This script assumes that no config files are being used with btsync, i.e. config is maintained through the web interface, and that only a single user is required. A multi-user version is available at https://gist.github.com/MendelGusmao/5398362.
Thanks also to nicoX at http://askubuntu.com/questions/284683/how-to-run-bittorrent-sync for the original idea.
On Ubuntu:
- Save the script to /etc/init.d/
- Modify the daemon location and user name as appropriate
- $ chmod 755 /etc/init.d/btsync
- $ update-rc.d btsync defaults
- $ sudo service btsync start