Develop Reference

Run a vb script using System.Diagnostics.Process but only partially successful in feeding in input text to the process' stdin

Edit: first things first
The point of the vbscript is to act like a REPL or command prompt/bash
environment, it is simplified to just reprinting the user input
So in other words the cscript process should stay alive and the user input for each pass should be sent to this process only.
And also it means that the internal state of the script should be kept for each pass (One pass = each time the "Send" button in the C# winform is clicked, or in the context of the vbscript, One pass = each time ^Z is input).
For example, if the vbscript is to be modified to demonstrate the state-keeping behavior, you can make the following mods:
At line dim wsh,stmt,l... append it with : dim passcnt : passcnt=1
At line wsh.Echo("Enter lines of strings, press ctrl-z..., replace the last closing bracket with & " (pass #" & passcnt & ")")
At line wsh.Echo("End output") append the code : passcnt = passcnt + 1
Running the vbscript the console will show the pass number incremented on each pass.
The C# winform can be modified in any way, as long as the above condition still holds.
Try to observe what the script does by cscript ask_SO.vbs, it should make things clear enough
I think this is the most clear I am able to made it.
I would like to use stdout/stdin redirection of System.Diagnostics.Process to feed input texts to the following VBScript.
What the vbscript does is that it allows the user to input multiple lines of strings to the console, and when the ^z character is input, the script will just output everything ver batim to the console:
Sample Output
Microsoft (R) Windows Script Host Version 5.812
Copyright (C) Microsoft Corporation. All rights reserved.
Enter lines of strings, press ctrl-z when you are done (ctrl-c to quit):
I come with no wrapping or pretty pink bows.
got line
I am who I am, from my head to my toes.
got line
I tend to get loud when speaking my mind.
got line
Even a little crazy some of the time.
got line
I'm not a size 5 and don't care to be.
got line
You can be you and I can be me.
got line
got line
Source: https://www.familyfriendpoems.com/poem/be-proud-of-who-you-are
got line
^Z
=====================================
You have entered:
I come with no wrapping or pretty pink bows.
I am who I am, from my head to my toes.
I tend to get loud when speaking my mind.
Even a little crazy some of the time.
I'm not a size 5 and don't care to be.
You can be you and I can be me.
Source: https://www.familyfriendpoems.com/poem/be-proud-of-who-you-are
End output
Enter lines of strings, press ctrl-z when you are done (ctrl-c to quit):
After that, the user can input another chunk of text and repeat the process.
This is the script code:
ask_SO.vbs
dim wsh,stmt,l : set wsh = WScript
do
wsh.Echo("Enter lines of strings, press ctrl-z when you are done (ctrl-c to quit):")
'stmt=wsh.StdIn.ReadAll()
do
l=wsh.StdIn.ReadLine()
wsh.echo("got line")
stmt = stmt & l & vbcrlf
loop while (not wsh.StdIn.AtEndOfStream)
wsh.Echo("=====================================")
wsh.Echo("You have entered:")
wsh.Echo(stmt)
wsh.Echo("End output")
loop
This is how to invoke the script:
cscript ask_SO.vbs
I came out with the following C# code (project type set to Console Application instead of Windows Forms):
frmPostSample
public class frmPostSample : Form
{
Process proc_cscr;
StreamWriter sw;
public frmPostSample()
{
InitializeComponent2();
}
#region Copied from generated code
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
private void InitializeComponent2()
{
this.txt_lines = new System.Windows.Forms.TextBox();
