Develop Reference

HandbrakeCLI wont automate via C# process

I am trying to automate HandbrakeCLI using C# via the System.Diagnostics.Process class. However, as long as my program is trying to run the process, it seems like the process never advances.
Here is my process setup:
Process process = new System.Diagnostics.Process();
ProcessStartInfo startInfo = new System.Diagnostics.ProcessStartInfo();
startInfo.RedirectStandardOutput = true;
startInfo.RedirectStandardError = true;
startInfo.UseShellExecute = false;
startInfo.CreateNoWindow = true;
startInfo.FileName = parameters.HandbrakeLocation;
startInfo.Arguments = arguments;
process.StartInfo = startInfo;
process.Start();
string output = string.Empty;
while ((output = process.StandardOutput.ReadLine()) != null)
{
Debug.WriteLine(output);
}
process.WaitForExit();
HandbrakeCLI.exe does appear in my processes list. The Debug.WriteLine(output); line continually prints out "Encoding: task 1 of 1, 0.00 %" and the process never completes. If I kill my C# app then HandbrakeCLI instantly shoots up from 7,000k in memory to 145,000k and then does the encoding that I want it to do. Its like my C# app is holding it back.
I have tried to use Read() instead of ReadLine() and I have tried flushing the StandardOutput stream before and after the read with no success. I have a suspicion that since HandbrakeCLI overwrites stdout when it writes the encoding progress, that it won't act like a normal process when automated via C#.

I figured it out. I was redirecting stderr to my C# application, but not consuming it. The process was hanging until stderr was consumed.

Batch process in c#

I am having a Java batch process which I used in C# to run process. I want to have a testcase to check whether the batch process is running or not.
I used the batch process as:
void batch_process(string process)
{
try
{
string strFilePath = Path.Combine(batch_process_path, process);
ProcessStartInfo psi = new ProcessStartInfo(strFilePath);
psi.RedirectStandardOutput = true;
psi.RedirectStandardError = true;
psi.WorkingDirectory = batch_process_path;
psi.WindowStyle = ProcessWindowStyle.Hidden;
psi.UseShellExecute = false;
psi.ErrorDialog = true;
}
}
How can this test be done?
I want to write an unit test case to check whether the process will start or not.

when you Start your new process you need to capture the returned Process, that provides access to newly started process, useful for starting, stopping, controlling, and monitoring applications.
Process exe = Process.Start(psi);
....
if exe.HasExited() ....

You could start the process using
Process process = new Process();
string strFilePath = Path.Combine(batch_process_path, process);
process.StartInfo.FileName = strFilePath;
//this line will hold this thread until the process is done.
process.WaitForExit();
then start the process on a different thread and let that thread fire an event after process.WaitForExit(); is done.

You should first start the process using the ProcessStartInfo you've just created like:
Process process = Process.Start(psi);
then you can use process.HasExited to check if the process has exited. Often, you don't need to do this, as process.WaitForExit() blocks the code until process exits.

I'm a bit unsure of the scenario from your question... but 4 techniques you can use are:
if you have started the process using var process = Process.Start(psi); then:
you can periodically check process.HasExited - http://msdn.microsoft.com/en-us/library/system.diagnostics.process.hasexited.aspx
or you can subscribe to Process.Exited - http://msdn.microsoft.com/en-us/library/system.diagnostics.process.exited.aspx
or you can block on Process.WaitForExit - http://msdn.microsoft.com/en-us/library/system.diagnostics.process.waitforexit.aspx
if your process is started in some other way and has some unique name, then you can inspect the enumeration returned by System.Diagnostics.Process.GetProcesses() to determine if your batch process is currently running.
In general... I'd prefer to use Process.Exited, but the other methods all have their place too!

Why won't "cmd.exe /C command" end when called via Process.Start()?

I'm trying to run a command via command prompt from an ASP.Net web application. I can see the process start in task manager on the web server, however the process just sits there and never exits nor does it run the commands I specified.
Process process = new Process();
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.FileName = "cmd.exe";
startInfo.Arguments = "/C " +command;
startInfo.UserName = "myuser";
startInfo.UseShellExecute = false;
startInfo.RedirectStandardOutput = true;
startInfo.Domain = "mydomain";
startInfo.CreateNoWindow = true;
String pass = "mypass";
System.Security.SecureString secPass = new System.Security.SecureString();
foreach (char c in pass.ToCharArray())
{
secPass.AppendChar(c);
}
secPass.MakeReadOnly();
startInfo.Password = secPass;
process.StartInfo = startInfo;
process.Start();
//output = process.StandardOutput.ReadToEnd();
process.WaitForExit();
process.Close();
I've tried both with and without reading the standard output.
The application will hang on process.WaitForExit(); until I kill the process via task manager.

