To backup your device, use this command. It will automatically insert the current date in the filename:
adb backup -apk -shared -all -f $(date '+%Y-%m-%d').db
If you are havong problems with the connection (“adb: unable to connect for backup”), check the listing of connected devices:
adb devices
Which may result in a listing like this:
List of devices attached ???????????? no permissions
You can solve this by restarting the adb server:
sudo adb kill-server sudo adb start-server
* daemon not running. starting it now on port 5037 * * daemon started successfully *
After this, the output of adb devices will look like this:
G65ABT632191 device
Now, try to start the backup again. Good luck!