this.Btn_Send = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// txt_lines2
//
this.txt_lines.Location = new System.Drawing.Point(41, 75);
this.txt_lines.Multiline = true;
this.txt_lines.Name = "txt_lines2";
this.txt_lines.Size = new System.Drawing.Size(689, 298);
this.txt_lines.TabIndex = 0;
//
// Btn_Send2
//
this.Btn_Send.Location = new System.Drawing.Point(695, 410);
this.Btn_Send.Name = "Btn_Send2";
this.Btn_Send.Size = new System.Drawing.Size(75, 23);
this.Btn_Send.TabIndex = 1;
this.Btn_Send.Text = "&Send";
this.Btn_Send.UseVisualStyleBackColor = true;
this.Btn_Send.Click += new System.EventHandler(this.Btn_Send_Click);
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(800, 450);
this.Controls.Add(this.Btn_Send);
this.Controls.Add(this.txt_lines);
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);
this.PerformLayout();
}
private System.Windows.Forms.TextBox txt_lines;
private System.Windows.Forms.Button Btn_Send;
#endregion
private void Btn_Send_Click(object sender, EventArgs e)
{
if (proc_cscr == null)
{
if (!File.Exists("ask_SO.vbs"))
{
MessageBox.Show("Script file not exist");
return;
}
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.FileName = "cscript";
startInfo.Arguments = "//nologo ask_SO.vbs";
startInfo.RedirectStandardInput = true;
startInfo.RedirectStandardOutput = true;
startInfo.UseShellExecute = false;
proc_cscr = new Process();
proc_cscr.StartInfo = startInfo;
proc_cscr.Start();
sw = proc_cscr.StandardInput;
}
OutPrint();
foreach (var vbsline in txt_lines.Lines)
{
sw.WriteLine(vbsline); // <-------- SW WRITELINE
sw.Flush();
OutPrint();
}
//sw.Flush();
sw.Close();
while (true)
{
var s2 = proc_cscr.StandardOutput.ReadLineAsync();
s2.Wait();
Console.WriteLine(s2.Result);
if (proc_cscr.StandardOutput.Peek() == -1) break;
}
}
private void OutPrint()
{
string l;
while (proc_cscr.StandardOutput.Peek() != -1)
{
l = proc_cscr.StandardOutput.ReadLine();
Console.WriteLine(l);
}
}
}
Run the program, and if you have correctly set the project type to "Console Application", a console window and a GUI Window should be shown.
You just paste the text to the text input area and press send, and observe the result in the console window.
However, what the C# form behaves is not the same as directly running the script cscript ask_SO.vbs:
The script can only accept one pass of input - the second pass throws the error "Cannot write to a closed TextWriter" at the line with comment SW WRITELINE - I know it is because I've closed the stdin stream, but otherwise I can't make the script go forward
Also, I've got the error shown: ...\ask_SO.vbs(8, 9) Microsoft VBScript runtime error: Input past end of file.
The "got line" echo is not shown immediately after the c# code write a line input to the stdin (again, at the line with comment SW WRITELINE).
I've searched online to find a solution, but most of the materials only shows input without using the ^z character, or in other words, only accepts one-pass input.
You can download the C# visual studio solution here (vbscript included - you just load the solution in visual studio 2019 and press F5 to run).
Note
The encoding I got from proc_cscr.StandardOutput.CurrentEncoding.BodyName and proc_cscr.StandardInput.Encoding.BodyName is big5, it is a DBCSCodePageEncoding, used for encoding Chinese characters.
I recognized that I need to mention this, when I tried the suggestion mentioned in an answer to write (char)26 to the stdin stream. As Encoding.GetEncoding("big5").GetBytes(new char[]{(char)26}) returns only one byte (two bytes for unicode: {byte[2]} [0]: 26 [1]: 0), I did a sw.Write((char)26);, and add a sw.flush() also. It still didn't work.

