Udev: Introduction to Device Management In Modern Linux System

"Udev supplies a dynamic device directory containing only the nodes for devices which are connected to the system. It creates or removes the device node files in the /dev directory as they are plugged in or taken out. Dbus is like a system bus which is used for inter-process communication. The HAL gets information from the Udev service, when a device is attached to the system and it creates an XML representation of that device. It then notifies the corresponding desktop application like Nautilus through the Dbus and Nautilus will open the mounted device's files.

"This article focuses only on Udev, which does the basic device identification. What is Udev?

"Udev is the device manager for the Linux 2.6 kernel that creates/removes device nodes in the /dev directory dynamically. It is the successor of devfs and hotplug. It runs in userspace and the user can change device names using Udev rules.

"Udev depends on the sysfs file system which was introduced in the 2.5 kernel. It is sysfs which makes devices visible in user space. When a device is added or removed, kernel events are produced which will notify Udev in user space."

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