ProcessStartInfo.RedirectStandardInput Property

 

Gets or sets a value indicating whether the input for an application is read from the Process.StandardInput stream.

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

Public Property RedirectStandardInput As Boolean

Property Value

Type: System.Boolean

true if input should be read from Process.StandardInput; otherwise, false. The default is 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 of a process. For example, instead of using keyboard input, you can provide text from the contents of a designated file or output from another application.

System_CAPS_noteNote

You must set UseShellExecute to false if you want to set 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 sort command is a console application that reads and sorts text input.

The example starts the sort command with redirected input. It then prompts the user for text, and passes the text to the sort process through 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

         myProcess.Start()

         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
         Do
            Console.WriteLine("Enter a line of text (or press the Enter key to stop):")

            inputText = Console.ReadLine()
            If inputText.Length > 0 Then
               numLines += 1
               myStreamWriter.WriteLine(inputText)
            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("------------------------")
         Else
            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.
         myStreamWriter.Close()


         ' Wait for the sort process to write the sorted text lines.
         myProcess.WaitForExit()
         myProcess.Close()

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

.NET Framework
Available since 1.1
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