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  4. How to close the subroutine of the program started by qprocess?
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How to close the subroutine of the program started by qprocess?

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  • JoeCFDJ JoeCFD

    Try this
    kill( m_process->pid(), SIGINT );
    before m_process is closed.

    or
    QString cmd = QString( "kill -9 %1" ).arg( m_process->pid() );
    call this
    exec( cmd.toStdString().c_str() );

    std::string exec(const char* cmd) {
    std::array<char, 128> buffer;
    std::string result;
    std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd, "r"), pclose);
    if (!pipe) {
    throw std::runtime_error("popen() failed!");
    }
    while (fgets(buffer.data(), buffer.size(), pipe.get()) != nullptr) {
    result += buffer.data();
    }
    return result;
    }
    from https://stackoverflow.com/questions/478898/how-do-i-execute-a-command-and-get-the-output-of-the-command-within-c-using-po

    J Offline
    J Offline
    jiaming
    wrote on last edited by
    #7

    @JoeCFD
    No kill function found. Do you need to import any files?

    1 Reply Last reply
    0
    • JoeCFDJ JoeCFD

      Try this
      kill( m_process->pid(), SIGINT );
      before m_process is closed.

      or
      QString cmd = QString( "kill -9 %1" ).arg( m_process->pid() );
      call this
      exec( cmd.toStdString().c_str() );

      std::string exec(const char* cmd) {
      std::array<char, 128> buffer;
      std::string result;
      std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd, "r"), pclose);
      if (!pipe) {
      throw std::runtime_error("popen() failed!");
      }
      while (fgets(buffer.data(), buffer.size(), pipe.get()) != nullptr) {
      result += buffer.data();
      }
      return result;
      }
      from https://stackoverflow.com/questions/478898/how-do-i-execute-a-command-and-get-the-output-of-the-command-within-c-using-po

      Christian EhrlicherC Offline
      Christian EhrlicherC Offline
      Christian Ehrlicher
      Lifetime Qt Champion
      wrote on last edited by
      #8

      @JoeCFD How should this help killing a sub-sub-process? Apart from this the OP is on windows...

      Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
      Visit the Qt Academy at https://academy.qt.io/catalog

      1 Reply Last reply
      1
      • J Offline
        J Offline
        jiaming
        wrote on last edited by
        #9

        My program runs on Ubuntu

        JonBJ 1 Reply Last reply
        0
        • Christian EhrlicherC Offline
          Christian EhrlicherC Offline
          Christian Ehrlicher
          Lifetime Qt Champion
          wrote on last edited by
          #10

          Then 'kill' should be available. But it still does not solve your problem. Fix your 'A' program to properly shut down it's spawned processes.

          Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
          Visit the Qt Academy at https://academy.qt.io/catalog

          1 Reply Last reply
          2
          • J jiaming

            My program runs on Ubuntu

            JonBJ Offline
            JonBJ Offline
            JonB
            wrote on last edited by JonB
            #11

            @jiaming

            My program runs on Ubuntu

            And so? As I & @Christian-Ehrlicher have said, you cannot use this to kill a "sub-sub-process". You don't know the PID of the process you want to kill.

            Can you please take the time to address what @Christian-Ehrlicher wrote earlier:

            Then fix A so it properly shuts down B

            [Under Linux you could try using pkill to kill all B processes, but I really wouldn't recommend it....]

            1 Reply Last reply
            0
            • J Offline
              J Offline
              jiaming
              wrote on last edited by
              #12

              I forgot to say that if A is opened in a terminal, B will also be closed when using Ctrl+C to close. What I am looking for is a method similar to sending a Ctrl+C signal.

              JonBJ JoeCFDJ 2 Replies Last reply
              0
              • J jiaming

                I forgot to say that if A is opened in a terminal, B will also be closed when using Ctrl+C to close. What I am looking for is a method similar to sending a Ctrl+C signal.

                JonBJ Offline
                JonBJ Offline
                JonB
                wrote on last edited by JonB
                #13

                @jiaming
                Use Linux man 2 kill call: kill(pid_of_A, SIGINT). But I doubt it will work from here.

                It's nice to see that you ignore every suggestion we make.... Best of luck.

                1 Reply Last reply
                0
                • J Offline
                  J Offline
                  jiaming
                  wrote on last edited by
                  #14

                  The main reason is that I didn't write A and B programs. They have formed a good system. It's troublesome for me to change them. It's better to have a simpler method.

