Extended attributes have been part of the Macintosh operating system in a few
different forms since 1984. Up until Mac OS 9, the only alternative was a
resource fork. In Mac OS 9, named forks were introduced, although only data and
resource were practically available, and under the Mac's Unixification in OS X,
they were implemented as extended attributes. You can add the @ symbol to the
ls command to list all available extended attributes on a file or directory
(yes, directories):
ls -al@
The details are a bit more complicated, but for most needs, even a backup
service, this should suffice. There are wikis that go into greater detail.
--
Gary L. Wade (Sent from my iPhone)
http://www.garywade.com/
On May 5, 2016, at 12:01 PM, Martin Wierschin <mar...@nisus.com> wrote:
>> Those files are compressed by the filesystem. In HFS+/MacOS Extended that
>> means that the data fork is empty and the file contents are stored in the
>> resource fork or extended attributes structure.
>>
>> http://wiki.sleuthkit.org/index.php?title=HFS#HFS.2B_File_Compression
>
> Huh, that's interesting and surprising, thanks for the link. Is this method
> of stashing compressed data in the xattrs something that's currently commonly
> used by OSX? Or is it just some weird infrequently used trick? I see this on
> the linked page:
>
>> Compression is most often used for files installed as part of Mac OS X; user
>> files are typically not compressed (but certainly can be!)
>
> Are a lot of system files compressed like this? Is there any way a user file
> might be compressed in such a way through normal user actions?
>
> ~Martin Wierschin
_______________________________________________
Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
