sudo apt-get upgrade
...
下列软件包的版本将保持不变：
linux-generic-hwe-16.04 linux-headers-generic-hwe-16.04
linux-image-generic-hwe-16.04 linux-signed-generic-hwe-16.04
linux-signed-image-generic-hwe-16.04
升级了 0 个软件包，新安装了 0 个软件包，要卸载 0 个软件包，有 5 个软件包未被升级。
1. 簡化來說 有遞迴相依套件 不滿足 (包含 版本 不滿足) 所以放棄升級 保持原版本
1-1. 詳細參閱
http://manpages.ubuntu.com/manpages/xen ... get.8.html
upgrade
upgrade is used to install the newest versions of all packages
currently installed on the system from the sources enumerated in
/etc/apt/sources.list. Packages currently installed with new
versions available are retrieved and upgraded; under no
circumstances are currently installed packages removed, or packages
not already installed retrieved and installed. New versions of
currently installed packages that cannot be upgraded without
changing the install status of another package will be left at
their current version. An update must be performed first so that
apt-get knows that new versions of packages are available.
2. 如果你進一步執行
sudo apt-get
dist-upgrade
則它會嘗試上網去把 相依套件 不滿足 (包含 版本不滿足) 的遞迴套件 下載來安裝 然後再把剛剛放棄升級的套件 完成升級
2-1. 在 上述過程 也許會移除一些已安裝套件 (包含 版本）影響 系統能否繼續穩定 所以 新手 請謹慎為之
2-2. 詳細參閱
http://manpages.ubuntu.com/manpages/xen ... get.8.html
dist-upgrade
dist-upgrade in addition to performing the function of upgrade,
also intelligently handles changing dependencies with new versions
of packages; apt-get has a "smart" conflict resolution system, and
it will attempt to upgrade the most important packages at the
expense of less important ones if necessary. The dist-upgrade
command may therefore remove some packages. The
/etc/apt/sources.list file contains a list of locations from which
to retrieve desired package files. See also apt_preferences(5) for
a mechanism for overriding the general settings for individual
packages.