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[SOLVED] Problem with cmd process

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  • C Cimmy
    25 Nov 2019, 18:39

    I'm trying to create a batch file. How can i set the path of this file?

    M Offline
    M Offline
    mrjj
    Lifetime Qt Champion
    wrote on 25 Nov 2019, 19:13 last edited by
    #10

    @Cimmy
    Hi Do you mean by the path ?
    You can place it the same place as the .exe if you wish.

    1 Reply Last reply
    0
    • C Offline
      C Offline
      Cimmy
      wrote on 25 Nov 2019, 19:23 last edited by
      #11

      void MainWindow::on_submitpath_clicked()
      {
      QString directory = ui->linepath->text() ;
      QString model = ui->linemodel->text();
      QString tracing = ui->linetracing->text();
      QString taskset = ui->linetaskset->text();
      QString sndstring="rtosim_ik_from_file --model ";
      sndstring.append(model);
      sndstring.append(" --trc ");
      sndstring.append(tracing);
      sndstring.append(" --task-set ");
      sndstring.append(taskset);
      sndstring.append(" -v");
      QString filenew = directory;
      filenew.append("/Filenew.bat");
      QFile file(filenew);
      if ( file.open(QIODevice::ReadWrite) )
      {
      QTextStream stream(&file);
      stream << sndstring <<endl;
      }
      QStringList arguments;
      arguments << "/c" << "Filenew.bat";
      QProcess *exec = new QProcess();
      exec->setWorkingDirectory(directory);
      exec->start("cmd.exe", arguments);
      }

      SOLVED!! Thanks to all!!

      J 1 Reply Last reply 26 Nov 2019, 06:06
      1
      • C Cimmy
        25 Nov 2019, 17:59

        618bc594-4d2e-4156-97b0-1f2962b716f3-image.png

        First try: use cmd, use rtosim_ik_from_file.exe as parameters. Message "destroyed while process is still running" and nothing happen

        b5ca4651-8541-4a09-9748-2860691ce233-image.png

        Second try: run directly rtosim_ik_from_file.exe with parameters (model, trc ect) but nothing happen. NO "destroyed while [...]" message.

        Any other suggestions?
        Don't know how to create a batch file. I will try...

        J Offline
        J Offline
        jsulm
        Lifetime Qt Champion
        wrote on 26 Nov 2019, 06:05 last edited by
        #12

        @Cimmy You're creating local QProcess instance on the stack! It is deleted when the slot finishes!
        I wrote before: "Simply add QProcess member to your class".

        https://forum.qt.io/topic/113070/qt-code-of-conduct

        1 Reply Last reply
        3
        • C Cimmy
          25 Nov 2019, 19:23

          void MainWindow::on_submitpath_clicked()
          {
          QString directory = ui->linepath->text() ;
          QString model = ui->linemodel->text();
          QString tracing = ui->linetracing->text();
          QString taskset = ui->linetaskset->text();
          QString sndstring="rtosim_ik_from_file --model ";
          sndstring.append(model);
          sndstring.append(" --trc ");
          sndstring.append(tracing);
          sndstring.append(" --task-set ");
          sndstring.append(taskset);
          sndstring.append(" -v");
          QString filenew = directory;
          filenew.append("/Filenew.bat");
          QFile file(filenew);
          if ( file.open(QIODevice::ReadWrite) )
          {
          QTextStream stream(&file);
          stream << sndstring <<endl;
          }
          QStringList arguments;
          arguments << "/c" << "Filenew.bat";
          QProcess *exec = new QProcess();
          exec->setWorkingDirectory(directory);
          exec->start("cmd.exe", arguments);
          }

          SOLVED!! Thanks to all!!

          J Offline
          J Offline
          jsulm
          Lifetime Qt Champion
          wrote on 26 Nov 2019, 06:06 last edited by
          #13

          @Cimmy said in Problem with cmd process:

          SOLVED!! Thanks to all!!

