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c # interop Can you tell which file excel is running using excel?

I want to quit Excel, which is opening certain files when there are a lot of excel running.
I know how to run Excel excel and know how to terminate the process, but I do not know how to exit excel that reads certain files.
I wonder if there is a way to shut down excel (or office) running a particular file through an interop or some other way.

Excel is a red herring here, what you're actually looking to do is discover which running process has locked a particular file on disk. It doesn't matter that it's an excel file in particular. This is a fairly common requirement and is well covered in other SO answers such as:
How do I find out which process is locking a file using .NET?

This is what you want:
foreach (var process in Process.GetProcessesByName("EXCEL"))
{
process.Kill();
}

To close a specific/particular excel file
private static void KillSpecificExcelFileProcess(string excelFileName)
{
var processes = from p in Process.GetProcessesByName("EXCEL")
select p;
foreach (var process in processes)
{
if (process.MainWindowTitle == excelFileName.Substring(0, excelFileName.IndexOf(".")) + " - Excel" )
process.Kill();
}
}
Pass the File name in the method call and in result the specific process will be close/kill

Adding attachments unlock file

I need some help.
My application works with Outlook files.
For example, I have a MSG format file is stored at my PC.
Let's imagine that I haven't got any running Outlook processes on my PC.
var myProcess = new Process { ProcessInfo = new ProcessStartInfo {FileName = targetPath}}
where targetPath is full path to my file.
Then I start process:
myProcess.Start();
At this moment Outlook runs at OS. Looking into TaskManager I see this process, and it's unique PID.
And there is my first question: why this PID is different from myProcess.Id ?
Moving on. I need to check is my file still opening at Outlook. I resolve this issue by trying to open this file in my application for a certain time.
var iterations = 3600;
while (iterations > 0 ) {
Thread.Sleep(1000);
var fInfo = new FileInfo(targetPath);
FileStream stream = null;
try {
stream = fInfo.Open(FileMode.Open, FileAccess.Read | FileAccess.Write, FileShare.None);
} catch {
//I expect if exception occurs then file is not lock and can send it to server.
}
finally{
if(stream != null)
stream.Close();
}
iteration--;
}
I think, while my MSG file is using by Outlook, I my application cant open file. In that way I decide that cant save my file and send it to server. But! If I add attachment but NOT close this e-mail at Outlook, my application CAN open this file. And I don't understand why Outlook change Read/Write attribute of this file? And how I can solve this issue?
Unfortunately, I haven't any idea why it happens and how to make it work.
I was looking on any info at web that can help to solve my issue, but has no result :(
Thank you for your time.

Firstly, Outlook is a singleton - if you start a new instance of outlook.exe, it will simply switch control to the already running instance and exit.
Outlook internally caches / references open MSG files, there is really northing you can do about that.

Dispose slow on very big filestreams?

I've got this code
string archiveFileName = BuildArchiveFileName(i, null);
string tmpArchiveFileName = BuildArchiveFileName(i, "tmp");
try
{
using (FileStream tmpArchiveMemoryStream = new FileStream(tmpArchiveFileName, FileMode.Create))
{
using (BinaryWriter pakWriter = new BinaryWriter(tmpArchiveMemoryStream))
{
if (i == 0)
{
WriteHeader(pakWriter, pakInfo.Header);
WriteFileInfo(pakWriter, pakInfo.FileList);
uint remainingBytesToDataOffset = pakInfo.Header.DataSectionOffset - CalculateHeaderBlockSize(pakInfo.Header);
pakWriter.Write(Util.CreatePaddingByteArray((int)remainingBytesToDataOffset));
}
foreach (String file in pakInfo.FileList.Keys)
{
DosPak.Model.FileInfo info = pakInfo.FileList[file];
if (info.IndexArchiveFile == i)
{
//Console.WriteLine("Writing " + file);
byte[] fileData = GetFileAsStream(file, false);
int paddingSize = (int)CalculateFullByteBlockSize((uint)fileData.Length) - fileData.Length;
pakWriter.Write(fileData);
pakWriter.Write(Util.CreatePaddingByteArray(paddingSize));
}
}
}
}
}
finally
{
File.Delete(archiveFileName);
File.Move(tmpArchiveFileName, archiveFileName);
}
I've tested this with NUnit on small file sizes and it works perfectly. Then when I tried it on a real life example , that are files over 1 GB. I get in trouble on the delete. It states the file is still in use by another process. While it shouldn't that file should have been disposed of after exiting the using branch. So I'm wondering if the dispose of the filestream is slow to execute and that is the reason I'm getting in trouble. Small note in all my file handling I use a FileStream with the using keyword.

