20.6 Influencing Kernel Device Event Handling with udev Rules
A udev rule can match any property the kernel adds to the event itself
or any information that the kernel exports to sysfs.
The rule can also request additional information from external programs.
Every event is matched against all provided rules. All rules are located in
the /etc/udev/rules.d directory.
Every line in the rules file contains at least one key value pair.
There are two kinds of keys, match and assignment keys. If all match keys
match their values, the rule is applied and the assignment keys
are assigned the specified value. A matching rule may specify the name of
the device node, add symlinks pointing to the node, or run a specified
program as part of the event handling. If no matching rule is found, the
default device node name is used to create the device node. The rule syntax
and the provided keys to match or import data are described in the udev man
page.