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Foo.cmd won't output lines in process (on website)

Tags:

c#

.net

process

cmd

I've a problem understanding the in's and out's of the ProcessStartInfo class in .NET. I use this class for executing .exe programs like FFmpeg with no issues whatsoever.

But when I use ProcessStartInfo to start a .cmd program like a simple foo.cmd containing only @echo Hello world it doesn't output anything.

    ProcessStartInfo oInfo = new ProcessStartInfo(@"C:\Program Files (x86)\itms\foo.cmd")
    {
        UseShellExecute = false,
        RedirectStandardError = true,
        RedirectStandardOutput = true,
        CreateNoWindow = true
    };

    using (Process p = new Process())
    {
        p.StartInfo = oInfo;
        p.OutputDataReceived += new DataReceivedEventHandler(transporter_OutputDataReceived);

        p.Start();

        p.BeginOutputReadLine();

        p.WaitForExit();
    }

private void transporter_OutputDataReceived(object sender, DataReceivedEventArgs e)
{
    Response.Write(e.Data + " - line<br/>");
}

I've seen a bunch of examples, where people use cmd.exe to start the .cmd program and I've tried this, but with no success. The program just keeps loading indefinitely.

    ProcessStartInfo oInfo = new ProcessStartInfo("cmd", "/c start foo.cmd")
    {
        UseShellExecute = false,
        RedirectStandardError = true,
        RedirectStandardOutput = true,
        CreateNoWindow = true,
        WorkingDirectory = @"C:\Program Files (x86)\itms"
    };

The foo.cmd program works and outputs successfully when using a command line tool in Windows and on Mac.

Could someone please demystify this for me.

Thanks

EDIT

The code behaves correctly when executed locally. The problem arises when I execute the code on our website. Either the program isn't allowed to execute or the output is somehow disabled.

Only cmd.exe is returning output ´"cmd", "/c dir"´ is e.g. returning information about the current folder content.

Could this actually be a permission issue?

like image 803
Marle1 Avatar asked Jul 20 '12 08:07

Marle1


2 Answers

I found the answer myself and will post a solution for anyone interested.

The source of the issue is fairly hard to debug, because the problem originated in how IIS handles users and processes.

As I thought, there was nothing wrong with the code itself.

Answer

In IIS, a website is running in a AppPool. An AppPool is assigned an user identity. The default identity is a virtual built-in account named ApplicationPoolIdentity. This user does not have the privilege to call any (as far as I know) external batch/command scripts.

Providing a username, password and domain for a administrative user when starting a new process, didn't solve anything for me - It might be that I'm just misunderstanding the whole concept.

Using <identity impersonate="true" userName="domain\user" password="pass" /> in the webconfig didn't solve anything either. This is apparently because the assigned AppPool user is still the author of all processes.

What really bugged me out, was that I could execute .exe files, but not .cmd or .bat files.

The solution for me, was to create a new user with privileges to execute batch scripts and select that user as the AppPool user in IIS.

Edit: As I have mentioned in the comments, the user I'm working with is created on an Active Directory server as this particular file server is on a network share. The user is part of the local server group IIS_IUSRS on my webserver and has read/write/execute privileges in the folder where the executable programs are stored.

Edit2: The solution works for local user accounts as well as long as the user is part of the local server group IIS_IUSRS and has read/write/execute privileges in the folder where the executable programs are stored.

like image 121
Marle1 Avatar answered Nov 14 '22 14:11

Marle1


you will need to use it this way

   using (Process p = Process.Start(oInfo))
    {
.....

Reason is becuase Process.Start() and Process.Star(startinfo) works slightly different

Process.Start() - Starts (or reuses) the process resource that is specified by the StartInfo property of this Process component and associates it with the component.

Return Value

Type: System.Boolean true if a process resource is started; false if no new process resource is started (for example, if an existing process is reused).

Process.Start(StartInfo) - Starts the process resource that is specified by the parameter containing process start information (for example, the file name of the process to start) and associates the resource with a new Process component.

Return Value

Type: System.Diagnostics.Process A new Process component that is associated with the process resource, or null if no process resource is started (for example, if an existing process is reused).

like image 31
HatSoft Avatar answered Nov 14 '22 12:11

HatSoft