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"Multi-Step" commands while using CMD.exe in C#

I'm trying to use "multi-step" command in a c# script, for example the command "net user usrname *" contains 3 steps to enter a password and then validate, i don't know if it is possible to send extra arguments while the Process is running
My code:
Process p = new Process();
p.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
p.StartInfo.CreateNoWindow = true;
p.StartInfo.FileName = "cmd.exe";
p.StartInfo.Arguments = "/C " + command;
p.StartInfo.WorkingDirectory = startupFolder;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.UseShellExecute = false;
p.Start();
string output = p.StandardOutput.ReadToEnd();
string error = p.StandardError.ReadToEnd();

You would concatenate each command with "&". For example, "cmd /k echo Test 1 & echo test 2".
Edit:
I created a remote control/remote admin solution a while back that uses this same technique to allow you to run batch and PowerShell scripts against remote computers via the web portal. As shown in the below screenshot, it works.
The C# that executes the command can be found here: https://github.com/Jay-Rad/InstaTech_Client/blob/master/InstaTech_Service/Socket.cs#L614
if (cmdProcess == null || cmdProcess.HasExited)
{
var psi2 = new ProcessStartInfo("cmd.exe", "/k " + command);
psi2.RedirectStandardOutput = true;
psi2.RedirectStandardInput = true;
psi2.RedirectStandardError = true;
psi2.UseShellExecute = false;
psi2.WorkingDirectory = Path.GetPathRoot(Environment.SystemDirectory);
cmdProcess = new Process();
cmdProcess.StartInfo = psi2;
cmdProcess.EnableRaisingEvents = true;
cmdProcess.OutputDataReceived += async (object sender, DataReceivedEventArgs args) =>
{
jsonMessage.Status = "ok";
jsonMessage.Output = args.Data;
await SocketSend(jsonMessage);
};
cmdProcess.ErrorDataReceived += async (object sender, DataReceivedEventArgs args) =>
{
jsonMessage.Status = "ok";
jsonMessage.Output = args.Data;
await SocketSend(jsonMessage);
};
cmdProcess.Start();
cmdProcess.BeginOutputReadLine();
cmdProcess.BeginErrorReadLine();
}
else
{
cmdProcess.StandardInput.WriteLine(command);
}

How to pass Ctrl+Enter command to Process when using C# StandardInput redirection

Im trying to make C# application that uses hunpos tagger.
Runing hunpos-tag.exe requires three input arguments: model, inputFile, outputFile
In cmd it would look something like this:
hunpos-tag.exe model <inputFile >outputFile
Although, hunpos-tag.exe can be run with just the model, at that point it'll wait for text input (from cmd) which is processed when the tagger receives Ctrl+Enter as input and the results are displayed through standard output. I've been trying to use StandardInput redirection in C# but I don't know how to send the Ctrl+Enter end command (Or if the redirection works at all). The code:
string inputFilePath = path + "\\CopyFolder\\rr";
string pathToExe = path + "\\CopyFolder\\hunpos-tag.exe";
ProcessStartInfo startInfo = new ProcessStartInfo
{
FileName = pathToExe,
UseShellExecute = false,
RedirectStandardInput = true,
WorkingDirectory = Directory.GetDirectoryRoot(pathToExe),
Arguments = path + "\\CopyFolder\\model.hunpos.mte5.defnpout",
};
try
{
Process _proc = new Process();
_proc.StartInfo.FileName = pathToExe;
_proc.StartInfo.UseShellExecute = false;
_proc.StartInfo.RedirectStandardInput = true;
_proc.StartInfo.Arguments = path + "\\CopyFolder\\model.hunpos.mte5.defnpout";
_proc.Start();
var streamReader = new StreamReader(inputFilePath);
_proc.StandardInput.Write(streamReader.ReadToEnd());
_proc.StandardInput.Flush();
_proc.StandardInput.Close();
_proc.WaitForExit();
}
catch (Exception e)
{
Console.WriteLine(e);
}
When I run the following code the tagger has the following output:
model loaded
tagger compiled
Fatal error: exception Sys_error("Bad file description")
The exception is caused by the .Close() command. The file is valid and works when runned from cmd. Any ideas on how could I send the end command or how to emulate cmd command without using redirection?

