There are two suggested configuration options to install post-install hooks into Debian's apt/dpkg system: DPkg::post-invoke(1) and DPkg::post-invoke-success(2).For me, only post-invoke seems to work and I could not find any documentation about post-invoke-success.  Can someone enlighten me about differences, if they exist, and maybe which alternative should be used?
What's the difference between DPkg::post-invoke and DPkg::post-invoke-success?
apt;dpkg
There are three different hooks called Post-Invoke or Post-Invoke-Success, all managed by the apt tools:DPkg::Post-Invoke, which is invoked after every execution of dpkg (by an apt tool, not manually);APT::Update::Post-Invoke-Success, which is invoked after successful updates (i.e. package information updates, not upgrades);APT::Update::Post-Invoke, which is invoked after updates, successful or otherwise (after the previous hook in the former case).These are handled respectively in apt-pkg/deb/dpkgpm.cc, line 1509 and apt-pkg/update.cc, lines 111 and 114. There is no DPkg::Post-Invoke-Success hook that I can find.If you want to add a hook to all dpkg invocations, you should look at the post-invoke hook in /etc/dpkg/dpkg.cfg, which is equivalent to DPkg::Post-Invoke above but is applied in all cases, not just apt-based executions of dpkg. To see examples of all the apt configuration options, look at /usr/share/doc/apt/examples/configure-index.gz.