While it shouldn't that file should have been disposed of after exiting the using branch
That's not what it is complaining about, you can't delete archiveFileName. Some other process has the file opened, just as the exception message says. If you have no idea what process that might be then start killing them off one-by-one with Task Manager's Processes tab. That being your own process is not entirely unusual btw. Best way is with SysInternals' Handle utility, it can show you the process name.
Deleting files is in general a perilous adventure on a multi-tasking operating system, always non-zero odds that some other process is interested in the file as well. They ought to open the file with FileShare.Delete but that's often overlooked.
The safest way to do this is with File.Replace(). The 3rd argument, the backup filename, is crucial, it allows the file to be renamed and continue to exist so that other process can continue to use it. You should try to delete that backup file at the start of your code. If that doesn't succeed then File.Replace() cannot work either. But do check that it isn't a bug in your program first, run the Handle utility.

what process is preventing my file from getting deleted in C#

I have a C# single thread application that creates a file. Uses that file and then deletes it. Some times the app has trouble deleting that file. The error I get is:
"The process cannot access the file --file path and file name-- because it is being used by another process."
How can I find out what process has a hold on this file and how can I make that process to let go so that the file can be deleted.

This thing rocks for that very "gotcha".
http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx
Process Monitor v3.05
It has a "Filter" submenu so you can fine tune it to the file that is locked.

You need to post the relevant code so we can see.
It is however always important to make sure that your app close the file that it has opened.
usually something like this will ensure that:
using(var f = File.OpenRead("myfile")) {
...
}
or the equivalent:
try {
var f = File.OpenRead("myfile");
} finally {
f.close()
}

Make sure that you are closing file before delete.
if you are using StreamWriter class make sure that you are closing with its variable
Ex. StreamWriter sw = new StreamWriter();
// some writing operation
sw.Close();

Is it possible to save data in another process with a C# app?

I have the following code:
p.StartInfo.FileName = "notepad.exe";
p.StartInfo.Arguments = "somefile.txt";
p.Start();
When "somefile.txt" is opened in notepad, its text will be modified. I want to save the new text in a temp file with the C# app automatically.
Is it possible to access this text and save it with C#?

It is sorta possible, you could use P/Invoke to call the SendMessage() method and generate the WM_COMMAND messages for the Edit + Select-All and Edit + Copy menu commands. That puts all text on the clip board, readily accessible to your program. You'll need to use the Spy++ utility to find out what the command identifiers are. Looks like 25 and 769 when I look at it on Win7.
There's a more direct way to discover the commands. In Visual Studio choose File + Open + File and select c:\windows\notepad.exe. Open the Menu node and double-click the "1" resource. That opens the menu editor, select Edit + Select-All and look at the Properties window for the ID.
Of course, this technique is specific to Notepad. The command IDs will be different for another program. As will be the code you need to find the proper window handle. Using Process.MainWindowHandle is treacherous at best, you don't know what specific instance of the process you need to select.

It would be very difficult to look at the text in-memory in the notepad process. It could be done, but it depends on the internal memory layout of notepad and your process may need administrative privileges depending on how the memory pages are protected.
Why not use a FileSystemWatcher to detect when the file has been modified, and then read the file in directly using c#?
http://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher.aspx

Copy the somefile.txt before you start notepad to a temporary file/folder. Start notepad using this temporary file. And wait for Notepad to exit.
Then you can examine if the file is changed (checksum?).
Probably delete the file after the processing, or your system will be full with temp files.

You can bring notepad window to front and send CTRL+S. You will need to use pinvoke for that.

I really don't understand why you would want to use notepad?
If you need a user to edit a text file, and then your app take some action on the text itself, why not just give the user the ability to edit the text right in your app?
What does notepad give you that the TextBox control doesn't have?
Try something like this
using System.Windows.Forms;
using System.IO;
TextBox myEditor = new TextBox();
myEditor.Multiline = true;
myEditor.ScrollBars = ScrollBars.Vertical;
myEditor.AcceptsReturn = true;
myEditor.AcceptsTab = true;
myEditor.WordWrap = true;
// Get the text from the file.
StreamReader sr = new StreamReader("SomeFile.txt"))
myEditor.Text = sr.ReadToEnd();