          Not really - you leak memory (exec is never deleted). As I wrote already add exec to your class as member, or pointer to QProcess to be able to delete it when you're done.

          https://forum.qt.io/topic/113070/qt-code-of-conduct

          1 Reply Last reply
          4
          • C Offline
            C Offline
            Cimmy
            wrote on 27 Nov 2019, 16:59 last edited by
            #14

            QProcess exec;
            exec.setWorkingDirectory(directory);
            exec.start("cmd.exe",arguments);

            right?

            J J 3 Replies Last reply 27 Nov 2019, 17:47
            0
            • C Cimmy
              27 Nov 2019, 16:59

              QProcess exec;
              exec.setWorkingDirectory(directory);
              exec.start("cmd.exe",arguments);

              right?

              J Offline
              J Offline
              JonB
              wrote on 27 Nov 2019, 17:47 last edited by JonB
              #15

              @Cimmy
              You need to make the

              QProcess exec;
              

              a member of your class (MainWindow), not a local variable in function on_submitpath_clicked.

              1 Reply Last reply
              3
              • C Cimmy
                27 Nov 2019, 16:59

                QProcess exec;
                exec.setWorkingDirectory(directory);
                exec.start("cmd.exe",arguments);

                right?

                J Offline
                J Offline
                jsulm
                Lifetime Qt Champion
                wrote on 28 Nov 2019, 06:17 last edited by
                #16

                @Cimmy said in Problem with cmd process:

                right?

                wrong. Then you will again have same issue: QProcess going out of scope and deleted.
                I write it now for the third time: "I wrote before: "Simply add QProcess member to your class"." (as @JonB suggested also).

                https://forum.qt.io/topic/113070/qt-code-of-conduct

                1 Reply Last reply
                4
                • C Cimmy
                  27 Nov 2019, 16:59

                  QProcess exec;
                  exec.setWorkingDirectory(directory);
                  exec.start("cmd.exe",arguments);

                  right?

                  J Offline
                  J Offline
                  JonB
                  wrote on 28 Nov 2019, 08:21 last edited by JonB
                  #17

                  @Cimmy
                  If you are interested (as I am!) as to why you have things this way. Here is what @jsulm has been telling you:

                  The issue is the QProcess destructor:

                  Destructs the QProcess object, i.e., killing the process.

                  Note that this function will not return until the process is terminated.

                  So if a QProcess gets destructed it will kill the process if it's still running. The problem is your code is only going to start() the sub-process running. It can/will continue running for a while. If your code were waiting for it to finish (e.g. QProcess::execute() or QProcess::waitForFinished()), there wouldn't be a problem, after that you could allow the QProcess to get destroyed.

                  If your QProcess is a local variable on the stack in a function like you propose, as soon as the function exits (variable goes "out of scope") the destructor would get called. So you can either:

                  • Move QProcess exec variable to a member of your class, not destructed till class instance destructed; or

                  • Use QProcess *exec = new QProcess(), allocated on the heap. Not destructed till delete exec. But then you need somewhere to save that pointer so that you can later delete it, no use as a local variable, so equally needs moving to class scope.

                  @jsulm
                  I have musing over this. If you want simple to start a sub-process and "forget" about it (yes, I know about "zombie" processes), this ~QProcess() behaviour is a bit problematic. I don't think startDetached() in itself would help here, it doesn't say that the destructor will not kill the process in this case:

                  If the calling process exits, the detached process will continue to run unaffected.

                  Yes, but if ~QProcess() called on exit it will still kill it, unless the docs are a bit vague here. Perhaps actually it does not? I wonder if QProcess() could do with a setNoKillOrWaitOnDestruct() flag, if startDetached() does not do that?

                  So.... I guess in this case the only safe thing to do would be to go new QProcess and deliberately not delete on exit? C++ doesn't go through everything you've newed and delete prior to exit, does it?! So accept that your program "leaks" prior to exit (e.g. a memory checker) and put up with it?

                  J 2 Replies Last reply 28 Nov 2019, 08:28
                  0
                  • J JonB
                    28 Nov 2019, 08:21

                    @Cimmy
                    If you are interested (as I am!) as to why you have things this way. Here is what @jsulm has been telling you:

                    The issue is the QProcess destructor:

                    Destructs the QProcess object, i.e., killing the process.

