Matt [Danger]

The current code base I’m working from is located on a network share and controlled by Subversion. I’ve been dealing with the Apple Double format problem a lot lately and scripted a simple clean up solution.

For those unfamiliar with the Apple Double problem, it is an old bug that exists from the early days of Mac OS X. Here’s the explanation from the Apple Knowledge Base:

Before Mac OS X, the Mac OS used ‘forked’ files, which have two components: a data fork and a resource fork. The Mac OS Standard (HFS) and Mac OS Extended (HFS Plus) disk formats support forked files. When you move these types of files to other disk formats, the resource fork can be lost.

With Mac OS X, there is a mechanism called “Apple Double” that allows the system to work with disk formats that do not have a forked file feature, such as remote NFS, SMB, WebDAV directories, or local UFS volumes. Apple Double does this by converting the file into two separate files. The first new file keeps the original name and contains the data fork of the original file. The second new file has the name of the original file prefixed by a “._ ” and contains the resource fork of the original file. If you see both files, the ._ file can be safely ignored. Sometimes when deleting a file, the ._ component will not be deleted. If this occurs you can safely delete the ._ file.

Essentially, when you’re working on files located on a network share you end up with duplicates of the file with a “._” prefix. The files are empty and are quite the annoyance. They are removed when the network share is unmounted. However, I leave my share mounted for long periods of time and the files make a mess of my Subversion status reports.

You can run the following command to clean the files up.

find . -name '._*' -exec rm '{}' ';'

You could also make this into a launchctl or cron task. Happy hacking!