Re: Union file system

Steven N. Hirsch (
Wed, 27 Nov 1996 17:55:27 -0500

Mikko J Rauhala wrote:
> On Wed, 27 Nov 1996, D. Chiodo wrote:
> > Symlinks? Mount all the cd, network, disk, etc, then make symlinks from
> > whereyou want you everything to appear to wherever the appropriate files
> > are...
> Won't cut it. We're talking about a system that would allow you to eg.
> mount a CD-ROM drive and then mount another filesystem "over" that, so
> that if you write to the file system, the CD-ROM files are hidden behind
> the new files on the writable media. Would be rather handy in some cases...

For any interested folks, there is a comprehensive discussion of Union
file systems in the book "Unix Internals" by Uresh Vahalia
(Prentice-Hall, 1996. ISBN 0-13-101908-2). This book is well worth
owning as a reference for some of the deeper technical topics that pop
up on the kernel mailing list :-)).