It wouldn't work with input redirection so I managed it with running cmd procces and passing it the required command.
using (Process process = new Process())
{
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardOutput = true;
process.StartInfo.RedirectStandardError = true;
process.StartInfo.WorkingDirectory = #"C:\";
process.StartInfo.FileName = Path.Combine(Environment.SystemDirectory, "cmd.exe");
// Redirects the standard input so that commands can be sent to the shell.
process.StartInfo.RedirectStandardInput = true;
// Runs the specified command and exits the shell immediately.
//process.StartInfo.Arguments = #"/c ""dir""";
process.OutputDataReceived += ProcessOutputDataHandler;
process.ErrorDataReceived += ProcessErrorDataHandler;
process.Start();
process.BeginOutputReadLine();
process.BeginErrorReadLine();
// Send a directory command and an exit command to the shell
process.StandardInput.WriteLine(path + "\\CopyFolder\\hunpos-tag.exe " + path + "\\CopyFolder\\model.hunpos.mte5.defnpout <" + path + "\\CopyFolder\\rr >" + path + "\\CopyFolder\\zz");
process.StandardInput.WriteLine("exit");
process.WaitForExit();
}

How to hide cmd window while running a batch file?

How to hide cmd window while running a batch file?
I use the following code to run batch file
process = new Process();
process.StartInfo.FileName = batchFilePath;
process.Start();

If proc.StartInfo.UseShellExecute is false, then you are launching the process and can use:
proc.StartInfo.CreateNoWindow = true;
If proc.StartInfo.UseShellExecute is true, then the OS is launching the process and you have to provide a "hint" to the process via:
proc.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
However the called application may ignore this latter request.
If using UseShellExecute = false, you might want to consider redirecting standard output/error, to capture any logging produced:
proc.StartInfo.UseShellExecute = false;
proc.StartInfo.RedirectStandardOutput = true;
proc.OutputDataReceived += new DataReceivedEventHandler(ProcessOutputHandler);
proc.StartInfo.RedirectStandardError = true;
proc.ErrorDataReceived += new DataReceivedEventHandler(ProcessOutputHandler);
And have a function like
private void ProcessOutputHandler(object sendingProcess, DataReceivedEventArgs outLine)
{
if (!String.IsNullOrEmpty(outLine.Data)) // use the output outLine.Data somehow;
}
There's a good page covering CreateNoWindow this on an MSDN blog.
There is also a bug in Windows which may throw a dialog and defeat CreateNoWindow if you are passing a username/password. For details
http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=98476
http://support.microsoft.com/?kbid=818858

According to the Process properties, you do have a:
Property: CreateNoWindow
Notes: Allows you to run a command line program silently.
It does not flash a console window.
and:
Property: WindowStyle
Notes: Use this to set windows as hidden.
The author has used ProcessWindowStyle.Hidden often.
As an example!
static void LaunchCommandLineApp()
{
// For the example
const string ex1 = "C:\\";
const string ex2 = "C:\\Dir";
// Use ProcessStartInfo class
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.CreateNoWindow = false;
startInfo.UseShellExecute = false;
startInfo.FileName = "dcm2jpg.exe";
startInfo.WindowStyle = ProcessWindowStyle.Hidden;
startInfo.Arguments = "-f j -o \"" + ex1 + "\" -z 1.0 -s y " + ex2;
try
{
// Start the process with the info we specified.
// Call WaitForExit and then the using statement will close.
using (Process exeProcess = Process.Start(startInfo))
{
exeProcess.WaitForExit();
}
}
catch
{
// Log error.
}
}

Use:
process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;

This is what worked for me,
When you redirect all of the input and output, and set the window hidden it should work
Process p = new Process();
p.StartInfo.RedirectStandardError = true;
p.StartInfo.RedirectStandardInput = true;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.UseShellExecute = false;
p.StartInfo.CreateNoWindow = true;

try with this and this where the c# code is embedded into the batch files:
#echo off
echo self minimizing
call getCmdPid.bat
call windowMode.bat -pid %errorlevel% -mode minimized
echo --other commands--
pause
Though it might be not so easy to unhide the window.

