How to Populate /Dev with a Custom Directory with Udev

Creating a new directory in /dev using udev rule

Try "synch!synchmess" as the last arg to dev_create(); reference:

lists.kernelnewbies.org

Also see this item on Stack Overflow

udev rules, mkdir

Create device symlink with udev based on device response, not udev device info

Blindly chatting on a serial port automatically the moment it is connected to the computer is quite a scary thing to do. Are you sure you want to do this? First of all it will take some time, which will delay the appearance of the device node if udev has to wait for a result before creating it. If the device happens to be powered off or its serial port is disconnected then you won't be able to name it properly (and you will need to have a timeout to detect this). Finally, if another device besides one of the ones you expect is connected, you may be sending it garbage that has unintended consequences.

You might consider relying on the adaptors' serial numbers to tell them apart, and associate each adaptor to an external device in a consistent fashion. If your adaptors even have real serial numbers instead of placeholder strings like 00000000 then you are already lucky!

Nevertheless, this is how you would do it.

As you suspected, you can't use RUN, because that's too late, the device node has already been created. You have to use PROGRAM. In your program you are going to have to create the device node yourself using mknod because udev hasn't done it yet. You should create a temporary node in a temporary location and destroy it before your program exits.

### Create the temporary device node in /tmp
device="/tmp/udev_device_guesser.$$"
# Note: mknod does not appear to be vulnerable to a symlink attack
mknod "$device" c "$MAJOR" "$MINOR"

### Use this device node to query what's attached to the serial port
insert your code here

### Get rid of the temporary node
rm -f "$device"
exit 0

How to find reasons why an udev rule is not applied?

For the udev rule
/ect/udev/rules.d/99-bizrfid.rules I would add the SUBSYSTEM:

ACTION=="add", SUBSYSTEM=="tty", ATTRS{idVendor}=="09d8", ATTRS{idProduct}=="0420", SYMLINK+="ttyMyDevice"

You could add also ATTRS{manufacturer}==, but idVendor and idProduct are sufficient.

Otherwise it looks correct and the test run creates the symlink:

creating link '/dev/ttyMyDevice' to '/dev/ttyACM0'

set up device for development (???????????? no permissions)

What works for me is to kill and start the adb server again. On linux: sudo adb kill-server and then sudo adb start-server. Then it will detect nearly every device out of the box.

How do I set up udev rules for debugging a physical android device with Android Studio?

be aware that it might report different IDs, depending on the current USB mode of the device.

therefore it's important is to enable USB debugging first ...

and then use lsusb in order to obtain the vendor & product IDs ...

Bus 001 Device 070: ID 18d1:4ee7 Google Inc.

the culprit might be the vendor ID, where 12d1 is Huawei - and 18d1 is Google.

... whatever lsusb outputs goes to udev rules:

# angler (Nexus 6P)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4ee7", MODE="0600", OWNER="yourusername"

then run:

sudo udevadm control --reload-rules

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