RedirectStandardOutput using C# - c#

I want to launch a .exe program using C# and read the values from the cmd generated from the .exe
The .exe launches successfully but I cannot read the values:
This is my code:
ProcessStartInfo start = new ProcessStartInfo();
start.FileName = (#"D:\BSC\Thesis\Raphael_Thesis\smiledetector\bin\smiledetector.exe");
start.WorkingDirectory = #"D:\BSC\Thesis\Raphael_Thesis\smiledetector\bin\";
start.UseShellExecute = false;
start.RedirectStandardOutput = true;
//Start the process
using (Process process = Process.Start(start))
{
// Read in all the text from the process with the StreamReader.
using (StreamReader reader = process.StandardOutput)
{
string result = reader.ReadToEnd();
textBox1.Text = result;
}
}

As Sam I Am has indicated, drop the using block for the StreamReader
using (Process process = Process.Start(start))
{
string result = process.StandardOutput.ReadToEnd();
textBox1.Text = result;
}
Keep in mind however your calling application will block until process completes and all the output can be read.

You need something like this:
private void btnStart_Click(object sender, EventArgs e)
{
p.StartInfo.FileName = #"D:\BSC\Thesis\Raphael_Thesis\smileDetector\vs2010\smiledetectorDebug";
p.StartInfo.WorkingDirectory = #"D:\BSC\Thesis\Raphael_Thesis\smileDetector\vs2010\";
p.StartInfo.RedirectStandardOutput = true;
p.EnableRaisingEvents = true;
p.StartInfo.UseShellExecute = false;
p.OutputDataReceived += new DataReceivedEventHandler(OutputHander);
p.Start();
p.BeginOutputReadLine();
p.WaitForExit();
}
where p is Process p = new Process();
void p_OutputDataReceived(object sender, DataReceivedEventArgs e)
{
data.Add(Convert.ToInt32(e.Data));
}
where data is a List of int

I don't see any weird thing in your code, it should work fine. Taking a look at the doc, it gives a brief example of how to redirect it:
// Start the child process.
using(Process p = new Process())
{
// Redirect the output stream of the child process.
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.FileName = #"D:\BSC\Thesis\Raphael_Thesis\smiledetector\bin\smiledetector.exe";
p.WorkingDirectory = #"D:\BSC\Thesis\Raphael_Thesis\smiledetector\bin\";
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();
}
source: Process.StandardOutput Property

Related

how to get Powershell output of this code? [duplicate]

