Linux rfcomm serial communication

Scan to discover Bluetooth device

Pair with Bluetooth device

Connect with SPP

In one shell/terminal - pipe the input from the Bluetooth device to a file

     cat /dev/rfcomm0 > datalog.txt

In another shell/terminal - echo some command to the Bluetooth device

     echo "8;" > /dev/rfcomm0

Quit the cat command

Inspect the output

     less datalog.txt