I do not think, this is possible to do.
Your point 3:
The "got line" echo is not shown immediately after the c# code write a line input to the stdin
This is because you have redirected output (startInfo.RedirectStandardOutput = true). If you redirect it, everything you write goes to the StandardOutput stream and you have to read it manually. So just do not redirect output and your got line messages will be immediate. If the output is not redirected, you can not use StandardOutput property (but you do not need it anyway).
The rest is more difficult. The thing is, it seems there is not a way how to send end of stream, because this is what stops your inner loop in vbs. The stream ends when you finish with it - technically when you close it, or finish your process. The character of value 26 is represented as end of stream (Ctrl + Z) somewhere. But it is not working here (I tried sw.Write(Convert.ToChar(26)).
I do not know if it is possible (I do not know vbs), but maybe you can change your logic there and not check for end of stream. Insted of it maybe read by bytes (characters) and check for specific char (for example that char(26)) to step out of the inner loop.

Your problem here is when you close the stream, cscript also terminates and you try to read from a dead process.
I've modified your sample to utilize async reading of cscript by calling BeginOutputReadLine and reading output in OutputDataReceived event. I've also added a WaitForExit which is required to ensure raising of async events.
By the way you really do not need to send CTRL+Z since it is just a character and it is not really the EOF marker. Console handler just handles that keystroke as EOF signal. Closing StandardInput does the trick.
var psi = new ProcessStartInfo
{
FileName = "cscript",
RedirectStandardError = true,
RedirectStandardOutput = true,
RedirectStandardInput = true,
UseShellExecute = false,
//CreateNoWindow = true,
WindowStyle = ProcessWindowStyle.Normal,
Arguments = "//nologo ask_SO.vbs"
};
var process = Process.Start(psi);
process.BeginOutputReadLine();
var buffer = new StringBuilder();
process.OutputDataReceived += (s, args) =>
{
buffer.AppendLine(args.Data);
};
foreach (var line in textBox1.Lines)
{
buffer.AppendLine(line);
process.StandardInput.WriteLine(line);
Thread.Sleep(50);
}
process.StandardInput.Flush();
process.StandardInput.Close();
process.WaitForExit();
output.Text = buffer.ToString();
EDIT: Updated to keep process alive
private Process process;
private void EnsureProcessStarted()
{
if (null != process)
return;
var psi = new ProcessStartInfo
{
FileName = "cscript",
RedirectStandardError = true,
RedirectStandardOutput = true,
RedirectStandardInput = true,
UseShellExecute = false,
//CreateNoWindow = true,
WindowStyle = ProcessWindowStyle.Normal,
Arguments = "//nologo ask_SO.vbs"
};
process = Process.Start(psi);
process.OutputDataReceived += (s, args) => AppendLineToTextBox(args.Data);
process.BeginOutputReadLine();
// time to warm up
Thread.Sleep(500);
}
private void AppendLineToTextBox(string line)
{
if (string.IsNullOrEmpty(line))
return;
if (output.InvokeRequired)
{
output.Invoke(new Action<string>(AppendLineToTextBox), line);
return;
}
output.AppendText(line);
output.AppendText(Environment.NewLine);
}
private void SendLineToProcess(string text)
{
EnsureProcessStarted();
if (string.IsNullOrWhiteSpace(text))
{
process.StandardInput.Flush();
process.StandardInput.Close();
//process.WaitForExit(); causes a deadlock
process = null;
}
else
{
AppendLineToTextBox(text); // local echo
process.StandardInput.WriteLine(text);
process.StandardInput.Flush();
// time to process
Thread.Sleep(50);
}
}

