File Write Permission Rules

[Rahul Dhesi]

In article <1177 at ubu.warwick.UUCP> mirk at uk.ac.warwick.cs (Mike Taylor) writes:
[the unix permissions scheme is intuitive because a directory
is a list of files]

There is still a flaw.

If a directory is like the card catalog in a library, and the files
themselves are like the books, then it is counter-intuitive that, when
somebody vandalizes the card catalog, all the books are destroyed too.

In UNIX, the existence of a file under normal circumstances is nearly
synonymous with the existence of its directory entry.  In a sense the
directory entry represents the file to the user, since he cannot look
at the file in any other way.  It *is* counterintuitive that a
read-only file cannot be written to but can still be deleted.

Thank heavens for the sticky bit on directories.  It came just in time,
and does invalidate much of the criticism.
-- 
Rahul Dhesi         UUCP:  <backbones>!{iuvax,pur-ee}!bsu-cs!dhesi
                    ARPA:  bsu-cs!dhesi at iuvax.cs.indiana.edu