REL=103
MODALIAS=input:b0003v046DpC03Ee0110-e0,1,2,k110,111,112,r0,1,8,amlsfw
udev also sends messages to syslog. The default syslog priority that controls which
messages are sent to syslog is specied in the udev conguration le /etc/udev/
udev.conf. The log priority of the running daemon can be changed with udevadm
control log_priority=level/number.
12.6 Inuencing Kernel Device Event
Handling with udev Rules
A udev rule can match any property the kernel adds to the event itself or any informa-
tion 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 le 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 specied value. A matching rule may specify
the name of the device node, add symlinks pointing to the node or run a specied pro-
gram as part of the event handling. If no matching rule is found, the default device node
name is used to create the device node. Detailed information about the rule syntax and
the provided keys to match or import data are described in the udev man page. The
following example rules provide a basic introduction to udev rule syntax. The example
rules are all taken from the udev default rule set that is located under /etc/udev/
rules.d/50-udev-default.rules.
Example 12.1:
Example udev Rules
# console
KERNEL=="console", MODE="0600", OPTIONS="last_rule"
# serial devices
KERNEL=="ttyUSB*", ATTRS{product}=="[Pp]alm*Handheld*", SYMLINK+="pilot"
# printer
SUBSYSTEM=="usb", KERNEL=="lp*", NAME="usb/%k", SYMLINK+="usb%k", GROUP="lp"
# kernel firmware loader
SUBSYSTEM=="firmware", ACTION=="add", RUN+="firmware.sh"
Dynamic Kernel Device Management with udev 211
