allow you to ignore the CTRL_CLOSE_EVENT. I tried it in a little test app, and it beeps when you close the window and prints the message, but the process still gets terminated.
Perhaps more worryingly, the documentation makes me think it is not possible to prevent this:
The system generates CTRL_CLOSE_EVENT, CTRL_LOGOFF_EVENT, and CTRL_SHUTDOWN_EVENT signals when the user closes the console, logs off, or shuts down the system so that the process has an opportunity to clean up before termination. Console functions, or any C run-time functions that call console functions, may not work reliably during processing of any of the three signals mentioned previously. The reason is that some or all of the internal console cleanup routines may have been called before executing the process signal handler.
It's that last sentence that catches my eye. If the console subsystem starts cleaning up after itself immediately in response to the user attempting to close the window, it may not be possible to halt it after the fact.
(At least now you understand the problem. Maybe someone else can come along with a solution!)

Unfortunately there's nothing you can do to really alter this behaviour.
Console windows are "special" in that they're hosted by another process and do not allow sub-classing. This limits your ability to modify their behaviour.
From what I know, your two options are:
1. Disable the close button altogether. You can do this with the following code fragment:
HWND hwnd = ::GetConsoleWindow();
if (hwnd != NULL)
{
HMENU hMenu = ::GetSystemMenu(hwnd, FALSE);
if (hMenu != NULL) DeleteMenu(hMenu, SC_CLOSE, MF_BYCOMMAND);
}
2. Stop using consoles altogether, and implement your own text output solution.
Option #2 is the more complicated option but would provide you the greatest control. I found an article on CodeProject that implements a console-like application using a rich edit control to display the text (rich edit controls have the ability to stream text like the console, so they are well suited to this sort of application).

On closing the console window obtained using AllocConsole or AttachConsole, the associated process will exit. There is no escape from that.
Prior to Windows Vista, closing the console window would present a confirmation dialogue to the user asking him whether the process should be terminated or not but Windows Vista and later do not provide any such dialogue and the process gets terminated.
One possible solution to work around this is avoiding AttachConsole altogether and achieving the desired functionality through other means.
For instance in the case described by OP, console window was needed to output some text on Console using Console static class.
This can be achieved very easily using inter-process communication. For example a console application can be developed to act as an echo server
namespace EchoServer
{
public class PipeServer
{
public static void Main()
{
var pipeServer = new NamedPipeServerStream(#"Com.MyDomain.EchoServer.PipeServer", PipeDirection.In);
pipeServer.WaitForConnection();
StreamReader reader = new StreamReader(pipeServer);
try
{
int i = 0;
while (i >= 0)
{
i = reader.Read();
if (i >= 0)
{
Console.Write(Convert.ToChar(i));
}
}
}
catch (IOException)
{
//error handling code here
}
finally
{
pipeServer.Close();
}
}
}
}
and then instead of allocating/attaching a console to the current application, the echo server can be started from within the application and Console's output stream can be redirected to write to the pipe server.
class Program
{
private static NamedPipeClientStream _pipeClient;
static void Main(string[] args)
{
//Current application is a Win32 application without any console window
var processStartInfo = new ProcessStartInfo("echoserver.exe");
Process serverProcess = new Process {StartInfo = processStartInfo};
serverProcess.Start();
_pipeClient = new NamedPipeClientStream(".", #"Com.MyDomain.EchoServer.PipeServer", PipeDirection.Out, PipeOptions.None);
_pipeClient.Connect();
StreamWriter writer = new StreamWriter(_pipeClient) {AutoFlush = true};
Console.SetOut(writer);
Console.WriteLine("Testing");
//Do rest of the work.
//Also detect that the server has terminated (serverProcess.HasExited) and then close the _pipeClient
//Also remember to terminate the server process when current process exits, serverProcess.Kill();
while (true)
continue;
}
}
This is just one of the possible solutions. In essence the work around is to allot the console window to its own process so that it can terminate without affecting the parent process.

