udev 自动创建设备节点

udev是一种工具，它能够根据系统中的硬件设备的状态动态更新设备文件，包括设备文件的创建，删除等。-udev is a tool, it can according to the system in the state of hardware devices dynamic update documents, including the creation of device files, delete and so on.

嵌入式linux环境下的udev最新版本-The latest version of udev