QString replace %U

sonichy · 26 Oct 2021, 08:09

@JonB This is new problem after modify the code, QProcess do not start in lambda !

jsulm · 26 Oct 2021, 08:24

@sonichy Would you mind to post the current code, or should we guess what is wrong?

JonB · 26 Oct 2021, 08:33

This is new problem after modify the code

Fair enough, I did say you would have see whether it causes problems. This raises a nasty question of what Qt requires the scope/lifetime of the process used in QProcess::startDetached() to be: it cannot be "forever", because we know detached processes survive even exiting the parent program. Maybe it requires it to exist till at least started() signal has been received, I don't know.

Actually, hang on! The overload of startDetached you are using is bool QProcess::startDetached(const QString &program, const QStringList &arguments, const QString &workingDirectory = QString(), qint64 *pid = nullptr). That is static!

Soooo:

process->setWorkingDirectory(sPath); has no effect (the method signature above takes an optional parameter for the working directory instead).
Your QProcess *process = new QProcess; is not used.
You can write QProcess::startDetached(sExec, QStringList()); instead, no QProcess instance needed, and no leaking.
Given this I find it hard to believe that changing QProcess *process to QProcess process can have any effect....

sonichy · 26 Oct 2021, 08:32

@jsulm Click QAction QProcess do not start, copy qDebug() content to terminal can run.

QString sExec = readSettings(desktop, "Desktop Entry", "Exec");
sExec.replace(QString("%U"), filepath, Qt::CaseInsensitive);
sExec.replace(QString("%F"), filepath, Qt::CaseInsensitive);
connect(action, &QAction::triggered, [=](){
       QProcess *process = new QProcess;
       process->setWorkingDirectory(path);
       qDebug() << sExec;
       //process->start(sExec);
       process->setProgram(sExec);
       process->startDetached();
});

JonB · wrote on 26 Oct 2021, 08:32

@sonichy
Is sExec set to the correct full path to the executable? What do you think your process->setWorkingDirectory(path); achieves? Because if you think it is used to locate the executable to run, it is not.

The bool QProcess::startDetached(qint64 *pid = nullptr) overload you are now using has a return value. Do you think you ought look at that if you are having a problem?

sonichy · 26 Oct 2021, 08:34

@JonB Two method:
bool QProcess::startDetached(qint64 *pid = nullptr)

[static] bool QProcess::startDetached(const QString &program, const QStringList &arguments, const QString &workingDirectory = QString(), qint64 *pid = nullptr)

And static do not start either.

QProcess::startDetached(sExec, QStringList(), path);

jsulm · wrote on 26 Oct 2021, 08:34

@sonichy Please add error handling - QProcess has functionality for that...

JonB · 26 Oct 2021, 08:46

@sonichy
Then I do not see that anything you have had so far can have succeeded, but it's most unclear from your comments what that case is.

As per my previous, could you please show what your qDebug() << sExec; is outputting, instead of making us guess?

sonichy · 26 Oct 2021, 08:49

@JonB deepin-draw "/home/sonichy/Desktop/KuGou.png"

jsulm · wrote on 26 Oct 2021, 08:49

@sonichy said in QString replace %U:

deepin-draw

This is a relative path. Pass whole path, so it can actually be found...
And please add error handling...

JonB · 26 Oct 2021, 08:58

@sonichy said in QString replace %U:

@JonB deepin-draw "/home/sonichy/Desktop/KuGou.png"

I previously wrote:

Is sExec set to the correct full path to the executable? What do you think your process->setWorkingDirectory(path); achieves? Because if you think it is used to locate the executable to run, it is not.

jsulm · 26 Oct 2021, 09:00

@JonB Yes, it is said that people often do not read carefully...

JonB · J jsulm 26 Oct 2021, 08:58

@jsulm
It would be nice if questioners answered questions and acted on recommendations before just reposting that something does not work. Makes we wonder sometimes why we bother. If I ask a question and somebody gives some suggestions I act on those carefully before asking again. But that's another topic... :)

sonichy · 26 Oct 2021, 09:19

@JonB
The Linux desktop file installed by root(deb) do not contain Path.
And absolute exe path do not work either:

/usr/bin/google-chrome-stable \"/home/sonichy/Desktop/description.xml\"

Error handle

connect(action, &QAction::triggered, [=](){
    QProcess *process = new QProcess;
    //process->setWorkingDirectory(path);
    qDebug() << sExec;
    //process->start(sExec); //crash
    process->setProgram(sExec);
    connect(process, &QProcess::readyReadStandardError, [=](){
         qDebug() << process->errorString(); //nothing
    });
    bool b = process->startDetached();
    qDebug() << b; //false
    //QProcess::startDetached(sExec, QStringList(), path);
});

JonB · 26 Oct 2021, 09:32

@sonichy

If you mean that qDebug() << sExec; outputs /usr/bin/google-chrome-stable \"/home/sonichy/Desktop/description.xml\" then that is your problem. That line is not a program/executable, is it? The first word is the executable and the second word is an argument (and when passed as an argument it should not then have "s around it). And if that is the case it would have saved a lot of time if you had shown this from the start.
qDebug() << process->errorString(); //nothing This is not what you are supposed to output if you receive some data on standard error, you are supposed to print the data you receive.

jsulm · 26 Oct 2021, 09:23

@sonichy I was talking about https://doc.qt.io/qt-5/qprocess.html#errorOccurred
"/usr/bin/google-chrome-stable" - I don't get it - didn't you want to start deepin-draw before?
So, what do you want to start actually?!

JonB · J jsulm 26 Oct 2021, 09:22

@jsulm Who knows....

sonichy · J jsulm 26 Oct 2021, 09:22

This post is deleted!

sonichy · 26 Oct 2021, 09:27

@jsulm said in QString replace %U:

@sonichy I was talking about https://doc.qt.io/qt-5/qprocess.html#errorOccurred
"/usr/bin/google-chrome-stable" - I don't get it - didn't you want to start deepin-draw before?
So, what do you want to start actually?!

deepin-draw is relative path.
google-chrome is absolute path.
I make openwith function, I can choose program to start.

jsulm · 26 Oct 2021, 09:28

@sonichy Third time: add error handling to see why QProcess fails to start the executable...
Also, sExec should NOT contain executable and parameter! Parameters to the executable are passed as another QStringList parameter https://doc.qt.io/qt-5/qprocess.html#setArguments