Develop Reference

C#: Calling a php script and beeing able to stop it

I am currently working on a C# Program which needs to call a local PHP script and write its output to a file. The problem is, that I need to be able to stop the execution of the script.
First, I tried to call cmd.exe and let cmd write the output to the file which worked fine. But I found out, that killing the cmd process does not stop the php cli.
So I tried to call php directly, redirect its output and write it from the C# code to a file. But here the problem seems to be, that the php cli does not terminate when the script is done. process.WaitForExit() does not return, even when I am sure that the script has been fully executed.
I cannot set a timeout to the WaitForExit(), because depending on the arguments, the script may take 3 minutes or eg. 10 hours.
I do not want to kill just a random php cli, there may be others currently running.
What is the best way to call a local php script from C#, writing its output to a file and beeing able to stop the execution?
Here is my current code:
// Create the process
var process = new System.Diagnostics.Process();
process.EnableRaisingEvents = true;
process.StartInfo.UseShellExecute = false;
process.StartInfo.FileName = "php.exe";
// CreateExportScriptArgument returns something like "file.php arg1 arg2 ..."
process.StartInfo.Arguments = CreateExportScriptArgument(code, this.content, this.options);
process.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
process.StartInfo.RedirectStandardOutput = true;
// Start the process or cancel, if the process should not run
if (!this.isRunning) { return; }
this.currentProcess = process;
process.Start();
// Get the output
var output = process.StandardOutput;
// Wait for the process to finish
process.WaitForExit();
this.currentProcess = null;
To kill the process I am using:
// Mark as not running to prevent starting new
this.isRunning = false;
// Kill the process
if (this.currentProcess != null)
{
this.currentProcess.Kill();
}
Thanks for reading!
EDIT
That the cli does not return seems to be not reproducible. When I test a different script (without arguments) it works, probably its the script or the passing of the arguments.
Running my script from cmd works just fine, so the script should not be the problem
EDIT 2
When disabling RedirectStandardOutput, the cli quits. could it be, that I need to read the output, before the process finishes? Or does the process wait, when some kind of buffer is full?
EDIT 3: Problem solved
Thanks to VolkerK, I / we found a solution. The problem was, that WaitForExit() did not get called, when the output is not read (probably due to a full buffer in the standard output). My script wrote much output.
What works for me:
process.Start();
// Get the output
var output = process.StandardOutput;
// Read the input and write to file, live to avoid reading / writing to much at once
using (var file = new StreamWriter("path\\file", false, new UTF8Encoding()))
{
// Read each line
while (!process.HasExited)
{
file.WriteLine(output.ReadLine());
}
// Read the rest
file.Write(output.ReadToEnd());
// flush to file
file.Flush();
}

Since the problem was that the output buffer was full and therefore the php process stalled while waiting to send its output, asynchronously reading the output in the c# program is the solution.
class Program {
protected static /* yeah, yeah, it's only an example */ StringBuilder output;
static void Main(string[] args)
{
// Create the process
var process = new System.Diagnostics.Process();
process.EnableRaisingEvents = true;
process.StartInfo.UseShellExecute = false;
process.StartInfo.FileName = "php.exe";
process.StartInfo.Arguments = "-f path\\test.php mu b 0 0 pgsql://user:pass#x.x.x.x:5432/nominatim";
process.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
process.StartInfo.RedirectStandardOutput = true;
output = new StringBuilder();
process.OutputDataReceived += process_OutputDataReceived;
// Start the process
process.Start();
process.BeginOutputReadLine();
// Wait for the process to finish
process.WaitForExit();
Console.WriteLine("test");
// <-- do something with Program.output here -->
Console.ReadKey();
}
static void process_OutputDataReceived(object sender, System.Diagnostics.DataReceivedEventArgs e)
{
if (!String.IsNullOrEmpty(e.Data)) {
// edit: oops the new-line/carriage-return characters are not "in" e.Data.....
// this _might_ be a problem depending on the actual output.
output.Append(e.Data);
output.Append(Environment.NewLine);
}
}
}
see also: https://msdn.microsoft.com/en-us/library/system.diagnostics.process.beginoutputreadline%28v=vs.110%29.aspx