I think we need to understand what commands you are actually trying to process in order to determine what's going on. Also we need to know what OS the server is running.
For example, I did see in your comments where you tried "echo test > C:\test.txt" Under Windows Server 2008 (and Windows 7) the root directory requires administrator permissions in order to create files. If this is executing under IIS, my guess is that your IIS user isn't an administrator and you are getting security exceptions.
Also, a number of commands may require elevated priviledges due to UAC. I don't remember exactly, but I'm guessing that if those commands are being caught by UAC then the process is waiting for UAC confirmation... Which I believe you cannot supply via a command line.
This type of problem won't be seen if you log into the machine and execute it directly... unless you are logging in with the worker process user account.
So, the very first thing you need to do is figure out what it is you are trying to run and see if the user the worker process is executing under can even perform those actions. Security is there to protect you, so be careful about granting additional permissions to the user.
The reason why it might work on one machine versus another again depends on the OS's those machines are running and the configuration of the user the commands are executing under.
If this is truly a security issue, as I suspect, then you should post a question on serverfault.com to ask what permission sets you need to execute various commands under your worker process user.
You might look at the machines event logs to see if there were any warnings or errors thrown about the command. Sometimes things like this can show up there to give you a bit more information as to what happened.

Once passed to CMD, the control has passed to the shell. It's better to add a close it like this:
private void closeSubProcess()
{
Process[] currentProcesses = Process.GetProcesses();
foreach (Process p in currentProcesses)
{
string s = p.ProcessName;
s = s.ToLower();
if (s.CompareTo("YOURPROGRAMNAMEHERE") == 0)
{
p.CloseMainWindow();
p.Close();
}
}
}

I am calling cmd.exe to start a node module in Windows. npm obviously must be installed first, along with the node module I need, and then I can call the module with args in C#. Problem was, the cmd.exe would not shut off, I'd have to use Task Mgr (just like this question!).
//This requires npm, and the module installed by npm...
ProcessStartInfo psi = new ProcessStartInfo();
psi.FileName = "cmd.exe";
psi.WindowStyle = ProcessWindowStyle.Hidden;
psi.UseShellExecute = true; //closes command window
psi.Arguments = "/c <nodemodulename>" + file1 + ".txt " + file2 + ".log";
Process p = Process.Start(psi);
p.Close();
The /c argument was key to closing down cmd.exe. When I started out, I had put in the /K argument, which keeps the darned thing running. Solved. Hope this helps. (This is like ancient, but we always forget)

ProcessStartInfo.UseShellExecute = true and waiting for process exit

I want to use shell executable in order to respect user preferences of application to be started, but I also need to know when that particular application is closed.
Process editProcess = new Process();
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.FileName = filename;
startInfo.Verb = "edit";
startInfo.UseShellExecute = true;
editProcess.StartInfo = startInfo;
// start the default editor
editProcess.Start();
editProcess.WaitForExit();
WaitForExit seems to return when the shell process exits and not when the real process exits.
Is there a better way of knowing when started application is exited than manually parsing registry, finding correct application to start and explicitly start that app without shell execute?

Handle the process exited event:
editProcess.Exited += process_Exited;

Force external process to be killed after time period

I have a command line executable that is run from a C# class library. In some very rare situations the executable will hang because of the command line data passed to it. Unfortunetely this causes the application calling the c# DLL to hang whilst it waits indefinitely for the process to exit.
If the command line exe doesnt finish execution within 1 second its never going to exit. What I'd like to do is spawn a timer just after the process has started and force close the process if it hasnt exited within a few seconds.
What is the best approach here? The solution needs to have minimal impact upon performance because this command line process is the bottleneck in a highly repetitive task.
Edit: Any reason why I should use System.Timer rather than Threading.Timer or vice versa?
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.CreateNoWindow = false;
startInfo.UseShellExecute = true;
startInfo.WorkingDirectory = workingDirectory;
startInfo.FileName = commandLineExe;
startInfo.WindowStyle = ProcessWindowStyle.Hidden;
startInfo.Arguments = strArguments;
// Call WaitForExit and then the using statement will close.
using (Process exeProcess = Process.Start(startInfo))
{
exeProcess.WaitForExit();
}
Please refrain from suggestions that I should try and figure out why the command line app is hanging, or that I should refactor the command line functionality into the source code. We are actively working on that problem but stability of the application needs to come first.

Just add:
// Call WaitForExit and then the using statement will close.
using (Process exeProcess = Process.Start(startInfo)) {
if(!exeProcess.WaitForExit(1000))
exeProcess.Kill();
}