Process.Id Property
Gets the unique identifier for the associated process.
Assembly: System (in System.dll)
| Exception | Condition |
|---|---|
| InvalidOperationException | The process's Id property has not been set. -or- There is no process associated with this Process object. |
| PlatformNotSupportedException | The platform is Windows 98 or Windows Millennium Edition (Windows Me); set the ProcessStartInfo.UseShellExecute property to false to access this property on Windows 98 and Windows Me. |
The process Id is not valid if the associated process is not running. Therefore, you should ensure that the process is running before attempting to retrieve the Id property. Until the process terminates, the process identifier uniquely identifies the process throughout the system.
You can connect a process that is running on a local or remote computer to a new Process instance by passing the process identifier to the GetProcessById method. GetProcessById is a static method that creates a new component and sets the Id property for the new Process instance automatically.
Process identifiers can be reused by the system. The Id property value is unique only while the associated process is running. After the process has terminated, the system can reuse the Id property value for an unrelated process.
Because the identifier is unique on the system, you can pass it to other threads as an alternative to passing a Process instance. This action can save system resources yet guarantee that the process is correctly identified.
This property is not available on this platform if you started the process with ProcessStartInfo.UseShellExecute set to true.
The following example demonstrates how to obtain the Id for all running instances of an application. The code creates a new instance of Notepad, lists all the instances of Notepad, and then allows the user to enter the Id number to remove a specific instance.
Imports System Imports System.Threading Imports System.Security.Permissions Imports System.Security.Principal Imports System.Diagnostics Class ProcessDemo Public Shared Sub Main() Dim notePad As Process = Process.Start("notepad") Console.WriteLine("Started notepad process Id = " + notePad.Id.ToString()) Console.WriteLine("All instances of notepad:") ' Get Process objects for all running instances on notepad. Dim localByName As Process() = Process.GetProcessesByName("notepad") Dim i As Integer = localByName.Length While i > 0 ' You can use the process Id to pass to other applications or to ' reference that particular instance of the application. Console.WriteLine(localByName((i - 1)).Id.ToString()) i -= 1 End While Dim chosen As Process i = localByName.Length While i > 0 Console.WriteLine("Enter a process Id to kill the process") Dim id As String = Console.ReadLine() If id = "" Then Exit While End If Try chosen = Process.GetProcessById(Int32.Parse(id)) Catch e As Exception Console.WriteLine("Incorrect entry.") GoTo ContinueWhile1 End Try If chosen.ProcessName = "notepad" Then chosen.Kill() chosen.WaitForExit() End If i -= 1 ContinueWhile1: End While End Sub 'Main End Class 'ProcessDemo
for full trust for the immediate caller. This member cannot be used by partially trusted code.
Available since 1.1