Process WaitForExit() never end (cmd openfiles)

this code works fine on my test-system (Copy of the original Windows-Server 2008 R2)
private string _getNetFiles()
{
// prepare execution process
ProcessStartInfo processStartInfo = new ProcessStartInfo("cmd.exe", "/c openfiles /query /Fo list");
processStartInfo.CreateNoWindow = true;
processStartInfo.UseShellExecute = false;
processStartInfo.RedirectStandardError = true;
processStartInfo.StandardOutputEncoding = System.Text.Encoding.GetEncoding(437);
processStartInfo.RedirectStandardOutput = true;
// execute
Process process = Process.Start(processStartInfo);
process.WaitForExit();
// read outputs
string stdOutput = process.StandardOutput.ReadToEnd();
string stdError = process.StandardError.ReadToEnd();
return stdOutput;
}
On the original system:
I see the "cmd.exe /c openfiles /query /Fo list" task in the Task-Manger, but this task never end (process.WaitForExit() process never end ).
Cmd on the original system: openfiles /query /fo list works also fine!
Where can the problem be?
regards raiserle
edit:
I can stop the process with task-manager.
The stdOutput is correct. Why don't end the cmd-taks.

The child process is either waiting for input or for its output to be read. The pipe buffers are not infinitely big. You need to constantly drain both standard output as well as standard error.
Get Values from Process StandardOutput looks reasonable. https://stackoverflow.com/a/24084220/122718 documents how to safely read both streams.
Also note Visual Basic Capture output of cmd as well as everything that Hans Passant says on this topic.
Using the Process class without output redirection is quite tricky and poorly documented.

How to pass a string from one process to another?

There is a process in my case which starts another process and subscribes to the Exited event.
The second process at the end should pass an error string somehow to the first process. The first process will display the message on the screen.
How to pass a string at the end of application in such a way that another app would be able to read the string and display it?

You can redirect the StandardError stream: http://msdn.microsoft.com/en-us/library/system.diagnostics.process.standarderror.aspx
Process myProcess = new Process();
ProcessStartInfo myProcessStartInfo = new ProcessStartInfo("net ","use "+ args[0]);
myProcessStartInfo.UseShellExecute = false;
myProcessStartInfo.RedirectStandardError = true;
myProcess.StartInfo = myProcessStartInfo;
myProcess.Start();
StreamReader myStreamReader = myProcess.StandardError;
// Read the standard error of net.exe and write it on to console.
Console.WriteLine( myStreamReader.ReadLine());
myProcess.Close();
Research the following, and pick the one that suites your needs best for your scenario. My guess is that you either need Output or Error if you're passing data back to the parent process.
StartInfo.RedirectStandardOutput
StartInfo.RedirectStandardError
StartInfo.RedirectStandardInput

C#: get external shell command result line by line

I am writing a C# winform application that starts a second process to execute shell commands like "dir" and "ping". I redirect the second process's output so my app can receive the command result. It roughly works fine.
The only problem is my winform app receives the command line output as a whole instead of line by line. For example, it has to wait for the external "ping" command to finish (which takes many seconds or longer) and then receives the whole output (many lines) at once.
What I want is the app receives the cmdline output in real-time, i.e. by lines not by block. Is this doable?
I am using this code to read the output:
while ((result = proc.StandardOutput.ReadLine()) != null)
But it does not work the way I expected.
Thanks in advance.
EDIT: here is the code I am using:
System.Diagnostics.ProcessStartInfo procStartInfo = new
System.Diagnostics.ProcessStartInfo("cmd", "/c " + command);
procStartInfo.WindowStyle = ProcessWindowStyle.Hidden;
// The following commands are needed to redirect the standard output.
procStartInfo.RedirectStandardOutput = true;
procStartInfo.UseShellExecute = false;
procStartInfo.CreateNoWindow = true;
// Now we create a process, assign its ProcessStartInfo and start it
System.Diagnostics.Process proc = new System.Diagnostics.Process();
proc.StartInfo = procStartInfo;
proc.Start();
// Get the output into a string
string result;
try {
while ((result = proc.StandardOutput.ReadLine()) != null)
{
AppendRtfText(result+"\n", Brushes.Black);
}
} // here I expect it to update the text box line by line in real time
// but it does not.

