On an external hard disk, I have MP3 files. Some of them have the permissions 0777:

ls -l 1*


-rwxrwxrwx  1 ronaldfischer  staff  16246125 Dec 10 18:09 1_SuicidalTrauma__MyMemories.mp3

Since the x-bit does not make sense for an audio file, I tried to adjust the permissions, but none of the following produced any change in the permissions:

chmod -x 1*
chmod u-x 1*
chmod ugo-x 1*
chmod 0666 1*

What could be the reason? Disk Utility describes the file system on that volume as USB External Physical Volume. I had formatted the disk originally under Windows as ExFAT.

1 Answer 1


ExFAT can't carry unix permissions at all, so everything is translated as having full perms. This will actually continue if you copy back to an HFS or APFS drive, as ExFAT has simply discarded the original data.


on original HFS drive
-rw-r--r--@ 1 glee  staff  19429492  8 May  2022 01 Orang.mp3
copied to ExFAT SD
-rwxrwxrwx@ 1 glee  staff  19429492  8 May  2022 01 Orang.mp3
Copied back to HFS
-rwxrwxrwx@ 1 glee  staff  19429492  8 May  2022 01 Orang.mp3

This is one of the reasons you shouldn't use any FAT format drive for items which are very 'specifically Mac' [Logic projects, iMovie, Photos libraries etc] as opposed to just generic data files such as mp3.

  • 1
    Thanks a lot. it makes sense to me. BTW, which file format would you recommend for volumes which are read and written on Mac and Windows? Jun 7 at 9:20
  • Whichever you do, you'll need to add support to the other platform. Mac can natively read NTFS but not write to it. Windows definitely needs 3rd party software to even read HFS or APFS. Personally, I mostly use HFS & Paragon's HFS for windows I also have their Mac NTFS version so I'm not limited in which way round I have to work.
    – Tetsujin
    Jun 7 at 9:28
  • You can get NTFS support on Mac with freeware, NTFS 3-g & MacFuse… but it's always felt a little flaky, so I stopped doing that many years ago.
    – Tetsujin
    Jun 7 at 9:28

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