Making rm undoable

[Guy Harris]

>Keeping a file open also does nothing under NFS -- there's no state,
>so the NFS server doesn't realize that the file is open and it will go
>away.  I hear that the next version of NFS supplies the capability to
>do file locking, but I don't know if this includes keeping track of
>busy files.

I'm not sure what you mean by "the next version of NFS".  The *current*
version of the ONC/NFS source as distributed by Sun includes a network
service to perform byte-span locking (which subsumes file locking) over
the network; said service is different from the file access service that
NFS refers to in the strict sense.  I think the previous version of the
ONC/NFS source had it as well. 

The next version of the NFS *protocol* doesn't include support for
byte-span locking; that's still left up to a separate service and
protocol.

Since the locking is a separate service, and since it's accessed on
typical UNIX implementations only through the "fcntl" system call
(POSIX/SVID-style), neither Version 2 (the current version of the
protocol) nor Version 3 (the next version of the protocol) of the NFS
service keeps track of files that a client has open, so no, this doesn't
include keeping track of busy files.