Notes on checking for circular dependencies

You almost certainly don't need to read this. I'm posting this here for the record in case someone wants to check TDE for circular dependencies in future. Bugs have been filed for all circular dependencies found in a standard --with-recommendations TDE R14 RC1 Wheezy install. (1) Why check for circular dependencies Although apt and dpkg do their best to handle any circular dependencies they encounter, circular dependencies can cause problems and a generally discouraged. (2) How to get rid of circular dependencies Usually one finds the least important dependency in the circle and changes it to a recommendation. If you're dealing with a maze rather than a circle you may to have convert several dependencies. (3) tsort non-method I first thought of using tsort on the dependencies listed in Packages.gz. However versioned dependencies, provides, conflicts, etc make this impractical. (4) Recommended elegant automatic method foreach PACKAGE in TRINITY { start with a minimal (non-TDE) base system install PACKAGE and all its dependencies remove just PACKAGE } There should be no errors installing or removing. However this method is somewhat time consuming even if you arrange it to use snapshots in a chroot so you can quickly revert to your minimal base system. (5) Grungy manual method Due to time constraints I used the following method for TDE R14 RC1. start with a non-TDE base system let TARGET be a list of all installed packages apt-get --install-recommends install desktop-base-trinity kde-trinity while (true) { let CURRENT be a list of all installed packages let REMOVE be TARGET (join -v) CURRENT let BUSY = false do { foreach PACKAGE in REMOVE { Try to remove PACKAGE, if successful set BUSY = true } while (BUSY); break if only TARGET packages are installed manually figure out why no remaining package is removable note and remove any set of co-dependent packages } This is overall a lot faster than the automatic method but it requires more manual work. The first time the removals stalled there were 76 packages still awaiting removal and you then have to look through these to find the loops. (6) Loops found in Wheezy TDE R14 RC1 (a) Bug #2194 kcontrol-trinity konqueror-nsplugins-trinity konqueror-trinity konsole-trinitytdebase-trinity ksmserver-trinity tdebase-runtime-data-common-trinity (b) Bug #2197 libkcal2b-trinity libtdepim1a-trinity (c) Pre-existing Debian Bug #626319 gnuift gnuift-perl