Under linux, the "right" thing to do is to write a udev rule so
that the device has a predictiable name (or symlink).
http://reactivated.net/writing_udev_rules.html
If you don't want to write a udev rule, you'll need to bascally
re-implement udev by parsing the sysfs directory tree until you
find the device you're looking for. Here's how to do it for USB
(I assume BT works in a similar fashion).
Let's say I know the device has vendor ID 0403, product ID
6001, and serial number 123456.
I search through the directories under /sys/devices until I
find a directory containing three files named
idProduct
idVendor
serial
Which contain the three strings I'm looking for.
In this case:
# cat /sys/devices/pci0000:00/0000:00:10.3/usb5/5-1/idVendor
0403
# cat /sys/devices/pci0000:00/0000:00:10.3/usb5/5-1/idProduct
6001
# cat /sys/devices/pci0000:00/0000:00:10.3/usb5/5-1/serial
12345678
Once you've found that directory, you can look at the other
entries to find out whatever you want to know about the device:
/sys/devices/pci0000:00/0000:00:10.3/usb5/5-1/
|-- 5-1:1.0
| |-- bAlternateSetting
| |-- bInterfaceClass
| |-- bInterfaceNumber
| |-- bInterfaceProtocol
| |-- bInterfaceSubClass
| |-- bNumEndpoints
| |-- bus -> ../../../../../../bus/usb
| |-- driver -> ../../../../../../bus/usb/drivers/ftdi_sio
| |-- ep_02 -> ../../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1/5-1:1.0/usbdev5.42_ep02
| |-- ep_81 -> ../../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1/5-1:1.0/usbdev5.42_ep81
| |-- interface
| |-- modalias
| |-- power
| | |-- state
| | `-- wakeup
| |-- subsystem -> ../../../../../../bus/usb
| |-- ttyUSB0
| | |-- bus -> ../../../../../../../bus/usb-serial
| | |-- driver -> ../../../../../../../bus/usb-serial/drivers/ftdi_sio
| | |-- power
| | | |-- state
| | | `-- wakeup
| | |-- subsystem -> ../../../../../../../bus/usb-serial
| | |-- tty:ttyUSB0 -> ../../../../../../../class/tty/ttyUSB0
| | `-- uevent
| |-- uevent
| |-- usb_endpoint:usbdev5.42_ep02 -> ../../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1/5-1:1.0/usbdev5.42_ep02
| |-- usb_endpoint:usbdev5.42_ep81 -> ../../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1/5-1:1.0/usbdev5.42_ep81
| |-- usbdev5.42_ep02
| | |-- bEndpointAddress
| | |-- bInterval
| | |-- bLength
| | |-- bmAttributes
| | |-- dev
| | |-- device -> ../../../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1/5-1:1.0
| | |-- direction
| | |-- interval
| | |-- power
| | | |-- state
| | | `-- wakeup
| | |-- subsystem -> ../../../../../../../class/usb_endpoint
| | |-- type
| | |-- uevent
| | `-- wMaxPacketSize
| `-- usbdev5.42_ep81
| |-- bEndpointAddress
| |-- bInterval
| |-- bLength
| |-- bmAttributes
| |-- dev
| |-- device -> ../../../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1/5-1:1.0
| |-- direction
| |-- interval
| |-- power
| | |-- state
| | `-- wakeup
| |-- subsystem -> ../../../../../../../class/usb_endpoint
| |-- type
| |-- uevent
| `-- wMaxPacketSize
|-- bConfigurationValue
|-- bDeviceClass
|-- bDeviceProtocol
|-- bDeviceSubClass
|-- bMaxPacketSize0
|-- bMaxPower
|-- bNumConfigurations
|-- bNumInterfaces
|-- bcdDevice
|-- bmAttributes
|-- bus -> ../../../../../bus/usb
|-- configuration
|-- devnum
|-- driver -> ../../../../../bus/usb/drivers/usb
|-- ep_00 -> ../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1/usbdev5.42_ep00
|-- event_char
|-- idProduct
|-- idVendor
|-- manufacturer
|-- maxchild
|-- power
| |-- state
| `-- wakeup
|-- product
|-- serial
|-- speed
|-- subsystem -> ../../../../../bus/usb
|-- uevent
|-- usb_device:usbdev5.42 -> ../../../../../class/usb_device/usbdev5.42
|-- usb_endpoint:usbdev5.42_ep00 -> ../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1/usbdev5.42_ep00
|-- usbdev5.42_ep00
| |-- bEndpointAddress
| |-- bInterval
| |-- bLength
| |-- bmAttributes
| |-- dev
| |-- device -> ../../../../../../devices/pci0000:00/0000:00:10.3/usb5/5-1
| |-- direction
| |-- interval
| |-- power
| | |-- state
| | `-- wakeup
| |-- subsystem -> ../../../../../../class/usb_endpoint
| |-- type
| |-- uevent
| `-- wMaxPacketSize
`-- version
If you want to search by something other than the product id,
vendor id and serial number, then pick some other of the files
above that will have identifiable contents and look for that.
