I share encrypted disk images (dmg) over Dropbox to share sensitive information with others (or across my own machines). Is there a way to 'lock' the DMG when it is mounted in one machine so that it doesn't get mounted simultaneously in another?

I'm happy for the solution to require folder actions or any other automator/applescript bits.


  • To be clear, you want to lock access to a single user on a Dropbox folder? Is that folder, by any chance on a shared network drive? – Allan Apr 19 at 18:29
  • @Allan, the DMG files are in a shared dropbox folder on my regular drive, not a shared network drive. – Carlos Apr 19 at 18:30
  • Shared files, including DMGs can be opened by multiple users simultaneously. This doesn’t mean they can be written (I.e they’re locked). If you’re sharing this “sensitive data” between users, the encrypted, shared DMG is probably not the way to go, unfortunately there’s not enough detail in your question to give a good recommendation. – Allan Apr 19 at 18:42
  • @Allan, a DMG seems like a reasonable trade-off that is supported by the system to share files we want to store in Dropbox with additional security. I think the question is clear as as I'm not looking for advice on alternative ways to store those files. The answer might be 'there's no way', but that's what I'm trying to find out. Thanks. – Carlos Apr 19 at 18:48
  • 1
    If it's shared over DropBox, then each user actually has their own copy, which would be synced back to the central DB folder at save or close. Unless DB have their own mechanism to prevent multiple simultaneous transactions, then it cannot be done from one of the remote computers. – Tetsujin Apr 20 at 9:11

You must log in to answer this question.

Browse other questions tagged .