Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!decwrl!waikato.ac.nz!canterbury!phys169
From: phys169@csc.canterbury.ac.nz
Newsgroups: comp.os.msdos.programmer
Subject: Re: Symbolic link in MS-DOS
Message-ID: <1991May30.142700.929@csc.canterbury.ac.nz>
Date: 30 May 91 02:27:00 GMT
References: <1991May29.153829.8742@bullet.ecf.toronto.edu> <1991May29.165933.12688@borland.com>
Organization: University of Canterbury, Christchurch, New Zealand
Lines: 27

In article <1991May29.165933.12688@borland.com>, alexande@borland.com (Mark Alexander) writes:
> In article <1991May29.153829.8742@bullet.ecf.toronto.edu> xiaoy@bullet.ecf (XIAO  Yan) writes:
>>When I used chkdsk and I was told two files were cross linked to the
>>same cluster [...] so I assume that it is feasible to have symbolic link...
> 
> Unfortunately, no.  It's possible to have a corrupted file system
> where two directory entries have the same starting cluster number, as
> in your case.  This is more like a UNIX hard link than a symbolic
> link.  But DOS doesn't keep a link count in an inode anywhere, so if
> you delete one or both of the directory entries, Bad Things will
> happen to your data in short order.
> 
True, it is a hard link, and you have problems when you delete the file or
directory, and you keep getting annoying warnings from CHKDSK. But you could
set some extra bits in the attribute word to stop it being deleted by anything
other than your own program (which would do it neatly). But the best thing is
to wait for a version of DOS with support for links a la Unix or AOS/VS.

It might be possible to get a soft link by playing with SUBST and JOIN; I
haven't succeeded yet, but it is worth tinkerring with.

> The DOS rename function (INT 21H, AH=56H) is actually capable of
> moving a file from one directory to another on the same disk. 
But it doesn't do subdirectories, except for renaming within the same directory.
You could temporarily take off the directory bit, of course.

Mark Aitchison.