File Write Permission Rules

[Barry Margolin]

In article <502 at maxim.ERBE.SE> prc at maxim.ERBE.SE (Robert Claeson) writes:
>it certainly makes more sense to have a "delete" attribute on a file,
>which must be set in order for me to remove it.

But since Unix allows a single file to be accessed using multiple
directory entries, a single delete attribute isn't enough.  How would
you specify that it is OK for anyone to remove some of the links, but
not others?  For instance, I might make a hard link in my directory to
something in a friend's directory.  Only I should be allowed to remove
my link, and only he should be allowed to remove his link, and he
shouldn't be able to prevent me from removing my link.

If you're going to allow multiple hard links, as Unix does, then it
doesn't make sense for deletability to be a file attribute, it must be
a link attribute.

Barry Margolin
Thinking Machines Corp.

barmar at think.com
{uunet,harvard}!think!barmar