"Important" control field is a bit confusing

Bug #1624681 reported by Sworddragon on 2016-09-17
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
apt (Debian)
New
Unknown
apt (Ubuntu)
Low
Unassigned
init-system-helpers (Ubuntu)
Undecided
Unassigned

Bug Description

I'm using Ubuntu 16.10 dev and noticing that the package init seems to be the only one with the "Important" control field which seems to be a bit curious:

- On removing a package with apt that has the "Important" field set to "yes" it seems to show the same warning like removing a package that has the "Essential" field set to "yes". Even the same term "essential" is used instead of "important" (maybe this should be changed?).
- "man deb-control" does not know this field and removing a package with dpkg that has the "Important" field set to "yes" does not throw an error while removing a package that has the "Essential" field set to "yes" does.
- I'm wondering what the difference between the "Essential" and "Important" field for apt is. I can't find any information about it and can't also find the manpage that documents the custom control fields that apt but not dpkg knows (does such a manpage exist?).
- I'm also wondering why init uses this control field instead of the "Essential" control field as this would additionally prevent removing it by accident with dpkg.

Julian Andres Klode (juliank) wrote :

Essential packages not installed will be installed automatically by APT, packages with the Important field will not be. Important also does not have the same ordering requirements as Essential. It's main use case is building configuration metapackages:

  https://juliank.wordpress.com/2012/01/24/managing-system-package-selections-using-custom-meta-packages/

But yes, this is not specified at all - it is an APT-specific feature. People do not like the field name, because it can be confused with Priority: important, so it has not been standardized and included in dpkg yet - also see https://wiki.debian.org/Teams/Dpkg/Spec/ImportantField and https://lists.debian.org/deity/2016/03/msg00025.html for further information.

Once this has a new name and is standardized we can actually produce good error messages.

Changed in apt (Ubuntu):
importance: Undecided → Low
status: New → Triaged
Julian Andres Klode (juliank) wrote :

Note that a normal user should never see this: They normally do not remove the init package.

Joshua Powers (powersj) wrote :

Marking init-system-helpers as invalid, keeping open for apt

Changed in init-system-helpers (Ubuntu):
status: New → Invalid
Changed in apt (Debian):
status: Unknown → New
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