                    Note that this function will not return until the process is terminated.

                    So if a QProcess gets destructed it will kill the process if it's still running. The problem is your code is only going to start() the sub-process running. It can/will continue running for a while. If your code were waiting for it to finish (e.g. QProcess::execute() or QProcess::waitForFinished()), there wouldn't be a problem, after that you could allow the QProcess to get destroyed.

                    If your QProcess is a local variable on the stack in a function like you propose, as soon as the function exits (variable goes "out of scope") the destructor would get called. So you can either:

                    • Move QProcess exec variable to a member of your class, not destructed till class instance destructed; or

                    • Use QProcess *exec = new QProcess(), allocated on the heap. Not destructed till delete exec. But then you need somewhere to save that pointer so that you can later delete it, no use as a local variable, so equally needs moving to class scope.

                    @jsulm
                    I have musing over this. If you want simple to start a sub-process and "forget" about it (yes, I know about "zombie" processes), this ~QProcess() behaviour is a bit problematic. I don't think startDetached() in itself would help here, it doesn't say that the destructor will not kill the process in this case:

                    If the calling process exits, the detached process will continue to run unaffected.

                    Yes, but if ~QProcess() called on exit it will still kill it, unless the docs are a bit vague here. Perhaps actually it does not? I wonder if QProcess() could do with a setNoKillOrWaitOnDestruct() flag, if startDetached() does not do that?

                    So.... I guess in this case the only safe thing to do would be to go new QProcess and deliberately not delete on exit? C++ doesn't go through everything you've newed and delete prior to exit, does it?! So accept that your program "leaks" prior to exit (e.g. a memory checker) and put up with it?

                    J Offline
                    J Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on 28 Nov 2019, 08:28 last edited by
                    #18

                    @JonB "If the calling process exits, the detached process will continue to run unaffected." - https://doc.qt.io/qt-5/qprocess.html#startDetached
                    So, the QProcess destructor will not terminate the detached process as it is detached.
                    "this ~QProcess() behaviour is a bit problematic" - in what way? If you use startDetached() then the destructor doesn't matter. If you use exec() then I don't see why ~QProcess() terminating process is a problem? At the end it's your job as developer to select the right approach.

                    https://forum.qt.io/topic/113070/qt-code-of-conduct

                    J 1 Reply Last reply 28 Nov 2019, 08:32
                    4
                    • J jsulm
                      28 Nov 2019, 08:28

                      @JonB "If the calling process exits, the detached process will continue to run unaffected." - https://doc.qt.io/qt-5/qprocess.html#startDetached
                      So, the QProcess destructor will not terminate the detached process as it is detached.
                      "this ~QProcess() behaviour is a bit problematic" - in what way? If you use startDetached() then the destructor doesn't matter. If you use exec() then I don't see why ~QProcess() terminating process is a problem? At the end it's your job as developer to select the right approach.

                      J Offline
                      J Offline
                      JonB
                      wrote on 28 Nov 2019, 08:32 last edited by JonB
                      #19

                      @jsulm

                      "If the calling process exits, the detached process will continue to run unaffected."

                      That describes what happens if the calling process exits. It does not state it countermands what I quoted from ~QProcess(), which states it kills & waits. The question (my question) is what happens, which "wins", if you do not use new but have a "global" scoped QProcess globProc variable (not *globProc), initiate glocProc.startDetached(), and then exit your program. To me the docs are unclear....

                      Can I try this myself? No, because I'm stinky Python, and there are no variables, only heap pointers....

                      J 1 Reply Last reply 28 Nov 2019, 08:33
                      0
                      • J JonB
                        28 Nov 2019, 08:21

                        @Cimmy
                        If you are interested (as I am!) as to why you have things this way. Here is what @jsulm has been telling you:

                        The issue is the QProcess destructor:

                        Destructs the QProcess object, i.e., killing the process.

                        Note that this function will not return until the process is terminated.

                        So if a QProcess gets destructed it will kill the process if it's still running. The problem is your code is only going to start() the sub-process running. It can/will continue running for a while. If your code were waiting for it to finish (e.g. QProcess::execute() or QProcess::waitForFinished()), there wouldn't be a problem, after that you could allow the QProcess to get destroyed.

