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FileSystemWatcher.Path Property

Gets or sets the path of the directory to watch.

[Visual Basic]
Public Property Path As String
[C#]
public string Path {get; set;}
[C++]
public: __property String* get_Path();
public: __property void set_Path(String*);
[JScript]
public function get Path() : String;
public function set Path(String);

Property Value

The path to monitor. The default is an empty string ("").

Exceptions

Exception Type Condition
ArgumentException The specified path contains wildcard characters.

-or-

The specified path contains invalid path characters.

-or-

The specified path specified does not exist or is null.

Remarks

This is a fully qualified path to a directory. The directory is the root at which the system watches for changes. To watch a specific file, set the Path property to the correct directory, and the Filter property to the filename.

The Path property supports Universal Naming Convention (UNC) paths.

Note   This property must be set before the component can watch for changes.

When a directory is renamed, the FileSystemWatcher automatically reattaches itself to the newly renamed item. For example, if you set the Path property to "C:\My Documents" and then manually rename the directory to "C:\Your Documents", the component continues listening for change notifications on the newly renamed directory. However, when you ask for the Path property, it contains the old path. This happens because the component determines what directory watches based on the handle, rather than the name of the directory. Renaming does not affect the handle. So, if you destroy the component, and then recreate it without updating the Path property, your application will fail because the directory no longer exists.

Example

[Visual Basic, C#, C++] The following example creates a FileSystemWatcher to watch the directory specified at runtime. The component is set to watch for changes in LastWrite and LastAccess time, the creation, deletion, or renaming of text files in the directory. If a file is changed, created, or deleted, the path to the file prints to the console. When a file is renamed, the old and new paths print to the console.

[Visual Basic, C#, C++] Use the System.Diagnostics and System.IO namespaces for this example.

[Visual Basic] 
Public Class Watcher
    
    Public Shared Sub Main()
        Dim args() As String = System.Environment.GetCommandLineArgs()
        ' If a directory is not specified, exit the program.
        If args.Length <> 2 Then
            ' Display the proper way to call the program.
            Console.WriteLine("Usage: Watcher.exe (directory)")
            Return
        End If
        
        ' Create a new FileSystemWatcher and set its properties.
        Dim watcher As New FileSystemWatcher()
        watcher.Path = args(1)
        ' Watch for changes in LastAccess and LastWrite times, and
        ' the renaming of files or directories. 
        watcher.NotifyFilter = (NotifyFilters.LastAccess Or NotifyFilters.LastWrite Or NotifyFilters.FileName Or NotifyFilters.DirectoryName)
        ' Only watch text files.
        watcher.Filter = "*.txt"
        
        ' Add event handlers.
        AddHandler watcher.Changed, AddressOf OnChanged
        AddHandler watcher.Created, AddressOf OnChanged
        AddHandler watcher.Deleted, AddressOf OnChanged
        AddHandler watcher.Renamed, AddressOf OnRenamed
        
        ' Begin watching.
        watcher.EnableRaisingEvents = True
        
        ' Wait for the user to quit the program.
        Console.WriteLine("Press 'q' to quit the sample.")
        While Chr(Console.Read()) <> "q"c
        End While
    End Sub
     
    ' Define the event handlers.
    Private Shared Sub OnChanged(source As Object, e As FileSystemEventArgs)
        ' Specify what is done when a file is changed, created, or deleted.
        Console.WriteLine("File: " & e.FullPath & " " & e.ChangeType)
    End Sub    
    
    Private Shared Sub OnRenamed(source As Object, e As RenamedEventArgs)
        ' Specify what is done when a file is renamed.
        Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath)
    End Sub
    
End Class


[C#] 
public class Watcher
{

    public static void Main()
    {

        string[] args = System.Environment.GetCommandLineArgs();
 
        // If a directory is not specified, exit program.
        if(args.Length != 2)
        {
            // Display the proper way to call the program.
            Console.WriteLine("Usage: Watcher.exe (directory)");
            return;
        }

        // Create a new FileSystemWatcher and set its properties.
        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.Path = args[1];
        /* Watch for changes in LastAccess and LastWrite times, and 
           the renaming of files or directories. */
        watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite 
           | NotifyFilters.FileName | NotifyFilters.DirectoryName;
        // Only watch text files.
        watcher.Filter = "*.txt";

        // Add event handlers.
        watcher.Changed += new FileSystemEventHandler(OnChanged);
        watcher.Created += new FileSystemEventHandler(OnChanged);
        watcher.Deleted += new FileSystemEventHandler(OnChanged);
        watcher.Renamed += new RenamedEventHandler(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)
    {
        // Specify what is done when a file is changed, created, or deleted.
       Console.WriteLine("File: " +  e.FullPath + " " + e.ChangeType);
    }

    private static void OnRenamed(object source, RenamedEventArgs e)
    {
        // Specify what is done when a file is renamed.
        Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
    }
}


[C++] 
public __gc class Watcher
{
public:
    // Define the event handlers.
    static void OnChanged(Object* /*source*/, FileSystemEventArgs* e)
    {
        // Specify what is done when a file is changed, created, or deleted.
        Console::WriteLine(S"File: {0} {1}", e->FullPath, __box(e->ChangeType));
    }

    static void OnRenamed(Object* /*source*/, RenamedEventArgs* e)
    {
        // Specify what is done when a file is renamed.
        Console::WriteLine(S"File: {0} renamed to {1}", e->OldFullPath, e->FullPath);
    }
};


int main()
{

    String* args[] = System::Environment::GetCommandLineArgs();

    // If a directory is not specified, exit program.
    if(args->Length != 2)
    {
        // Display the proper way to call the program.
        Console::WriteLine(S"Usage: Watcher.exe (directory)");
        return 0;
    }

    // Create a new FileSystemWatcher and set its properties.
    FileSystemWatcher* watcher = new FileSystemWatcher();
    watcher->Path = args[1];
    /* Watch for changes in LastAccess and LastWrite times, and 
    the renaming of files or directories. */
    watcher->NotifyFilter = static_cast<NotifyFilters>( NotifyFilters::LastAccess | NotifyFilters::LastWrite 
        | NotifyFilters::FileName | NotifyFilters::DirectoryName );
    // Only watch text files.
    watcher->Filter = S"*.txt";

    // Add event handlers.
    watcher->Changed += new FileSystemEventHandler(0, Watcher::OnChanged);
    watcher->Created += new FileSystemEventHandler(0, Watcher::OnChanged);
    watcher->Deleted += new FileSystemEventHandler(0, Watcher::OnChanged);
    watcher->Renamed += new RenamedEventHandler(0, Watcher::OnRenamed);

    // Begin watching.
    watcher->EnableRaisingEvents = true;

    // Wait for the user to quit the program.
    Console::WriteLine(S"Press \'q\' to quit the sample.");
    while(Console::Read()!='q');
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows NT Server 4.0, Windows NT Workstation 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

FileSystemWatcher Class | FileSystemWatcher Members | System.IO Namespace | FileSystemWatcher | Filter

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