Hi I've run in a strange behaviour on a MacBook today: I had a directory named "FOO" (all capitals) on the desktop, then I created a file named "foo" (no extension) in another directory and moved it to the desktop, the system asked me if I wanted to overwrite the directory. It looked strange and I maked some test with other files and directory and it turned out the system don't make any difference between files and folders (which is reasonable since they're both iNode) but even stranger it don't care about the case of the names. I also tried via command line and the situation is the same. That don't happen on other mac I tested. I never seen such a behaviour on a unix system. Can somebody explain this to me and tell me if there's some setting the mac user messed up with?


If you check the filesystem it is likely to be HFS+ (case insensitive, journaled). On OS X this will preserve case when naming files, but will see any variation of Foo, foo, fOO etc. as being the same, and so cause overwriting.

Run Disk Utility to see the disk case sensitivity, or in Terminal run diskutil info (eg. disk0s1). The "Name" record will tell you what the format it.

To force the system to be case sensitive you will need to reformat the drive and lose all data so, if you are able to, back up user documents etc before running any restore.

The behaviour is coming from Classic Mac OS HFS file system, UFS will force case sensitivity on the disk.

  • thank you. It's incredble that it come out of the box like that. – jack_the_beast Dec 1 '16 at 14:27

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