.deb files open with Archive Manager by default

defaults.list is referencing the correct desktop file. It's installed in /var/lib/snapd/desktop/applications/snap-store_ubuntu-software-local-file.desktop

I don't know why it's not the default though, perhaps alphabetical in the picker?

$ mimeopen -D gnome-control-center_1%3a41.4-1ubuntu13_amd64.deb
> Data dirs are: /home/jeremy/.local/share, /usr/share/ubuntu, /usr/local/share, /usr/share, /var/lib/snapd/desktop
> Checking inode type
> Checking globs for basename 'gnome-control-center_1%3a41.4-1ubuntu13_amd64.deb'
> Checking for extension '.deb'
Opening "gnome-control-center_1%3a41.4-1ubuntu13_amd64.deb" with Archive Manager (application/vnd.debian.binary-package)

Beginning of the Fix
====================
1. Add application/vnd.debian.binary-package;
to the MimeType line of
snap-store_ubuntu-software-local-file.desktop

2. Then run
sudo update-desktop-database /var/lib/snapd/desktop/applications

$ mimeopen -D gnome-control-center_1%3a41.4-1ubuntu13_amd64.deb
> Data dirs are: /home/jeremy/.local/share, /usr/share/ubuntu, /usr/local/share, /usr/share, /var/lib/snapd/desktop
> Checking inode type
> Checking globs for basename 'gnome-control-center_1%3a41.4-1ubuntu13_amd64.deb'
> Checking for extension '.deb'
Please choose a default application for files of type

 1) Archive Manager (org.gnome.FileRoller)
 2) Software Install (snap-store_ubuntu-software-local-file)
 3) Other...

use application #

That got me a step closer but then it looks like at least mimeopen isn't sure which app to use.

GNOME 40 and newer doesn't use /usr/share/applications/defaults.list file, I think this is the main issue why deb files are opened by Archive Manager, for more info look at

https://help.gnome.org/admin/system-admin-guide/stable/mime-types-application.html.en

Quick fix could be to change the name of /usr/share/applications/defaults.list symlink to mimeapps.list , but I'm not 100% sure, because there is a line in /usr/share/applications/gnome-mimeapps.list
application/x-deb=org.gnome.FileRoller.desktop

The /usr/share/applications/mimeapps.list and /usr/share/applications/gnome-mimeapps.list files specify which application is registered to open specific MIME types by default. These files are provided by the distribution.

To override the system defaults for all users on the system, you need to create a /etc/xdg/mimeapps.list or /etc/xdg/gnome-mimeapps.list file with a list of MIME types for which you want to override the default registered application.

Files located in /etc/xdg/ take precedence over files found in /usr/share/applications/. Additionally, /etc/xdg/gnome-mimeapps.list takes precedence over /etc/xdg/mimeapps.list

Btw, there is a bug #1559129 (Replace defaults.list by mimeapps.list) already reported few years ago by Ubuntu developer, but it seems someone forgot to fix that :(

Manatas, do you have more detail about when you think the behavior changed?

The defaults.list handling is still valid,
https://gitlab.gnome.org/GNOME/glib/-/blob/main/gio/gdesktopappinfo.c#L985

The issue is that it ranks lower than gnome-mimeapps.list which got install by error since a gnome-session merge this cycle
http://launchpadlibrarian.net/569661464/gnome-session_40.1.1-1ubuntu1_40.1.1-3ubuntu1.diff.gz

the
>- don't install gnome-mimeapps.list (installed by desktop-file-utils in Ubuntu)

was undone there
+debian/gnome-mimeapps.list usr/share/applications/

or that list isn't customized by Ubuntu and taking over our defaults

We should revisit how we ship the default going forward, at least use the non deprecated filename. The reason we ship from desktop-file-utils was that it was a smaller and less risky package to upload to change default.

But for now the first fix would probably be to remove the .install line from gnome-session again

bug #1559129 is also a report about replacing the outdated default.list which we should do next cycle

Missing 'where problems could occur' per https://wiki.ubuntu.com/StableReleaseUpdates#SRU_Bug_Template

And I do see significant risk of problems; while the mime handler for .deb files is incorrect, a diff of /etc/gnome/defaults.list vs /usr/share/applications/gnome-mimeapps.list shows a number of differences, including some types that are only handled in /usr/share/applications/gnome-mimeapps.list. Given that shipping /usr/share/applications/gnome-mimeapps.list was unintentional and it's so soon after release we might accept wholesale dropping of the file, however I would still want to see analysis of the impact.

This bug was fixed in the package gnome-session - 42.0-1ubuntu3

---------------
gnome-session (42.0-1ubuntu3) kinetic; urgency=medium

  * debian/gnome-session-common.install: Don't install gnome-mimeapps.list
    (installed by desktop-file-utils in Ubuntu) (LP: #1970248)
  * Have gnome-session and ubuntu-session depend on
    xdg-desktop-portal-gnome | xdg-desktop-portal-backend (LP: #1970424)

 -- Jeremy Bicha <email address hidden> Sun, 01 May 2022 11:35:12 -0400