In addition to the thread jabulon linked to earlier, and spidergawds neat example, you could try etree-scripts.

Get it from this ppa: https://launchpad.net/~ketilwaa/+archive/etree-scripts

When creating flac files, it will generate an ffp file, but I really only use it for the md5check command, which will check and verify any md5 or ffp checksums in a folder (it also checks all flac files for integrity).