I would like to run an external command line program from my Mono/.NET app.
For example, I would like to run mencoder. Is it possible:
To get the command line shell output, and write it on my text box?
To get the numerical value to show a progress bar with time elapsed?
When you create your Process object set StartInfo appropriately:
var proc = new Process
{
StartInfo = new ProcessStartInfo
{
FileName = "program.exe",
Arguments = "command line arguments to your executable",
UseShellExecute = false,
RedirectStandardOutput = true,
CreateNoWindow = true
}
};
then start the process and read from it:
proc.Start();
while (!proc.StandardOutput.EndOfStream)
{
string line = proc.StandardOutput.ReadLine();
// do something with line
}
You can use int.Parse() or int.TryParse() to convert the strings to numeric values. You may have to do some string manipulation first if there are invalid numeric characters in the strings you read.
You can process your output synchronously or asynchronously.
1. Synchronous example
static void runCommand()
{
Process process = new Process();
process.StartInfo.FileName = "cmd.exe";
process.StartInfo.Arguments = "/c DIR"; // Note the /c command (*)
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardOutput = true;
process.StartInfo.RedirectStandardError = true;
process.Start();
//* Read the output (or the error)
string output = process.StandardOutput.ReadToEnd();
Console.WriteLine(output);
string err = process.StandardError.ReadToEnd();
Console.WriteLine(err);
process.WaitForExit();
}
Note that it's better to process both output and errors: they must be handled separately.
(*) For some commands (here StartInfo.Arguments) you must add the /c directive, otherwise the process freezes in the WaitForExit().
2. Asynchronous example
static void runCommand()
{
//* Create your Process
Process process = new Process();
process.StartInfo.FileName = "cmd.exe";
process.StartInfo.Arguments = "/c DIR";
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardOutput = true;
process.StartInfo.RedirectStandardError = true;
//* Set your output and error (asynchronous) handlers
process.OutputDataReceived += new DataReceivedEventHandler(OutputHandler);
process.ErrorDataReceived += new DataReceivedEventHandler(OutputHandler);
//* Start process and handlers
process.Start();
process.BeginOutputReadLine();
process.BeginErrorReadLine();
process.WaitForExit();
}
static void OutputHandler(object sendingProcess, DataReceivedEventArgs outLine)
{
//* Do your stuff with the output (write to console/log/StringBuilder)
Console.WriteLine(outLine.Data);
}
If you don't need to do complicate operations with the output, you can bypass the OutputHandler method, just adding the handlers directly inline:
//* Set your output and error (asynchronous) handlers
process.OutputDataReceived += (s, e) => Console.WriteLine(e.Data);
process.ErrorDataReceived += (s, e) => Console.WriteLine(e.Data);
Alright, for anyone who wants both Errors and Outputs read, but gets deadlocks with any of the solutions, provided in other answers (like me), here is a solution that I built after reading MSDN explanation for StandardOutput property.
Answer is based on T30's code:
static void runCommand()
{
//* Create your Process
Process process = new Process();
process.StartInfo.FileName = "cmd.exe";
process.StartInfo.Arguments = "/c DIR";
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardOutput = true;
process.StartInfo.RedirectStandardError = true;
//* Set ONLY ONE handler here.
process.ErrorDataReceived += new DataReceivedEventHandler(ErrorOutputHandler);
//* Start process
process.Start();
//* Read one element asynchronously
process.BeginErrorReadLine();
//* Read the other one synchronously
string output = process.StandardOutput.ReadToEnd();
Console.WriteLine(output);
process.WaitForExit();
}
static void ErrorOutputHandler(object sendingProcess, DataReceivedEventArgs outLine)
{
//* Do your stuff with the output (write to console/log/StringBuilder)
Console.WriteLine(outLine.Data);
}
The standard .NET way of doing this is to read from the Process' StandardOutput stream. There is an example in the linked MSDN docs. Similar, you can read from StandardError, and write to StandardInput.
It is possible to get the command line shell output of a process as described here : http://www.c-sharpcorner.com/UploadFile/edwinlima/SystemDiagnosticProcess12052005035444AM/SystemDiagnosticProcess.aspx
