2

I am trying to read all lines of log file that being used by some program.

When I tried to do it I am receiving exception: 

System.IO.IOException was unhandled  : file used by another process

So I searched on the web and found number of solutions:
C# exception. File is being used by another process
Read log file being used by another process
What's the least invasive way to read a locked file in C# (perhaps in unsafe mode)?
C# The process cannot access the file ''' because it is being used by another process
File is being used by another process
http://coding.infoconex.com/post/2009/04/21/How-do-I-open-a-file-that-is-in-use-in-C

The common solutions are to use using to wrap the FileStream and add the FileShare.ReadWrite.

I tried those solutions but I am still receiving the exception that the file is being used by another process.

In my below code I open the file D:\process.log to make the file used (for testing) and then trying to open the file.
The exception is on row: 

 using (FileStream fileStream = File.Open(i_FileNameAndPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))

CODE:

 private void openToolStripMenuItem_Click(object sender, EventArgs e)
    {
        OpenFileDialog openFileDialog = new OpenFileDialog();

        DialogResult dialogResult = openFileDialog.ShowDialog();
        if (dialogResult == DialogResult.OK)
        {
          listView.Items.Clear();
          File.Open(@"D:\process.log", FileMode.Open);  //make the file being used
          String fileNameAndPath = openFileDialog.FileName;
          String[] fileContent = readAllLines(fileNameAndPath);
        }
}

private String[] readAllLines(String i_FileNameAndPath)
{
    String[] o_Lines = null;
    int i = 0;
    using (FileStream fileStream = File.Open(i_FileNameAndPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
    {
        using (StreamReader streamReader = new StreamReader(fileStream))
        {
            while (streamReader.Peek() > -1)
            {
                String line = streamReader.ReadLine();
                //o_Lines[i] = line;
                i++;
            }
        }
    }

    return o_Lines;
}
Community
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E235
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  • all of that is of no use if that other process is exclusively locking the file – BrokenGlass Jan 04 '15 at 23:06
  • Can't you just use `File.ReadAllLines` ? – T.S. Jan 04 '15 at 23:10
  • Its likely that the other process that is creating the log file has locked the file so that other processes cannot read it. You can't do anything about this while the log file handle is being used. You can only process that log file after it has been closed. – Kerry Kobashi Jan 04 '15 at 23:11
  • @T.S. I can and I did but it works only if the file is not being used. My problem is when I want to read the lines of file that is being used – E235 Jan 04 '15 at 23:12
  • @KerryKobashi but I can open this log file with notepad or notepad++ so if these programs can open it, it not locked. – E235 Jan 04 '15 at 23:13
  • Try changing the FileShare to FileShare.None – Kerry Kobashi Jan 04 '15 at 23:16

1 Answers1

5

use an overload of File.Open in your menuclick event handler like this:

File.Open(@"C:\process.log", FileMode.Open,FileAccess.ReadWrite, FileShare.ReadWrite);

The last param is a value specifying the type of access other threads have to the file.

see this article from msdn

Mr Balanikas
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    Did it and now it works, Thanks :). Instead of: using (FileStream fileStream = File.Open(i_FileNameAndPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)) I wrote what you wrote. – E235 Jan 05 '15 at 08:53