How to embed interactive python process in C# WinForm

Question
I am trying to start Python as a System.Diagnostics.Process and redirect its standard output, input and error to a RichTextBox on a Windows form, so that I can have a python REPL on my form.
The process starts correctly (Start() returns true) however no output or error data is ever sent from the process:
If I try to Read from the StandardOutput or StandardError the read just hangs.
If I instead subscribe to OutputDataReceived and ErrorDataReceived they never fire.
started with ProcessStartInfo("Python.exe")
I only see output from python once I kill it by sending Ctrl + C (sent after pressing Enter at the end of the line asd, hence the 3rd line).
To clarify, I want to see "2" sent from python (either from Reading the StandardOutput stream, or in the data event), after I pressed enter after entering "1 + 1".
Why is no data being sent to the Standard outputs and no events raised whilst python is executing? Is it possible to have this work as I want it (so that response from python is given immediately).
Additional
If instead I start cmd.exe then everything is fine and I can use the form as I would a regular command prompt. So to some extent my application is working.
However if I try to start python using this form, then it hangs until I kill the process by sending Ctrl + C as before:
started with ProcessStartInfo("cmd.exe")
Evidently the standard input is getting to python (since the line number reported by the python error message changes depending on how many lines before it)
I am using:
Python 3.5.2 |Anaconda 4.2.0 (64-bit)| (default, Jul 5 2016, 11:41:13) [MSC v.1900 64 bit (AMD64)] on win32
Again:
Why does python not send any data to standard out or cause any events to be raised until it dies? How can I make it?
Code
Some of this follows the pattern of www.codeproject.com/Articles/335909/Embedding-a-Console-in-a-C-Application
Setup
var processStartInfo = new ProcessStartInfo("python.exe");
processStartInfo.UseShellExecute = false;
processStartInfo.ErrorDialog = false;
processStartInfo.RedirectStandardError = true;
processStartInfo.RedirectStandardInput = true;
processStartInfo.RedirectStandardOutput = true;
processStartInfo.CreateNoWindow = true;
process = new Process();
process.StartInfo = processStartInfo;
bool processStarted = process.Start();
outputReader = process.StandardOutput;
errorReader = process.StandardError;
inputWriter = process.StandardInput;
// start reading from standard output
outputWatchWorker.WorkerSupportsCancellation = true;
outputWatchWorker.DoWork += (o, e) =>
{
while (!outputWatchWorker.CancellationPending)
{
int nChars = 0;
string str;
char[] buffer = new char[1024];
nChars = outputReader.Read(buffer, 0, buffer.Length);
if (nChars > 0)
{
str = new string(buffer, 0, nChars);
Invoke((MethodInvoker)(() =>
{
WriteOutput(str, Color.Black);
}));
}
}
};
outputWatchWorker.RunWorkerAsync();
// I've removed an almost identical block of code for errorWatchWorker to read from the error stream
KeyDown event of RichTextBox
// some extra code here I haven't included to prevent deletion of stuff printed from standard out
// just checks the cursor position and then suppresses the event if certain keys are pressed
// I can provide if it will help
if (e.KeyCode == Keys.Return)
{
string input = textConsole.Text.Substring(inputStart, textConsole.SelectionStart - inputStart);
lastInput = input;
inputStart = textConsole.SelectionStart + 1; // inluding the new line
inputWriter.WriteLine(input);
inputWriter.Flush();
if (string.IsNullOrWhiteSpace(input)) e.SuppressKeyPress = true;
}
WriteOutput
public void WriteOutput(string output, Color color)
{
if (string.IsNullOrEmpty(lastInput) == false &&
(output == lastInput || output.Replace("\r\n", "") == lastInput))
return;
Invoke((Action)(() =>
{
// Write the output.
textConsole.SelectionColor = color;
textConsole.AppendText(output);
inputStart = textConsole.SelectionStart;
}));
}
The click listener of the "Ctrl + C" button to send Ctrl+C
just does
inputWriter.WriteLine("\x3");
based on this question How do I send ctrl+c to a process in c#?

Read Command (CMD) Window That Is Already Running

I'll try and simplify the problem I'm having. Firstly, I'd like to do this is C# but I'd be perfectly fine with any solution.
There's a console application running in a CMD window on a machine that spits out a new line of text every so often. This application is extremely unstable and sometimes freezes, but the window is still responsive so Windows has no idea.
I want to be able to read the contents of this screen so I can restart the process if there hasn't been an update within a certain threshold. I can do the logic no problem, but how can I tell if the screen has any new data?
I was thinking of screen shotting the window and comparing A to B. I know how to do the screen shots but I was looking for something a bit more elegant and to be honest, something that's not as resource intensive as taking a screen shot (The system is quite taxed whilst this application is running).
The application is launched via a .bat script which is why it resides in a CMD window (though obviously the process itself is accessible).
Thank you for any help and ideas.

