Another heavily-publicized feature of Lion is Versions, which keeps older copies of files as you save new ones and allows you to go back to previous copies to compare, restore, and copy-paste things you didn't mean to change. Unlike Resume, applications will need to be changed to support this functionality.

In a Versions-supporting program like TextEdit or Preview, you'll notice that the normal "Save" or command-S function is now called "Save a Version" instead. There's no special command you need to know to save Versions - if the app supports it, this happens automatically.

 

When you want to go back and look at your previous versions, select the Revert to Saved option in the menu to open the Versions interface.

You'll be presented with a very Time Machine-esque interface that will let you browse through your previously saved copies, compare them to your working copy, and restore an old copy to be your new working copy.

So how does this work? Versions stores its data at the root of your OS volume in a hidden and locked-down folder called 'DocumentRevisions-V100". Files are saved using the UID for each user account (the UID is a unique number assigned to each user account at time of creation, and is normally hidden from the user. All UNIX and UNIX-like operating systems use UIDs for user accounts). In the screenshot below, "501" is my account's UID, and the numbered folders each correspond to an individual file.

Drill down into any of the folders stored here, and you can see where OS X is keeping the older copies of your files.

Whenever you delete the source file, all stored versions of it are also deleted, so don't try to use Versions to recover accidentally deleted files - that's not what it's for, and you'll still need to be careful about what you do and don't keep.

It's not immediately obvious how many files OS X will store versions for, or how much disk space this hidden folder will take up if you let it, but disk space seems to be the limitation here - I was able to save 63 versions of an individual file without overwriting any older copies. Given Apple's desire to hide the seams and inner workings of OS X from regular users, I feel confident in saying that (1) OS X won't allow this system folder to take up so much space that it impacts OS performance or storage of regular files, and (2) there's probably some sort of safeguard present that will eventually begin deleting older versions of things as disk space runs low. This is how Time Machine works, and Versions is obviously taking cues from that feature.

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  • quiksilvr - Wednesday, July 20, 2011 - link

    $29 is indeed a solid improvement. However, given the Mac Store now being out there, their desktop OS should follow the formula of their mobile OS: Free to upgrade. These features are nice but I can't help shake the feeling that these are Service Packs (because they are). And with their "app" store available on the OS and the means of most of their cash inflow, it makes more sense to make this a free upgrade for everyone instead of a $29 upgrade.
  • xype - Wednesday, July 20, 2011 - link

    Service packs? Are you serious? Read up on the changes and try to come up with one service pack that changed as much.

    Some people…
  • danielkza - Wednesday, July 20, 2011 - link

    XP SP3 would be a good candidate, but yes, 10.7 is a bit beyond what one could reasonably call a Service Pack.
  • Taft12 - Wednesday, July 20, 2011 - link

    You're thinking of XP SP2, and if you have to go back 7 years to come up with a comparable "service pack", it's certainly fair to say OSX 10.7 is more than a service pack.
  • AfroPhysics - Friday, July 22, 2011 - link

    I fail to see how the age of the service pack matters. Xype asked for an example and qualified nothing.
  • ltcommanderdata - Wednesday, July 20, 2011 - link

    Are we really going through the tired argument that every 10.x update to OS X is just a service pack and should be free? Then at what point should Apple try to recoup costs for OS development, because even if individual point updates are evolutionary, going from the original 10.0 to 10.7 has got to be a major change in anyones eyes. And the same questions could be raised about Windows NT 6.1 aka Windows 7 where the server version is bluntly labeled Windows 2008 R2 and Windows NT 6.0 aka Vista/2008 or Windows NT 5.1 aka XP and Windows NT 5.0 aka 2000.

    Besides, even if you discount the user facing changes, Lion has seem some major security infrastructure changes. Both the 32-bit and 64-bit kernel have been rewritten with full NX-bit and ALSR support as in place in Windows Vista/7 addressing the major security complaint Charlie Miller had with OS X. Application sandboxing frameworks are now available and soon to be mandatory for Lion apps in the Mac App Store which I believe is a security feature that even Windows isn't pushing yet. With the dropping of the Core Duo, the Lion has also be rewritten to make more use of SSSE3 instead of just SSE3 as pointed out by the Hackintosh community. Lion isn't just Snow Leopard with a few features added on top, but the entire OS has seem updates at a low level even if the user might not necessary see all the differences.
  • ltcommanderdata - Wednesday, July 20, 2011 - link

    And about the App Store being a major source of income for Apple, Apple has consistently said they aim to run their stores as a break even venture.

    http://www.macrumors.com/2011/07/19/apple-reports-...

    I'm not clear if the iTunes Store in the graphic in the above link includes the App Store, but at the very least as an example of Apple's digital store, the revenue stream really hasn't increased in the last 2 years. Apple's sales growth is clearly from their hardware, iPhone, iPad, and even Mac.
  • GotThumbs - Wednesday, July 20, 2011 - link

    $1,634,000,000 in revenue from Other Music Related Products and Services (3)

    (3) Includes sales from the iTunes Store, App Store, and iBookstore in addition to sales of iPod services and Apple-branded and third-party iPod accessories

    I'd say their goal of a break even venture is not an accurate description of their stores. Hence the creation of the MAC Store. It sounds like a nice thought, but Apple is in business to make money and it seems their VERY good at it. Perhaps their projection analysis was a bit off.

    Hey, this is good news for the investors and I understand that they are a business. Lets not be too naive and just don't drink the cool-aid.
  • ltcommanderdata - Wednesday, July 20, 2011 - link

    Perhaps my finance terms are wrong, but I'd hope the Apps Store is taking in revenue. But if Apple should be offering some of their other products like OS X updates for free, shouldn't we be concerned with whether the App Store is making major profits, such that there is money to spare to pay for OS development?
  • solipsism - Wednesday, July 20, 2011 - link

    Revenue ≠ Profit

    They've paid billions to both developers, and music and video cotent owners. They've also spent money on the infrastructure to support their stores. I'm sure they're making a profit as all good for-profit companies should, but it's not the cash cow you've attempted to present here.

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