Below is a fully working example. You want to use the Process class as you tried but you need to RedirectStandardOutput on the process's StartInfo. Then you can just read the process's StandardOutput. The sample below is written using VB 2010 but works pretty much the same for older versions.
Option Explicit On Option Strict On Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load ''//This will hold the entire output of the command that we are running Dim T As String ''//Create our process object Using P As New Process() ''//Pass it the EXE that we want to execute ''//NOTE: you might have to use an absolute path here P.StartInfo.FileName = "ping.exe" ''//Pass it any arguments needed ''//NOTE: if you pass a file name as an argument you might have to use an absolute path P.StartInfo.Arguments = "127.0.0.1" ''//Tell the process that we want to handle the commands output stream ''//NOTE: Some programs also write to StandardError so you might want to watch that, too P.StartInfo.RedirectStandardOutput = True ''//This is needed for the previous line to work P.StartInfo.UseShellExecute = False ''//Start the process P.Start() ''//Wrap a StreamReader around the standard output Using SR = P.StandardOutput ''//Read everything from the stream T = SR.ReadToEnd() End Using End Using ''//At this point T will hold whatever the process with the given arguments kicked out ''//Here we are just dumping it to the screen MessageBox.Show(T) End Sub End Class
EDIT
Here is an updated version that reads from both StandardOutput and StandardError. This time it reads asynchronously. The code calls the CHOICE exe and passes an invalid command line switch which will trigger writing to StandardError instead of StandardOutput. For your program you should probably monitor both. Also, if you're passing a file into the program make sure that you are specifying the absolute path to the file and make sure that if you have spaces in the file path that you are wrapping the path in quotes.
Option Explicit On Option Strict On Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load ''//This will hold the entire output of the command that we are running Dim T As String ''//Create our process object Using P As New Process() ''//Pass it the EXE that we want to execute ''//NOTE: you might have to use an absolute path here P.StartInfo.FileName = "choice" ''//Pass it any arguments needed ''//NOTE: if you pass a file name as an argument you might have to use an absolute path ''//NOTE: I am passing an invalid parameter to show off standard error P.StartInfo.Arguments = "/G" ''//Tell the process that we want to handle the command output AND error streams P.StartInfo.RedirectStandardOutput = True P.StartInfo.RedirectStandardError = True ''//This is needed for the previous line to work P.StartInfo.UseShellExecute = False ''//Add handlers for both of the data received events AddHandler P.ErrorDataReceived, AddressOf ErrorDataReceived AddHandler P.OutputDataReceived, AddressOf OutputDataReceived ''//Start the process P.Start() ''//Start reading from both error and output P.BeginErrorReadLine() P.BeginOutputReadLine() ''//Signal that we want to pause until the program is done running P.WaitForExit() Me.Close() End Using End Sub Private Sub ErrorDataReceived(ByVal sender As Object, ByVal e As DataReceivedEventArgs) Trace.WriteLine(String.Format("From Error : {0}", e.Data)) End Sub Private Sub OutputDataReceived(ByVal sender As Object, ByVal e As DataReceivedEventArgs) Trace.WriteLine(String.Format("From Output : {0}", e.Data)) End Sub End Class
Its important that you put your entire file path in quotes if it has spaces in it (in fact, you should always enclose it in quotes just in case.) For instance, this won't work:
P.StartInfo.FileName = "attrib" P.StartInfo.Arguments = "C:\Program Files\Windows NT\Accessories\wordpad.exe"
But this will:
P.StartInfo.FileName = "attrib" P.StartInfo.Arguments = """C:\Program Files\Windows NT\Accessories\wordpad.exe"""
EDIT 2
Okay, I'm an idiot. I thought you were just wrapping a filename in angled brackets like <input.txt> or [input.txt], I didn't realize that you were using actual stream redirectors! (A space before and after input.txt would have helped.) Sorry for the confusion.
There are two ways to handle stream redirection with the Process object. The first is to manually read input.txt and write it to StandardInput and then read StandardOutput and write that to output.txt but you don't want to do that. The second way is to use the Windows command interpreter, cmd.exe which has a special argument /C. When passed it executes any string after it for you. All stream redirections work as if you typed them at the command line. Its important that whatever command you pass gets wrapped in quotes so along with the file paths you'll see some double-quoting. So here's a version that does all that:
Option Explicit On Option Strict On Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load ''//Full path to our various files Dim FullExePath As String = "C:\PROG.exe" Dim FullInputPath As String = "C:\input.txt" Dim FullOutputPath As String = "C:\output.txt" ''//This creates our command using quote-escaped paths, all completely wrapped in an extra set of quotes ''//""C:\PROG.exe" < "C:\input.txt" > "C:\output.txt"" Dim FullCommand = String.Format("""""{0}"" < ""{1}"" > ""{2}""""", FullExePath, FullInputPath, FullOutputPath) ''//Create our process object Using P As New Process() ''//We are going to use the command shell and tell it to process our command for us P.StartInfo.FileName = "cmd" ''//The /C (capitalized) means "execute whatever else is passed" P.StartInfo.Arguments = "/C " & FullCommand ''//Start the process P.Start() ''//Signal to wait until the process is done running P.WaitForExit() End Using Me.Close() End Sub End Class
EDIT 3
The entire command argument that you pass to cmd /C needs to be wrapped in a set of quotes. So if you concat it it would be:
Dim FullCommand as String = """""" & FullExePath & """" & " <""" & FullInputPath & """> " & """" & FullOutputPath & """"""
Here's what the actual command that you pass should look like:
cmd /C ""C:\PROG.exe" < "C:\INPUT.txt" > "C:\output.txt""
Here's a full code block. I've added back the error and output readers just in case you're getting a permission error or something. So look at the Immediate Window to see if any errors are kicked out. If this doesn't work I don't know what to tell you.
Option Explicit On Option Strict On Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load ''//Full path to our various files Dim FullExePath As String = "C:\PROG.exe" Dim FullInputPath As String = "C:\INPUT.txt" Dim FullOutputPath As String = "C:\output.txt" ''//This creates our command using quote-escaped paths, all completely wrapped in an extra set of quotes Dim FullCommand As String = """""" & FullExePath & """" & " <""" & FullInputPath & """> " & """" & FullOutputPath & """""" Trace.WriteLine("cmd /C " & FullCommand) ''//Create our process object Using P As New Process() ''//We are going to use the command shell and tell it to process our command for us P.StartInfo.FileName = "cmd" ''//Tell the process that we want to handle the command output AND error streams P.StartInfo.RedirectStandardError = True P.StartInfo.RedirectStandardOutput = True ''//This is needed for the previous line to work P.StartInfo.UseShellExecute = False ''//Add handlers for both of the data received events AddHandler P.ErrorDataReceived, AddressOf ErrorDataReceived AddHandler P.OutputDataReceived, AddressOf OutputDataReceived ''//The /C (capitalized) means "execute whatever else is passed" P.StartInfo.Arguments = "/C " & FullCommand ''//Start the process P.Start() ''//Start reading from both error and output P.BeginErrorReadLine() P.BeginOutputReadLine() ''//Signal to wait until the process is done running P.WaitForExit() End Using Me.Close() End Sub Private Sub ErrorDataReceived(ByVal sender As Object, ByVal e As DataReceivedEventArgs) Trace.WriteLine(String.Format("From Error : {0}", e.Data)) End Sub Private Sub OutputDataReceived(ByVal sender As Object, ByVal e As DataReceivedEventArgs) Trace.WriteLine(String.Format("From Output : {0}", e.Data)) End Sub End Class
