Generate a New udev Rule¶

Get Info on a Device¶

udevadm info --name=${dev_node} --attribute-walk

Produce Rule¶

/etc/udev/rules.d/ec25

ACTION=="add", ENV{ID_VENDOR_ID}=="2c7c", ENV{ID_MODEL_ID}=="0125", ATTRS{bInterfaceNumber}=="03", SYMLINK+="ec25-at"

Tip

The match keys are KERNEL, SUBSYSTEM, DRIVER and ATTR... To match a parent's property too, use the plural, e.g: ATTRS.

Warning

When matching against parent properties (e.g: using ATTRS), all parent matches must be valid for a single parent.

Multiple Parents¶

It sounds like it should be possible to use multiple parents, like this... but I couldn't get it to work.

/etc/udev/rules.d/50-ec25.rules

ACTION=="add", SUBSYSTEM=="usb", ATTRS{idVendor}=="2c7c", ATTRS{idProduct}=="0125", ENV{ec25}="yes"
ACTION=="add", ENV{ec25}=="yes", ATTRS{bInterfaceNumber}=="03", SYMLINK+="ec25-at"

/etc/udev/rules.d/50-cr10-v3.rules

ACTION=="add", SUBSYSTEM=="tty", KERNELS=="1-2", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="7523", SYMLINK+="cr10-v3"

Reload Rules¶

udevadm control --reload-rules
udevadm trigger

Test Rule¶

dev_path="$( udevadm info -q path -n ${dev_node} )"
action="add"
udevadm test -a "${action}" "${dev_path}"

Tip

udevadm test gives you a list of the environment variables that are available!

Reference¶

Writing udev Rules