How to match dangling blobs with file names in Git

Question

I have yet another example of doing a git rm -rf without an initial commit. (I realized I had added lots of useless files and wanted to add some filters.)

Now I am left with 23000 dangling blobs with no tree, but with a complete Git history!

I'll use a script to loop over the blobnames (using git show 'blobname' > 'filename'), but can I associate these filenames from the history to the blobs?

Answer 1

For all of you who did/will do the exact mistake I made, here's the end of the story.

First off, a brief summary of what I did.

1. Created an empty repository
2. moved many files/directory to it
3. gid add .
4. realized that I just added a TON of useless/not-so-important/redundant files
5. git rm -rf with the intent of then adding some filters in .gitignore
6. realized that all my files were gone...

I tried all sort of data recovery tools; no luck. The best I could do was the following procedure.

1. Immediately copy the working directory to a different volume (external HD).
2. git fsck --lost-found possibly with --unreachable --cache
   This creates the folder .git/lost-found/other with all (most of?) the original files were re-created, but without filenames. Now the problem was how to recover the file names. Unfortunately, all the files I recovered were blobs, no roots, so I had no information about the tree structure of the directories.
3. Even though I had the complete list of lost filenames (only names, not sizes), I could not find any root, so this information was basically useless.
4. In general, one can write a script that uses file to look at the type of a file (file <filename>), and attaches the corresponding extension to it. The problem of matching files with filenames still remains.
   Alternatively, one can use brute force. For instance, to recover pdfs, I sorted the recovered files by length, attached a .pdf extension to them, and looked at them one by one. The files that were actual pdfs show something, the others don't.
5. To recover text-based files (txt, tex, c, h..), I used grep, looking for a string that I remember belongs to a specific (group of) file(s).
6. Now I keep the directory with all the lost-recovered files, and every time I need one of them, I use a slight variant of bullet 4.

Good luck!