PaulDavisThe1st 5 days ago

Sorry, but systemd has absolutely nothing, or even less than nothing to do with user-space GUI desktop applications.

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  • dTal 4 days ago

    Ah, if only! GNOME and even to an extent KDE both depend on systemd components, to the point that systemd-free distros are compelled to fork it if they want a GUI: https://wiki.gentoo.org/wiki/Elogind

    Only yesterday I was wondering how it is that my brightness keys work in my desktop environment, when /sys/class/backlight/intel_backlight/brightness is only writeable by root. The (somewhat horrifying) answer is that applications can send a request to logind over DBUS, which checks the request against opaque and arbitrarily byzantine Polkit rules, and then writes to the sysfs file on the application's behalf, which it can do because it runs as root. It's unclear quite what this achieves that simply making the file writeable by the "video" group does not, but hey at least systemd gets to be involved.

    Incidentally, the correct command to change the brightness as a normal user from the command line is as follows:

      busctl  --timeout=1 call org.freedesktop.login1 /org/freedesktop/login1/session/self org.freedesktop.login1.Session SetBrightness ssu "backlight" "intel_backlight" <brightness>
    So simple, so easy to remember, so superior to "echo <brightness> > /sys/class/backlight/intel_backlight/brightness". Google it for a fun thread on why the --timeout=1 is neccessary (it won't work without it!) - although I suppose I should be thankful for that little foible, as without it the thread wouldn't exist and I would never have figured out the command in the first place.
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    • PaulDavisThe1st 4 days ago

      As noted by others below, this has nothing to do with GUI desktop applications.

      Sure, systemd is involved in running the system on which those applications run, but the discussion was about some sort of equivalent to the unified GUI stack offered by macOS (the Core* frameworks) which are used by essentially every GUI application on that platform. Linux doesn't have that, and there's nobody in a position to force that on developers. systemd has nothing to do with this.

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  • eptcyka 5 days ago

    Systemd runs each userspace desktop application in it's own control group.

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    • jcgl 4 days ago

      Not exactly. Desktop environments (or whatever the program is that launches the application) decides to use systemd to run each application in its own cgroup.

      Systemd is certainly relevant to the Linux desktop as a whole, especially regarding logind. But there's no specific relation to GUI desktop applications that I'm aware of at least.

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    • gf000 5 days ago

      No it doesn't. It could, but as far as I know this is not used at all.

      There are user services, but that's a separate concept.

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