How to use dpkg-divert to temporarily remove/replace symlink when package is installed?

Solution 1:

If you want to divert a file owned by another package:

• In your preinst, divert the file away.

  dpkg-divert --add --package $your_package_name --rename \
     --divert /etc/nginx/sites-available/default.disabled \
              /etc/nginx/sites-available/default
  

• In your postrm, divert the file back.

  dpkg-divert --remove --package $your_package_name --rename \
              /etc/nginx/sites-available/default
  

This won't work for the symlink /etc/nginx/sites-enabled/default, because it's created by the nginx package's postinst rather than being part of the package. Since the symlink is part of the package, you can just rename it with mv. I don't know if this is compliant with the Debian packaging policy; if this matters to you, as this is a rather specialized question, I recommend searching or asking on debian-devel.