mjhjmtu

I'm reposting Gnome Session Doesn't Start on Remote X Server, here, because I believe it's a Gnome question, not just an Ubuntu one.

I have an Ubuntu host, which I reach via ssh -Y. The client is my macOS laptop, running XQuartz. I can do xclock or other X apps from the host and see them on my laptop. What I cannot run is gnome-session, which, as far as I understand, should be the whole thing that comes up when I login to the machine from the local console. DISPLAY is correctly set, but seems to be ignored.

Passing --display="$DISPLAY" to gnome-session yields:

** (gnome-session-binary:5943): WARNING **: Unknown option --display=localhost:10.0

Indeed, my manpage for gnome-session doesn't mention --display, while manpages around Internet do. So, I guess, it was removed at some point, do I still have a way to do it?

I've also discovered that other gnome applications (e.g., gnome-software) have a --display option, but they ignore it and the application runs on the console desktop, rather than on my laptop.

I've also discovered that other gnome applications (e.g., gnome-software) have a --display option, but they ignore it and the application runs on the console desktop, rather than on my laptop.

I assume you are running Gnome 3 on the server, too, not only per SSH? I assume it runs as a wayland session. The Gnome apps may use WAYLAND_DISPLAY instead of DISPLAY. Check XDG_SESSION_TYPE. If it is set to wayland, Gnome apps will use the wayland display instead of your SSH display.
Try to run them with XDG_SESSION_TYPE=x11.

Indeed, my manpage for gnome-session doesn't mention --display, while manpages around Internet do. So, I guess, it was removed at some point, do I still have a way to do it?

gnome-session should regard DISPLAY, you don't need --display. However, gnome-shell has option --display.

What I cannot run is gnome-session

I found that gnome-session and libmutter often have segfaults if not running with native display hardware. Check dmesg on your server.

Maybe you can run env XDG_SESSION_TYPE=x11 gnome-session, but I suspect it will segfault, too. Also, you can try gnome-shell instead of gnome-session.

I recommend to use another and more lightweight desktop environment for SSH, for example lxde (lxsession) or xfce (startxfce4), or just a window manager like openbox (openbox --sm-disable).