aptitude safe-upgrade完成运行后，会输出如下所示的内容：
Current status: 0 updates [-14].
“[-14]”是什么意思？
我想这是已经升级的软件包数量。 您是否在确认提示中看到如下所示的内容：
14 packages upgraded, 4 newly installed, 0 to remove and 0 not upgraded. Need to get 230 MB/231 MB of archives. After unpacking 187 MB will be used. Do you want to continue? [Y/n/?]