Mail Archives: opendos/1997/02/10/07:43:55
On Thu, 6 Feb 1997, Paul J. Thompson wrote:
> I was thinking today how useful the directory links from unix would be in
> dos (OD). Now, I don't remember the exact name of what they are called,
> but it should be added to the improvement list. I am sure it would be a
> very simple addition...
Symbolic links (soft links), and hard links. Every file in a
UNIX filesystem is given a unique number called an inode number.
A directory entry points to that inode. When a HARD link is made
on a file, 2 directory entries end up being the exact same file.
for example: file1.txt allready exists
$ ln file1.txt file2.txt
This creates a hard link between file1.txt and file2.txt. There
is only one copy of the file stored on the disk, however that
file has 2 directory names and can be accessed by either name.
The file isn't deleted from the filesystem until ALL links are
removed.
A symbolic link is different in that it "points" to a filename.
Symlinks can thus span filesystems. However if you delete the
file that a symlink points to, then the symlink now points to a
non-existant file and any file accesses will generate an error.
$ ln -s file1.txt file2.txt
This creates a symlink from file1.txt to file2.txt. If file1.txt
is deleted, then file2.txt points to a non-existant file.
To implement such a "linking" mechanism in DOS would require
extensive modifications. This puts the FAT filesystem out of the
picture. However under a new IFS API, symlinks/hardlinks would
certainly be possible.
You COULD manually create 2 directory entries in a dir on your
hard disk that would point to the same file in your FAT (a
hardlink), however any disk maintenance software (such as CHKDSK,
SCANDISK, NDD) will detect this and label it as an error. Ever
hear of crosslinked files?
A symlink under DOS is impossible on FAT without the IFS API, but
would be a hack (ala microsloth) even if it were to be
implemented in DOS FAT. Either way, those diagnostic programs
would still have a fit and destroy files on you.
Mike A. Harris | http://blackwidow.saultc.on.ca/~mharris
Computer Consultant | My webpage has moved and my address has changed.
My dynamic address: http://blackwidow.saultc.on.ca/~mharris/ip-address.html
mailto:mharris AT blackwidow DOT saultc DOT on DOT ca
Xwindows: Forget '95. Use a REAL GUI.
- Raw text -