                        If your QProcess is a local variable on the stack in a function like you propose, as soon as the function exits (variable goes "out of scope") the destructor would get called. So you can either:

                        • Move QProcess exec variable to a member of your class, not destructed till class instance destructed; or

                        • Use QProcess *exec = new QProcess(), allocated on the heap. Not destructed till delete exec. But then you need somewhere to save that pointer so that you can later delete it, no use as a local variable, so equally needs moving to class scope.

                        @jsulm
                        I have musing over this. If you want simple to start a sub-process and "forget" about it (yes, I know about "zombie" processes), this ~QProcess() behaviour is a bit problematic. I don't think startDetached() in itself would help here, it doesn't say that the destructor will not kill the process in this case:

                        If the calling process exits, the detached process will continue to run unaffected.

                        Yes, but if ~QProcess() called on exit it will still kill it, unless the docs are a bit vague here. Perhaps actually it does not? I wonder if QProcess() could do with a setNoKillOrWaitOnDestruct() flag, if startDetached() does not do that?

                        So.... I guess in this case the only safe thing to do would be to go new QProcess and deliberately not delete on exit? C++ doesn't go through everything you've newed and delete prior to exit, does it?! So accept that your program "leaks" prior to exit (e.g. a memory checker) and put up with it?

                        J Offline
                        J Offline
                        jsulm
                        Lifetime Qt Champion
                        wrote on 28 Nov 2019, 08:32 last edited by
                        #20

                        @JonB And there are static methods in QProcess to execute a process without even creating a QProcess instance.

                        https://forum.qt.io/topic/113070/qt-code-of-conduct

                        J 1 Reply Last reply 28 Nov 2019, 08:35
                        5
                        • J JonB
                          28 Nov 2019, 08:32

                          @jsulm

                          "If the calling process exits, the detached process will continue to run unaffected."

                          That describes what happens if the calling process exits. It does not state it countermands what I quoted from ~QProcess(), which states it kills & waits. The question (my question) is what happens, which "wins", if you do not use new but have a "global" scoped QProcess globProc variable (not *globProc), initiate glocProc.startDetached(), and then exit your program. To me the docs are unclear....

                          Can I try this myself? No, because I'm stinky Python, and there are no variables, only heap pointers....

                          J Offline
                          J Offline
                          jsulm
                          Lifetime Qt Champion
                          wrote on 28 Nov 2019, 08:33 last edited by jsulm
                          #21

                          @JonB said in Problem with cmd process:

                          That describes what happens if the calling process exits

                          Yes, and if an application exits ~QProcess() will be called (at least if it exits normally)...
                          It's the whole point of startDetached() - it detaches the QProcess instance from the started process. Just try.

                          https://forum.qt.io/topic/113070/qt-code-of-conduct

                          1 Reply Last reply
                          3
                          • J jsulm
                            28 Nov 2019, 08:32

                            @JonB And there are static methods in QProcess to execute a process without even creating a QProcess instance.

                            J Offline
                            J Offline
                            JonB
                            wrote on 28 Nov 2019, 08:35 last edited by JonB
                            #22

                            @jsulm
                            Ah!! (And you don't think those create an instance internally?). OK, so if I use static QProcess::startDetached() that really should not call ~QProcess, even on program exit?

                            It's the whole point of startDetached() - it detaches the QProcess instance from the started process.

                            Just because a process is detached that does not mean you cannot wait on or kill it, does it? It just means things like it's in its own session.

                            But it should not matter as the process is detached and the destructor should NOT terminate it.

                            OK, but I don't get that from the docs! Maybe we read them differently. I'm also having a deeper think about C++ static, too long now of having to do Python... :(

                            Time for me to have a play....

                            J 1 Reply Last reply 28 Nov 2019, 08:36
                            1
                            • J JonB
                              28 Nov 2019, 08:35

                              @jsulm
                              Ah!! (And you don't think those create an instance internally?). OK, so if I use static QProcess::startDetached() that really should not call ~QProcess, even on program exit?

                              It's the whole point of startDetached() - it detaches the QProcess instance from the started process.