You can do this by disabling keyboard mouse input by external program called Keyfreez.
you can use it multiple times in your program where no user input required. And if any user input require u can add a process Takskkill /f /IM .
https://www.sordum.org/7921/bluelife-keyfreeze-v1-4-block-keyboard-and-mouse/
Hope this helps all of you

Process.Start() and continue with my code

My program is in win forms (c#). It should open an external program, do a printscreen of it's main window, and close it.
By using Process.Start() I can open the the program, but then all the focus is on it and my code is halted. Only when I close it myself my form continues- but it's too late for the screenshot.
So how do I force my code to keep running?
public void Runttk(string maromnum)
{
Process runttk = new Process();
runttk.StartInfo.UseShellExecute = true;
runttk.StartInfo.FileName = #"C:\\program.exe";
runttk.StartInfo.WindowStyle = ProcessWindowStyle.Normal;
runttk.Start();
this.Focus();
try
{
if (runttk.WaitForInputIdle()==true)
{
PringJpg(maromnum);
Killttk();
}
}
catch (Exception e)
{
}
}
Thank you
UPDATE:
eventuanlly I've used Thread.Sleep(3000). Crued but do the trick.
I didn't used backgroundworker because the sync between the finale uplaod the the extenral program and my code wasn't clear enough.

Trying your code, but with another program like notepad.exe, Notepad runs and then control drops through to where you call PringJpg.
So I think the problem is that it is blocking on if (runttk.WaitForInputIdle()==true), please try adding a timeout to this operation.

Maybe your programm is never idle - means that runttk.WaitForInputIdle()==true let your app wait until you close it.
Add a limit ( for example runttk.WaitForInputIdle(500)==true) should fulfill your needings.

Restarting current process C#

I have an app that has some installer inside I want to reload everything associated to the app therefor I want to restart the process. I've searched and saw the Application.Restart() and it's drawbacks and wondered what's the best way to do what I need - closing the process and restarting it. or if there's any better way to reinitialize all objects.

I would start a new instance and then exit the current one:
private void Restart()
{
Process.Start(Application.ExecutablePath);
//some time to start the new instance.
Thread.Sleep(2000);
Environment.Exit(-1);//Force termination of the current process.
}
private static void Main()
{
//wait because we maybe here becuase of the system is restarted so give it some time to clear the old instance first
Thread.Sleep(5000);
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(...
}
Edit: However you should also consider adding some sort of mutex to allow only one instance of the application to run at time, Like:
private const string OneInstanceMutexName = #"Global\MyUniqueName";
private static void Main()
{
Thread.Sleep(5000);
bool firstInstance = false;
using (System.Threading.Mutex _oneInstanceMutex = new System.Threading.Mutex(true, OneInstanceMutexName, out firstInstance))
{
if (firstInstance)
{
//....
}
}
}

In my WPF application (single instance by a mutex), I use Process.Start with a ProcessStartInfo, which send a timed cmd command to restart the app:
ProcessStartInfo Info = new ProcessStartInfo();
Info.Arguments = "/C ping 127.0.0.1 -n 2 && \"" + Application.GetCurrentProcess()+ "\"";
Info.WindowStyle = ProcessWindowStyle.Hidden;
Info.CreateNoWindow = true;
Info.FileName = "cmd.exe";
Process.Start(Info);
ShellView.Close();
The command is sent to the OS, the ping pauses the script for 2-3 seconds, by which time the application has exited from ShellView.Close(), then the next command after the ping starts it again.
Note: The \" puts quotes around the path, incase it has spaces, which cmd can't process without quotes.
(My code references this answer)

I think starting a new process and closing the existing process is the best way. In this way you have the ability to set some application state for the existing process in between starting and closing processes.
This thread discusses why Application.Restart() may not work in some cases.
System.Diagnostics.Process.Start(Application.ResourceAssembly.Location);
// Set any state that is required to close your current process.
Application.Current.Shutdown();
Or
System.Diagnostics.Process.Start(Application.ExecutablePath);
// Set any state that is required to close your current process.
Application.Exit();

How do I restart my C# WinForm Application?

Developing a C# .NET 2.0 WinForm Application. Need the application to close and restart itself.
Application.Restart();
The above method has proven to be unreliable.
What is a better way to restart the application?

A much simpler approach that worked for me is:
Application.Restart();
Environment.Exit(0);
This preserves the command-line arguments and works despite event handlers that would normally prevent the application from closing.
The Restart() call tries to exit, starts a new instance anyway and returns. The Exit() call then terminates the process without giving any event handlers a chance to run. There is a very brief period in which both processes are running, which is not a problem in my case, but maybe in other cases.
The exit code 0 in Environment.Exit(0); specifies a clean shutdown. You can also exit with 1 to specify an error occurred.

