Yosemite is hiding files that I thought were deleted!
Q I was using Spotlight in OS X Yosemite when I spotted a few files I knew I had deleted some time ago. I discovered a whole new world of hidden files contained in folders called containers. I also found that most, if not all, of my iMessage history is contained within these folders! What is this all about? Mark Darby A Containers are used by OS X to restrict an application’s access to the rest of your system. This is called sandboxing and the idea is that the more limits an app has, the less damage it can cause if a hacker discovers a vulnerability in the code that allows them to take control of the app. Sandboxed apps get their own special folder, called a container, in your user library. So each user has their own container for each sandboxed app.
These folders are for temporary files, indexes, caches and so on. If an app stores data that isn’t explicitly saved by the user as a document via the Save As dialog, then that data is also stored in the container. That’s why Messages puts the chat history there. Some files will have the same name as documents you have created (and thus show up in Spotlight) but they are meant to be invisible backups, caches or other support files.
Sometimes you can delete this data through the app interface – Messages has the Delete Conversation option, for example. You can also explicitly delete them through Finder if you want, but you shouldn’t normally need to.
Many apps quietly save data in the background, but you can delete it if you want to.