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I don't know why you can't delete them, unless someone has them open in a browser, but this old article should explain what the are:
Mac OS X: Apple Double Format Creates File Name With the Prefix '._'
- Last Modified: September 18, 2003
- Article: TA20578
- Old Article: 106510
In some cases involving the Apple Double format, moving a file to a different file system will cause the prefix "._" to appear on a file name.
Mac OS X 10.2, Mac OS X 10.0
The prefix "._" appears on a file name.
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.
Thanks Bob. I wonder if that applies for newer versions of OSX as well? as I don't think anyone is still using 10.2 or older anymore
It does. I still get this question fairly frequently. Less and less as the years (and versions) go by, but yes.
Darn. So was that eventually eliminated in a later version of OSX? or is there a way to prevent OSX from making them in general?
Appreciate the help here Bob.
Darn. So was that eventually eliminated in a later version of OSX?
I do see it far less with later versions, And not at all with the latest (yet).
is there a way to prevent OSX from making them in general?
None that I've found. I just delete them as I find them.
As I said (perhaps none too clearly) earlier; about the only thing I've found to keep me from deleting them is if someone else on the network has that folder open. Thus, I try to do my deleting either early in the morning, or late in the afternoon, when no-one else is around.
the files on my servers appear to get some wacky permissions on them, preventing users from deleting them through the file share, or when they try to burn CDs of the folders for example it causes the burning to fail.
Sounds like I should just script something to search for that string with a wildcard and delete the files every night or something along those lines.