Why can I write to a READ-ONLY NFS file system?

[Ernest Hua]

I can do the following:

% cd /my/favorite/read/only/nfs/file/system
% cat some.file >> another.file
% vi another.file

And ... guess what?  No errors from "cat", and "vi" tells me that I
successfully did it.  Just to verify it, I went to the NFS server and
reverified that the append worked.

Why is this possible?  Please respond by E-MAIL only.

Ernest Hua
Tandem Computers
408-285-5580
ernest at tandem.com