If you look at a part or assembly file with family table instances by editing it with an text editor that is capable of opening it, you'll see that the majority of such a file is binary and compressed.
This makes use of a batch file impossible, since there is nothing in the file to parse to build the index file.
Also, I'm not really sure what the structure of the index file is. What the syntax of each line needs to be to be useful.
Finally, if I look at an index file of an oft-visited directory, it's loaded with outdated listings of instances of parts that are no longer in that directory. Parts that were renamed or deleted, etc. It doesn't seem like the indexing does any cleanup or updating. I suspect that things are only added to the file, but never removed. Perhaps this is a problem you are trying to address.
