Redirect process output C#

Use RedirectStandardOutput.

Sample from MSDN:

// Start the child process.
Process p = new Process();
// Redirect the output stream of the child process.
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.FileName = "Write500Lines.exe";
p.Start();
// Do not wait for the child process to exit before
// reading to the end of its redirected stream.
// p.WaitForExit();
// Read the output stream first and then wait.
string output = p.StandardOutput.ReadToEnd();
p.WaitForExit();

Also see OutputDataReceived and BeginOutputReadLine() for an alternative to ReadToEnd(), that will better fulfill your "see output while the process is running" requirement.

If you want to execute an exe from your c# application and get the output from it then you can use the below code

System.Diagnostics.Process p = new System.Diagnostics.Process();            

p.StartInfo.FileName = "PATH TO YOUR FILE";
p.StartInfo.UseShellExecute = false;
p.StartInfo.Arguments = metalType + " " + graphHeight + " " + graphWidth;
p.StartInfo.CreateNoWindow = true;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardError = true;              

p.EnableRaisingEvents = true;
p.Start();            
svgText = p.StandardOutput.ReadToEnd();

using(StreamReader s = p.StandardError)
{
    string error = s.ReadToEnd();
    p.WaitForExit(20000);
}

Don't forgete to write p.EnableRaisingEvents = true;