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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