File Write Permission Rules

[Leo de Wit]

In article <632 at uva.UUCP> dik at uva.UUCP (Casper H.S. Dik) writes:
|If you have 4.3BSD, SunOS 4.x etc the solution is even more obvious:
|Set the sticky bit on your directory. This prevents people other than
|the owner of the file or the owner of the directory in which the link
|resides to unlink or rename the link.

A pity (is it really?) that ordinary users are not allowed to set
'sticky mode', this makes it hard to use by anyone but root. I fail to
understand what the possibility of unlinking has to do with sticky bits
(but then, you can fill me in); I thought that a sticky bit keeps a
file on the swap disk, once it is loaded.

If a user can put a file in a directory (write the directory file) he
can also remove ANY file in that directory (he can write the directory
file, so delete any links in that file). The only exception I can think
of, are non-empty subdirectories of the directory. And that is the way
I put stuff in /tmp that should not be removed by others:

$ cd /tmp
$ mkdir leo
$ chmod 700 leo
$ >leo/.guard

	Leo.