Another way to receive console output is attach to the cmd process:
var poList= Process.GetProcesses().Where(process => process.ProcessName.Contains("cmd"));
var a = poList.First();
//FreeConsole();//if you use console application you must free self console
AttachConsole((uint) a.Id);
var err=Marshal.GetLastWin32Error();
var ptr=GetStdHandle(-11);
SMALL_RECT srctReadRect= new SMALL_RECT
{
Top = 0,Left = 0,Bottom = 1,Right = 79
};
CHAR_INFO[,] chiBuffer = new CHAR_INFO[2,80]; // [2][80];
COORD coordBufSize= new COORD
{
X = 2,Y = 80
};
COORD coordBufCoord = new COORD
{
X = 0,
Y = 0
};
bool fSuccess;
fSuccess = ReadConsoleOutput( ptr,chiBuffer,coordBufSize,chiBuffer coordBufCoord,ref srctReadRect);
all pinvoke functions can be copied form PInvike ConsoleFunctions
Let me know if you need mode detailed information

If you able to start batch file from C# wrapper application, create process via C# app:
Process proc = new Process();
proc.StartInfo = new ProcessStartInfo("d:\\batch.bat")
{
RedirectStandardOutput = true,
UseShellExecute = false
};
bool updated = false;
Timer waitTimer= new Timer(state =>
{
if (!updated)
{
proc.Kill();
return;
}
updated = false;
});
waitTimer.Change(1000, 1000);
proc.Start();
while (! proc.StandardOutput.EndOfStream)
{
var line = proc.StandardOutput.ReadLine();
updated = true;
Console.WriteLine(line);
}

Why does StandardOutput.Read() never return? (deadlock?)

Using C#, I want to automate a third-party Windows command-line program. Usually, it is an interactive console, you send commands, it may prompt for details, send back a result and display a prompt to ask for more commands. Typically:
c:\>console_access.exe
Prompt> version
2.03g.2321
Prompt>
I used .NET classes Process and ProcessStartInfo along with redirections of stdin/stdout/stderr.
public ConsoleAccess()
{
if (!File.Exists(consoleAccessPath)) throw new FileNotFoundException(consoleAccessPath + " not found");
myProcess = new Process();
ProcessStartInfo myProcessStartInfo = new ProcessStartInfo(consoleAccessPath, ""); // even "2>&1" as argument does not work; my code still hangs
myProcessStartInfo.CreateNoWindow = true;
myProcessStartInfo.UseShellExecute = false;
myProcessStartInfo.RedirectStandardOutput = true;
myProcessStartInfo.RedirectStandardError = true;
myProcessStartInfo.RedirectStandardInput = true;
//myProcessStartInfo.ErrorDialog = true; // I tried, to no avail.
myProcess.StartInfo = myProcessStartInfo;
outputQueue = new ConcurrentQueue<string>(); // thread-safe queue
errorQueue = new ConcurrentQueue<string>();
myProcess.Start();
myStandardOutput = myProcess.StandardOutput;
myStandardError = myProcess.StandardError;
myStandardInput = myProcess.StandardInput;
stdOutPumper = new Thread(new ThreadStart(PumpStdOutLoop));
stdOutPumper.Start();
stdErrPumper = new Thread(new ThreadStart(PumpStdErrLoop));
stdErrPumper.Start();
string empty = getResponse(); // check for prompt
string version = getVersion(); // one simple command
}
// [...]
private void PumpStdErrLoop()
{
while (true)
{
string message = myStandardError.ReadLine();
errorQueue.Enqueue(message);
}
}
private void PumpStdOutLoop()
{
while (true)
{
bool done = false;
string buffer = "";
//int blocksize = 1024;
string prompt = "Prompt> ";
while (!done)
{
//char[] intermediaire = new char[blocksize];
//int res = myStandardOutput.Read(intermediaire, 0, blocksize);
//buffer += new string(intermediaire).Substring(0, res);
byte b = (byte)myStandardOutput.Read(); // I go byte per byte, just in case the char[] above is the source of the problem. To no avail.
buffer += (char)b;
done = buffer.EndsWith(prompt);
}
buffer = buffer.Substring(0, buffer.Length - prompt.Length);
outputQueue.Enqueue(buffer);
}
}
Since this program returns "Prompt> " (important : without "\n" at the end) when it's waiting for commands, I can't use myProcess.BeginOutputReadLine();
However, I have to use threads because I must listen stdout AND stderr at the same time.
This is why I used threads and thread-safe queues for a class producer/consumer pattern.
"You can use asynchronous read operations to avoid these dependencies and their deadlock potential. Alternately, you can avoid the deadlock condition by creating two threads and reading the output of each stream on a separate thread." source: http://msdn.microsoft.com/en-us/library/system.diagnostics.process.standardoutput%28v=vs.100%29.aspx
With this design, all sequences like
* cmd -> result with no err (something on stdout, nothing on stderr)
* cmd -> error (something on stderr, nothing on stdout)
works as expected. no problem.
cmd -> result with warning (something on both stderr and stdout)
should work (I'm trying to reproduce this scenario)
however, for one command in particular -- a command that prompts for a password during its execution -- does not work:
main thread principal loops forever on
if (errorQueue.Count == 0 && outputQueue.Count == 0) { System.Threading.Thread.Sleep(500); }
thread pumping stdout waits forever on
byte b = (byte)myStandardOutput.Read();
thread pumping stdout waits a line forever on
string message = myStandardError.ReadLine();
What I don't get is why byte b = (byte)myStandardOutput.Read(); does not pump the message "password:". Nothing happens. I never get the first 'p'.
I feel I hit a deadlock scenario, but I do not understand why.
What's wrong?
(I don't think it is very relevant but I tried the above on .NET 4.0 with MS Visual Studio 2010 on Windows 7 32-bit.)

