What files can only be used in Root?
My Mac keeps my temporary Vim files, Scanner log files and mach_kernel files for my root. I have not installed this procedure.
At the moment I am deleting files to my root as many of them seem to be just swap files. I have an idea that there should only be folders and system symlinks at the root.
What files should only be in Root?
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Mac OS X doesn't quite comply with the FHS Standard - in particular, it stores its kernel (2 versions, I'm not sure why) and the kernel symbol file in /, not / boot, so that's okay (for OS X).
There are other differences from the standard layout: OS X stores user's home directories in / Users instead of / home, mounts points in / Volumes (or / Network in some cases) instead of / mnt, and saves, etc., tmp, and var in / private, not / (with symbolic links in /, so they can be referenced in normal paths). It also stores some (invisible) filesystem support files / files - things like Spotlight, FSEvents and hot file , etc.
The only reason I can think of vim storing temporary files in / is if you edited files in / - as far as I understand, this is not the case?
As for the scanner ... what is it and how is it started? It can only be started with the current working directory set to / and logged there because it doesn't know any better. If you can figure out how to control it, I would recommend that it go to / var / log (a traditional unix location), / Library / Logs (which Apple likes to put its log files to), or / Users / yourname / Library / Logs (if it depends on the user, not the whole system).
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The standard file system hierarchy can be helpful.
It specifies in the section about the root filesystem that:
The contents of the root file system must be sufficient to boot, restore, restore and / or restore the system.
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