ubuntu apt-get install: has no installation candidate

今天在安装vim的时候出现了Package has no installation candidate的问题，如：

#  apt-get install vim
Reading package lists... Done
Building dependency tree... Done
Package aptitude is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package <packagename> has no installation candidate

解决方法如下：
# apt-get update
# apt-get upgrade
# apt-get install <packagename>

这样就可以正常使用apt-get了～

添加第三方地址：

sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"

sudo apt-get update

还是没解决，但是在/etc/apt/sources.list 下 添加如下url， 重新update，就可以安装了。

deb http://archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu/ trusty-proposed main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse