It runs in userspace and the user can change device names using Udev rules. It is the successor of devfs and hotplug.

Udev is the device manager for the Linux 2.6 kernel that creates/removes device nodes in the /dev directory dynamically. This article focuses only on¬† Udev, which does the basic device identification. It then notifies the corresponding desktop application like Nautilus through the Dbus and Nautilus will open the mounted device‚Äôs files. 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. Dbus is like a system bus which is used for inter-process communication. It creates or removes the device node files in the /dev directory as they are plugged in or taken out. Udev supplies a dynamic device directory containing only the nodes for devices which are connected to the system. Hotplugging (which is the word used to describe the process of inserting devices into a running system) is achieved in a Linux distribution by a combination of three components:¬† Udev, HAL, and Dbus. There are a lot of user-friendly distributions like Ubuntu, which will automatically run specific applications like Rhythmbox when a portable device like an iPod is plugged into the system. Modern Linux distributions are capable of identifying a hardware component which is plugged into an already-running system.

Device manager operating system