if (p.HasExited)
            {                
                //从输出流获取执行结果 
                strRst = p.StandardOutput.ReadToEnd();
            }

------解决方案--------------------

C# code
static void Main(string[] args)
        {
            Process ps = new Process();
            ps.StartInfo.FileName = "cmd.exe";
            ps.StartInfo.RedirectStandardOutput = true;
            ps.StartInfo.RedirectStandardInput = true;
            ps.StartInfo.CreateNoWindow = true;
            ps.StartInfo.UseShellExecute = false;
            ps.StartInfo.StandardOutputEncoding = System.Text.Encoding.Default;
            ps.StartInfo.RedirectStandardError = false;
            ps.OutputDataReceived += new DataReceivedEventHandler(ps_OutputDataReceived);

            ps.Start();
            ps.BeginOutputReadLine();
            ps.StandardInput.WriteLine(@"dir c:\");
            ps.StandardInput.Close();
            ps.WaitForExit();
            ps.Close();
        }
        static void ps_OutputDataReceived(object sender, DataReceivedEventArgs e)
        {
            if (e.Data == null)
            {
                return;
            }
            Console.Write(e.Data+"\n");
        }

------解决方案--------------------

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p.StandardInput.WriteLine("exit");