@J-Hilk Thanks for your help! It works!

@JonB: yes, and then use QString::fromUtf8()

@JonB This is a quote from the example given on the link listed. It's from QT, in an explanation of how this works. It's not a string that I came up with, or that I'm using.

@nikko1991 said in Can't kill QProcess in overriden closeEvent(): I believe shutting down ROS from Qt/other program is slower than from terminal I don't claim to understand what you are saying in your post, and I probably won't understand even if you try to explain more! But I do not know what you could mean by this sentence. The "terminal" (i.e. a "shell") simply is "from other program". There is no difference between a shell and any other program under Linux, and if you can do something from a shell you can do it from a program you write. As a separate matter, I wouldn't use the blocking QProcess::waitFor...() methods anyway, at least not in the case of issues with the program spawned. There is no need to, as there are the asynchronous signals from QProcess available to you, which is how the waitFor()s are implemented anyway. So if you are saying these are causing you problems, don't use them.

@Amirhos Unfortunately this is difficult, especially under Windows. If, for whatever reason, the third-party app is buffering its output at its own side then you cannot force it down the pipe to your parent, it depends how the code is written at their side....

I am really thankful to everyone who replied to me and corrected my mistakes. Your help will help me finish my work quicker. Thanks @Christian-Ehrlicher , @Bonnie @JonB

@SGaist as a matter of fact it did... Then I used Qthread::msleep(500); I will try using it asynchronously today and get back to you with the result...

@JonB sorry if i reply now, but my company has closed for a week, launching a script was an example, any qprocess gives me that message also if i start ls, arp-scan or others. if i start a program locally i don't have this problem, the problem occurs if i start a program in remote debug, but the versions (local and remote) of gdb and linux are the same

@SGaist Thank you, this has solved my issue!! :D

@cstevenson Please also connect a slot to https://doc.qt.io/qt-5/qprocess.html#errorOccurred The process is probably not running when you call write().

@Kyeiv OK, but please put the error checking code in anyway. With OS commands you never know what might go wrong (just like you discovered), so it's important to check for & report all errors! And especially if you are going to be distributing this....

The problem might be that you have two nested calls to PowerShell without exiting them. A quick search shows people reporting the inner PowerShell call (with -Verb runas) keeps the console window open. So, instead of the netsh command you might want to provide a script that has the netsh command and an exit. Or maybe you can concatenate the two directly in the -ArgumentList (I don't have much experience with PowerShell, but in Linux I could separate commands with a semicolon).

@mrjj ...Which is one of the 1,000 reasons I would not be accepting this Qt application if it says I need to run it sudo... :)

Thanks @JonB . The problem seems gone when I remove these "process terminate" code.

@jsulm I did :-) but I have no more information... Anyway I will stop using the QProcess class to reccord video with my webcam, it seems too tricky, instead I think I will use a library like LibVLC to do it...

@JonB Thank you for correct direction. I will modify my code and use it finished Signal for updating dialog box.

@JonB Thanks! That saved me a good deal of troubleshooting. It turned out the problem was a hard path to a file inside the C program which caused it to run correctly when invoked from it's native directory, but caused a segfault when called by Qt since the paths were different. The problem is completely fixed now.

Hi, Thank you for your reply. I totally changed my implementation using the signal and slots. Thank you so much again.

@BitFlipper b) I tried that already with no luck Then you did not try right! There is an example of just what you need at the link I posted. The outline of this approach would be: QProcess ddProcess, md5sumProcess; ddProcess.setStandardOutputProcess(&md5sumProcess); ddProcess.start("sudo dd if=/dev/sda2 of=/dev/sdb2 bs=4096 conv=noerror"); md5sumProcess.start("md5sum"); md5sumProcess.waitForFinished(); However, it's probably more suitable for you to issue the whole lot as a single string passed to /bin/sh or /bin/bash with the -c argument, and let it figure the | for you., as per my example earlier. So my command changes in this function, should I build a custom string every time and pass it in as one statement? Yes. I always practice in terminal first For this purpose make yourself use /bin/sh -c "sudo dd ... | md5sum" as that is what you will need. Be careful if anything in your command requires its own quoting (your current example does not), as the whole command itself is now inside quotes. As I wrote earlier, your md5sum is not going to see the contents from the dd. Your example does not lend itself to checksumming as it uses a single dd if=... of=... which does the input & output in one go. What you want is for the output from the dd to go both to the output file and to md5sum. Here are two possibilities for you to play with: sudo dd if=/dev/sda2 bs=4096 conv=noerror | sudo tee /dev/sdb2 | md5sum sudo dd if=/dev/sda2 bs=4096 conv=noerror | tee >(md5sum 1>&2) | sudo dd of=/dev/sdb2 bs=4096 In the first case we tee the output off to /dev/sdb2 as well as letting it through to md5sum. Simpl-ish, but you lose the ability to specify the bs= for the output to /dev/sdb2. I don't know if that matters to you. In the second case you use "shell magic" (you'll probably have to use /bin/bash not /bin/sh, I think) to send tee's output to md5sum process as well as passing it onto a second dd to do the output. I have made it so md5sum's output goes to standard error instead of standard output. Finally: is all this dd and checksum stuff worth it? Probably not. Have a read of, say, https://unix.stackexchange.com/a/45854/104736 for alternative suggestions.

