在编译bluez-5.25时，配置的过程中，说udev没有发现，导致无法配置。
于是就安装libudev-dev，可是报错libudev1 (= 204-5ubuntu20) 但是 204-5ubuntu20.5 正要被安装，无法安装。找了好久未果。
最后的解决办法是，更新系统的源为阿里的源，不适用官方的源，阿里的又快又能解决问题，好用。
打开源的文件
sudo gedit /etc/apt/sources.list
然后替换成下面的内容（如果可以，先备份之前的源sudo cp /etc/apt/source.list /etc/apt/source.list.backup）
deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
libudev-dev 错误 libudev1 (= 204-5ubuntu20) 但是 204-5ubuntu20.5 正要被安装 解决方法
原文：http://blog.csdn.net/wang_shuai_ww/article/details/41720605