Apple Mac OS X tips and tweaks
Date: 24th August 2011
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OS X Lion: Versions is more complicated than you might think
Versions is a new feature in OS X Lion on the Apple Mac and at first sight it looks really good and it is a sort of Time Machine for individual files. You don't save files any more, you save versions and there can be multiple versions of a document, image and so on in a file. At any time you can step back in time to an earlier version, undoing any changes that were made. It's a sort of backup and restore facility for files.
No longer do you have to save Document1, Document2, Document3 and so on as you edit it, OS X Lion just does it automatically within the same file. However, it's not hard to think of scenarios that might catch it out. What if you move a file to the Trash and later copy it out? What if you email the file to someone? What if you copy it to a USB flash memory drive? What happens to the versions?
Let's consider moving and copying. It's more complicated than you might think. If you copy a file then only the latest version is copied. This means that if you select a file in a Finder window and press Command+C to copy it then go to another folder on the disk and press Command+V to paste it, only the latest version is copied. You can't go to File, Revert to Saved and see and select previous versions of the file. If you click and drag the file to a new folder to move it then the file and all its previous versions are copied too. Moving files from one folder to another on the Mac's internal hard disk drive is fine.
Suppose you copy the file to another drive, such as a USB flash memory drive. This is like copying a file and only the latest version is copied. Suppose you edit the file on the USB flash memory drive. Although you can still select Save a version on the File menu (I'm editing a photo in Preview), only the latest version is saved. You aren't warned that Versions is not working. Save a version is just plain old Save and selecting File, Revert to Saved just shows the one version. The reason is because the USB flash memory drive is FAT formatted and it does not use OS X's disk format. All USB flash memory drives come FAT formatted for compatibility and Versions does not work on them. It's worth remembering that.
If you email a file to someone as an attachment, they won't have access to all the previous versions. Only the latest version is sent. If you delete a file by dropping it in the Trash, you can copy the file back out and all the versions are still available. That's useful.
Here's something clever that you might not expect. Suppose you copy a file to a USB flash memory drive, change it, and then copy it back to the Mac. You may do this when copying work files from one Mac to another. When you copy the file back to the original Mac you'll be asked if you want to keep both files or replace the original. If you choose to replace the original, it actually adds it as a new version. So if you open it and choose File, Revert to saved, all the previous versions are displayed. That's great.
Versions is OK when you're playing around with files seeing what happens in certain circumstances, but it's too scary to use in real situations. After 25 years of using Save As whenever I change a document I just can't get used to trusting Versions. Mind you, Preview and TextEdit are the only two apps that use Versions because they came bundled with OS X Lion. Every other app on my Mac was released before Lion and so doesn't support Versions. This means I'll be be using Save As for some time to come. Having some apps that use Versions and some that don't will be confusing and the only way to tell is to look at the File menu and see whether it says Save as or Save a version.
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