Can anybody explain some details about how is implemented the automatic file versioning in the Lion?

  • It is transparent for any file? (for example, for files created in the Terminal.app with shell command like ls >file.txt and ls -l > file.txt mean than the file.txt got versioning?, or
  • every application should call some versioning API at the save?
  • lion questions are currently off-topic.
    – user6124
    Jun 19, 2011 at 11:15

1 Answer 1


The only information has released to non-Mac Developer Program members is the following.

If you have a document-based application, Lion offers an efficient, built-in auto save feature that stores changes to the working document instead of creating additional copies on a disk. Versions automatically records a history of changes made to your documents and lets your app display a Time Machine like interface so users can browse through previous versions. ADC

There is more information available for Mac Developer Program subscribers. The information, however, is currently restricted by a non-disclosure agreement . The information will most likely be made available for everyone once the final version of Lion is released. This is how Apple have done it in the past.

Personally I am a bit disappointed that Apple chose to go with ‘something else’ instead of the native handling of this offered by the ZFS file system. (As rumored as far back as Leopard.)

  • 2
    ZFS would've been great from a technical perspective, but became a non-option the moment it was announced that Oracle might buy Sun. AIUI there's just no way Apple was going to give Oracle that sort of licensing leverage. Jun 19, 2011 at 13:46
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    Just browsed a bit and for now im sure than versioning will need support from developer, so the application must be built with some API to support versioning. It is not OS level.
    – clt60
    Jun 19, 2011 at 13:53

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