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Forum Update on Monday, May 27th 2025

problem with System()

Scheduled Pinned Locked Moved Unsolved General and Desktop
system commandsystem
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  • mrjjM mrjj

    @AlvaroS

    well you can use
    qDebug() "qproc: " << myProcess->error();

    and check the code in
    http://doc.qt.io/qt-5/qprocess.html#ProcessError-enum

    AlvaroSA Offline
    AlvaroSA Offline
    AlvaroS
    wrote on last edited by
    #25

    @mrjj Yes thanks!! See my last post. Thanks again. It gives me Unknow error...

    mrjjM 1 Reply Last reply
    0
    • AlvaroSA AlvaroS

      @mrjj Yes thanks!! See my last post. Thanks again. It gives me Unknow error...

      mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by
      #26

      @AlvaroS

      " This is the default return value of error()."

      You do call it AFTER u call
      myProcess->start(program,arguments); ?

      AlvaroSA 1 Reply Last reply
      1
      • mrjjM mrjj

        @AlvaroS

        " This is the default return value of error()."

        You do call it AFTER u call
        myProcess->start(program,arguments); ?

        AlvaroSA Offline
        AlvaroSA Offline
        AlvaroS
        wrote on last edited by
        #27

        @mrjj Yes:

            myProcess->start(program, arguments);
        
            QProcess::ProcessError error = myProcess->error();
        
        mrjjM 1 Reply Last reply
        0
        • AlvaroSA AlvaroS

          @mrjj Yes:

              myProcess->start(program, arguments);
          
              QProcess::ProcessError error = myProcess->error();
          
          mrjjM Offline
          mrjjM Offline
          mrjj
          Lifetime Qt Champion
          wrote on last edited by
          #28

          @AlvaroS
          hmm really odd then
          it should say FailedToStart

          Just to be 100% clear.

          princi is never run ?

          AlvaroSA 1 Reply Last reply
          1
          • mrjjM mrjj

            @AlvaroS
            hmm really odd then
            it should say FailedToStart

            Just to be 100% clear.

            princi is never run ?

            AlvaroSA Offline
            AlvaroSA Offline
            AlvaroS
            wrote on last edited by
            #29

            @mrjj said:

            @AlvaroS
            hmm really odd then
            it should say FailedToStart

            Just to be 100% clear.

            princi is never run ?

            okey look.
            if I write:

                myProcess->start(program, arguments);
            
                myProcess->waitForFinished(3000);
            
                QProcess::ProcessError error = myProcess->error();
            
            

            Now error says:
            QProcess::Crashed The process crashed some time after starting successfully.

            1 Reply Last reply
            0
            • mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by mrjj
              #30

              so it sounds like your princi do run but it crashes?

              oh. sorry my bad. start is async so calling error right after was
              not correct.

              waitForFinished fixed that.

              AlvaroSA 1 Reply Last reply
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              • mrjjM mrjj

                so it sounds like your princi do run but it crashes?

                oh. sorry my bad. start is async so calling error right after was
                not correct.

                waitForFinished fixed that.

                AlvaroSA Offline
                AlvaroSA Offline
                AlvaroS
                wrote on last edited by
                #31

                @mrjj Yes... I think so...
                How should I pass the arguments?

                the arguments of princi are:

                0 wps.front().x() wps.front().y() 0 wps.back().x() wps.front().y() prueba_princi.bmp 0 0 +
                

                so my QStringList arguments is:

                 QStringList arguments;
                arguments << "0" << QString::number(wps.front().x()) << QString::number(wps.front().y()) << "0" << QString::number(wps.back().x()) << QString::number(wps.back().y()) << "prueba_princi.bmp" << "0" << "0" << "+" ;
                
                
                1 Reply Last reply
                0
                • mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #32

                  it seems fine
                  You should look inside princi for how it
                  reads it. it must be that part that is crashing ?

                  AlvaroSA 2 Replies Last reply
                  0
                  • mrjjM mrjj

                    it seems fine
                    You should look inside princi for how it
                    reads it. it must be that part that is crashing ?

                    AlvaroSA Offline
                    AlvaroSA Offline
                    AlvaroS
                    wrote on last edited by
                    #33

                    @mrjj yes, but it really rare that if I run from terminal princi runs good...

                    1 Reply Last reply
                    0
                    • mrjjM mrjj

                      it seems fine
                      You should look inside princi for how it
                      reads it. it must be that part that is crashing ?

                      AlvaroSA Offline
                      AlvaroSA Offline
                      AlvaroS
                      wrote on last edited by AlvaroS
                      #34

                      @mrjj And if I write:

                      system ("./princi 0 5 10 0 7 8 prueba_princi.bmp 0 0 +")
                      where 5,10,7 and 8 are wps.front,wps.back....
                      it runs well...

                      mrjjM 1 Reply Last reply
                      0
                      • SGaistS Offline
                        SGaistS Offline
                        SGaist
                        Lifetime Qt Champion
                        wrote on last edited by
                        #35

                        What is that + sign doing as parameter ?

                        Interested in AI ? www.idiap.ch
                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                        AlvaroSA 1 Reply Last reply
                        1
                        • SGaistS SGaist

                          What is that + sign doing as parameter ?

                          AlvaroSA Offline
                          AlvaroSA Offline
                          AlvaroS
                          wrote on last edited by
                          #36

                          @SGaist + is just and argument that i have to pass to princi

                          1 Reply Last reply
                          0
                          • AlvaroSA AlvaroS

                            @mrjj And if I write:

                            system ("./princi 0 5 10 0 7 8 prueba_princi.bmp 0 0 +")
                            where 5,10,7 and 8 are wps.front,wps.back....
                            it runs well...

                            mrjjM Offline
                            mrjjM Offline
                            mrjj
                            Lifetime Qt Champion
                            wrote on last edited by
                            #37

                            @AlvaroS
                            well you must debug it then.
                            Try to qDebug inside princi what you read and compare that to what u read for
                            system ("./princi 0 5 10 0 7 8 prueba_princi.bmp 0 0 +")

                            Sadly We cannot guess why you crash from the code shown.

                            Also you dump the arguments to qDebug before u
                            call start, just to see what u are sending also.

                            and then take it from there.

                            1 Reply Last reply
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