title: After I upgrade my R version, how can I easily reinstall all the packages that were installed in the old version?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1401904/painless-way-to-install-a-new-version-of-r">Painless way to install a new version of R?</a>  </p>
  </blockquote>
  
  
  
  <p>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?</p>
  
  <p>Edit: I can't easily access the old version of R, since I upgrade via apt.</p>