A few years ago at $DAYJOB, we were evaluating Apache Nifi, which is basically a data routing tool. I wanted to use it for reading some files from one directory and just writing them back out to another. So, I figured, I have two stray files in my home-directory, I’ll just tell it to read straight from the home-directory. What I didn’t expect, is that it would recurse into subdirectories. And even less so, that it would remove the files it had read. So, all the files in my home-directory were gone. Although, it had written them dutifully to that other directory. So, in theory, I still had all my files. But it hadn’t copied the folder structure. Documents, SSH keys, cache files, everything was placed into a single, flat folder.