udev (userspace /dev) is a device manager for the Linux kernel.
udevd listens to kernel uevents and passes the incoming events to udev.
Users can register custom rules in
If you want to know the information of
/dev/i2c-1, run the below command.
The information displayed is useful for writing rules for the device.
Files should be named xx-descriptive-name.rules, the xx should be chosen first according to the following sequence points:
\< 60 most user rules; if you want to prevent an assignment being overriden by default rules, use the := operator. These cannot access persistent information such as that from vol_id
\< 70 rules that run helpers such as vol_id to populate the udev db
\< 90 rules that run other programs (often using information in the udev db)
>=90 rules that should run last
The first line means that if i2c-dev is detected, the group is set to i2c and the mode is set to 0660.