                              Just because a process is detached that does not mean you cannot wait on or kill it, does it? It just means things like it's in its own session.

                              But it should not matter as the process is detached and the destructor should NOT terminate it.

                              OK, but I don't get that from the docs! Maybe we read them differently. I'm also having a deeper think about C++ static, too long now of having to do Python... :(

                              Time for me to have a play....

                              J Offline
                              J Offline
                              jsulm
                              Lifetime Qt Champion
                              wrote on 28 Nov 2019, 08:36 last edited by
                              #23

                              @JonB said in Problem with cmd process:

                              And you don't think those create an instance internally?

                              I don't know. But it should not matter as the process is detached and the destructor should NOT terminate it.

                              https://forum.qt.io/topic/113070/qt-code-of-conduct

                              J 1 Reply Last reply 28 Nov 2019, 09:02
                              1
                              • J jsulm
                                28 Nov 2019, 08:36

                                @JonB said in Problem with cmd process:

                                And you don't think those create an instance internally?

                                I don't know. But it should not matter as the process is detached and the destructor should NOT terminate it.

                                J Offline
                                J Offline
                                JonB
                                wrote on 28 Nov 2019, 09:02 last edited by JonB
                                #24

                                @jsulm
                                Just to confirm your interpretation.

                                From Python/PySide2, from a terminal if I run an interactive python3 and do

                                >>> from PySide2.QtCore import QProcess
                                >>> p = QProcess(); p.start("./script")
                                

                                and then exit the python session (python will auto-delete everything created), I get a message

                                QProcess: Destroyed while process ("./script") is still running.
                                

                                But if I use

                                >>> p = QProcess(); p.startDetached("./script")
                                # or
                                >>> QProcess.startDetached("./script")
                                

                                no message, and I continue to see ./script's output after the python session has exited.

                                J 1 Reply Last reply 28 Nov 2019, 09:05
                                1
                                • J JonB
                                  28 Nov 2019, 09:02

                                  @jsulm
                                  Just to confirm your interpretation.

                                  From Python/PySide2, from a terminal if I run an interactive python3 and do

                                  >>> from PySide2.QtCore import QProcess
                                  >>> p = QProcess(); p.start("./script")
                                  

                                  and then exit the python session (python will auto-delete everything created), I get a message

                                  QProcess: Destroyed while process ("./script") is still running.
                                  

                                  But if I use

                                  >>> p = QProcess(); p.startDetached("./script")
                                  # or
                                  >>> QProcess.startDetached("./script")
                                  

                                  no message, and I continue to see ./script's output after the python session has exited.

                                  J Offline
                                  J Offline
                                  jsulm
                                  Lifetime Qt Champion
                                  wrote on 28 Nov 2019, 09:05 last edited by
                                  #25

                                  @JonB said in Problem with cmd process:

                                  no message, and I continue to see ./script's output after the python session has exited.

                                  This is expected, isn't it? As stated in the documentation. ~QProcess() is called in both cases.

                                  https://forum.qt.io/topic/113070/qt-code-of-conduct

                                  J 1 Reply Last reply 28 Nov 2019, 09:09
                                  1
                                  • J jsulm
                                    28 Nov 2019, 09:05

                                    @JonB said in Problem with cmd process:

                                    no message, and I continue to see ./script's output after the python session has exited.

                                    This is expected, isn't it? As stated in the documentation. ~QProcess() is called in both cases.

                                    J Offline
                                    J Offline
                                    JonB
                                    wrote on 28 Nov 2019, 09:09 last edited by JonB
                                    #26

                                    @jsulm

                                    This is expected, isn't it? As stated in the documentation. ~QProcess() is called in both cases.

                                    Expected by you apparently, but not by me. If ~QProcess() is called, docs state

                                    Destructs the QProcess object, i.e., killing the process.

                                    Note that this function will not return until the process is terminated.

                                    If it said "but not when started via (non-static) QProcess::startDetached()" then I would be happy. Like I said, perhaps different doc interpretation between you & me.