Execute multiple command lines with the same process using .NET

I'm trying to execute multiple commands without create a new process each time. Basically, I want to start the DOS command shell, switch to the MySQL command shell, and execute a command. Here's how I am calling the procedure (also below). Also, how do I handle the "\"'s in the command?
ExecuteCommand("mysql --user=root --password=sa casemanager", 100, false);
ExecuteCommand(#"\. " + Environment.CurrentDirectory + #"\MySQL\CaseManager.sql", 100, true);
private void ExecuteCommand(string Command, int Timeout, Boolean closeProcess)
{
ProcessStartInfo ProcessInfo;
Process Process;
ProcessInfo = new ProcessStartInfo("cmd.exe", "/C " + Command);
ProcessInfo.CreateNoWindow = false;
ProcessInfo.UseShellExecute = false;
Process = Process.Start(ProcessInfo);
Process.WaitForExit(Timeout);
if (closeProcess == true) { Process.Close(); }
}

You can redirect standard input and use a StreamWriter to write to it:
Process p = new Process();
ProcessStartInfo info = new ProcessStartInfo();
info.FileName = "cmd.exe";
info.RedirectStandardInput = true;
info.UseShellExecute = false;
p.StartInfo = info;
p.Start();
using (StreamWriter sw = p.StandardInput)
{
if (sw.BaseStream.CanWrite)
{
sw.WriteLine("mysql -u root -p");
sw.WriteLine("mypassword");
sw.WriteLine("use mydb;");
}
}

const string strCmdText = "/C command1&command2";
Process.Start("CMD.exe", strCmdText);

Couldn't you just write all the commands into a .cmd file in the temp folder and then execute that file?

As another answer alludes to under newer versions of Windows it seems to be necessary to read the standard output and/or standard error streams otherwise it will stall between commands. A neater way to do that instead of using delays is to use an async callback to consume output from the stream:
static void RunCommands(List<string> cmds, string workingDirectory = "")
{
var process = new Process();
var psi = new ProcessStartInfo();
psi.FileName = "cmd.exe";
psi.RedirectStandardInput = true;
psi.RedirectStandardOutput = true;
psi.RedirectStandardError = true;
psi.UseShellExecute = false;
psi.WorkingDirectory = workingDirectory;
process.StartInfo = psi;
process.Start();
process.OutputDataReceived += (sender, e) => { Console.WriteLine(e.Data); };
process.ErrorDataReceived += (sender, e) => { Console.WriteLine(e.Data); };
process.BeginOutputReadLine();
process.BeginErrorReadLine();
using (StreamWriter sw = process.StandardInput)
{
foreach (var cmd in cmds)
{
sw.WriteLine (cmd);
}
}
process.WaitForExit();
}

I prefer to do it by using a BAT file.
With BAT file you have more control and can do whatever you want.
string batFileName = path + #"\" + Guid.NewGuid() + ".bat";
using (StreamWriter batFile = new StreamWriter(batFileName))
{
batFile.WriteLine($"YOUR COMMAND");
batFile.WriteLine($"YOUR COMMAND");
batFile.WriteLine($"YOUR COMMAND");
}
ProcessStartInfo processStartInfo = new ProcessStartInfo("cmd.exe", "/c " + batFileName);
processStartInfo.UseShellExecute = true;
processStartInfo.CreateNoWindow = true;
processStartInfo.WindowStyle = ProcessWindowStyle.Normal;
Process p = new Process();
p.StartInfo = processStartInfo;
p.Start();
p.WaitForExit();
File.Delete(batFileName);

ProcessStartInfo pStartInfo = new ProcessStartInfo();
pStartInfo.FileName = "CMD";
pStartInfo.Arguments = #"/C mysql --user=root --password=sa casemanager && \. " + Environment.CurrentDirectory + #"\MySQL\CaseManager.sql"
pStartInfo.WindowStyle = ProcessWindowStyle.Hidden;
Process.Start(pStartInfo);
The && is the way to tell the command shell that there is another command to execute.

