cvs difference between cvs two tags - without touching...

Hi friends

I have a nice script coming soon, where I want to be able to list
exactly which files that were changed between cvs tag BLA and
and another cvs tag FOO, where FOO is normally the HEAD version.

I have solved this, but have the problem that I will be cvs updating all 
files 
$ cvs -Q update -d -r BLA
$ cvs -q update -d -r FOO > boing.txt
$ cvs -Q update -A -d # leave the files at HEAD

For each file in boing.txt do
$ cvs log -r BLA -r FOO <some_file>
to log the changes. Works quite ok - but I am joggling the files back to 
BLA and leaving them at HEAD.

I am working on a prototype script where I try to identify the changed 
files *without* modifying any local files (i.e. even their cvs 
editor rights/change status). Can I idenfify the changed files 
between two cvs tags without any local file change??

I can do
$ cvs -nq update -d -r BLA > list.txt
$ cvs -nq update -d -r FOO >> list.txt
where I then traverse the list.txt file afterwards, but there are several 
special cases (such as false identifications of files changes) which makes 
this approach a bit annoying...

Unfortunally it seems that I cannot do
$ cvs -nq update -r BLA -r FOO > list.txt
to identify the changes.

Hope to hear from you!

Best

-- 
Peter Toft, Ph.D. [[email protected]] http://petertoft.dk
I blog at http://www.version2.dk/blogs/petertoft