I am writing to the text file some data. I am using this code:
using (FileStream fs = new FileStream(path, FileMode.Append, FileAccess.Write, FileShare.ReadWrite))
{
using (TextWriter tw = new StreamWriter(fs))
{
tw.WriteLine("sample_data");
}
}
When file is opened by notepad my app can write into it. When this file is opened by MS Excel I get following error: The process cannot access the file myfile.csv because it is being used by another process. What can cause this situation and how can I solve this problem?
Notepad opens the file, reads in the entire contents and then closes the file. You can even delete the file that is open in notepad.
Excel on the other hand keeps the file open as long as it is displayed. There are some special sharing tools that can be enabled in Excel for excel format files. In that case I assume that it is opened non-exlusively. Otherwise Excel opens the file exclusively and keeps it open.
It doesn't matter that you specify a share option when opening, if the file is already opened by someone else in exclusive mode.
Excel will lock the file when it is open which prevents interaction with the file. One way I worked around this is that I wrote code to scan for excel processes on the local machine and would kill those processes before accessing a file that was open with excel. You could determine if a file is locked by looking at How to check for file lock? and then running the process killing code in the exception handler.
Open the csv file using OleDB and use INSERT and/or UPDATE statements.
Related
I'm trying to open a file, rewrite it, save it and close it for multiple times in my app, and I observed a strange behavior
I open the file with:
System.IO.StreamReader file = new System.IO.StreamReader(filePath);
Write it with this:
using (System.IO.StreamWriter file = new System.IO.StreamWriter(filePath)) {
file.WriteLine(myString);
file.Close();
}
But the file does not change until I close the app, why is this happening ?
I checked the file myself and it content doesn't change just after the app is closed
It looks like you are not flushing the changes to disk. This is probably due to the open StreamReader handle. Close the reader after each write and re-open it. Or better close the reader before you write and re-open it afterwards.
I use StreamWriter to write logs. I sometimes open this log file with Excel while my program is running.
I find that Excel lock this file so I get IOException when my program try to write logs.
Can I take out the lock which was set by other process?
I know I can lock the file while my program is running but it cause similar problem when I open it with Excel.
Note that I won't write anything with the other process.
using(var sw = new StreamWriter(
new FileStream(filename, FileMode.Append, FileAccess.Write), Encoding.GetEncoding("UTF-16")))
No, you can't "take ownership of lock on file" (unless other application is designed o allow such access).
The other application must be opening file with particular share mode to allow your to simultaneously access the file.
Note that most application don't open files in such mode due to problems keeping state consistent.
.Net way of specifying share mode - use desired value from FileShare enumeration when opening files. There are multiple samples and discussion about it on SO like C# multiple instances of program reading from same file.
Is there a way to read binary data from a read-only file? I have an Excel worksheet, which might be opened in Excel but I want to open it for read purposes only.
I tried to do it this way:
using (FileStream fileStream = File.Open(filepath, FileMode.Open, FileAccess.Read, FileShare.Read))
And I am getting
The process cannot access the file 'something.xlsx' because it is being used by another process.
Is there any way to achieve that?
Change this argument:
FileShare.Read
to this:
FileShare.ReadWrite
You are attempting to deny write access to the file, which is causing your issue as Excel already has it open for writing.
You can't open a file who are already open. Be careful to close your file after open it. And you should verify that you didn't use the file in another software (at the same time)...
I have a process that builds an Excel report, then opens it for the user. The problem is if someone leaves the file open, it stays locked and nobody else can build the report until the first person exits the excel file.
Is there a way to open an Excel file without locking it, using either Process.Start or Microsoft's Interop.Excel library?
I use the Interop library to build the file each time the report is run, and save it as a static file name in a shared network folder where this application is run from
using Excel = Microsoft.Office.Interop.Excel;
...
xlsBook.SaveAs(newFileName, Excel.XlFileFormat.xlWorkbookNormal);
And open the file using Process.Start
Process.Start(newFileName);
You can try to open the file in read-only mode:
var app = new Microsoft.Office.Interop.Excel.Application();
var workbook = app.Workbooks.Open(filename, ReadOnly: true);
Or you can try to save it in shared mode:
workbook.SaveAs(filename, AccessMode: XlSaveAsAccessMode.xlShared);
If the end user only has to read the file instead of also modifying it, you could create a shadow copy and then open that copy.
Simply copy the original file to a temporary location and open it from there. The original file remains untouched and can thus be opened by others.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Open file ReadOnly
In my application I am writing some information to Log.txt using Debug.WriteLine(), and I want to provide a form which will show the contents of Log.txt.
But when I try to open the file Log.txt I am getting an exception:
The process cannot access the file 'F:\Rajeev\10-11-2012\Temp\Temp\bin\Debug\Log.txt' because it is being used by another process.
How do I overcome this problem?
And here another issue is, I am able to open the same file using Notepad. Then why can't I open the same file using my application?
The following is the code I am using for specifying the log file:
TextWriterTraceListener tr = new TextWriterTraceListener(System.IO.File.CreateText("Log.txt"));
Debug.Listeners.Add(tr);
Debug.AutoFlush = true;
The following is the code I am using for writing to the log file:
Debug.WriteLine("ERROR: Invalid Username " + s);
The following is the code I am using for opening a log file (which is already opened by "Debug") to show in Log Viewer (a "Form" in my application):
File.Open(LogFilePath, FileMode.Open, FileAccess.Read,FileShare.Read);
This is determined by the permissions the file is opened with. If a program opens the file in any type of exclusive mode, then other programs will have limited or no access.
So you can make sure you don't try to open the file exclusively (you didn't show your code). However, if you don't have the source code for the other program, then you can only hope that that program doesn't open the file exclusively. Otherwise, I don't see what you could do about it except terminate the other program.
EDIT
The following code:
File.Open(LogFilePath, FileMode.Open, FileAccess.Read, FileShare.Read);
Says that other files can also read the file that is open, but I believe they can't write to it. So if the other program was writing to the file, that would not be allowed. You could try FileShare.ReadWrite instead but I'm still not seeing where you've indicated if you have source to the other program. Did I just miss it?