Dynamic device management with Udev, HAL, and D-Bus

In the old days, Linux pioneers were expected to install new hardware manually, but Linux now offers automatic hardware detection at system boot time, as well as on-the-fly configuration of pluggable devices – whether the device is a USB stick, a digital camera, or a Bluetooth phone.

The Udev subsystem takes the pain out of accessing new devices, and a pair of components known as the Hardware Abstraction Layer (HAL) and D-Bus provide an interface from the hardware to desktop applications.

Under the Hood

Udev [1], which runs in the background as the udevd daemon, creates dynamic device files under /dev whenever it identifies a new device. The Udev daemon finds the devices at system boot time, and it also sets up new devices that are plugged in while the system is running – a feature that is commonly called hot plugging. The program might also create symbolic links for mass storage media such as disks or USB sticks under /dev/disk to point to the physical device files under /dev.

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