If you are in main app form try to use
System.Diagnostics.Process.Start( Application.ExecutablePath); // to start new instance of application
this.Close(); //to turn off current app

Unfortunately you can't use Process.Start() to start an instance of the currently running process. According to the Process.Start() docs:
"If the process is already running, no additional process resource is started..."
This technique will work fine under the VS debugger (because VS does some kind of magic that causes Process.Start to think the process is not already running), but will fail when not run under the debugger. (Note that this may be OS-specific - I seem to remember that in some of my testing, it worked on either XP or Vista, but I may just be remembering running it under the debugger.)
This technique is exactly the one used by the last programmer on the project on which I'm currently working, and I've been trying to find a workaround for this for quite some time. So far, I've only found one solution, and it just feels dirty and kludgy to me: start a 2nd application, that waits in the background for the first application to terminate, then re-launches the 1st application. I'm sure it would work, but, yuck.
Edit: Using a 2nd application works. All I did in the second app was:
static void RestartApp(int pid, string applicationName )
{
// Wait for the process to terminate
Process process = null;
try
{
process = Process.GetProcessById(pid);
process.WaitForExit(1000);
}
catch (ArgumentException ex)
{
// ArgumentException to indicate that the
// process doesn't exist? LAME!!
}
Process.Start(applicationName, "");
}
(This is a very simplified example. The real code has lots of sanity checking, error handling, etc)

I might be late to the party but here is my simple solution and it works like a charm with every application I have:
try
{
//run the program again and close this one
Process.Start(Application.StartupPath + "\\blabla.exe");
//or you can use Application.ExecutablePath
//close this one
Process.GetCurrentProcess().Kill();
}
catch
{ }

I had the same exact problem and I too had a requirement to prevent duplicate instances - I propose an alternative solution to the one HiredMind is proposing (which will work fine).
What I am doing is starting the new process with the processId of the old process (the one that triggers the restart) as a cmd line argument:
// Shut down the current app instance.
Application.Exit();
// Restart the app passing "/restart [processId]" as cmd line args
Process.Start(Application.ExecutablePath, "/restart" + Process.GetCurrentProcess().Id);
Then when the new app starts I first parse the cm line args and check if the restart flag is there with a processId, then wait for that process to Exit:
if (_isRestart)
{
try
{
// get old process and wait UP TO 5 secs then give up!
Process oldProcess = Process.GetProcessById(_restartProcessId);
oldProcess.WaitForExit(5000);
}
catch (Exception ex)
{
// the process did not exist - probably already closed!
//TODO: --> LOG
}
}
I am obviously not showing all the safety checks that I have in place etc.
Even if not ideal - I find this a valid alternative so that you don't have to have in place a separate app just to handle restart.

Start/Exit Method
// Get the parameters/arguments passed to program if any
string arguments = string.Empty;
string[] args = Environment.GetCommandLineArgs();
for (int i = 1; i < args.Length; i++) // args[0] is always exe path/filename
arguments += args[i] + " ";
// Restart current application, with same arguments/parameters
Application.Exit();
System.Diagnostics.Process.Start(Application.ExecutablePath, arguments);
This seems to work better than Application.Restart();
Not sure how this handles if your program protects against multiple instance. My guess is you would be better off launching a second .exe which pauses and then starts your main application for you.

It's simple, you just need to call the Application.Restart() method, this will invoke your application to be restarted. You must also exit from the local environment with an error code:
Application.Restart();
Environment.Exit(int errorcode);
You can create an enumeration of error codes so that you application will exit efficeintly.
Another method is to just exit from the application and start the process using the executable path:
Application.Exit();
System.Diagnostics.Process.Start(Application.ExecutablePath);

Try this code:
bool appNotRestarted = true;
This code must also be in the function:
if (appNotRestarted == true) {
appNotRestarted = false;
Application.Restart();
Application.ExitThread();
}

I figured an another solution out, perhaps anyone can use it, too.
string batchContent = "/c \"#ECHO OFF & timeout /t 6 > nul & start \"\" \"$[APPPATH]$\" & exit\"";
batchContent = batchContent.Replace("$[APPPATH]$", Application.ExecutablePath);
Process.Start("cmd", batchContent);
Application.Exit();
Code is simplified so take care of Exceptions and stuff ;)