This depends on mencoder. If it ouputs this status on the command line then yes :)
you can use shared memory for the 2 processes to communicate through, check out MemoryMappedFile
you'll mainly create a memory mapped file mmf in the parent process using "using" statement then create the second process till it terminates and let it write the result to the mmf using BinaryWriter, then read the result from the mmf using the parent process, you can also pass the mmf name using command line arguments or hard code it.
make sure when using the mapped file in the parent process that you make the child process write the result to the mapped file before the mapped file is released in the parent process
Example:
parent process
private static void Main(string[] args)
{
using (MemoryMappedFile mmf = MemoryMappedFile.CreateNew("memfile", 128))
{
using (MemoryMappedViewStream stream = mmf.CreateViewStream())
{
BinaryWriter writer = new BinaryWriter(stream);
writer.Write(512);
}
Console.WriteLine("Starting the child process");
// Command line args are separated by a space
Process p = Process.Start("ChildProcess.exe", "memfile");
Console.WriteLine("Waiting child to die");
p.WaitForExit();
Console.WriteLine("Child died");
using (MemoryMappedViewStream stream = mmf.CreateViewStream())
{
BinaryReader reader = new BinaryReader(stream);
Console.WriteLine("Result:" + reader.ReadInt32());
}
}
Console.WriteLine("Press any key to continue...");
Console.ReadKey();
}
Child process
private static void Main(string[] args)
{
Console.WriteLine("Child process started");
string mmfName = args[0];
using (MemoryMappedFile mmf = MemoryMappedFile.OpenExisting(mmfName))
{
int readValue;
using (MemoryMappedViewStream stream = mmf.CreateViewStream())
{
BinaryReader reader = new BinaryReader(stream);
Console.WriteLine("child reading: " + (readValue = reader.ReadInt32()));
}
using (MemoryMappedViewStream input = mmf.CreateViewStream())
{
BinaryWriter writer = new BinaryWriter(input);
writer.Write(readValue * 2);
}
}
Console.WriteLine("Press any key to continue...");
Console.ReadKey();
}
to use this sample, you'll need to create a solution with 2 projects inside, then you take the build result of the child process from %childDir%/bin/debug and copy it to %parentDirectory%/bin/debug then run the parent project
childDir and parentDirectory are the folder names of your projects on the pc
good luck :)
You can log process output using below code:
ProcessStartInfo pinfo = new ProcessStartInfo(item);
pinfo.CreateNoWindow = false;
pinfo.UseShellExecute = true;
pinfo.RedirectStandardOutput = true;
pinfo.RedirectStandardInput = true;
pinfo.RedirectStandardError = true;
pinfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Normal;
var p = Process.Start(pinfo);
p.WaitForExit();
Process process = Process.Start(new ProcessStartInfo((item + '>' + item + ".txt"))
{
UseShellExecute = false,
RedirectStandardOutput = true
});
process.WaitForExit();
string output = process.StandardOutput.ReadToEnd();
if (process.ExitCode != 0) {
}
How to launch a process (such as a bat file, perl script, console program) and have its standard output displayed on a windows form:
processCaller = new ProcessCaller(this);
//processCaller.FileName = #"..\..\hello.bat";
processCaller.FileName = #"commandline.exe";
processCaller.Arguments = "";
processCaller.StdErrReceived += new DataReceivedHandler(writeStreamInfo);
processCaller.StdOutReceived += new DataReceivedHandler(writeStreamInfo);
processCaller.Completed += new EventHandler(processCompletedOrCanceled);
processCaller.Cancelled += new EventHandler(processCompletedOrCanceled);
// processCaller.Failed += no event handler for this one, yet.
this.richTextBox1.Text = "Started function. Please stand by.." + Environment.NewLine;
// the following function starts a process and returns immediately,
// thus allowing the form to stay responsive.
processCaller.Start();
You can find ProcessCaller on this link: Launching a process and displaying its standard output
I was running into the infamous deadlock problem when calling Process.StandardOutput.ReadLine and Process.StandardOutput.ReadToEnd.
My goal/use case is simple. Start a process and redirect it's output so I can capture that output and log it to the console via .NET Core's ILogger<T> and also append the redirected output to a file log.