This is a very common failure mode for these kind of interactive console mode programs. The C runtime library automatically switches the stderr and stdout streams to buffered mode when it detects that output is being redirected. Important to improve throughput. So output goes into that buffer instead of getting directly written to the console. Getting your program to see the output requires the buffer to be flushed.
There are three scenarios where the buffer gets flushed. A flush occurs when the buffer is full, typically around 2 kilobytes. Or when the program writes a line terminator (\n). Or when the program explicitly calls fflush(). The first two scenarios do not occur, not enough output and the program isn't using \n. Which points at the problem, the original programmer forgot to call fflush(). Forgetting this is very common, the programmer simply never intended the program to be used other than in an interactive way.
Nothing can do about it, you'll need to ask the owner or author of the program to add fflush(). Maybe you can limp along by just assuming that the prompt is being written.

Capture output of process synchronously (i.e. "when it happens")

I am trying to start a process and capture the output, have come a far way, but am not quite at the solution I'd want.
Specifically, I am trying to reset the IIS on my development machine from a small utility application that I am writing. I have come to the conclusion, by experimenting, that the safe way to do this is by running iisreset.exe in a child process.
If you run iisreset.exe on a command prompt, you get feedback during the process. Running iisreset takes several seconds, and several lines of feedback is generated, with pauses in between.
I'd like to capture this feedback and present it in my Windows Forms application (in a ListBox), and I have succeeded with that. My remaining concern is that I dont get it until the child process finishes. I'd like to get the output from the child process, line by line, immediately when the lines are created.
I have tried to do my homework, reading/testing things from e.g. these:
How to spawn a process and capture its STDOUT in .NET?
Capturing console output from a .NET application (C#)
http://www.aspcode.net/ProcessStart-and-redirect-standard-output.aspx
and several more with similar content. Most (all?) get the output asynchronously (e.g. with Process.ReadToEnd()). I want the output synchonously, which acording to the MSDN documentation involves establishing an event handler etc and I've tried that. It works, but the event handler does not get called until the process exits. I get the output from iisreset.exe, but not until it has finished.
To rule out the possibility that this has something to do with iisreset.exe in particular, I wrote a small console application that generates some output, pausing in between:
namespace OutputGenerator
{
class Program
{
static void Main(string[] args)
{
System.Console.WriteLine("OutputGenerator starting and pausing for 10 seconds..");
System.Threading.Thread.Sleep(10000);
System.Console.WriteLine("Pausing for another 10 seconds..");
System.Threading.Thread.Sleep(10000);
System.Console.WriteLine("Exiting!");
}
}
}
Testing with this it turns out that I get captured data diretly when I want. So, to some extent it seems that the way iisreset.exe outputs the data come into play here.
Here is the code of the program (a Windows Forms application) that does the capture:
using System;
using System.Windows.Forms;
using System.Diagnostics;
namespace OutputCapturer
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void btnRun_Click(object sender, EventArgs e)
{
// Running this will show all output after the process has exited
//String path = #"C:\Windows\system32\iisreset.exe";
// Running this will show all output "when it happens"
String path = #"C:\OutputGenerator.exe";
var p = new Process();
p.StartInfo.FileName = path;
p.StartInfo.UseShellExecute = false; // ShellExecute = true not allowed when output is redirected..
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.CreateNoWindow = true;
p.OutputDataReceived += OutputDataReceived;
p.Start();
p.BeginOutputReadLine();
}
private delegate void OutputDataToTextboxDelegate(String s);
void OutputDataToTextbox(String s)
{
tbxOutput.Text += s + Environment.NewLine;
tbxOutput.Refresh();
}
private void OutputDataReceived(object sender, DataReceivedEventArgs e)
{
if (e.Data != null && e.Data.ToString() != "")
{
// Must run the update of the textbox in the same thread that created it..
tbxOutput.Invoke(
new OutputDataToTextboxDelegate(OutputDataToTextbox),
DateTime.Now.ToString() + ": " + e.Data.ToString()
);
}
}
}
}
Thinking it was an EOL-encoding problem (the output of iisreset.exe apearing as one line to my app)), I ran a debug session. Nope. The event handler for StandardOutput gets called several times (one time for each output line from iisreset.exe), buth these calls come in one burst after the process exits.
I would LOVE if I could get the output from iisreset.exe "when it happens" so that I can show it as a progress indication.
I've seen one other thread with the same/similar problem, Asynchronous capture from a process output not working properly , but w/o a solution.
I'm sort of stumped.

