File Write Permission Rules

[John Young]

In article <23095 at conexch.UUCP>, root at conexch.UUCP (Larry Dighera) writes:
> In article <630 at jonlab.UUCP> jon at jonlab.UUCP (Jon H. LaBadie) writes:
> <This is a future direction of UNIX question.
> <I stumbled upon a system with /tmp directory permissions as follows:
> <
> <	drwsrwxrwx ......
> <
> <Note the "s". 
> <[...] namely a meaning for the set user id bit on directories.
> <The meaning?  Anyone could create files in the directory,
> <but only the owner of the directory, OR the owner of the individual
> <files could remove them.
> <So, the questions:
> <	1. Anyone know of the future fate of this useful tweak?
> 
> At a presentation to the Orange County Unix Users Group last month the
> AT&T speaker mentioned that Release 4 will support use of the suid bit
> on directories.  He didn't elaberate on its use, but I'll bet this is it.
> 
> Larry Dighera

Release 3.2 already supports this feature (only file owner & directory owner
(and root)) may remove a file.  This is implemented using the 't', sticky
bit on the directory.