从ASPX页面运行命令行，并将输出返回到页面

Question

I'm trying to access the command line and execute a command, and then return the output to my aspx page. A good example would be running dir on page load of an aspx page and returning the output via Response.Write(). I have tried using the code below. When I try debugging this it runs but never finishes loading and no output is rendered. I am using C# and .NET Framework 3.5sp1. Any help much appreciated.

Thanks, Bryan

public partial class CommandLine : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        System.Diagnostics.Process si = new System.Diagnostics.Process();
        si.StartInfo.WorkingDirectory = @"c:\";
        si.StartInfo.UseShellExecute = false;
        si.StartInfo.FileName = "cmd.exe";
        si.StartInfo.Arguments = "dir";
        si.StartInfo.CreateNoWindow = true;
        si.StartInfo.RedirectStandardInput = true;
        si.StartInfo.RedirectStandardOutput = true;
        si.StartInfo.RedirectStandardError = true;
        si.Start();
        string output = si.StandardOutput.ReadToEnd();
        si.Close();
        Response.Write(output);
    }
}

Answer 1

You have a problem with the syntax of commandline arguments to cmd.exe. This is why cmd never exits.
In order to have cmd.exe run a program and then quit, you need to send it the syntax "/c [command]". Try running the same code with the line

        si.StartInfo.Arguments = "dir";

replaced with

        si.StartInfo.Arguments = "/c dir";

and see if it works.

Answer 2

Most likely your problem is with the permissions. The user under which ASP.NET process runs is with very limited rights.

So, either you have to set the proper permissions for that user, or run ASP.NET under some other user.

This hides a security risks though, so you have to be very careful.

Answer 3

This is madness! Use the System.IO namepace to create your file list from inside your C# program! It's very easy to do; although this technique also has authorization issues.

Answer 4

Use System.Diagnostics.Process.

Here is some ASP.NET code shelling out to run subversion commands on the command line.

    ///////////////////////////////////////////////////////////////////////
    public static string run_svn(string args_without_password, string svn_username, string svn_password)
    {
        // run "svn.exe" and capture its output

        System.Diagnostics.Process p = new System.Diagnostics.Process();
        string svn_path = Util.get_setting("SubversionPathToSvn", "svn");
        p.StartInfo.FileName = svn_path;
        p.StartInfo.UseShellExecute = false;
        p.StartInfo.RedirectStandardOutput = true;
        p.StartInfo.RedirectStandardError = true;

        args_without_password += " --non-interactive";
        Util.write_to_log ("Subversion command:" + svn_path + " " + args_without_password);

        string args_with_password = args_without_password;

        if (svn_username != "")
        {
            args_with_password += " --username ";
            args_with_password += svn_username;
            args_with_password += " --password ";
            args_with_password += svn_password;
        }

        p.StartInfo.Arguments = args_with_password;
        p.Start();
        string stdout = p.StandardOutput.ReadToEnd();
        p.WaitForExit();
        stdout += p.StandardOutput.ReadToEnd();

        string error = p.StandardError.ReadToEnd();

        if (error != "")
        {
            Util.write_to_log(error);
            Util.write_to_log(stdout);
        }

        if (error != "")
        {
            string msg = "ERROR:";
            msg += "<div style='color:red; font-weight: bold; font-size: 10pt;'>";
            msg += "<br>Error executing svn.exe command from web server.";
            msg += "<br>" + error;
            msg += "<br>Arguments passed to svn.exe (except user/password):" + args_without_password;
            if (error.Contains("File not found"))
            {
                msg += "<br><br>***** Has this file been deleted or renamed? See the following links:";
                msg += "<br><a href=http://svn.collab.net/repos/svn/trunk/doc/user/svn-best-practices.html>http://svn.collab.net/repos/svn/trunk/doc/user/svn-best-practices.html</a>";
                msg += "<br><a href=http://subversion.open.collab.net/articles/best-practices.html>http://subversion.open.collab.net/articles/best-practices.html</a>";
                msg += "</div>";
            }
            return msg;
        }
        else
        {
            return stdout;
        }
    }