I fear that restarting the entire application using Process is approaching your problem in the wrong way.
An easier way is to modify the Program.cs file to restart:
static bool restart = true; // A variable that is accessible from program
static int restartCount = 0; // Count the number of restarts
static int maxRestarts = 3; // Maximum restarts before quitting the program
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
while (restart && restartCount < maxRestarts)
{
restart = false; // if you like.. the program can set it to true again
restartCount++; // mark another restart,
// if you want to limit the number of restarts
// this is useful if your program is crashing on
// startup and cannot close normally as it will avoid
// a potential infinite loop
try {
Application.Run(new YourMainForm());
}
catch { // Application has crashed
restart = true;
}
}
}

You are forgetting the command-line options/parameters that were passed in to your currently running instance. If you don't pass those in, you are not doing a real restart. Set the Process.StartInfo with a clone of your process' parameters, then do a start.
For example, if your process was started as myexe -f -nosplash myfile.txt, your method would only execute myexe without all those flags and parameters.

I wanted the new application start up after the old one shuts down.
Using process.WaitForExit() to wait for your own process to shutdown makes no sense. It will always time out.
So, my approach is to use Application.Exit() then wait, but allow events to be processed, for a period of time. Then start a new application with the same arguments as the old.
static void restartApp() {
string commandLineArgs = getCommandLineArgs();
string exePath = Application.ExecutablePath;
try {
Application.Exit();
wait_allowingEvents( 1000 );
} catch( ArgumentException ex ) {
throw;
}
Process.Start( exePath, commandLineArgs );
}
static string getCommandLineArgs() {
Queue<string> args = new Queue<string>( Environment.GetCommandLineArgs() );
args.Dequeue(); // args[0] is always exe path/filename
return string.Join( " ", args.ToArray() );
}
static void wait_allowingEvents( int durationMS ) {
DateTime start = DateTime.Now;
do {
Application.DoEvents();
} while( start.Subtract( DateTime.Now ).TotalMilliseconds > durationMS );
}

You could also use Restarter.
Restarter is an application that automatically monitor and restarts crashed or hung programs and applications. It was originally developed to monitor and restart game servers, but it will do the job for any console or form based program or application

public static void appReloader()
{
//Start a new instance of the current program
Process.Start(Application.ExecutablePath);
//close the current application process
Process.GetCurrentProcess().Kill();
}
Application.ExecutablePath returns your aplication .exe file path
Please follow the order of calls. You might want to place it in a try-catch clause.

The problem of using Application.Restart() is, that it starts a new process but the "old" one is still remaining. Therefor I decided to Kill the old process by using the following code snippet:
if(Condition){
Application.Restart();
Process.GetCurrentProcess().Kill();
}
And it works proper good. In my case MATLAB and a C# Application are sharing the same SQLite database. If MATLAB is using the database, the Form-App should restart (+Countdown) again, until MATLAB reset its busy bit in the database. (Just for side information)

How about create a bat file, run the batch file before closing, and then close the current instance.
The batch file does this:
wait in a loop to check whether the process has exited.
start the process.

Here's my 2 cents:
The sequence Start New Instance->Close Current Instance should work even for the applications that don't allow running multiple copies simultaneously as in this case the new instance may be passed a command-line argument which will indicate that there is a restart in progress so checking for other instances running will not be necessary. Waiting for the first instance to actually finish my be implemented too if it's absolutely imperative that no two intstances are running in parallel.

Application.Restart();
Environment.Exit(0);