A command-line process such cmd.exe or mysql.exe will usually read (and execute) whatever you (the user) type in (at the keyboard).
To mimic that, I think you want to use the RedirectStandardInput property: http://msdn.microsoft.com/en-us/library/system.diagnostics.processstartinfo.redirectstandardinput.aspx

You could also tell MySQL to execute the commands in the given file, like so:
mysql --user=root --password=sa casemanager < CaseManager.sql

You need to READ ALL data from input, before send another command!
And you can't ask to READ if no data is avaliable... little bit suck isn't?
My solutions... when ask to read... ask to read a big buffer... like 1 MEGA...
And you will need wait a min 100 milliseconds... sample code...
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim oProcess As New Process()
Dim oStartInfo As New ProcessStartInfo("cmd.exe", "")
oStartInfo.UseShellExecute = False
oStartInfo.RedirectStandardOutput = True
oStartInfo.RedirectStandardInput = True
oStartInfo.CreateNoWindow = True
oProcess.StartInfo = oStartInfo
oProcess.Start()
Dim Response As String = String.Empty
Dim BuffSize As Integer = 1024 * 1024
Dim x As Char() = New Char(BuffSize - 1) {}
Dim bytesRead As Integer = 0
oProcess.StandardInput.WriteLine("dir")
Threading.Thread.Sleep(100)
bytesRead = oProcess.StandardOutput.Read(x, 0, BuffSize)
Response = String.Concat(Response, String.Join("", x).Substring(0, bytesRead))
MsgBox(Response)
Response = String.Empty
oProcess.StandardInput.WriteLine("dir c:\")
Threading.Thread.Sleep(100)
bytesRead = 0
bytesRead = oProcess.StandardOutput.Read(x, 0, BuffSize)
Response = String.Concat(Response, String.Join("", x).Substring(0, bytesRead))
MsgBox(Response)
End Sub
End Class

I'm using these methods:
public static Process StartCommand(params string[] commands) => StartCommand(commands, false);
public static Process StartCommand(IEnumerable<string> commands, bool inBackground, bool runAsAdministrator = true)
{
Process p = new Process();
p.StartInfo.FileName = "cmd.exe";
if(commands.Any()) p.StartInfo.Arguments = #"/C " + string.Join("&&", commands);
if (runAsAdministrator)
p.StartInfo.Verb = "runas";
if (inBackground)
{
p.StartInfo.CreateNoWindow = true;
p.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
}
p.Start();
return p;
}
Enjoy...

How To: Execute command line in C#, get STD OUT results

How do I execute a command-line program from C# and get back the STD OUT results? Specifically, I want to execute DIFF on two files that are programmatically selected and write the results to a text box.

// 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 = "YOURBATCHFILE.bat";
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();
Code is from MSDN.

Here's a quick sample:
//Create process
System.Diagnostics.Process pProcess = new System.Diagnostics.Process();
//strCommand is path and file name of command to run
pProcess.StartInfo.FileName = strCommand;
//strCommandParameters are parameters to pass to program
pProcess.StartInfo.Arguments = strCommandParameters;
pProcess.StartInfo.UseShellExecute = false;
//Set output of program to be written to process output stream
pProcess.StartInfo.RedirectStandardOutput = true;
//Optional
pProcess.StartInfo.WorkingDirectory = strWorkingDirectory;
//Start the process
pProcess.Start();
//Get program output
string strOutput = pProcess.StandardOutput.ReadToEnd();
//Wait for process to finish
pProcess.WaitForExit();

There one other parameter I found useful, which I use to eliminate the process window
pProcess.StartInfo.CreateNoWindow = true;
this helps to hide the black console window from user completely, if that is what you desire.