To do autoflushing of printfs / stdouts
C equivalent of autoflush (flush stdout after each write)?
This saved my ass...

It seems that sixlettervariables is correct, and that this has something to do with iisreset.exe isn't flushing it's buffers for each line. (I still wonder what makes it work on a plain command line - i.e. what does cmd.exe do?)
Anyhow.. I tried what apacay suggested, and wrote this:
private void btnRun_Click(object sender, EventArgs e)
{
// Running this will show the output after the process has finished
//String path = #"C:\Windows\system32\iisreset.exe";
// Running this will show all output "when it happens"
String path = #"C:\OutputGenerator.exe";
var p = new Process();
p.StartInfo.FileName = path;
p.StartInfo.UseShellExecute = false; // ShellExecute = true not allowed when output is redirected..
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.CreateNoWindow = true;
p.Start();
StreamReader sr = p.StandardOutput;
while (!sr.EndOfStream)
{
String s = sr.ReadLine();
if (s != "")
{
tbxOutput.Text += DateTime.Now.ToString() + ": " + s + Environment.NewLine;
}
tbxOutput.Refresh();
}
}
Notice that I am timestamping when I get each line. For my OutputGenerator I get this:
2011-07-06 17:49:11: OutputGenerator starting and pausing for 10 seconds..
2011-07-06 17:49:21: Pausing for another 10 seconds..
2011-07-06 17:49:31: Exiting!
And for iisreset.exe I get this:
2011-07-06 17:57:11: Attempting stop...
2011-07-06 17:57:11: Internet services successfully stopped
2011-07-06 17:57:11: Attempting start...
2011-07-06 17:57:11: Internet services successfully restarted
Running iisreset.exe on the command line, those lines come with pauses in between, over a span of perhaps 10 seconds.
The case seems more or less closed now. Not that I am all that satisfied, but I'm at roads end it seems. I'll reluctantly live with it..
To summarise: In the general case, it is quite possible to capture output synchronously with when it is generated. This thread presents code for two ways to do that - by establishing an event handler, and by "polling" the stream. In my specific case there is something with how iisreset.exe generates output that prevents this.
Thanks to those who participated and contributed!

Well.... you could kick it old-school. Output can be redirected to the input of another program using old-school DOS commands (foo.exe | bar.exe). Write a program that reads from standard in, and you'll get it every time the stream flushes.
Edit
You could also redirect the ouput to a named pipe and read from that. That would also be "as it happens".

