After installing some Flatpak package on my KDE Neon the application icon was not displaying neither in the window header nor in the panel. I wanted to fix it and discovered that is related to zsh package. Here is my troubleshooting path.

Flatpak

Let’s start with Flatpak. It’s a way to distribute applications in Linux. It has some pros and cons but I prefer it to install some proprietary apps and appps that are not supplied in the distro repositories. After installing Telegram from Flatpak I noticed that the application icon is missing in the task panel and in the window header. I started to search how Flatpak propagates information about the app.

Freedesktop

First of all such application resources as icons are stored in share directories. In Debian and Ubuntu it’s /usr/local/share and /usr/share. And there is an environments variable XDG_DATA_DIRS which is a part of Freedesktop specification. Flatpak has its own directories for application resources $HOME/.local/share/flatpak/exports/share and /var/lib/flatpak/exports/share. And obviously it should add these directories into XDG_DATA_DIRS. But they were not there.

Again Flatpak

So how Flatpak updates XDG_DATA_DIRS. Arch wiki has a mention of it:

Flatpak expects window managers to respect the XDG_DATA_DIRS environment variable to discover applications. This variable is set by the script /etc/profile.d/flatpak.sh. Updating the environment may require restarting the session.

This is it. flatpak.sh is executed from your /etc/profile.d/ directory. But wait. This directory is used by /etc/profile script. Basically it’s the very first script that is executed by bash when it’s invoked.

Zsh

But I use zsh not bash. I even use it as a login shell. Here is an excerpt from my /etc/passwd:

dmisharo:x:1000:1000:Dmitry Misharov:/home/dmisharo:/usr/bin/zsh

Zsh doesn’t source /etc/profile, it sources zprofile instead. And here is the most interesting part. Unlike other popular Linux distributions Debian (and Ubuntu) supplies empty /etc/zsh/zprofile:

# /etc/zsh/zprofile: system-wide .zprofile file for zsh(1).
#
# This file is sourced only for login shells (i.e. shells
# invoked with "-" as the first character of argv[0], and
# shells invoked with the -l flag.)
#
# Global Order: zshenv, zprofile, zshrc, zlogin

Fedora 36:

#
# /etc/zprofile and ~/.zprofile are run for login shells
#

_src_etc_profile()
{
    #  Make /etc/profile happier, and have possible ~/.zshenv options like
    # NOMATCH ignored.
    #
    emulate -L ksh

    # source profile
    if [ -f /etc/profile ]; then
            source /etc/profile
    fi
}
_src_etc_profile

unset -f _src_etc_profile

Arch:

emulate sh -c 'source /etc/profile'

Debian developers intentionally do not source /etc/profile in zprofile:

We need to keep so-called login-shell always as Bash if you don’t want to drive yourself crazy. Adding workarounds for all possible choices of so-called POSIX shell is just waste of resource. If we make work around for zsh, then we need to do it for ksh, posh, …. POSIX is no magic word for shells to be treated as equal since there are subtle differences.

My solution

I ended up just copying Arch way and my zprofile sources /etc/profile via emulation.

References:

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