// usage
const string ToolFileName = "example.exe";
string output = RunExternalExe(ToolFileName);
public string RunExternalExe(string filename, string arguments = null)
{
var process = new Process();
process.StartInfo.FileName = filename;
if (!string.IsNullOrEmpty(arguments))
{
process.StartInfo.Arguments = arguments;
}
process.StartInfo.CreateNoWindow = true;
process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardError = true;
process.StartInfo.RedirectStandardOutput = true;
var stdOutput = new StringBuilder();
process.OutputDataReceived += (sender, args) => stdOutput.AppendLine(args.Data); // Use AppendLine rather than Append since args.Data is one line of output, not including the newline character.
string stdError = null;
try
{
process.Start();
process.BeginOutputReadLine();
stdError = process.StandardError.ReadToEnd();
process.WaitForExit();
}
catch (Exception e)
{
throw new Exception("OS error while executing " + Format(filename, arguments)+ ": " + e.Message, e);
}
if (process.ExitCode == 0)
{
return stdOutput.ToString();
}
else
{
var message = new StringBuilder();
if (!string.IsNullOrEmpty(stdError))
{
message.AppendLine(stdError);
}
if (stdOutput.Length != 0)
{
message.AppendLine("Std output:");
message.AppendLine(stdOutput.ToString());
}
throw new Exception(Format(filename, arguments) + " finished with exit code = " + process.ExitCode + ": " + message);
}
}
private string Format(string filename, string arguments)
{
return "'" + filename +
((string.IsNullOrEmpty(arguments)) ? string.Empty : " " + arguments) +
"'";
}

The accepted answer on this page has a weakness that is troublesome in rare situations. There are two file handles which programs write to by convention, stdout, and stderr.
If you just read a single file handle such as the answer from Ray, and the program you are starting writes enough output to stderr, it will fill up the output stderr buffer and block. Then your two processes are deadlocked. The buffer size may be 4K.
This is extremely rare on short-lived programs, but if you have a long running program which repeatedly outputs to stderr, it will happen eventually. This is tricky to debug and track down.
There are a couple good ways to deal with this.
One way is to execute cmd.exe instead of your program and use the /c argument to cmd.exe to invoke your program along with the "2>&1" argument to cmd.exe to tell it to merge stdout and stderr.
var p = new Process();
p.StartInfo.FileName = "cmd.exe";
p.StartInfo.Arguments = "/c mycmd.exe 2>&1";
Another way is to use a programming model which reads both handles at the same time.
var p = new Process();
p.StartInfo.FileName = "cmd.exe";
p.StartInfo.Arguments = #"/c dir \windows";
p.StartInfo.CreateNoWindow = true;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardInput = false;
p.OutputDataReceived += (a, b) => Console.WriteLine(b.Data);
p.ErrorDataReceived += (a, b) => Console.WriteLine(b.Data);
p.Start();
p.BeginErrorReadLine();
p.BeginOutputReadLine();
p.WaitForExit();

System.Diagnostics.ProcessStartInfo psi =
new System.Diagnostics.ProcessStartInfo(#"program_to_call.exe");
psi.RedirectStandardOutput = true;
psi.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
psi.UseShellExecute = false;
System.Diagnostics.Process proc = System.Diagnostics.Process.Start(psi); ////
System.IO.StreamReader myOutput = proc.StandardOutput;
proc.WaitForExit(2000);
if (proc.HasExited)
{
string output = myOutput.ReadToEnd();
}

You will need to use ProcessStartInfo with RedirectStandardOutput enabled - then you can read the output stream. You might find it easier to use ">" to redirect the output to a file (via the OS), and then simply read the file.
[edit: like what Ray did: +1]

One-liner run command:
new Process() { StartInfo = new ProcessStartInfo("echo", "Hello, World") }.Start();
Read output of command in shortest amount of reable code:
var cliProcess = new Process() {
StartInfo = new ProcessStartInfo("echo", "Hello, World") {
UseShellExecute = false,
RedirectStandardOutput = true
}
};
cliProcess.Start();
string cliOut = cliProcess.StandardOutput.ReadToEnd();
cliProcess.WaitForExit();
cliProcess.Close();

In case you also need to execute some command in the cmd.exe, you can do the following:
// 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 = "cmd.exe";
p.StartInfo.Arguments = "/C vol";
p.Start();
// Read the output stream first and then wait.
string output = p.StandardOutput.ReadToEnd();
p.WaitForExit();
Console.WriteLine(output);
This returns just the output of the command itself:
You can also use StandardInput instead of StartInfo.Arguments:
// Start the child process.
Process p = new Process();
// Redirect the output stream of the child process.
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardInput = true;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.FileName = "cmd.exe";
p.Start();
// Read the output stream first and then wait.
p.StandardInput.WriteLine("vol");
p.StandardInput.WriteLine("exit");
string output = p.StandardOutput.ReadToEnd();
p.WaitForExit();
Console.WriteLine(output);
The result looks like this:

