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

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© James Steidl, Fotolia

© James Steidl, Fotolia

Article from Issue 95/2008
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Udev, HAL, and D-Bus provide automated hardware configuration, even if you plug in on the fly. We'll help you easily access new devices.

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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