I had a similar problem, but mine was related to unmanageable memory leak that I couldn't find on an app that has to run 24/7. With the customer I agreed that safe time to restart the app was 03:00AM if the memory consumption was over the defined value.
I tried Application.Restart, but since it seems to use some mechanism that starts new instance while it is already running, I went for another scheme. I used the trick that file system handles persist until process that created them dies. So, from The Application, i dropped the file to the disk, and didn't Dispose() the handle. I used the file to send 'myself' executable and starting directory also (to add flexibility).
Code:
_restartInProgress = true;
string dropFilename = Path.Combine(Application.StartupPath, "restart.dat");
StreamWriter sw = new StreamWriter(new FileStream(dropFilename, FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite));
sw.WriteLine(Application.ExecutablePath);
sw.WriteLine(Application.StartupPath);
sw.Flush();
Process.Start(new ProcessStartInfo
{
FileName = Path.Combine(Application.StartupPath, "VideoPhill.Restarter.exe"),
WorkingDirectory = Application.StartupPath,
Arguments = string.Format("\"{0}\"", dropFilename)
});
Close();
Close() at the end would initiate app shutdown, and file handle I used for StreamWriter here would be held open until process really dies. Then...
Restarter.exe comes into action. It TRIES to read the file in exclusive mode, preventing it to gain access until main app wasn't dead, then starts main app, deletes the file and exists. I guess that it can't be simpler:
static void Main(string[] args)
{
string filename = args[0];
DateTime start = DateTime.Now;
bool done = false;
while ((DateTime.Now - start).TotalSeconds < 30 && !done)
{
try
{
StreamReader sr = new StreamReader(new FileStream(filename, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite));
string[] runData = new string[2];
runData[0] = sr.ReadLine();
runData[1] = sr.ReadLine();
Thread.Sleep(1000);
Process.Start(new ProcessStartInfo { FileName = runData[0], WorkingDirectory = runData[1] });
sr.Dispose();
File.Delete(filename);
done = true;
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
Thread.Sleep(1000);
}
}

I use the following and it does exactly what you are looking for:
ApplicationDeployment ad = ApplicationDeployment.CurrentDeployment;
UpdateCheckInfo info = null;
info = ad.CheckForDetailedUpdate();
if (info.IsUpdateRequired)
{
ad.UpdateAsync(); // I like the update dialog
MessageBox.Show("Application was upgraded and will now restart.");
Environment.Exit(0);
}

for using As logout you need to terminate all app from Ram Cache
so close The Application first and then Rerun it
//on clicking Logout Button
foreach(Form frm in Application.OpenForms.Cast<Form>().ToList())
{
frm.Close();
}
System.Diagnostics.Process.Start(Application.ExecutablePath);

You could enclose your code inside a function and when restart is needed you can just call the function.

Take for instance an application that:
While application is not registered; (upon start) the application should prompt the user to register the application and create a login account.
Once registration is submitted and login credentials are created; the application should restart, check for registration and prompt the user to login with the inserted credentials (so the user can access to all the application features).
Problem:
By building and launching the application from Visual Studio; any of the 4 alternatives bellow will fail to accomplish the tasks required.
/*
* Note(s):
* Take into consideration that the lines bellow don't represent a code block.
* They are just a representation of possibilities,
* that can be used to restart the application.
*/
Application.Restart();
Application.Exit();
Environment.Exit(int errorCode);
Process.GetCurrentProcess().Kill();
What happens is: After creating the Registration, Login and calling Application.Restart(); the application will (strangely) reopen the Registration Form and skip data in a Database (even though the resource is set to "Copy if Newer").
Solution:
Batch Building the application was (for me) a proof that any of the lines above were actually working as expected.
Just not when building and running the application with Visual Studio.
In first place I'd try batch building the application; run it outside Visual Studio and check if Application.Restart() actually works as expected.
Also Check further Info regarding this thread subject:
How do I restart my C# WinForm Application?

I've found a new way that's pretty convenient and has quite a few upsides.
There's never more than one instance running.
Command line args are persisted.
No exit events are raised from the application.
No process handles are broken.
I had a third party application managing my application with Process.Start and using Exit event to reload the application. Many of these solutions would break this implementation which is how I ended up on the following solution.
public static CancellationTokenSource _restartTokenSource;
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args)
{
// To customize application configuration such as set high DPI settings or default font,
// see https://aka.ms/applicationconfiguration.
ApplicationConfiguration.Initialize();
while (_restartTokenSource == null || _restartTokenSource.IsCancellationRequested)
{
_restartTokenSource = new System.Threading.CancellationTokenSource();
_restartTokenSource.Token.Register(() =>
{
foreach (Form form in Application.OpenForms)
form.Close();
});
Application.Run(new FlashMain(args));
}
}
Since Application.Run blocks until all forms in the application are closed I put this portion of the initialization into a loop that only executes when a CancellationTokenSource is null (the first run) or IsCancellationRequested is true (restart requested).
I register an event on the CancellationTokenSource that closes all forms in the application when .Cancel() is called, therefore unblocking Application.Run and restarting the loop.
Call Program._restartTokenSource.Cancel(); anywhere in the application to restart it.
P.S. This also works great for injecting into a BlazorWebView to restart the application from .NET Core.