After I upgrade my R version, how can I easily reinstall all the packages that were installed in the old version?

Question

Possible Duplicate:
Painless way to install a new version of R?

In R, packages are not compatible across upgrades, and must be reinstalled. Is there any way to easily install the same set of packages in the new version as what I had installed in the old version?

Edit: I can't easily access the old version of R, since I upgrade via apt.

Answer 1

I just posted a question with a possible solution:

update.packages(checkBuilt=TRUE, ask=FALSE)

What about that doesn't work for you?