I am going to format my OS X Machine (El Capitan 10.11.6).

I created manually a disk image file (.dmg) of /myUser folder on an external HDD using Disk Utility.

Will I be able to access/mount this disk image (.dmg) file after re-installing OS X or am I going to have problems with permissions and etc ?

Disk image file had read/write format (not compressed) with no encryption.

1 Answer 1


Your problem will not be mounting or accessing the .dmg file, as you can always set any drive except your current boot drive to 'Ignore Ownership' from Get Info on that partition.

Where I foresee difficulty is in re-integrating that extracted folder into your new OS. I'm not too sure the system will let you simply overwrite a lot of the data in your new User folder.

I'm sure the ideal solution would be to do it the recognised way, using a Time Machine backup.

  • I understand but I mostly need my (non-system) files and not to re-integrate my previous installations.
    – Vasikos
    Commented Nov 10, 2016 at 13:04
  • 1
    If what you wish to copy back is really only Documents, Downloads, Pictures etc etc then you should have no issues. The external files will have no permissions you cannot simply override from your new account, even if you have unexpected perms. The problem would be trying to bulk copy, including Library files etc, which are system-managed.
    – Tetsujin
    Commented Nov 10, 2016 at 13:08

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