Without the correct filename extension, macOS appears unable to associate files with apps, preview then using QuickLook, or index them for Spotlight. But there’s more to determining file types than extensions, there’s also a little magic involved.
SpotTest
Adds file type identification to the Drop window, to help explain why Spotlight might misclassify a file and refuse to index its content as expected.
One JSON text file consistently found a search term that another contained, but could never find. How do some documents get fully indexed, but others don’t, and can’t be searched?
Many document formats store metadata with their data. Choosing the right ones to use must ensure their access, indexing and search. Here’s how to check those, and why Keywords are usually a good choice.
If generating QuickLook thumbnails and previews, and indexing metadata for Spotlight, depend on UTIs, how come they tolerate misleading file extensions? A simple practical demo.
Traces the path of metadata from inside a PDF document and its extended attributes, to those in Spotlight’s indexes and displayed in the Finder. Only a third survived that journey.
This new version adds a drag-and-drop window to inspect the metadata of files using mdimport and mdls.
When Spotlight can’t find the files you expect it to, it could be that they weren’t indexed, or that Spotlight’s search has failed to find their index entries. Here’s how to tell those apart and work out what went wrong.
Notes on how search depends on index structure, effects of language on different types of search term, and the benefits and limitations of search methods.
Running the basic test on a folder in your Home folder, extending that to documents that use a custom mdimporter, to other volumes and locations, and other search terms.
The Eclectic Light Company 