Since the most answers here dont implement the using statemant for IDisposable and some other stuff wich I think could be nessecary I will add this answer.
For C# 8.0
// Start a process with the filename or path with filename e.g. "cmd". Please note the
//using statemant
using myProcess.StartInfo.FileName = "cmd";
// add the arguments - Note add "/c" if you want to carry out tge argument in cmd and
// terminate
myProcess.StartInfo.Arguments = "/c dir";
// Allows to raise events
myProcess.EnableRaisingEvents = true;
//hosted by the application itself to not open a black cmd window
myProcess.StartInfo.UseShellExecute = false;
myProcess.StartInfo.CreateNoWindow = true;
// Eventhander for data
myProcess.Exited += OnOutputDataRecived;
// Eventhandler for error
myProcess.ErrorDataReceived += OnErrorDataReceived;
// Eventhandler wich fires when exited
myProcess.Exited += OnExited;
// Starts the process
myProcess.Start();
//read the output before you wait for exit
myProcess.BeginOutputReadLine();
// wait for the finish - this will block (leave this out if you dont want to wait for
// it, so it runs without blocking)
process.WaitForExit();
// Handle the dataevent
private void OnOutputDataRecived(object sender, DataReceivedEventArgs e)
{
//do something with your data
Trace.WriteLine(e.Data);
}
//Handle the error
private void OnErrorDataReceived(object sender, DataReceivedEventArgs e)
{
Trace.WriteLine(e.Data);
//do something with your exception
throw new Exception();
}
// Handle Exited event and display process information.
private void OnExited(object sender, System.EventArgs e)
{
Trace.WriteLine("Process exited");
}

Here is small example:
using System;
using System.Diagnostics;
class Program
{
static void Main(string[] args)
{
var p = Process.Start(
new ProcessStartInfo("git", "branch --show-current")
{
CreateNoWindow = true,
UseShellExecute = false,
RedirectStandardError = true,
RedirectStandardOutput = true,
WorkingDirectory = Environment.CurrentDirectory
}
);
p.WaitForExit();
string branchName =p.StandardOutput.ReadToEnd().TrimEnd();
string errorInfoIfAny =p.StandardError.ReadToEnd().TrimEnd();
if (errorInfoIfAny.Length != 0)
{
Console.WriteLine($"error: {errorInfoIfAny}");
}
else {
Console.WriteLine($"branch: {branchName}");
}
}
}
I believe this is shortest form.
Please notice that most of command line tools easily confuse standard output and standard error, sometimes it makes sense just to clue those together into single string.
Also p.ExitCode might be sometimes useful.
Example above serves for purpose of writing command line utility like tools if you want to do it by yourself. Please note that for cli automation it's also possible to use Cake Frosten and Cake Git extension.

You can launch any command line program using the Process class, and set the StandardOutput property of the Process instance with a stream reader you create (either based on a string or a memory location). After the process completes, you can then do whatever diff you need to on that stream.

This might be useful for someone if your attempting to query the local ARP cache on a PC/Server.
List<string[]> results = new List<string[]>();
using (Process p = new Process())
{
p.StartInfo.CreateNoWindow = true;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.UseShellExecute = false;
p.StartInfo.Arguments = "/c arp -a";
p.StartInfo.FileName = #"C:\Windows\System32\cmd.exe";
p.Start();
string line;
while ((line = p.StandardOutput.ReadLine()) != null)
{
if (line != "" && !line.Contains("Interface") && !line.Contains("Physical Address"))
{
var lineArr = line.Trim().Split(' ').Select(n => n).Where(n => !string.IsNullOrEmpty(n)).ToArray();
var arrResult = new string[]
{
lineArr[0],
lineArr[1],
lineArr[2]
};
results.Add(arrResult);
}
}
p.WaitForExit();
}

This may not be the best/easiest way, but may be an option:
When you execute from your code, add " > output.txt" and then read in the output.txt file.

There is a ProcessHelper Class in PublicDomain open source code which might interest you.

