Met die underscore erachter is het veel herkenbaarder voor mij. Als je zoekt op "dot underscore files" vind je er veel over.
De mac heeft er zelfs een speciaal terminal commando voor om zo'n ._ file weer aan het oorspronkelijke bestand te koppelen.
DOT_CLEAN(1) BSD General Commands Manual DOT_CLEAN(1)
NAME
dot_clean -- Merge ._* files with corresponding native files.
SYNOPSIS
dot_clean [-fmnsv] [--keep=[mostrecent|dotbar|native]] [dir ...]
DESCRIPTION
For each dir, dot_clean recursively merges all ._* files with their corresponding native files
according to the rules specified with the given arguments. By default, if there is an
attribute on the native file that is also present in the ._ file, the most recent attribute
will be used.
If no operands are given, a usage message is output. If more than one directory is given,
directories are merged in the order in which they are specified.
OPTIONS
-f Flat merge. Do not recursively merge all directories in the given dir. This is off
by default.
-h Help. Prints verbose usage message.
-m Always delete dot underbar files.
-n Delete dot underbar file if there is no matching native file.
-s Follow symbolic links. This will follow symbolic dot underbar files when they are
found.
-v Print verbose output.
--keep=mostrecent
The default option. If an attribute is associated with a data fork, use that. Other-
wise, use information stored in the AppleDouble file. Note that the native fork's
data is preferred even if the data in the AppleDouble file is newer.
--keep=dotbar
Always use information stored in the AppleDouble file, replacing any extended
attributes associated with the native file.
--keep=native
Always use the information associated with the data fork, ignoring any AppleDouble
files.
EXAMPLES
The following is how to do an dot_clean merge on the mounted volume test, always using the dot
underbar information.
dot_clean --keep=dotbar /Volumes/test
DIAGNOSTICS
The dot_clean utility exits 0 on success, and >0 if an error occurs.
BUGS
None known.
BSD Sept 27, 2012 BSD
In deze metadata kan staan:
- Het programma waarmee de file geopend moet worden (i.p.v. het default voor die extensie)
- De plaats van de cursor bij het sluiten van een pdf (of ander tekst document)
- etc.
Allemaal mac specifiek en nooit essentieel. Alleen aanwezig voor het gemak.