Question

I’ve got a web application that has a page full of batch files which the user can run, view the output, and send input. My problem occurs when the process hits something which causes it to pause, such as a pause, or a question that requires the user to press Y or N to continue. We’ll go with pause for the purposes of this question.

This is my batch file:

pause

When run in windows, I get the output displayed on my screen “Press any key to continue…”, I press enter, and it exits. But when my app runs this batch file, I dont get any output, but I know what it’s waiting for so I press enter, and only then do I see the output “Press any key to continue…”.

I’ve created a simplified version of my code in a console app, and the same thing happens, I get a blank screen, I press enter, and then I see “Press any key to continue…”

Any idea how I go about getting this line of output BEFORE I am required to press the key?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.IO;

namespace BatchCaller
{
    class Program
    {
        static void Main(string[] args)
        {
            ProcessStartInfo psi = new ProcessStartInfo()
            {
                FileName = @"C:\Projects\BatchCaller\BatchCaller\Test2.bat",
                RedirectStandardOutput = true,
                RedirectStandardInput = true,
                UseShellExecute = false,
                CreateNoWindow = true
            };

            Process proc = new Process();

            proc.StartInfo = psi;
            proc.OutputDataReceived += new DataReceivedEventHandler(proc_OutputDataReceived);
            proc.Start();
            proc.BeginOutputReadLine();

            // Problem is not here, ignore this, just my temporary input method.
            // Problem still occurs when these two lines are removed.
            string inputText = Console.ReadLine();
            proc.StandardInput.WriteLine(inputText);

            proc.WaitForExit();
        }

        static void proc_OutputDataReceived(object sender, DataReceivedEventArgs e)
        {
            // This method doesnt get called for output: "Press any key to continue..."
            // Why?
            if (e.Data != null)
                Console.WriteLine(e.Data);
        }
    }
}

Answer 1

I realised it wasn’t reading the last line because the data received event was only being triggered after there was a whole line of output, but when it pauses or asks a question, the cursor is still on the same line. A new thread that continuously checked the output stream was the solution to this small problem.

I also managed to solve my whole problem so that now what I’ve got when I run a script close ly resembles a command prompt window.

Here’s a very basic summary of how it works:

I start a new process that runs a batch file. At the same time I start a new thread that continuously loops asking the process for more output, and storing that output in a queue. My .NET timer continuously checks the queue for text, and outputs it into my ajax panel. I use a text box and ajax to input text into the process input and into my ajax panel. I also needed a lot of javascript and I had to use session variables to make it run smoothly.

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true"
    CodeBehind="Scripts.aspx.cs" Inherits="MITool.Scripts" %>

<asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
    <script type="text/javascript" language="javascript">
        var script = '';

        function ShowScriptModal() {
            $('#overlay').css({ width: $(document).width(), height: $(document).height(), 'display': 'block' }).animate({ opacity: 0.85 }, 0, function () { $('#scriptModal').show(); });
        }

        function ScriptInputKeypress(e) {
            if (e.keyCode == 13) {
                ScriptInput();
            }
        }

        function ScriptInput() {
            var txtInput = document.getElementById("txtInput");
            var input = txtInput.value;
            var hiddenInput = document.getElementById("hiddenInput");

            if (input == '')
                return;

            hiddenInput.value = input;

            txtInput.value = '';
        }

        function CheckForNewOutput() {
            var outputUpdatePanel = document.getElementById("OutputUpdatePanel");
            var pageScript = outputUpdatePanel.innerHTML;
            if (script != pageScript) {
                script = pageScript;
                ScrollToBottom();
            }
            setTimeout("CheckForNewOutput()", 100);
        }