Here's my solution using the built in async event handlers Process.OutputDataReceived and Process.ErrorDataReceived.
var p = new Process
{
StartInfo = new ProcessStartInfo(
command.FileName, command.Arguments
)
{
RedirectStandardOutput = true,
RedirectStandardError = true,
UseShellExecute = false,
}
};
// Asynchronously pushes StdOut and StdErr lines to a thread safe FIFO queue
var logQueue = new ConcurrentQueue<string>();
p.OutputDataReceived += (sender, args) => logQueue.Enqueue(args.Data);
p.ErrorDataReceived += (sender, args) => logQueue.Enqueue(args.Data);
// Start the process and begin streaming StdOut/StdErr
p.Start();
p.BeginOutputReadLine();
p.BeginErrorReadLine();
// Loop until the process has exited or the CancellationToken is triggered
do
{
var lines = new List<string>();
while (logQueue.TryDequeue(out var log))
{
lines.Add(log);
_logger.LogInformation(log)
}
File.AppendAllLines(_logFilePath, lines);
// Asynchronously sleep for some time
try
{
Task.Delay(5000, stoppingToken).Wait(stoppingToken);
}
catch(OperationCanceledException) {}
} while (!p.HasExited && !stoppingToken.IsCancellationRequested);
The solution that worked for me in win and linux is the folling
// GET api/values
[HttpGet("cifrado/{xml}")]
public ActionResult<IEnumerable<string>> Cifrado(String xml)
{
String nombreXML = DateTime.Now.ToString("ddMMyyyyhhmmss").ToString();
String archivo = "/app/files/"+nombreXML + ".XML";
String comando = " --armor --recipient bibankingprd#bi.com.gt --encrypt " + archivo;
try{
System.IO.File.WriteAllText(archivo, xml);
//String comando = "C:\\GnuPG\\bin\\gpg.exe --recipient licorera#local.com --armor --encrypt C:\\Users\\Administrador\\Documents\\pruebas\\nuevo.xml ";
ProcessStartInfo startInfo = new ProcessStartInfo() {FileName = "/usr/bin/gpg", Arguments = comando };
Process proc = new Process() { StartInfo = startInfo, };
proc.StartInfo.RedirectStandardOutput = true;
proc.StartInfo.RedirectStandardError = true;
proc.Start();
proc.WaitForExit();
Console.WriteLine(proc.StandardOutput.ReadToEnd());
return new string[] { "Archivo encriptado", archivo + " - "+ comando};
}catch (Exception exception){
return new string[] { archivo, "exception: "+exception.ToString() + " - "+ comando };
}
}
System.Diagnostics.Process is not the most pleasant to work with, so you may want to try CliWrap. It offers many different models for working with output, including piping, buffering, and real-time streaming. Here are some examples (taken from readme).
Simply launch a command line executable:
using CliWrap;
var result = await Cli.Wrap("path/to/exe")
.WithArguments("--foo bar")
.WithWorkingDirectory("work/dir/path")
.ExecuteAsync();
// Result contains:
// -- result.ExitCode (int)
// -- result.StartTime (DateTimeOffset)
// -- result.ExitTime (DateTimeOffset)
// -- result.RunTime (TimeSpan)
Launch a command line executable and buffer stdout/stderr in-memory:
using CliWrap;
using CliWrap.Buffered;
// Calling `ExecuteBufferedAsync()` instead of `ExecuteAsync()`
// implicitly configures pipes that write to in-memory buffers.
var result = await Cli.Wrap("path/to/exe")
.WithArguments("--foo bar")
.WithWorkingDirectory("work/dir/path")
.ExecuteBufferedAsync();
// Result contains:
// -- result.StandardOutput (string)
// -- result.StandardError (string)
// -- result.ExitCode (int)
// -- result.StartTime (DateTimeOffset)
// -- result.ExitTime (DateTimeOffset)
// -- result.RunTime (TimeSpan)
Launch a command line executable with manual pipe configuration:
using CliWrap
var buffer = new StringBuilder();
var result = await Cli.Wrap("foo")
.WithStandardOutputPipe(PipeTarget.ToFile("output.txt"))
.WithStandardErrorPipe(PipeTarget.ToStringBuilder(buffer))
.ExecuteAsync();
Launch a command line executable as an event stream:
using CliWrap;
using CliWrap.EventStream;
var cmd = Cli.Wrap("foo").WithArguments("bar");
await foreach (var cmdEvent in cmd.ListenAsync())
{
switch (cmdEvent)
{
case StartedCommandEvent started:
_output.WriteLine($"Process started; ID: {started.ProcessId}");
break;
case StandardOutputCommandEvent stdOut:
_output.WriteLine($"Out> {stdOut.Text}");
break;
case StandardErrorCommandEvent stdErr:
_output.WriteLine($"Err> {stdErr.Text}");
break;
case ExitedCommandEvent exited:
_output.WriteLine($"Process exited; Code: {exited.ExitCode}");
break;
}
}

