今天在安装软件的时候出现了Package has no installation candidate的问题，如：
# apt-get install <packagename>
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
Linux下的apt-get命令学习笔记：http://www.linuxdiyf.com/linux/13364.html
Ubuntu14.04 apt-fast加速apt-get：http://www.linuxdiyf.com/linux/13278.html
使用apt-fast代替apt-get大幅度提升下载速度：http://www.linuxdiyf.com/linux/9905.html
Ubuntu的apt加速工具：apt-fast：http://www.linuxdiyf.com/linux/7474.html
Ubuntu 15.04下apt-get安装JDK：http://www.linuxdiyf.com/linux/11669.html