Process.StandardInput Property


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Gets a stream used to write the input of the application.

Namespace:   System.Diagnostics
Assembly:  System (in System.dll)

Public ReadOnly Property StandardInput As StreamWriter

Property Value

Type: System.IO.StreamWriter

A StreamWriter that can be used to write the standard input stream of the application.

Exception Condition

The StandardInput stream has not been defined because ProcessStartInfo.RedirectStandardInput is set to false.

A Process can read input text from its standard input stream, typically the keyboard. By redirecting the StandardInput stream, you can programmatically specify the input. For example, instead of using keyboard input, you can provide text from the contents of a designated file or output from another application.


To use StandardInput, you must set ProcessStartInfo.UseShellExecute to false, and you must set ProcessStartInfo.RedirectStandardInput to true. Otherwise, writing to the StandardInput stream throws an exception.

The following example illustrates how to redirect the StandardInput stream of a process. The example starts the sort command with redirected input. It then prompts the user for text, and passes that to the sort process by means of the redirected StandardInput stream. The sort results are displayed to the user on the console.

Imports System
Imports System.IO
Imports System.Diagnostics
Imports System.ComponentModel
Imports Microsoft.VisualBasic

Namespace Process_StandardInput_Sample

   Class StandardInputTest

      Shared Sub Main()

         Console.WriteLine("Ready to sort one or more text lines...")

         ' Start the Sort.exe process with redirected input.
         ' Use the sort command to sort the input text.
         Dim myProcess As New Process()

         myProcess.StartInfo.FileName = "Sort.exe"
         myProcess.StartInfo.UseShellExecute = False
         myProcess.StartInfo.RedirectStandardInput = True


         Dim myStreamWriter As StreamWriter = myProcess.StandardInput

         ' Prompt the user for input text lines to sort. 
         ' Write each line to the StandardInput stream of
         ' the sort command.
         Dim inputText As String
         Dim numLines As Integer = 0
            Console.WriteLine("Enter a line of text (or press the Enter key to stop):")

            inputText = Console.ReadLine()
            If inputText.Length > 0 Then
               numLines += 1
            End If
         Loop While inputText.Length <> 0

         ' Write a report header to the console.
         If numLines > 0 Then
            Console.WriteLine(" {0} sorted text line(s) ", numLines)
            Console.WriteLine(" No input was sorted")
         End If

         ' End the input stream to the sort command.
         ' When the stream closes, the sort command
         ' writes the sorted text lines to the 
         ' console.

         ' Wait for the sort process to write the sorted text lines.

      End Sub 'Main
   End Class  'StandardInputTest
End Namespace 'Process_StandardInput_Sample


for full trust for the immediate caller. This member cannot be used by partially trusted code.

.NET Framework
Available since 1.1
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