C#写的自动关机及执行CMD命令

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
int i = 0;
private int ti;
public Form1()
{
InitializeComponent();
timer1.Enabled = false;
}
public string CmdPc(string cmdinput)
{
Process p = new Process();
p.StartInfo.FileName = "cmd.exe";
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardInput = true;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.CreateNoWindow = true;
try
{
p.Start();
p.StandardInput.WriteLine(cmdinput);
p.StandardInput.WriteLine("exit");
string ss=p.StandardOutput.ReadToEnd();
p.WaitForExit();
p.Close();
return ss;
}
catch
{
string ss = "命令执行失败";
return ss;
}
}
private void button1_Click(object sender, EventArgs e)
{
//label1.Text = ClosePc();
if (textBox2.Text != "")
{
ti = Convert.ToInt32(textBox2.Text);
timer1.Enabled = true;
button3.Enabled = true;
button4.Enabled = true;
button1.Enabled = false;
}
else { label4.Text = "请输入时间，单位/分钟"; }
}
private void timer1_Tick(object sender, EventArgs e)
{

if (ti - i == 1)//从5开始到计时
{
timer1.Enabled = false;
label4.Text = "时间到，关机！！";
label1.Text = CmdPc("Shutdown.exe -s -f");
button4.Visible = true;
}
else
{
i++;
string j = (ti - i).ToString();
label4.Text = j;
}
}
private void button3_Click(object sender, EventArgs e)
{
timer1.Enabled = true;
button4.Enabled = true;
button1.Enabled = true;
}
private void button2_Click(object sender, EventArgs e)
{
label1.Text=CmdPc(textBox1.Text);
}
private void button4_Click_1(object sender, EventArgs e)
{
timer1.Enabled = false;
button4.Enabled = false;
button1.Enabled = true;
label4.Text = "停止";
}
private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 13)
{
ti = Convert.ToInt32(textBox2.Text);
timer1.Enabled = true;
button3.Enabled = true;
button4.Enabled = true;
button1.Enabled = false;
}
}

}
}