        function ScrollToBottom() {
            $('#OutputPanel').scrollTop($('#OutputUpdatePanel').height());
        }
    </script>
    <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true" EnablePartialRendering="true" LoadScriptsBeforeUI="true" />
    <div id="scriptModal">
        <div id="ScriptInputOutput">
            <asp:Panel ID="OutputPanel" runat="server" Width="700" Height="250" ScrollBars="Vertical"
                Style="margin: 10px auto; border: 1px solid #CCC; padding: 5px;" ClientIDMode="Static">
                <controls:ScriptOutput ID="ScriptOutputControl" runat="server" />
            </asp:Panel>
            <asp:Panel ID="InputPanel" runat="server" DefaultButton="btnScriptInput" >
                <asp:TextBox ID="txtInput" runat="server" ClientIDMode="Static" onkeypress="ScriptInputKeypress(event)" />
                <asp:HiddenField ID="hiddenInput" runat="server" ClientIDMode="Static" />
                <asp:Button ID="btnScriptInput" runat="server" Text="Script Input" ClientIDMode="Static" OnClick="btnScriptInput_Click" style="display:none" />           
                <asp:Button ID="btnExit" runat="server" CssClass="floatRight" Text="Exit" OnClick="btnExit_Click" />
            </asp:Panel>
        </div>
    </div>
    <asp:Literal ID="litScript" runat="server" />
    <ul id="breadcrumb">
        <li><a href="/dashboard.aspx">Main page</a> &gt;</li>
        <li class="current">Scripts</li>
    </ul>
    <div class="content">
        <h2>
            <asp:Label ID="lblHeader" runat="server" Text="Scripts" /></h2>
        <div class="clear">
        </div>
        <div class="table-content">
            <asp:Label ID="lblMessage" runat="server" CssClass="redMessage" />
            <asp:Repeater ID="rptScripts" runat="server" OnItemCommand="rptScripts_ItemCommand">
                <HeaderTemplate>
                    <table class="table" cellpadding="0" cellspacing="0">
                        <tr>
                            <th>
                                ID
                            </th>
                            <th>
                                Name
                            </th>
                            <th>
                                Location
                            </th>
                            <th>
                            </th>
                        </tr>
                </HeaderTemplate>
                <ItemTemplate>
                    <tr>
                        <td>
                            <%# Eval("ScriptId") %>
                        </td>
                        <td>
                            <%# Eval("Name") %>
                        </td>
                        <td>
                            <%# Eval("Path") %>
                        </td>
                        <td>
                            <asp:LinkButton ID="btnRunScript" runat="server" Text="Run" CommandName="Run" CommandArgument='<%# Eval("ScriptId") %>' />
                        </td>
                    </tr>
                </ItemTemplate>
                <FooterTemplate>
                    </table>
                </FooterTemplate>
            </asp:Repeater>
            <div>
            </div>
        </div>
    </div>
    <script type="text/javascript" language="javascript">
        CheckForNewOutput();
    </script>
</asp:Content>

// ====== ====== ====== ====== ====== ====== ====== ====== ====== ====== ======//

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using MITool.Data.ScriptManager;
using System.Diagnostics;
using System.IO;
using System.Web.Security;
using System.Web.Services;
using System.Collections.Concurrent;
using System.Threading;

namespace MITool
{
    public partial class Scripts : System.Web.UI.Page
    {
        ConcurrentQueue<char> ScriptOutputQueue
        {
            get
            {
                return (ConcurrentQueue<char>)Session["ScriptOutputQueue"];
            }
            set
            {
                Session["ScriptOutputQueue"] = value;
            }
        }
        Process CurrentProcess
        {
            get
            {
                return (Process)Session["CurrentProcess"];
            }
            set
            {
                Session["CurrentProcess"] = value;
            }
        }
        bool ScriptRunning
        {
            get
            {
                if (CurrentProcess == null)
                    return false;
                if (!CurrentProcess.HasExited || !CurrentProcess.StandardOutput.EndOfStream)
                    return true;
                return false;
            }
        }
        bool OutputProcessing
        {
            get
            {
                if (ScriptOutputQueue != null && ScriptOutputQueue.Count != 0)
                    return true;
                return false;
            }
        }

        Thread OutputThread;

        void Reset()
        {
            ScriptOutputControl.SetTimerEnabled(false);
            ScriptOutputControl.ClearOutputText();
            if (CurrentProcess != null && !CurrentProcess.HasExited)
                CurrentProcess.Kill();
            if (OutputThread != null && OutputThread.IsAlive)
                OutputThread.Abort();
            ScriptOutputQueue = new ConcurrentQueue<char>();

            litScript.Text = string.Empty;
            txtInput.Text = string.Empty;
        }

        void Page_Load(object sender, EventArgs e)
        {
            if (IsPostBack) return;

            Reset();

            FormsIdentity id = (FormsIdentity)HttpContext.Current.User.Identity;
            string role = id.Ticket.UserData;

            ScriptData data = new ScriptData();
            List<Script> scripts = data.GetScriptsByRole(role);
            rptScripts.DataSource = scripts;
            rptScripts.DataBind();
        }

        protected void rptScripts_ItemCommand(object source, RepeaterCommandEventArgs e)
        {
            switch (e.CommandName)
            {
                case "Run": StartScript(Int32.Parse(e.CommandArgument.ToString()));
                    break;
            }
        }

        void StartScript(int id)
        {
            if (ScriptRunning || OutputProcessing)
                return;

            Reset();

            ScriptData data = new ScriptData();
            History history = new History()
            {
                UserName = HttpContext.Current.User.Identity.Name,
                BatchFileId = id,
                DateRun = DateTime.Now
            };
            data.CreateHistory(history);            

