> It seems to me that te question is "Shall a device
> exist in a non-existing directory ?"

I don't think that's the correct question.  I think there are two questions.  
The first question is, "Does a device exist in a non-existent directory?"  The 
answer to that is no -- a device does not exist in an "imaginary" place that 
you cannot actually navigate to.  In that sense, it has the same 
characteristics as a "normal" file.

The second questions is, "Does a device exist in all existing directories, or 
only certain ones?"  The answer to that question is that it is supposed to 
"exist" in ALL directories.  If you can navigate to a directory, ALL devices 
"exist" there (at least for the purposes of an "IF EXIST" test).  For example, 
if you navigate to an existing directory on a floppy drive that's already full 
and has no room left for any "real" files, or a read-only device like a CD-ROM, 
the NUL device (and all other character devices) still "exist" there.  In 
addition, you can write to a character device (like NUL) even if the directory 
itself is read-only.  In that sense, it is different than a "normal" file.

That's why you can use the IF EXIST test (with a character device name in place 
of the file name) to test for the existence of a directory instead of a file, 
and it should work for any directory that is navigable.


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