Julian's solution is tested working with some minor corrections. The following is an example that also used https://sourceforge.net/projects/bat-to-exe/ GenericConsole.cs and https://www.codeproject.com/Articles/19225/Bat-file-compiler program.txt for args part:
using System;
using System.Text; //StringBuilder
using System.Diagnostics;
using System.IO;
class Program
{
private static bool redirectStandardOutput = true;
private static string buildargument(string[] args)
{
StringBuilder arg = new StringBuilder();
for (int i = 0; i < args.Length; i++)
{
arg.Append("\"" + args[i] + "\" ");
}
return arg.ToString();
}
static void Main(string[] args)
{
Process prc = new Process();
prc.StartInfo = //new ProcessStartInfo("cmd.exe", String.Format("/c \"\"{0}\" {1}", Path.Combine(Environment.CurrentDirectory, "mapTargetIDToTargetNameA3.bat"), buildargument(args)));
//new ProcessStartInfo(Path.Combine(Environment.CurrentDirectory, "mapTargetIDToTargetNameA3.bat"), buildargument(args));
new ProcessStartInfo("mapTargetIDToTargetNameA3.bat");
prc.StartInfo.Arguments = buildargument(args);
prc.EnableRaisingEvents = true;
if (redirectStandardOutput == true)
{
prc.StartInfo.UseShellExecute = false;
}
else
{
prc.StartInfo.UseShellExecute = true;
}
prc.StartInfo.CreateNoWindow = true;
prc.OutputDataReceived += OnOutputDataRecived;
prc.ErrorDataReceived += OnErrorDataReceived;
//prc.Exited += OnExited;
prc.StartInfo.RedirectStandardOutput = redirectStandardOutput;
prc.StartInfo.RedirectStandardError = redirectStandardOutput;
try
{
prc.Start();
prc.BeginOutputReadLine();
prc.BeginErrorReadLine();
prc.WaitForExit();
}
catch (Exception e)
{
Console.WriteLine("OS error: " + e.Message);
}
prc.Close();
}
// Handle the dataevent
private static void OnOutputDataRecived(object sender, DataReceivedEventArgs e)
{
//do something with your data
Console.WriteLine(e.Data);
}
//Handle the error
private static void OnErrorDataReceived(object sender, DataReceivedEventArgs e)
{
Console.WriteLine(e.Data);
}
// Handle Exited event and display process information.
//private static void OnExited(object sender, System.EventArgs e)
//{
// var process = sender as Process;
// if (process != null)
// {
// Console.WriteLine("ExitCode: " + process.ExitCode);
// }
// else
// {
// Console.WriteLine("Process exited");
// }
//}
}
The code need to compile inside VS2007, using commandline csc.exe generated executable will not show console output correctly, or even crash with CLR20r3 error. Comment out the OnExited event process, the console output of the bat to exe will be more like the original bat console output.

Just for fun, here's my completed solution for getting PYTHON output - under a button click - with error reporting. Just add a button called "butPython" and a label called "llHello"...
private void butPython(object sender, EventArgs e)
{
llHello.Text = "Calling Python...";
this.Refresh();
Tuple<String,String> python = GoPython(#"C:\Users\BLAH\Desktop\Code\Python\BLAH.py");
llHello.Text = python.Item1; // Show result.
if (python.Item2.Length > 0) MessageBox.Show("Sorry, there was an error:" + Environment.NewLine + python.Item2);
}
public Tuple<String,String> GoPython(string pythonFile, string moreArgs = "")
{
ProcessStartInfo PSI = new ProcessStartInfo();
PSI.FileName = "py.exe";
PSI.Arguments = string.Format("\"{0}\" {1}", pythonFile, moreArgs);
PSI.CreateNoWindow = true;
PSI.UseShellExecute = false;
PSI.RedirectStandardError = true;
PSI.RedirectStandardOutput = true;
using (Process process = Process.Start(PSI))
using (StreamReader reader = process.StandardOutput)
{
string stderr = process.StandardError.ReadToEnd(); // Error(s)!!
string result = reader.ReadToEnd(); // What we want.
return new Tuple<String,String> (result,stderr);
}
}