            Script script = data.GetScript(id);

            ProcessStartInfo psi = new ProcessStartInfo()
            {
                FileName = script.Path,
                RedirectStandardOutput = true,
                RedirectStandardInput = true,
                UseShellExecute = false,
                CreateNoWindow = true
            };

            CurrentProcess = new Process();
            CurrentProcess.StartInfo = psi;

            OutputThread = new Thread(Output);

            CurrentProcess.Start();
            OutputThread.Start();

            ScriptOutputControl.SetTimerEnabled(true);

            litScript.Text = "<script type=\"text/javascript\" language=\"javascript\">ShowScriptModal();</script>";

            SetFocus("txtInput");
        }

        void Output()
        {
            while (ScriptRunning)
            {
                var x = CurrentProcess.StandardOutput.Read();
                if (x != -1)
                    ScriptOutputQueue.Enqueue((char)x);
            }
        }

        public void btnScriptInput_Click(object sender, EventArgs e)
        {
            string input = hiddenInput.Value.ToString();

            ScriptOutputControl.Input(input);

            foreach (char x in input.ToArray())
            {
                if (CurrentProcess != null && !CurrentProcess.HasExited)
                {
                    CurrentProcess.StandardInput.Write(x);
                }
                Thread.Sleep(1);
            }
        }

        protected void btnExit_Click(object sender, EventArgs e)
        {
            Reset();
        }
    }
}

// ====== ====== ====== ====== ====== ====== ====== ====== ====== ====== ======//

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="ScriptOutput.ascx.cs"
    Inherits="MITool.Controls.ScriptOutput" %>
<asp:Label ID="lblStats" runat="server" Style="color: Red" />
<br />
<asp:UpdatePanel ID="OutputUpdatePanel" runat="server" ClientIDMode="Static">
    <Triggers>
        <asp:AsyncPostBackTrigger ControlID="UpdateTimer" EventName="Tick" />
        <asp:AsyncPostBackTrigger ControlID="btnScriptInput" EventName="Click" />
    </Triggers>
    <ContentTemplate>
        <asp:Literal ID="litOutput" runat="server" />
    </ContentTemplate>
</asp:UpdatePanel>
<asp:Timer ID="UpdateTimer" Interval="100" runat="server" OnTick="UpdateTimer_Tick" Enabled="false" />

// ====== ====== ====== ====== ====== ====== ====== ====== ====== ====== ======//

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections.Concurrent;
using System.Diagnostics;

namespace MITool.Controls
{
    public partial class ScriptOutput : System.Web.UI.UserControl
    {
        string Output
        {
            get
            {
                if (Session["Output"] != null)
                    return Session["Output"].ToString();
                return string.Empty;
            }
            set
            {
                Session["Output"] = value;
            }
        }

        ConcurrentQueue<char> ScriptOutputQueue
        {
            get
            {
                return (ConcurrentQueue<char>)Session["ScriptOutputQueue"];
            }
            set
            {
                Session["ScriptOutputQueue"] = value;
            }
        }
        Process CurrentProcess
        {
            get
            {
                return (Process)Session["CurrentProcess"];
            }
            set
            {
                Session["CurrentProcess"] = value;
            }
        }
        bool ScriptRunning
        {
            get
            {
                if (CurrentProcess == null)
                    return false;
                if (!CurrentProcess.HasExited || CurrentProcess.StandardOutput.Peek() != -1)
                    return true;
                return false;
            }
        }
        bool OutputProcessing
        {
            get
            {
                if (ScriptOutputQueue != null && ScriptOutputQueue.Count != 0)
                    return true;
                return false;
            }
        }

        public void SetTimerEnabled(bool enabled)
        {
            UpdateTimer.Enabled = enabled;
        }
        public void ClearOutputText()
        {
            Output = string.Empty;
            litOutput.Text = Output;
        }

        protected void UpdateTimer_Tick(object sender, EventArgs e)
        {
            ProcessOutput();

            if (!ScriptRunning && !OutputProcessing)
            {
                UpdateTimer.Enabled = false;

                Output += "<br />// SCRIPT END //<br />";
                litOutput.Text = Output;
            }
        }

        public void Input(string s) 
        {
            Output += "<br />// " + s + "<br />";
        }

        void ProcessOutput()
        {
            string s = string.Empty;

            while (ScriptOutputQueue != null && ScriptOutputQueue.Any())
            {
                char x;
                if (ScriptOutputQueue.TryDequeue(out x))
                {
                    s += x;
                }
            }

            if (s != string.Empty)
            {
                s = Server.HtmlEncode(s);
                s = s.Replace("\r\n", "<br />");

                Output += s;
            }

            litOutput.Text = Output;
        }
    }
}