How read command output from existing command process using C#

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C#

Dear all,

I need to get output of command window , its already existing process , from this process i need to read output(command line output) by using c#.

Note: I am not starting any process from here. Process already executed in diff place and need to verify string from command line.

Regard's
Suri

What I have tried:

By using this i am getting output , i need without process start already running process need to get output data :

string command = "/c " + richTextBox2.Text;

           ProcessStartInfo procStartInfo = new ProcessStartInfo("CMD", command);

           Process proc = new Process();
           proc.StartInfo = procStartInfo;
          // proc.Start();
           procStartInfo.RedirectStandardOutput = true;
           procStartInfo.UseShellExecute = false;
           proc.OutputDataReceived += new DataReceivedEventHandler(proc_OutputDataReceived);
           proc.Start();
           proc.BeginOutputReadLine();
           proc.WaitForExit();

void proc_OutputDataReceived(object sender, DataReceivedEventArgs e)
       {
           if (e.Data != null)
           {
               string newLine = e.Data.Trim() + Environment.NewLine;
             //  MethodInvoker append = () => richTextBox1.Text += newLine;
               MethodInvoker append = () => richTextBox1.AppendText(newLine);
               richTextBox1.BeginInvoke(append);
           }
       }