Well, I tried a helper class that I know works: http://csharptest.net/browse/src/Library/Processes/ProcessRunner.cs
ProcessRunner runner = new ProcessRunner("iisreset.exe");
runner.OutputReceived += OutputDataReceived;
runner.Start("/RESTART", "/STATUS");
However, this still doesn't solve the problem with this specific executable. It seems that iisreset was written in such a way that this is not possible. Even running the following from the command line:
iisreset.exe /RESTART /STATUS > temp.txt
Still nothing is written to the text file 'temp.txt' until after all services have been restarted.
As for your example code, I would recommend reading a post I wrote some time ago: How to use System.Diagnostics.Process correctly. Specifically you are not reading the std::err stream or redirecting and closing the std::in stream. This can cause very undesirable results in your program. You can look at the example wrapper class linked above for how to do it with the output events, or if you want to directly read the streams you need to use two of your own threads.
static void Main()
{
ProcessStartInfo psi = new ProcessStartInfo(#"C:\Windows\system32\iisreset.exe", "/RESTART /STATUS");
psi.CreateNoWindow = true;
psi.UseShellExecute = false;
psi.RedirectStandardError = true;
psi.RedirectStandardOutput = true;
psi.RedirectStandardInput = true;
ManualResetEvent output_complete = new ManualResetEvent(false);
ManualResetEvent error_complete = new ManualResetEvent(false);
Process p = Process.Start(psi);
new ReadOutput(p.StandardOutput, output_complete);
new ReadOutput(p.StandardError, error_complete);
p.StandardInput.Close();
p.WaitForExit();
output_complete.WaitOne();
error_complete.WaitOne();
}
private class ReadOutput
{
private StreamReader _reader;
private ManualResetEvent _complete;
public ReadOutput(StreamReader reader, ManualResetEvent complete)
{
_reader = reader;
_complete = complete;
Thread t = new Thread(new ThreadStart(ReadAll));
t.Start();
}
void ReadAll()
{
int ch;
while(-1 != (ch = _reader.Read()))
{
Console.Write((char) ch);
}
_complete.Set();
}
}
I wrote this just to see if anything was coming through. Still got nothing until the end, so I think your just SOL on getting asynchronous output from iisreset.

I've had that problem and had to solve it when my logs where too long to read in a single readtoend.
This is what I've done to solve it. It's been doing Ok so far.
myProcess.StartInfo.FileName = path;
myProcess.StartInfo.Arguments = args;
myProcess.StartInfo.UseShellExecute = false;
myProcess.StartInfo.ErrorDialog = false;
myProcess.StartInfo.CreateNoWindow = true;
myProcess.StartInfo.RedirectStandardError = true;
myProcess.StartInfo.RedirectStandardInput = (stdIn != null);
myProcess.StartInfo.RedirectStandardOutput = true;
myProcess.Start();
int index;
OpenLogFile(myLog); //LOGGGGGGGGGGGGG
if (myProcess.StartInfo.RedirectStandardInput)
{
StreamWriter sw = myProcess.StandardInput;
sw.Write(stdIn + Convert.ToChar(26));
}
StreamReader sr = myProcess.StandardOutput;
/*stdOut = new ArrayLi
*/
while (!sr.EndOfStream)
{ //LOGGGGGGGGGGGGG
Log(sr.ReadLine(), true);
}
Here's OpenLogFile
private void OpenLogFile(string fileName)
{
if (file == StreamWriter.Null)
{
file = new StreamWriter(fileName, true);
file.AutoFlush = true;
}
}
Of course that Log is a function that does something elsewhere. But the solution to you question lies here:
while (!sr.EndOfStream)
{ //LOGGGGGGGGGGGGG
Log(sr.ReadLine(), true);
}
while stream reader is still reading, you can be writing it down as the log comes out.

For my specific situation, the solution is what Mr Moses suggested in a comment above, i.e. run iisreset /stop followed by iisreset /start.
I need a proper answer, rather than a comment, in order to mark it as my "accepted answer", so this answer is more of administrativa than a new contribution. The cred should go to Mr Moses.. :-)