Have a look at the example in this msdn article on how to do the reading completly async.
Beyond that I expect your code does to read line by line now but the UI doesn't get any time to repaint (missing Application.DoEvents(); after updating the RTFTextBox

Instead of loop using while ((result = proc.StandardOutput.ReadLine()) != null) you should of using:
...
proc.OutputDataReceived += proc_DataReceived;
proc.Start();
proc.BeginOutputReadLine();
proc.WaitForExit();
This will start asynchronous reading the lines when they arrives, you then handle the lines read by e.Data in proc_DataReceived handler, since you are use BeginOutputReadline the e.Data will be a string lines.

This could be usefull:
http://social.msdn.microsoft.com/Forums/en-US/csharplanguage/thread/8d6cebfc-9b8b-4667-85b5-2b92105cd0b7/
http://www.dotnetperls.com/redirectstandardoutput

I had the same issue and got around it with the following. I found that if I had an error in the external app I was getting no output at all using the ReadToEnd() method, so switched to use the line by line streamreader. Will be switching over to use the answer provided by Saa'd though as that looks like the proper way to handle it.
Also found this solution: c# coding convention public/private contexts which provides for error handling at the same time and giving a fuller explanation to the use of externalApp.OutputDataReceived += (sender, args) => Console.WriteLine(args.Data);
Process externalApp = new Process();
externalApp.StartInfo.FileName = config.ExternalApps + #"\location\DeleteApp.exe";
externalApp.StartInfo.Arguments = Directory.GetCurrentDirectory() + #"\..\..\..\project\argumentsForDeleteApp.xml";
externalApp.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
externalApp.StartInfo.UseShellExecute = false;
externalApp.StartInfo.RedirectStandardOutput = true;
Console.Out.WriteLine(DateTime.UtcNow.ToLocalTime().ToString() +
":###### External app: " + externalApp.StartInfo.FileName + " - START");
externalApp.Start();
using (StreamReader reader = externalApp.StandardOutput)
{
while (!reader.EndOfStream)
{
string result = reader.ReadLine();
Console.Out.WriteLine(result);
}
}
externalApp.WaitForExit();

Command line program/app + C# class method

When working with a command line program, via a c# class method.
How do you determine if the commandline program was successfully executed and the operation it has performed is ok or has failed?
Also how do you get the screen commandline output into the c# class method?

You can use the Process class to execute a command line command.
The following code captures the standard output to output, and assigns the processes exit code to exitCode.
using (Process p = new Process())
{
p.StartInfo.FileName = exeName;
p.StartInfo.Arguments = args;
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.Start();
string output = p.StandardOutput.ReadToEnd();
p.WaitForExit();
int exitCode = p.ExitCode;
}

Something like:
Process mycommand = new Process();
mycommand.StartInfo.FileName = "myexe.exe";
mycommand.StartInfo.Arguments = "param1";
mycommand.StartInfo.UseShellExecute = false;
mycommand.StartInfo.RedirectStandardOutput = true;
mycommand.Start();
Console.WriteLine(mycommand.StandardOutput.ReadToEnd());
mycommand.WaitForExit();
You usually determine an exe's state wether the exit code is 0, but that is arguably down to the writer of the exe

I assume you're using the Process class to call the command line app.
You can find the exit code of the process using Process.ExitCode. You can redirect its standard output by setting ProcessStartInfo.RedirectStandardOutput before starting it, and then either using Process.StandardOutput or the Process.OutputDataReceived event.

Take a look at this questionenter link description here.
The additional information you might need is process.ExitCode to see if it was sucessful. Of course, the Main method of the console app must return an exit code when it is unsuccessful, which many do not.

For this, you use the Process.Start method. You can control how the process runs with the passed in ProcessStartInfo:
var myProcess = Process.Start(new ProcessStartInfo {
FileName = "process.exe",
UseShellExecute = false,
RedirectStandardOutput = true,
CreateNoWindow = true
});
if (!myProcess.WaitForExit(5000)) { // give it 5 seconds to exit
myProcess.Kill();
}
if (myProcess.ExitCode != 0) {
// error!
}
var output = myProcess.StandardOutput.ReadToEnd(); // access output