Hi, I have found something that works but that is not really "clean" in my opinion : QString password = "yourRootPassword"; //could be asked with QInputDialog::getText(...) QString cmd = QString("sudo -S kextunload -b %1 > /dev/null").arg(driverName); FILE *pipe = popen(cmd.toStdString().c_str(), "w"); if(pipe != nullptr) { fprintf(pipe, "%s\n", password.toStdString().c_str()); if (ferror(pipe)) { qDebug() << "Failed to write to pipe"; } else { qDebug() << "Written to pipe"; } } else { qDebug() << "Failed to open pipe"; } qDebug() << "Pipe returned : " << pclose(pipe); I don't know how to use the Apple method linked by SGaist...

thanks !! . I will look into both of them

You might have modified PATH in your terminal session only for example. Or you may have modified PATH in the Run part of the Project panel.

@Thanos thanks for your feedback. So please mark this topic as SOLVED now.

Hi and welcome to devnet, You should take a look at the various IPC options provided by Qt.

IIRC, you have QTest;:wait for that kind of stuff.

@Naim Use http://doc.qt.io/qt-5/qprocess.html#readyReadStandardOutput and http://doc.qt.io/qt-5/qprocess.html#readyReadStandardError to get notifications each time the process writes something to stdout or stderr and read it using http://doc.qt.io/qt-5/qprocess.html#readAllStandardOutput and http://doc.qt.io/qt-5/qprocess.html#readAllStandardError. Do not call waitForFinished, just make sure your proc does not go out of scope (make it class member).

@gizalp Why do you think python (or anything else) is going to open any terminal window? And what OS are you on anyway? For QProcess:setProgram you should have process.setProgram("python");, only. But in this case I think it's getting overridden by your process.start("python test.py"); so it doesn't matter, but it's wrong. If you want to grab a sub-process's output, you have to handle QProcess::readyReadStandardOutput(), and in there something like QByteArray QProcess::readAllStandardOutput(), if that's what you mean by "How can I get the 'Hello' output?". How this relates to Trying to implement thumbnail list I have no idea....

@gizalp said in Qt Signal Slot: @mostefa Thanks, that fixed my problem! You are welcome =)

@kshegunov I see, now i understand. Thank you for your help and for your patience.

You can't read from a finished program. you have to connect to readyRead(); replace process->start(cmd,comandlist,QIODevice::ReadOnly ); if (!process->waitForFinished()) { lstr = QString(); } else { lstr = QString(process->readAll().constData()); } return lstr; with QObject::connect(process,&QProcess::readyReadStandardOutput,[&lstr,process]()->void{lstr.append(QString::fromLatin1(process->readAllStandardOutput()));}); process->start(cmd,comandlist,QIODevice::ReadOnly ); if (process->waitForFinished()) return lstr; return QString();

@SGaist Good one! Though I had to use the C++11 version since C++14 is still in Debian Sid. // C++11 connect(process, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, &MainWindow::close); For those who want to know, this is the C++14-version: // C++14 connect(process, qOverload<int, QProcess::ExitStatus>(&QProcess::finished), this, &MainWindow::close); Since the actual problem of this thread is solved, I will mark this thread as solved tomorrow. In the mean time comments on the above code can be made.

Well, actually it does work! But if bash is not running interactively, it won't read the .bashrc where the shell-variables are stored. So I did the following: sh.start("bash -i"); // the -i tell bash to run interactively if(sh.waitForStarted()) sh.write("printenv JAVA_HOME"); // or sh.write("echo $JAVA_HOME") sh.closeWriteChannel(); In case you were wondering, I connected the QProcess::finished signal to a slot where the QProcess::readAllStandardOutput is put in a QPlainTextEdit. The QProcess::processEnvironment is not updated however. Even if I try to export JAVA_HOME with sh.write("export JAVA_HOME"). While that is not what I expected, I now can find the local shell-variables. So I will mark this problem as solved. Thanks!

Can you share the QProcess code you have written to execute the script ?

@JonB I don't know why this example does the output like this....

@VRonin said in Send arrow keys via QProcess in any platform: @Mark81 Then do you really need Qt? there are already mature tools to do those kind of things, for windows: http://ahkscript.org/ and for linux: http://www.semicomplete.com/projects/xdotool/ I don't need Qt for this. But I have a quite large application that does a lot of things. One of those, is to launch external applications and send them keystrokes as you would type in front of a keyboard.

Thanks! Marking solved.

How can I fix this problem?