According to https://support.apple.com/kb/HT201262 a safe boot will perform the following:
- Verifies your startup disk, and attempts to repair directory issues if needed
- Loads only required kernel extensions
- Prevents Startup Items and Login Items from opening automatically
- Disables user-installed fonts
- Deletes font caches, Kernel cache and other system cache files
Apple as usual is somewhat vague. Does anyone have a list of the exact cache files deleted and where to find them?
Why I need this: I have two labs of iMacs where after a week or so of student use, they will freeze and when rebooted get stuck at 100% of the progress bar. About 80% of the time a safe boot fixes them (the remaining I usually end up wiping). I've looked at /Library/Caches and /System/Library/Caches before and after a safe boot and there appears to be no change.
Any clues what cache files I should look at next? If I can pinpoint the culprit, I can design a manual purge of this file and hopefully keep my uptime of these machines beyond a week.