Run command line command passing STDIN [duplicate]

This question already has answers here:
Capturing console output from a .NET application (C#)
(8 answers)
Closed 6 years ago.
I need to spawn a child process that is a console application, and capture its output.
I wrote up the following code for a method:
string retMessage = String.Empty;
ProcessStartInfo startInfo = new ProcessStartInfo();
Process p = new Process();
startInfo.CreateNoWindow = true;
startInfo.RedirectStandardOutput = true;
startInfo.RedirectStandardInput = true;
startInfo.UseShellExecute = false;
startInfo.Arguments = command;
startInfo.FileName = exec;
p.StartInfo = startInfo;
p.Start();
p.OutputDataReceived += new DataReceivedEventHandler
(
delegate(object sender, DataReceivedEventArgs e)
{
using (StreamReader output = p.StandardOutput)
{
retMessage = output.ReadToEnd();
}
}
);
p.WaitForExit();
return retMessage;
However, this does not return anything. I don't believe the OutputDataReceived event is being called back, or the WaitForExit() command may be blocking the thread so it will never callback.
Any advice?
EDIT: Looks like I was trying too hard with the callback. Doing:
return p.StandardOutput.ReadToEnd();
Appears to work fine.
Here's code that I've verified to work. I use it for spawning MSBuild and listening to its output:
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardOutput = true;
process.OutputDataReceived += (sender, args) => Console.WriteLine("received output: {0}", args.Data);
process.Start();
process.BeginOutputReadLine();
I just tried this very thing and the following worked for me:
StringBuilder outputBuilder;
ProcessStartInfo processStartInfo;
Process process;
outputBuilder = new StringBuilder();
processStartInfo = new ProcessStartInfo();
processStartInfo.CreateNoWindow = true;
processStartInfo.RedirectStandardOutput = true;
processStartInfo.RedirectStandardInput = true;
processStartInfo.UseShellExecute = false;
processStartInfo.Arguments = "<insert command line arguments here>";
processStartInfo.FileName = "<insert tool path here>";
process = new Process();
process.StartInfo = processStartInfo;
// enable raising events because Process does not raise events by default
process.EnableRaisingEvents = true;
// attach the event handler for OutputDataReceived before starting the process
process.OutputDataReceived += new DataReceivedEventHandler
(
delegate(object sender, DataReceivedEventArgs e)
{
// append the new data to the data already read-in
outputBuilder.Append(e.Data);
}
);
// start the process
// then begin asynchronously reading the output
// then wait for the process to exit
// then cancel asynchronously reading the output
process.Start();
process.BeginOutputReadLine();
process.WaitForExit();
process.CancelOutputRead();
// use the output
string output = outputBuilder.ToString();
Here's some full and simple code to do this. This worked fine when I used it.
var processStartInfo = new ProcessStartInfo
{
FileName = #"C:\SomeProgram",
Arguments = "Arguments",
RedirectStandardOutput = true,
UseShellExecute = false
};
var process = Process.Start(processStartInfo);
var output = process.StandardOutput.ReadToEnd();
process.WaitForExit();
Note that this only captures standard output; it doesn't capture standard error. If you want both, use this technique for each stream.
I needed to capture both stdout and stderr and have it timeout if the process didn't exit when expected. I came up with this:
Process process = new Process();
StringBuilder outputStringBuilder = new StringBuilder();
try
{
process.StartInfo.FileName = exeFileName;
process.StartInfo.WorkingDirectory = args.ExeDirectory;
process.StartInfo.Arguments = args;
process.StartInfo.RedirectStandardError = true;
process.StartInfo.RedirectStandardOutput = true;
process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
process.StartInfo.CreateNoWindow = true;
process.StartInfo.UseShellExecute = false;
process.EnableRaisingEvents = false;
process.OutputDataReceived += (sender, eventArgs) => outputStringBuilder.AppendLine(eventArgs.Data);
process.ErrorDataReceived += (sender, eventArgs) => outputStringBuilder.AppendLine(eventArgs.Data);
process.Start();
process.BeginOutputReadLine();
process.BeginErrorReadLine();
var processExited = process.WaitForExit(PROCESS_TIMEOUT);
if (processExited == false) // we timed out...
{
process.Kill();
throw new Exception("ERROR: Process took too long to finish");
}
else if (process.ExitCode != 0)
{
var output = outputStringBuilder.ToString();
var prefixMessage = "";
throw new Exception("Process exited with non-zero exit code of: " + process.ExitCode + Environment.NewLine +
"Output from process: " + outputStringBuilder.ToString());
}
}
finally
{
process.Close();
}
I am piping the stdout and stderr into the same string, but you could keep it separate if needed. It uses events, so it should handle them as they come (I believe). I have run this successfully, and will be volume testing it soon.
It looks like two of your lines are out of order. You start the process before setting up an event handler to capture the output. It's possible the process is just finishing before the event handler is added.
Switch the lines like so.
p.OutputDataReceived += ...
p.Start();
Redirecting the stream is asynchronous and will potentially continue after the process has terminated. It is mentioned by Umar to cancel after process termination process.CancelOutputRead(). However that has data loss potential.
This is working reliably for me:
process.WaitForExit(...);
...
while (process.StandardOutput.EndOfStream == false)
{
Thread.Sleep(100);
}
I didn't try this approach but I like the suggestion from Sly:
if (process.WaitForExit(timeout))
{
process.WaitForExit();
}
You need to call p.Start() to actually run the process after you set the StartInfo. As it is, your function is probably hanging on the WaitForExit() call because the process was never actually started.
The answer from Judah did not work for me (or is not complete) as the application was exiting after the first BeginOutputReadLine();
This works for me as a complete snippet, reading the constant output of a ping:
var process = new Process();
process.StartInfo.FileName = "ping";
process.StartInfo.Arguments = "google.com -t";
process.StartInfo.RedirectStandardOutput = true;
process.StartInfo.UseShellExecute = false;
process.OutputDataReceived += (sender, a) => Console.WriteLine(a.Data);
process.Start();
process.BeginOutputReadLine();
process.WaitForExit();
Here's a method that I use to run a process and gets its output and errors :
public static string ShellExecute(this string path, string command, TextWriter writer, params string[] arguments)
{
using (var process = Process.Start(new ProcessStartInfo { WorkingDirectory = path, FileName = command, Arguments = string.Join(" ", arguments), UseShellExecute = false, RedirectStandardOutput = true, RedirectStandardError = true }))
{
using (process.StandardOutput)
{
writer.WriteLine(process.StandardOutput.ReadToEnd());
}
using (process.StandardError)
{
writer.WriteLine(process.StandardError.ReadToEnd());
}
}
return path;
}
For example :
#"E:\Temp\MyWorkingDirectory".ShellExecute(#"C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bin\svcutil.exe", Console.Out);

