Problem executing process

[EricF]

I'm trying to execute a third party process using QProcess and it's almost working but fails to write the output file.

I connected my main process to signal error, readyReadStandardOutput and readyReadStandardError and I've received all of them and it helped me debug my command line but my process should output a file and the file isn't showing.

I searched a bit on here and had the idea to start the process detached and then it works but it pops a terminal which I don't want to see.

Considering that the only change I made was to start it detached as opposed to a normal start, what could be the problem ? I'd guess that the processes don't have the same right but I'm not sure.

In anyway, I'm sick of battling with this problem, help

[wysota]

Can we see the code used to spawn the process? Did you check what is the current working directory when you spawn the process?

[EricF]

Here's the code:

QString dotExec("dot");
 
	// Then set arguments
	QStringList args;
	args << QString("-T%1").arg(extension);
	args << QString("-o%1").arg(filename);
	args << QString("%1").arg(newFilename);
 
	// Finally call the process
	mProcess = new QProcess;
	connect( mProcess, SIGNAL(error(QProcess::ProcessError)), this, SLOT(OnProcessError(QProcess::ProcessError)) );
	connect( mProcess, SIGNAL(readyReadStandardOutput()), this, SLOT(OnStandardOutput()) );
	connect( mProcess, SIGNAL(readyReadStandardError()), this, SLOT(OnErrorOutput()) );
	mProcess->startDetached( dotExec, args );
 
	bool processReturn = mProcess->waitForFinished();
 
	delete mProcess;
	mProcess = NULL;
 
	return processReturn;

QString dotExec("dot");

	// Then set arguments
	QStringList args;
	args << QString("-T%1").arg(extension);
	args << QString("-o%1").arg(filename);
	args << QString("%1").arg(newFilename);

	// Finally call the process
	mProcess = new QProcess;
	connect( mProcess, SIGNAL(error(QProcess::ProcessError)), this, SLOT(OnProcessError(QProcess::ProcessError)) );
	connect( mProcess, SIGNAL(readyReadStandardOutput()), this, SLOT(OnStandardOutput()) );
	connect( mProcess, SIGNAL(readyReadStandardError()), this, SLOT(OnErrorOutput()) );
	mProcess->startDetached( dotExec, args );

	bool processReturn = mProcess->waitForFinished();

	delete mProcess;
	mProcess = NULL;

	return processReturn;

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Of course waitForFinished returns false when use with startDetached() but works okay when calling start(). Right now, I'm using full path so I don't think working directory has an impact because the input file can be opened no matter what starting technique I use. It's just the output file that doesn't get written.

[wysota]

Could you add the following statement somewhere after filling args and show us its output?

qDebug() << args;

qDebug() << args;

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You'll need to #include <QtDebug> for that to work of course.

Also make sure the process indeed gets started...

[EricF]

Here's the output:

("-Tpng", "-oc:\temp\graph.png", "c:\temp\graph.dot")

as I said, if I start it detached it works perfect except for the console popping up. So I don't think my args could be wrong.

Also, when I start it normally(using start()), I receive the signal finished with ExitStatus = NormalExit. So I figured the process gets started.