Determining OS X version from Time Machine backup

I have Time Machine backups from my iMac Early 2008 (20"). Can I determine from those backups what OS X version was running on the machine at the time of latest backup?

Just open the file

/Volumes/BackupVolumeName/BackupName.ext/ComputerName/latest/VolumeName/System/Library/CoreServices/SystemVersion.plist

to determine the product version ("latest" is a sym-link).

BackupName.ext, BackupVolumeName, ComputerName and VolumeName are all variable and depend on the type of backup or the names configured/given to your backup volume, Mac and main system volume. BackupName.ext is often Backups.backupdb though.

Here is my SystemVersion.plist (it's the original file and not a file in a backup) opened in PlistEdit Pro. You may also open it with an arbitrary text editor or Xcode:

Yes you can look at the value of the ProductVersion in the SystemVersion.plist file located at, e.g., /Volumes/Backup/Backups.backupdb/<ComputerName>/yyyy-mm-dd-hhmmss/Macintosh HD/System/Library/CoreServices/.

The SystemVersion.plist is an XML plist file so, you can just open it in TextEdit, if you do not have a .plist editor and you'll see as an example:

<key>ProductVersion</key>
<string>10.8.5</string>