Turn Off File Locking in OS X Lion
Mac OS X Lion introduced automatic file locking for any file that hasn’t been edited recently. You’ll have noticed this when you try and open an older file and make changes to it, a dialog box asks to duplicate the file or to manually unlock it. This is fine for files that you don’t want to accidentally Auto-Save over, but sometimes it’s just plain annoying.
Disable Automatic File Locking in Mac OS X
- Open System Preferences, click on “Time Machine” and then click on “Options”
- Uncheck the box next to “Lock documents [2 weeks] after last edit”
Without file locking enabled, apps that support auto-save will overwrite the existing file. This is best disabled with either some variation of restoring the “Save As” option or an understanding of how to use Duplicate so that you files are not accidentally overwritten.