Linux – How to match a ttyUSBX device to a usb serial device

First, make sure that the device not reporting a serial number is really the problem. adb devices will list the serial number as all question marks if it doesn't have permission to access the corresponding device under /dev/bus/usb/. Also remember the adb starts up a server, you may need to kill that to get it to re-probe.

Assuming it really is a problem with the device, I quickly checked the adb source code. It appears register_device in core/adb/usb_linux.c reads the serial number straight from the device. core/adb/usb_libusb.c calls libusb_get_device_descriptor to do it, which (checking the libusb source code) grabs it from sysfs or directly from the device. So no udev trickery is going to help, unfortunately.

Your choices would seem to be:

• figure out how to make adb work without a serial number. Possibly, patch adb (it is open source). This is a question more for Stack Overflow, I think.
• patch to kernel usbfs driver to fake a response to adb's request. This sounds much harder than patching adb to me.
• patch the kernel to allow faking the serial # in syfs, assuming adb is using libusb.
• fix the broken hardware.

When you see the handlers like gphoto2:// and smb:// these are special interfaces that the GNOME desktop or whatever file browser you're using is making available to access these devices. In the case of gphoto2, the desktop is using the application gphoto2`

lsof

The only way I can think to gain access to a mount such as this would be to mount it as you did before using Nautilus or whatever file browser, and then using a tool such as lsof to see what files/devices are opened by Nautilus.

$ lsof -p $(pgrep nautilus)

But if you're having to connect to your phone via gphoto2 then you're likely not mounting the device a a mass storage device but rather a PTP - Picture Transfer Protocol. There's a Linux FUSE implementation for PTP too.

gvfs?

I would also look in your $HOME directory for a sub-directory called .gvfs. Usually when GNOME or Nautilus are doing the mounting this directory is created as a convenience.

In newer versions of GNOME (3+) this directory has moved and is now here, /run/user/$UID/gvfs.

Example

$ ls -l /run/user/$UID/gvfs/smb-share\:server\=tank\,share\=t 
total 2
drwx------. 1 saml saml    0 Oct 31 09:16 Development
drwx------. 1 saml saml    0 Nov 18 14:52 home
drwx------. 1 saml saml    0 May 14  2013 incoming
...

NOTE: That's a environment variable $UID that is often set in Bash on most modern systems. If it isn't set you can find your user's ID like so:

$ id
uid=1000(saml) gid=1000(saml) groups=1000(saml),10(wheel) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023