Lock file for writing/deleting while allowing any process to read

Question

I am developing an application in C# (.NET), and am having trouble dealing with file locking.

• My main application (A) needs read/write access to a certain fil

Answer 1

Use FileShare.Read to only allow reads from other applications. You can lock the file by having a stream open while the application A runs. You need a NonClosingStreamWrapper to avoid disposing the stream when you dispose your StreamWriter (this happens automatically with using)

NonClosingStreamWrapper by Jon Skeet can be found from here

Example

When application starts use this to lock the file

FileStream fileStream = new FileStream(file, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.Read);

When writing to a file use

using (StreamWriter sr = new StreamWriter(new NonClosingStreamWrapper(fileStream)))
{
    // File writing as usual
}

When application ends use this to release the file

fileStream.Close();