[Info-vax] Request description of UFS for VMS person

[Bob Eager]

On Tue, 21 Apr 2009 17:57:11 UTC, glen herrmannsfeldt 
<gah at ugcs.caltech.edu> wrote:

> Bob Koehler <koehler at eisner.nospam.encompasserve.org> wrote:
>  
> >   This is an area in which every file system I've studied operates the
> >   same.  There is no file delete primitive at the lowest levels of
> >   the VMS or UNIX kernel, and I think not Windows, MS-DOS, or classis
> >   MacOS, either.
> 
> Well, for unix there is no file delete operation.
> 
> There is unlink(), which removes a link to the file, which
> may or may not be the last one.  I am not so sure how MS-DOS
> did this, though.

As you say, unlink just removes a directory entry; all directory entries
are 'equal', so when the last one goes, the use count in the inode drops
to zero. At that point, the inode is cleared and the file blocks 
returned to free space.

On MS-DOS, the first byte of the directory entry was set to a special 
'deleted' value, and file blocks were marked as free. Basic, but 
sufficient.

-- 
Bob Eager