FileSystemWatcher is a powerful .NET class that allows developers to monitor changes to the file system. This can be particularly useful for applications that need to respond to changes in real-time, such as file synchronization tools, log monitoring systems, or automated backup solutions. In the Windows environment, FileSystemWatcher is fully supported and can be implemented using C# in a .NET application. This article will guide you through the process of creating and using FileSystemWatcher in a Windows environment, providing practical examples and sample code.

Examples:

Example 1: Setting Up FileSystemWatcher in a C# Console Application

1. Create a new C# Console Application:

• Open Visual Studio.


• Create a new project and select "Console App (.NET Core)".


• Name your project and click "Create".

2. Add FileSystemWatcher Code:

• 
  

  Open the Program.cs file and replace its content with the following code:

  
  

  using System;
  
  using System.IO;
  
  
  
  namespace FileSystemWatcherExample
  
  {
  
      class Program
  
      {
  
          static void Main(string[] args)
  
          {
  
              using (FileSystemWatcher watcher = new FileSystemWatcher())
  
              {
  
                  watcher.Path = @"C:\Path\To\Directory"; // Set the directory to watch
  
  
  
                  // Watch for changes in LastWrite times, and the renaming of files or directories.
  
                  watcher.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName;
  
  
  
                  // Only watch text files.
  
                  watcher.Filter = "*.txt";
  
  
  
                  // Add event handlers.
  
                  watcher.Changed += OnChanged;
  
                  watcher.Created += OnChanged;
  
                  watcher.Deleted += OnChanged;
  
                  watcher.Renamed += OnRenamed;
  
  
  
                  // Begin watching.
  
                  watcher.EnableRaisingEvents = true;
  
  
  
                  // Wait for the user to quit the program.
  
                  Console.WriteLine("Press 'q' to quit the sample.");
  
                  while (Console.Read() != 'q') ;
  
              }
  
          }
  
  
  
          // Define the event handlers.
  
          private static void OnChanged(object source, FileSystemEventArgs e) =>
  
              Console.WriteLine($"File: {e.FullPath} {e.ChangeType}");
  
  
  
          private static void OnRenamed(object source, RenamedEventArgs e) =>
  
              Console.WriteLine($"File: {e.OldFullPath} renamed to {e.FullPath}");
  
      }
  
  }

  
  

3. Run the Application:

• Build and run the application.


• The console will display messages when changes are detected in the specified directory.

Example 2: Running FileSystemWatcher via PowerShell

1. Open PowerShell:

• Press Win + X and select "Windows PowerShell (Admin)".

2. Create a PowerShell Script:

• 
  

  Open a text editor and paste the following script:

  
  

  $path = "C:\Path\To\Directory"
  
  $filter = "*.txt"
  
  
  
  $FileSystemWatcher = New-Object System.IO.FileSystemWatcher
  
  $FileSystemWatcher.Path = $path
  
  $FileSystemWatcher.Filter = $filter
  
  $FileSystemWatcher.IncludeSubdirectories = $true
  
  $FileSystemWatcher.EnableRaisingEvents = $true
  
  
  
  $onChange = Register-ObjectEvent $FileSystemWatcher Changed -SourceIdentifier FileChanged -Action {
  
      Write-Host "File $($Event.SourceEventArgs.FullPath) has been changed"
  
  }
  
  
  
  $onCreate = Register-ObjectEvent $FileSystemWatcher Created -SourceIdentifier FileCreated -Action {
  
      Write-Host "File $($Event.SourceEventArgs.FullPath) has been created"
  
  }
  
  
  
  $onDelete = Register-ObjectEvent $FileSystemWatcher Deleted -SourceIdentifier FileDeleted -Action {
  
      Write-Host "File $($Event.SourceEventArgs.FullPath) has been deleted"
  
  }
  
  
  
  $onRename = Register-ObjectEvent $FileSystemWatcher Renamed -SourceIdentifier FileRenamed -Action {
  
      Write-Host "File $($Event.SourceEventArgs.OldFullPath) has been renamed to $($Event.SourceEventArgs.FullPath)"
  
  }
  
  
  
  Write-Host "Monitoring changes to $path. Press Enter to exit."
  
  [System.Console]::ReadLine() | Out-Null
  
  
  
  Unregister-Event -SourceIdentifier FileChanged
  
  Unregister-Event -SourceIdentifier FileCreated
  
  Unregister-Event -SourceIdentifier FileDeleted
  
  Unregister-Event -SourceIdentifier FileRenamed

  
  

3. Save and Run the Script:

• Save the script as FileSystemWatcher.ps1.


• Run the script in PowerShell by navigating to its directory and executing:
  

   .\FileSystemWatcher.ps1