Re: What are these ._something files???

John N. Alegre <info@xxxxxxxxxxxxxx> wrote:

When I do work from the bash shell(OS X 10.4.5), I often find files in
directories that are ._something where there is a file called something.

What is going on here? Anybody have a clue? Naturally they are hidden and
never show up in finder windows.

This is the method used by Mac OS X to store the resource fork and
Mac-specific file system metadata (such as the file type and creator
codes) on foreign file systems.

On HFS or HFS+ volumes, this information is supported directly by the
file system, and can be stored in the directory or a second fork of the
same file. Unix shells and other utilities will see this as a single
file, but it actually has two data streams (data fork and resource fork)
and most Unix tools will only access the data fork.

On other file systems, e.g. UFS, FAT32, or on network file servers other
than Mac File Sharing (AFP), the file system has nowhere to keep this
extra information, so Mac OS X compromises by saving it in a file named
as ._something (for a file called something). The leading dot should
mean it is normally hidden in directory listings on Unix shells
(including the Mac OS X command line) unless you use an option in the ls
command to show hidden files.

David Empson

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