Spotlight fails to index the content of text files starting with odd characters like ‘LG’ and ‘Draw’, Although we understand this is caused by checking the file type using file(1), this suggests an explanation of why it should do that. And whether it will ever get fixed for Intel Macs.
UTI
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.
How to discover what went wrong when a document doesn’t show the right thumbnail, but a generic icon instead. How to dive deeper to solve problems with 3rd party thumbnail and preview generators.
Will now list apps installed on systems running with primary languages other than English. Problems resulted from unexpected behaviour of Spotlight and search with mdfind, as explained here in detail.
For the last 10 years, macOS has relied on Uniform Type Identifiers to recognise different types of files, for opening in apps, QuickLook, Spotlight and in other features.
Four little utilities now compatible with macOS Tahoes, covering repair of Finder aliases, creating test sparse files and checking special file types, looking up UTI types, and analysing language.
How to discover which QuickLook generator or app extension should be creating Thumbnails or Previews for different file types, using this new version of Mints.
Details of the chain of information, from the UTI of the file to be opened, through LaunchServices’ database of document types. How to deal with problems.
What if, when you double-click a document, the wrong app tries to open it, or maybe the right app but wrong version? Includes command tool use.
How does the Finder know the right app to open a file with? Or QuickLook how to preview its contents? Or other services like Spotlight know how to index and handle files? UTIs.
The Eclectic Light Company 