                  I found that PPID of B is 1......

                  I'm sorry for the trouble.

                  jsulmJ JonBJ 3 Replies Last reply
                  0
                  • J jiaming

                    The main reason is that I didn't write A and B programs. They have formed a good system. It's troublesome for me to change them. It's better to have a simpler method.

                    I found that PPID of B is 1......

                    I'm sorry for the trouble.

                    jsulmJ Offline
                    jsulmJ Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on last edited by
                    #15

                    @jiaming said in How to close the subroutine of the program started by qprocess?:

                    I found that PPID of B is 1

                    You need PID if you want to kill it...

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

                    1 Reply Last reply
                    0
                    • J jiaming

                      The main reason is that I didn't write A and B programs. They have formed a good system. It's troublesome for me to change them. It's better to have a simpler method.

                      I found that PPID of B is 1......

                      I'm sorry for the trouble.

                      jsulmJ Offline
                      jsulmJ Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by
                      #16

                      @jiaming You could try to get PID from B using PID from A, see https://stackoverflow.com/questions/17743879/how-to-get-child-process-from-parent-process

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

                      1 Reply Last reply
                      0
                      • J jiaming

                        The main reason is that I didn't write A and B programs. They have formed a good system. It's troublesome for me to change them. It's better to have a simpler method.

                        I found that PPID of B is 1......

                        I'm sorry for the trouble.

                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on last edited by JonB
                        #17

                        @jiaming said in How to close the subroutine of the program started by qprocess?:

                        I found that PPID of B is 1......

                        Which is why I said I do not think that sending a SIGINT to the parent (A) will have any effect on B...!

                        A process ID value of 1 indicates that there is no parent process associated with the [...] process."

                        1 Reply Last reply
                        1
                        • J jiaming

                          I forgot to say that if A is opened in a terminal, B will also be closed when using Ctrl+C to close. What I am looking for is a method similar to sending a Ctrl+C signal.

                          JoeCFDJ Offline
                          JoeCFDJ Offline
                          JoeCFD
                          wrote on last edited by JoeCFD
                          #18

                          @jiaming kill( m_process->pid(), SIGINT ); <==this does what you need. You need somehow to find the pid of B.
                          std::string pid_str = exec( "pidof B" ); exec is defined in the post above and "pidof" is a linux command to find process id.
                          if( !pid_str.empty() ) {
                          int pid = std::stoi( pid_str );
                          kill( pid, SIGINT );
                          }

                          JonBJ 1 Reply Last reply
                          0
                          • JoeCFDJ JoeCFD

                            @jiaming kill( m_process->pid(), SIGINT ); <==this does what you need. You need somehow to find the pid of B.
                            std::string pid_str = exec( "pidof B" ); exec is defined in the post above and "pidof" is a linux command to find process id.
                            if( !pid_str.empty() ) {
                            int pid = std::stoi( pid_str );
                            kill( pid, SIGINT );
                            }

                            JonBJ Offline
                            JonBJ Offline
                            JonB
                            wrote on last edited by
                            #19

                            @JoeCFD said in How to close the subroutine of the program started by qprocess?:

                            You need somehow to find the pid of B.

                            But he doesn't know the PID of B.

                            1 Reply Last reply
                            0
                            • JoeCFDJ Offline
                              JoeCFDJ Offline
                              JoeCFD
                              wrote on last edited by
                              #20

                              Be aware that Control + C ( kill( pid, SIGINT ); ) may not kill your process all the time.
                              exec( "kill -9 pid" ) will be very clean.

                              1 Reply Last reply
                              0
                              • Kent-DorfmanK Offline
                                Kent-DorfmanK Offline
                                Kent-Dorfman
                                wrote on last edited by
                                #21

                                Nothing original to add, but I recommend all participants in this thread read http://morningcoffee.io/killing-a-process-and-all-of-its-descendants.html as he does a fair job explaining the relationships in POSIX environments.

                                JoeCFDJ 1 Reply Last reply
                                3
                                • Kent-DorfmanK Kent-Dorfman

                                  Nothing original to add, but I recommend all participants in this thread read http://morningcoffee.io/killing-a-process-and-all-of-its-descendants.html as he does a fair job explaining the relationships in POSIX environments.

                                  JoeCFDJ Offline
                                  JoeCFDJ Offline
                                  JoeCFD
                                  wrote on last edited by
                                  #22

                                  @Kent-Dorfman thanks for sharing.

                                  1 Reply Last reply
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