Read file that's already used by another process

Question

I have a C# app that tries to read a log file which is being written to by another app. When I try to read the file, I get IOException

"The process cannot access the file ... because it is being used by another process."

What I tried using so far are the following, but none of them fix the problem

var log = File.ReadAllText(logPath);

var stream = new FileStream(logPath, FileMode.Open);

using (var stream = File.Open(logPath, FileMode.Open))
  {

  }

http://stackoverflow.com/questions/3709104/how-do-you-read-a-file-which-is-in-use — Eric Hotinger, Apr 11 '16 at 21:56
[stackoverflow.com/questions/4964588/open-file-readonly](http://stackoverflow.com/questions/4964588/open-file-readonly) — Jason Massey, Apr 11 '16 at 21:58

score 4 · Answer 1 · edited Feb 03 '20 at 19:30

4

try this:

FileStream logFileStream = new FileStream("c:\test.txt", FileMode.Open,   FileAccess.Read, FileShare.ReadWrite);
StreamReader logFileReader = new StreamReader(logFileStream);

while (!logFileReader.EndOfStream)
{
    string line = logFileReader.ReadLine();
    // Your code here
}

// Clean up
logFileReader.Close();
logFileStream.Close();

edited with MethodMan's suggestions

using(FileStream logFileStream = new FileStream(@"c:\test.txt", FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
    using(StreamReader logFileReader = new StreamReader(logFileStream))
    {
        string text = logFileReader.ReadToEnd();
        // Your code..
    }
}

edited Feb 03 '20 at 19:30

Glen Little

6,951
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answered Apr 11 '16 at 21:57

Spongebrot

211
1
9

1

I would wrap the code around a using to handle the auto dipsosing of the FileStream and StreamReader Objects just a suggestion. also `"c:\test.txt"` should be `@"c:\test.txt"` to avoid the compiler seeing the single backslash as an escape character.. – MethodMan Apr 11 '16 at 21:59
You can also use the ReadToEnd method of the StreamReader instead of reading lines one at time to shorten your code. – Fabien ESCOFFIER Apr 11 '16 at 22:07

score -1 · Answer 2 · answered Apr 11 '16 at 22:06

-1

You can do nothing, if the "another app" does not use Share.Read while creating/opening the file.

answered Apr 11 '16 at 22:06

Sergei Zinovyev

1,238
14
14

Read file that's already used by another process

2 Answers2