                                    J 1 Reply Last reply 28 Nov 2019, 09:12
                                    1
                                    • J JonB
                                      28 Nov 2019, 09:09

                                      @jsulm

                                      This is expected, isn't it? As stated in the documentation. ~QProcess() is called in both cases.

                                      Expected by you apparently, but not by me. If ~QProcess() is called, docs state

                                      Destructs the QProcess object, i.e., killing the process.

                                      Note that this function will not return until the process is terminated.

                                      If it said "but not when started via (non-static) QProcess::startDetached()" then I would be happy. Like I said, perhaps different doc interpretation between you & me.

                                      J Offline
                                      J Offline
                                      jsulm
                                      Lifetime Qt Champion
                                      wrote on 28 Nov 2019, 09:12 last edited by
                                      #27

                                      @JonB Well, again:
                                      "If the calling process exits, the detached process will continue to run unaffected." - https://doc.qt.io/qt-5/qprocess.html#startDetached

                                      And you even confirmed this behaviour by yourself :-)

                                      You can upload a patch fixing ~QProcess() documentation.

                                      https://forum.qt.io/topic/113070/qt-code-of-conduct

                                      J 1 Reply Last reply 28 Nov 2019, 09:26
                                      1
                                      • J jsulm
                                        28 Nov 2019, 09:12

                                        @JonB Well, again:
                                        "If the calling process exits, the detached process will continue to run unaffected." - https://doc.qt.io/qt-5/qprocess.html#startDetached

                                        And you even confirmed this behaviour by yourself :-)

                                        You can upload a patch fixing ~QProcess() documentation.

                                        J Offline
                                        J Offline
                                        JonB
                                        wrote on 28 Nov 2019, 09:26 last edited by JonB
                                        #28

                                        @jsulm
                                        I already wrote above: "calling process exits" does not tell you whether ~QProcess() is or is not called. In C++, if I glob_dangling = new QProcess(); exit(0); C++ cleanup does not call ~QProcess(), does it?

                                        But when ~QProcess() is called for whatever reason, https://code.woboq.org/qt5/qtbase/src/corelib/io/qprocess.cpp.html#_ZN8QProcessD1Ev has

                                        QProcess::~QProcess()
                                        {
                                            Q_D(QProcess);
                                            if (d->processState != NotRunning) {
                                                qWarning().nospace()
                                                    << "QProcess: Destroyed while process (" << QDir::toNativeSeparators(program()) << ") is still running.";
                                                kill();
                                                waitForFinished();
                                            }
                                        

                                        so presumably somewhere qProcess->startDetached() ends up causing d->processState = NotRunning.

                                        J 1 Reply Last reply 28 Nov 2019, 09:32
                                        1
                                        • J JonB
                                          28 Nov 2019, 09:26

                                          @jsulm
                                          I already wrote above: "calling process exits" does not tell you whether ~QProcess() is or is not called. In C++, if I glob_dangling = new QProcess(); exit(0); C++ cleanup does not call ~QProcess(), does it?

                                          But when ~QProcess() is called for whatever reason, https://code.woboq.org/qt5/qtbase/src/corelib/io/qprocess.cpp.html#_ZN8QProcessD1Ev has

                                          QProcess::~QProcess()
                                          {
                                              Q_D(QProcess);
                                              if (d->processState != NotRunning) {
                                                  qWarning().nospace()
                                                      << "QProcess: Destroyed while process (" << QDir::toNativeSeparators(program()) << ") is still running.";
                                                  kill();
                                                  waitForFinished();
                                              }
                                          

                                          so presumably somewhere qProcess->startDetached() ends up causing d->processState = NotRunning.

                                          J Offline
                                          J Offline
                                          jsulm
                                          Lifetime Qt Champion
                                          wrote on 28 Nov 2019, 09:32 last edited by
                                          #29

                                          @JonB If allocated on the stack destructor ALWAYS is called if app is closing in a clean way. If allocated on the heap you have to delete it. I'm sure Python has clean memory management and deletes what it allocates (so destrcutor is called).

                                          https://forum.qt.io/topic/113070/qt-code-of-conduct

                                          J 1 Reply Last reply 28 Nov 2019, 09:45
                                          1

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