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I am using Ubuntu MATE 17.10. The release notes never mentioned anything about Wayland, and I've always assumed this system was using the Xorg display server.

However, today I ran the usual

sudo apt update && sudo apt full-upgrade

and noticed that the output included:

The following packages will be upgraded:
  libwayland-client0 libwayland-cursor0 libwayland-server0 [...]

I thought, that's odd. Is my system using Wayland after all?

As suggested by Byte Commander in chat, I looked for running processes (using pgrep Xorg and pstree), and found Xorg but no Wayland. So I'm pretty sure Wayland is not running. I looked for Wayland packages:

dpkg -l | grep [Ww]ayland
ii  kwayland-data                         4:5.38.0-0ubuntu1                        all          Qt library wrapper for Wayland libraries - data files
ii  kwayland-integration:amd64            4:5.10.5-0ubuntu1                        amd64        kwayland runtime integration plugins
ii  libkf5waylandclient5:amd64            4:5.38.0-0ubuntu1                        amd64        Qt library wrapper for Wayland libraries
ii  libqt5waylandclient5:amd64            5.9.1-2                                  amd64        QtWayland client library
ii  libqt5waylandcompositor5:amd64        5.9.1-2                                  amd64        QtWayland compositor library
ii  libwayland-client0:amd64              1.14.0-1ubuntu0.1                        amd64        wayland compositor infrastructure - client library
ii  libwayland-cursor0:amd64              1.14.0-1ubuntu0.1                        amd64        wayland compositor infrastructure - cursor library
ii  libwayland-egl1-mesa:amd64            17.2.8-0ubuntu0~17.10.1                  amd64        implementation of the Wayland EGL platform -- runtime
ii  libwayland-server0:amd64              1.14.0-1ubuntu0.1                        amd64        wayland compositor infrastructure - server library
ii  qtwayland5:amd64                      5.9.1-2                                  amd64        QtWayland platform plugin

Why do I have these packages related to Wayland even though I'm not using Wayland?

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  • 2
    Thanks for asking this! I noticed some Wayland packages today on a trial install of Lubuntu 18.04, which particularly confused me! Apr 10, 2018 at 14:52

1 Answer 1

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Thanks to Byte Commander and Eliah Kagan making suggestions in chat I was able to figure out that these packages were installed as dependencies.

As suggested I simulated removing Wayland related packages... When I tried pretending to remove all Wayland-related packages...

apt remove '.*wayland.*' -s

the result looked apocalyptic, with a full-screen terminal full of packages being removed, including the entire ubuntu-mate-desktop metapackage and all its adjuncts, the xorg package (oops!) and marco (MATE's default window manager).

But just removing kwayland-data only seemed to remove a couple of other mysterious packages kwayland-integration and libkf5waylandclient5...

So as Eliah Kagan suggested I tried asking aptitude why I had these packages, for example

$ aptitude why kwayland-data
i   konsole              Depends    libkf5windowsystem5 (>= 4.96.0)                           
i A libkf5windowsystem5  Recommends kwayland-integration                                      
i A kwayland-integration Depends    libkf5waylandclient5 (>= 4:5.27.0+p16.10+git20161029.2052)
i A libkf5waylandclient5 Depends    kwayland-data (= 4:5.38.0-0ubuntu1) 

Ahh! That makes sense. I installed Konsole because other terminal emulators don't support CTL.

By asking aptitude why over and over like a persistent toddler, it's possible to find out why any particular package is required or has been installed, for example:

$ aptitude why libwayland-egl1-mesa
i   libwebkit2gtk-4.0-37 Depends libwayland-egl1-mesa (>= 10.0.2) | libwayland-egl1
$ aptitude why libwayland-cursor0
i   libgtk-3-0 Depends libwayland-cursor0 (>= 1.9.91)
$ aptitude why libgtk-3-0
i   mate-utils Depends libgtk-3-0 (>= 3.16.2)
$ aptitude why mate-utils
i   ubuntu-mate-desktop Depends mate-utils

Simulating removal of packages like libgtk-3-0 (be careful not to actually remove them...) reveals more about the dependency structures in play.

Conclusion

I have these packages because other packages surprisingly depend on them. Some, such as kwayland-data, installed as a dependency of a dependency of a package recommended by a dependency of a non-essential package I installed myself, could be safely removed, but others, such as libwayland-egl1-mesa are dependencies of packages integral to my system, and removing them would be disastrous! With APT's --simulate or -s flag and aptitude we can safely investigate these matters.

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  • This's not a genuine explanation but only an analysis. We need to know WHY Canonical insists integrating Wayland components into Ubuntu Desktop Environment so much that one cannot remove them readily, even when he only uses x11.
    – funicorn
    Oct 23, 2020 at 8:46

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