HI Robert, Scott, and Others,

>> Robert Carter wrote:
>>>
>>> I am curious if anybody can explain this. I have been going to the
>>> Nfb Newsline Online site and having my Newspaper emailed to me. The
>>> Newspaper consists of 4 DAISY files. If I copy and paste these files
>>> onto an SAID card using my iMac, I end up with 8 files in the folder
>>> which seem to be two duplicates of each of the original 4 files.
>>> Does anybody understand why this happens? I am just curious about  
>>> it.
>>


and Scott asked:
>
> Not got a sollution, more of a question.  I think I've seen the same
> behaviour you described.  Next time it happens, can you check the file
> sizes of both copies you get?  For me, it was always that one was the
> full size of the file, the other would be tiny like 32kb or something.

I think what you're seeing is something called "Apple Double format",  
and it occurs when you do a copy and paste to a FAT32 formatted device  
like your SAID card or a USB memory stick (among other  
circumstances).  The set of files which Scott mentions as being 32kb  
in size will have names that are preceded by a period and then an  
underline character followed by the regular file name, and are  
referred to as "dot underscore" files. (You'll have to read the  
filenames by character to hear the prefix characters with VoiceOver.)  
Basically, Apple's file system keeps track of two kinds of information  
-- a data fork and a resource fork.  You know that when you open files  
on the Mac you can specify which application is used on a per file  
basis. Mp3 files can be played with VLC, QuickTime, iTunes, Amadeus  
Pro, etc.  That kind of data (and other information about the file) is  
stored in the resource fork.  It doesn't get used when you transfer  
files from a Mac to Windows, but it does have information if you were  
to transfer the files (say, on a USB memory key) to another Mac. This  
is described in Apple's Knowledge Base:

http://support.apple.com/kb/TA20578
(Apple Double Format Creates File Name With the Prefix '._')

You can safely delete the small dot underscore files.  Under Leopard,  
there's a "dot_clean" command available from terminal that will do  
this.  Here's the description of the dot_clean man page:
http://developer.apple.com/documentation/Darwin/Reference/ManPages/man1/dot_clean.1.html
With your SAID card mounted, launch a Terminal session (e.g. from  
Finder use Command-Shift-U then press "t e" to go to "Terminal" and  
Command-Down Arrow to open).
Type a command like:
dot_clean /Volumes/SAID/
where you substitute the actual path to your mounted SAID card as the  
argument for dot_clean (and press enter after you type the command).   
You can find the device in your Finder sidebar and use the Get Info  
window (Command-I) to find the path to mounted device. Remember to  
close the Get Info window with Command-W when you're done.
There are commercial solutions GUI-based solutions like BlueHarvest,  
too.
http://zeroonetwenty.com/blueharvest/
Incidentally, this is also an issue for people trying to move files  
between the Mac and linux via tar savesets.  You can disable the  
extended attributes from the bash shell in terminal with:
export COPY_EXTENDED_ATTRIBUTES_DISABLE=true
to avoid including created dot underscore files, or you can just  
transfer the files via FTP or SFTP.

HTH
Cheers,
Esther








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