Where are the udev system rules typically located?

The udev system rules are typically located in multiple locations, with a primary directory being /etc/udev/rules.d. This directory is where user-defined rules are placed, allowing customization of device management. While /usr/lib/udev/rules.d is associated with default rules provided by the system, it is generally considered less optimal for user-defined adjustments. The path /run/udev/rules.d is used for runtime rules that may be created during system operation but are temporary in nature. The directory /lib/udev/rules.d can also contain system rules but is generally not where custom rules are placed.

Thus, the most typical and recommended location for maintaining user-defined udev rules is /etc/udev/rules.d, which is where changes are sustained across system reboots and upgrades, making it the correct choice.