open a file with FileShare.Read does not lock the file.

See more:

C#2.0

C#3.0

C#

Hi guys,

I am opening a text file (.csv) with the below command:

_FileStream = System.IO.File.Open(_CSVFileName, System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.Write, System.IO.FileShare.Read);

and I do not close the file while my program is runing.
when I open a file in my program and after that when I open the same file with Excel ( althogh Excel ask me to open the file as readonly ) sometimes I get the following Error:
The process cannot access the file because another process has locked a portion of the file.

It seems that .net does not lock the file completely !! (It works fine when I open the file with notepad)

Is there any solution?!

Thanks.

Edited:
I am just writing in the file. so I open the file with FileAccess.Write. but I want other users can read the file when it is open by my App.
( It is my Application log file)

Edited 2:
This is my Code:

try
{
    oMutex.WaitOne();
    byte[] obyte;
    obyte = System.Text.Encoding.ASCII.GetBytes(str);
    _FileStream.Write(obyte, 0, str.Length);
    _FileStream.WriteByte(13);
    _FileStream.WriteByte(10);
    _Line++;
    _FileStream.Flush();
    obyte = null;
}
finally
{
    oMutex.ReleaseMutex();
}