Reading cmd output real time

I'm writing a program that reads python script output and shows the results in textbox.
Since the script runnning for a long time, I want to be able to see the output every 1 second (or after each line is writen).
Now i can see the output only when the process ends.
Does someone know what is the problem?
snippet of my code:
Process p = new Process();
p.StartInfo.CreateNoWindow = true;
p.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
p.OutputDataReceived += new DataReceivedEventHandler (p_OutputDataReceived);
p.ErrorDataReceived += new DataReceivedEventHandler (p_ErrorDataReceived);
p.Exited += new EventHandler (p_Exited);
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.UseShellExecute = false;
p.StartInfo.FileName = "python.exe";
p.StartInfo.Arguments = "path " + commandline;
p.Start();
StreamReader s = p.StandardOutput;
String output = s.ReadToEnd();
textBox3.Text = output;
p.WaitForExit();
I'm doing it the following way in my own programs:
private static void startProgram(
string commandLine )
{
var fileName = commandLine;
var arguments = string.Empty;
checkSplitFileName( ref fileName, ref arguments );
var info = new ProcessStartInfo();
info.FileName = fileName;
info.Arguments = arguments;
info.UseShellExecute = false;
info.RedirectStandardOutput = true;
info.RedirectStandardError = true;
using ( var p = new Process() )
{
p.StartInfo = info;
p.EnableRaisingEvents = true;
p.OutputDataReceived += (s,o) => {
Console.WriteLine(o.Data);
};
p.Start();
p.BeginOutputReadLine();
p.WaitForExit();
}
}
I.e. I'm subscribing to the OutputDataReceived event and calling BeginOutputReadLine method. See also this similar Stack Overflow question.
(The method checkSplitFileName in my above source code can be found here)
I had this same problem running my Python script from C#. The problem is that Python buffers the output from stdout (print()).
You could do one of two things here.
1.
Add the following to your Python script, after every print() line to flush the output.
import sys
print('Hello World!')
sys.stdout.flush()
2.
Run the Python compiler with the -u command line parameter. This way you don't need to add the above flush line after every print.
...
p.StartInfo.FileName = "cmd.exe";
p.StartInfo.Arguments = "python.exe -u path " + commandline;
...
Python, by default, buffers its output.
The way to go is to pass a "-u" command line argument to python.
so if you want to execute say hello.py, you would do :
python.exe -u hello.py
Heres the C# code that works for me.
Process p = new Process();
string op = "";
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.CreateNoWindow = true;
p.StartInfo.FileName = "c:\\python27\\python.exe";
StreamReader outputStream = p.StandardOutput;
StreamReader errorStream = p.StandardError;
p.StartInfo.Arguments = #"-u hello.py";
p.Start();
string output = "";
int offset = 0, readBytes = 0;
char[] buffer = new char[512];
do
{
output = outputStream.ReadLine();
if (!string.IsNullOrEmpty(output))
{
txtOutput.AppendText(output);
txtOutput.AppendText(Environment.NewLine);
offset += readBytes;
Application.DoEvents();
}
Thread.Sleep(3);
} while (!p.HasExited);

