protected function unixParams()
    {
        if ($this->windows) {
            return;
        }
        
        $this->the_command .= $this->redirect_output ? ' > /dev/null 2>&1' : '';
        $this->the_command .= $this->background ? ' &' : '';
        $this->the_command = $this->run_as_user 
                ? 'su -u '.$this->run_as_user.' -c "'.$this->the_command.'"' 
                : $this->the_command;
    }