Process.StandardInput Property
Gets a stream used to write the input of the application.
Assembly: System (in System.dll)
Property Value
Type: System.IO.StreamWriterA StreamWriter that can be used to write the standard input stream of the application.
| Exception | Condition |
|---|---|
| InvalidOperationException | 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.
Note |
|---|
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 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
for full trust for the immediate caller. This member cannot be used by partially trusted code.
Available since 1.1
