The same 4 sqlite dbfiles you need reside under each user's $HOME/.mozilla/firefox/XXXXX.default on GNU/Linux.
Forgot to mention this earlier but assuming you are working on a forensics image (you are working on an image?), a good tool to use is
Web Cache View.
If you really want to do it manually, here are some poiinters. The actual cache is stored across four or more files. The cache map file contains records of the location of the cache metadata as well as the location of the cache block and cache data files. A fairly complicated algorithm determines whether metadata and data are stored in the cache block files or in the cache data files. The algorithm also determines the name of the cache data file, if that's where the data is to be stored. See
SecurityFocus for more information.
All the cache map, block and data files are deleted when a user uses the Clear Private Data command. The map and block files are regenerated when Firefox is (1) directed to a website or (2) when the it is restarted.
"Deleted Firefox History Retrieval"