如何用QT调用linux系统的指令

想用QT调用linux里的指令，指令要求光驱弹出然后收回，怎样能够实现。最好能用QT做两个GUI按钮，一个弹出，一个收回。怎么样编写程序啊，哪位高手能帮个忙，本人第一次接触，是菜鸟啊，请哪位大神帮帮我

cdrom.h
C/C++ code

#include <QDialog>
#include <QPushButton>

class ControlDialog : public QDialog
{
    Q_OBJECT
public:
    ControlDialog(QWidget* parent = 0); 

private slots:
    void EjectCdrom();
    void CloseCdrom();

private:
    QPushButton* buttonEject;
    QPushButton* buttonClose;
};

cdrom.cpp
C/C++ code

#include <QtGui>
#include <QApplication>
#include <cstdlib>
#include "cdrom.h"

ControlDialog::ControlDialog(QWidget* parent)
    : QDialog(parent)
{
    buttonEject = new QPushButton(tr("Eject"));
    buttonClose = new QPushButton(tr("Close"));

    connect(buttonEject, SIGNAL(clicked()),
            this, SLOT(EjectCdrom()));
    connect(buttonClose, SIGNAL(clicked()),
            this, SLOT(CloseCdrom()));

    QHBoxLayout* mainLayout = new QHBoxLayout;
    mainLayout->addWidget(buttonEject);
    mainLayout->addWidget(buttonClose);
    setLayout(mainLayout);
}

void ControlDialog::EjectCdrom()
{
    system("eject /dev/cdrom");
}

void ControlDialog::CloseCdrom()
{
    system("eject -t /dev/cdrom");
}

int main(int argc, char* argv[])
{
    QApplication app(argc, argv);
    ControlDialog* dialog = new ControlDialog;
    dialog->show();
    return app.exec();
}