BibTeX, biblatex and biber ⇒ bibtool or other sort/select mechanism

[nashjc]

I'm having trouble using bibtool to sort a bibtex file by anything other than the entry key. I'd like to reorganize the file by reverse year or year (and save a copy) and also by entry type (book, article, etc.). I'd rather keep several smaller files than one big one. Items tend to get lost in the big files.

This seems like it ought to be something readily available, but I'm not finding anything that seems to work (I use Ubuntu, and am willing to build packages if necessary).

[nashjc]

I found a web posting that suggested that controls for bibtool need to be in a resource file (.btl type). A preliminary test shows some promise, but easier solutions would definitely be desirable.

JN