可能重复：
亚马逊EC2的Ubuntu 10.04服务器更新
当我loginUbuntu 10.04.2 LTS服务器时，我看到以下消息：
42 packages can be updated. 18 updates are security updates. 但是，当我尝试更新这个，没有得到升级，如预期的那样：
$ sudo apt-get update ....snip.... Reading package lists... Done $ sudo apt-get upgrade Reading package lists... Done Building dependency tree Reading state information... Done The following packages have been kept back: linux-generic-pae linux-headers-generic-pae linux-image-generic-pae 0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.
任何想法为什么没有更新，或者为什么3（从apt-get）的计数是不同于42？ 什么软件说42不适合？
（其他细节：这是服务器版本，没有GUI;我没有触及aptconfiguration文件;当我安装软件，我拒绝允许自动更新）
此消息来自MOTD（当天的消息）系统。 最近在这个答案中详细说明了如何解决这个消息和软件包pipe理器之间不协调的细节。
为了安装软件包，你必须运行：
sudo apt-get update && sudo apt-get dist-upgrade
尝试只运行sudo apt-get update && sudo apt-get upgrade不会安装软件包，因为默认情况下apt-get upgrade不会尝试安装新软件包（如新的内核版本）。 从手册页： 在任何情况下都不会安装已经安装的软件包，或者已经安装的软件包没有被检索和安装。
然而， apt-get dist-upgrade允许你在需要的时候安装新的软件包（比如新的内核版本）。 从手册页：
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. So, dist-upgrade command may 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.
sudo apt-get升级
它应该为你工作，欢呼声