puppe

Which version number do you mean? That from the QPKG Center or that from the BitTorrent Sync Web UI. Only the latter is really relevant. Go to the Bittorent Sync download page Click the download button Download the Linux ARM, Linux i386 or Linux x64 archive depending on what you installed the last time. (As your TS-259Pro apparently has an Intel Atom processor, it should be either i386 or x64. If you're not sure, login via ssh and type `uname -m`) Extract the binary (btsync) from the archive and put it on your NAS.

Yes, that should be the way to go. Alternatively, you could replace the BitTorrent Sync binary manually: Stop BitTorrent Sync via the QPKG Center. Find out where the binary is located (/share/MD0_DATA/.qpkg/BitTorrentSync/btsync, for my setup at least) and replace it with the new one. Start BitTorrent Sync via the QPKG Center. I am not at home right now (and won't be for another two months), so I have not tested updating.

This seems to be a problem with qbuild. Apparently it relies on bash being available. Luckily, it doesn't seem to use any bash-specific features. I've added a troubleshooting section to the README. Thanks!

Done :-)

I have successfully installed BitTorrent Sync on my QNAP TS-412 NAS device. I have done this by building QPKG packages which can be installed via QPKG Center. All necessary instructions and scripts can be found at https://github.com/puppe/btsync-qpkg. I hope this will be helpful to other people. If you have any questions, ask them here or file an issue. Pull requests are always welcome!