I'm attempting to a produce a command class hierarchy. Essentially each command is going to be certain to a QAction. When the action is triggered, it'll call an online method.

This is actually the code:

class Command  : QObject
{
    Q_OBJECT

public:
    Command(QWidget *parent);

public slots:
    virtual void execute();

protected:
    QAction *commandAct;
};

Command::Command(QWidget *parent)
{
    commandAct = new QAction(parent);
    parent->addAction(commandAct);
    connect(commandAct,SIGNAL(triggered()),this,SLOT(execute()));
}

QAction *Command::getAction()
{
    return commandAct;
}

If I derive a category and override the execute method, could it be known as enjoy it should be?

I want this to operate mix platform.

Yes, overriding virtual slots works simply with almost every other virtual method. Ultimately, the signal/slot connect is simply a method call, which may be either virtual or non-virtual.