qDebug() is not working anymore in QT-Creator (Installed from QT-Installer from QT.io, OS: Manjaro Linux

[hskoglund]

Hi, if you try a
qDebug() << "Hello: ";
directly after QApplication a(argc, argv); in your main.cpp,
does that qDebug() work?

[JonB]

@HansKottmann
You seem to have a UI application but your configuration is CONFIG += console. Is that an issue?

not able to get the qDebug() function to work anymore

So since when/what does it not work "anymore"?

[HansKottmann]

I tried all you've suggested and what I found in the Internet. Without success, I assume that this is a severe bug in QtCreator, at least in the Linux version, I did not try any other platforms like Windows, etc. I use now a QTextEdit to output all debug messages I need, so my problem is creatively solved and I can go ahead.

[HansKottmann]

Now I have another problem, I can't get QProcess to work, it fails always with unknown error. The program I'm writing should do at the moment to call FFMPEG (ffprobe) to get the duration of the video I've selected in the gui, here the debug output. The commands for both videos are working fine when I copy them into a Linux terminal. Here the debug output:

/home/hk/Videos/gay-thai.mp4
/usr/bin/ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "/home/hk/Videos/gay-thai.mp4"
Unbekannter Fehler
 Hallo 0
/home/hk/Videos/Moderne Frauen sind überteuert liefern zu wenig und Männer haben.mp4
/usr/bin/ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "/home/hk/Videos/Moderne Frauen sind überteuert liefern zu wenig und Männer haben.mp4"
Unbekannter Fehler
 Hallo 0

As suggested in the net, I've set the working directory in QT: QDir::setCurrent(QDir::rootPath());

[JonB]

@HansKottmann
May depend on how you use QProcess and where you get the error message from.

[HansKottmann]

Here my code, I would be happy to learn from you

Declaration of QProcess in the header file:

QProcess *procTime = new QProcess(this)

Code in the *.cpp file

QString cmd = "/usr/bin/ffprobe";
    QStringList args;
    args << "-v error" << "-show_entries" << "format=duration" << "-of default=noprint_wrappers=1:nokey=1" << inputFileName.trimmed().prepend("\"").append("\"");

    connect(procTime, SIGNAL(readyRead()), this, SLOT(collectTimeData()));
    procTime->start(cmd, args);
    sendDebug(procTime->program() + " " + procTime->arguments().join(" "));
    sendDebug(procTime->errorString());
    procTime->waitForStarted();

sendDebug() is the function that sends the debug messages to a QTextEdit window as I was not able to get QDebug to work.
My platform is Manjaro Linux, QtCreator was installed with the installer from qt.io

[JonB]

@HansKottmann said in qDebug() is not working anymore in QT-Creator (Installed from QT-Installer from QT.io, OS: Manjaro Linux:

procTime->start(cmd, args);
sendDebug(procTime->program() + " " + procTime->arguments().join(" "));
sendDebug(procTime->errorString());
procTime->waitForStarted();

You are printing errorString() after start() but before even waitForStarted(). I would suggest your Unbekannter Fehler is because there is no error at this point. You have not shown any error occurs.

I do not know about your argument quoting. Is -v error really supposed to be a single argument, it isn't if you pasted it on a command line? You are quoting the filepath? I am not sure all this quoting is correct/desired as arguments directly to ffprobe, you might need to sh -c "..." it if you are not sure. But this comes after you sort out your error tester/printing.

[jsulm]

@HansKottmann To add to @JonB you should connect a slot to https://doc.qt.io/qt-6/qprocess.html#errorOccurred and print the error there.

[JonB]

@HansKottmann
As @jsulm has written. And/or, both waitForStarted() and waitForFinished() return a bool, only if they return false can you then get a meaningful error()/errorString() (can do that without signal/slot).

As I wrote before, I am dubious about your argument passing. I would expect you to use/need something more like:

args << "-v" << "error" << "-show_entries" << "format=duration"
     << "-of" << "default=noprint_wrappers=1:nokey=1" << inputFileName.trimmed();

based on what you say works from the command line.

[HansKottmann]

I've changed the args stringlist as you proposed and I still get Unknown Error. I assume as qDebug is not working too, that QT isn't working with Manjaro. It's a mess as I relayed for year in QT, but it got obviously useless.

[HansKottmann]

I switched to openSuSE tumbleweed. QDebug works but the unknown error remains

[JonB]

Show your updated code.

[HansKottmann]

The only thing I've changed is the args QStringList, it looks now exactly like yours, the only difference are the quotation marks at the beginning and the end of the file path string because filenames can have white spaces:

args << "-v" << "error" << "-show_entries" << "format=duration" << "-of" << "default=noprint_wrappers=1:nokey=1" << inputFileName.trimmed().prepend("\"").append("\"");

The problem with QCommand is not yet solve, I will try first very simple commands first without args, then with one, then two... I think this is the only way to debug this.

[JonB]

@HansKottmann said in qDebug() is not working anymore in QT-Creator (Installed from QT-Installer from QT.io, OS: Manjaro Linux:

The only thing I've changed is the args QStringList, it looks now exactly like yours, the only difference are the quotation marks at the beginning and the end of the file path string because filenames can have white spaces:

I already explained earlier that you are calling errorString() too early. So did @jsulm . And what to do about it. Your Unknown Error currently does not indicate anything has gone wrong. You need to change your code.

Your understanding of whitespace as it appears when you type a command into a shell versus how to pass arguments to spawned processes is not right. The arglist should be as a wrote and not have quotes. Or send the whole command line to bash -c.