I didn't follow up on my question because when I did $ rm
jabref*.save.bib, not only did I recover space in that partition, but
henceforth sames too the form jabref*.save (if I recall correctly).
But now you ask about the jabref log file. I never new jabref had a log
file. but in searching for it, I discovered my old problem had
returned. I have now about 60 backups in the form /tmp/jabref*.save.bib
of each of my seven .bib database files.
Please, where is this jabref.log file? I looked at the manual and did an
online search briefly, and nothing popped up.