Sending cmd commands and reading results in C#

I want to send commands with arguments and read their answers from cmd. So, I wrote the code below, but it is not working and locks on screen (myString is usually null - ""). I only want to send commands to an opened command prompt. Where is the problem? Thanks in advance. (for example: How can I fetch the result of a ping request?)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.IO;
namespace CallBatchFile
{
class Program
{
[STAThread]
static void Main()
{
Process p = new Process();
p.StartInfo.FileName = "cmd.exe";
p.StartInfo.Arguments = "/c date";
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.CreateNoWindow = true;
p.StartInfo.RedirectStandardOutput = true;
p.Start();
string myString = p.StandardOutput.ReadToEnd();
p.WaitForExit();
}
}
}
cmd /c date is blocking. you can either use
p.StartInfo.Arguments = "/c date /T";
To stop date waiting for input, or give input to cmd
p.StartInfo.RedirectStandardInput = true;
...
p.StandardInput.Write("\n");
..or read async so you can get the output while cmd is waiting for your input:
p.BeginOutputReadLine();
p.OutputDataReceived += (_, e) => Console.WriteLine(e.Data);
This code might help you
string strOutput;
//Starting Information for process like its path, use system shell i.e. control process by system etc.
ProcessStartInfo psi = new ProcessStartInfo(#"C:\WINDOWS\system32\cmd.exe");
// its states that system shell will not be used to control the process instead program will handle the process
psi.UseShellExecute = false;
psi.ErrorDialog = false;
// Do not show command prompt window separately
psi.CreateNoWindow = true;
psi.WindowStyle = ProcessWindowStyle.Hidden;
//redirect all standard inout to program
psi.RedirectStandardError = true;
psi.RedirectStandardInput = true;
psi.RedirectStandardOutput = true;
//create the process with above infor and start it
Process plinkProcess = new Process();
plinkProcess.StartInfo = psi;
plinkProcess.Start();
//link the streams to standard inout of process
StreamWriter inputWriter = plinkProcess.StandardInput;
StreamReader outputReader = plinkProcess.StandardOutput;
StreamReader errorReader = plinkProcess.StandardError;
//send command to cmd prompt and wait for command to execute with thread sleep
inputWriter.WriteLine("C:\\PLINK -ssh root#susehost -pw opensuselinux echo $SHELL\r\n");
Thread.Sleep(2000);
// flush the input stream before sending exit command to end process for any unwanted characters
inputWriter.Flush();
inputWriter.WriteLine("exit\r\n");
// read till end the stream into string
strOutput = outputReader.ReadToEnd();
//remove the part of string which is not needed
int val = strOutput.IndexOf("-type\r\n");
strOutput = strOutput.Substring(val + 7);
val = strOutput.IndexOf("\r\n");
strOutput = strOutput.Substring(0, val);
MessageBox.Show(strOutput);

how to redirect the output as well as get the output on shell screen at same time

This is windows-application-form code; I want the batch file which is going to be executed to show the output on shell screen which I got by RedirectStandardOutput = false;, but I also want output to be redirected to a log file at the same time. For this, I use RedirectStandardOutput = true;.
Of course, only one can be used at one time!
System.Diagnostics.Process p = new System.Diagnostics.Process();
p.StartInfo.FileName = "c:\test\build.bat";
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true; // if I use false all the commented lines below are not applicable for comments
p.Start();
string output = null;
//try
//{
output = p.StandardOutput.ReadToEnd();
//}
//catch (Exception ex)
//{
// MessageBox.Show(ex.ToString());
//}
System.IO.File.WriteAllText("c:\test\log.txt", output);
Capture the output and print it to the screen yourself. That's how the tee command meets this need on most non-Windows operating systems.
You could try something like this:
System.Diagnostics.Process p = new System.Diagnostics.Process();
p.StartInfo.FileName = "c:\test\build.bat";
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.OutputDataReceived += new DataReceivedEventHandler(SortOutputHandler);
p.Start();
And have an event handler somewhere in your code:
private static void SortOutputHandler(object sendingProcess, DataReceivedEventArgs outLine)
{
if (!String.IsNullOrEmpty(outLine.Data))
{
Console.WriteLine(outLine.Data);
System.IO.File.AppendAllText("c:\test\log.txt", outLine.Data);
}
}
Example taken from MSDN: Process.BeginOutputReadLine Method. It would be more efficient to keep the file open for writing, or even to buffer it but this keeps the example short.

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