Every directory under /sys/devices that contains a file called “uevent” represents a device. This file can be written to in order to synthesize “ADD” events, “REMOVE” events, or other events that can be processed by udev. It can be read to show context information that accompanies those events.

What does UDEV stand for?

udev (userspace /dev) is a device manager for the Linux kernel. As the successor of devfsd and hotplug, udev primarily manages device nodes in the /dev directory.

What is udev rules?

It allows you to identify devices based on their properties, like vendor ID and device ID, dynamically. udev runs in userspace (as opposed to devfs which was executed in kernel space). udev allows for rules that specify what name is given to a device, regardless of which port it is plugged into.