I want know if there any way to write command to cli by using c#.
That because I want to write simple GUI program wich writes command like "ping" "telnet" to the CLI of windows.

thanks alot

You can use methods of System.Diagnostics.Process & ProcessStartInfo class.

System.Diagnostics.ProcessStartInfo ps = new System.Diagnostics.ProcessStartInfo(put_here_commandOrfilename);
            ps.Arguments = put_here_arguments;
            ps.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
            ps.UseShellExecute = false;
            ps.RedirectStandardInput = true;
            ps.RedirectStandardOutput = true;
            ps.RedirectStandardError = true;
            

            System.Diagnostics.Process process=System.Diagnostics.Process.Start(ps);
            
            process.WaitForExit();

            string output = process.StandardOutput.ReadToEnd();
            
            process.Close();