set or pass through DESKTOP_SESSION?

[markstos]

I've researched the DESKTOP_SESSION variable some but am not sure who usually sets. It shows up in recipes like this for starting gnome-keyring-daemon:

if [ -n "$DESKTOP_SESSION" ];then
    eval $(gnome-keyring-daemon --start)
    export SSH_AUTH_SOCK
fi

I think forSway, I think DESKTOP_SESSION is usually set to sway. Should sway-systemd set DESKTO_SESSION or pass it through?

[alebastr]

That's something usually set by a DM - GDM, LightDM or SDDM (but not greetd or ly). Here's the list of variables for desktop detection that I'm aware of:

• DESKTOP_SESSION non-standard, set by a DM to the name of a session file sans extension - sway
• GDMSESSION - non-standard, same value as above, appears to be set by all the DMs that support DESKTOP_SESSION
• XDG_SESSION_DESKTOP - documented in systemd, different DMs will use different values, but none will follow the spec and give you what you expect
• XDG_CURRENT_DESKTOP - part of a Freedesktop specification, recommended for use to detect a desktop session type, all DMs agree to read the value from DesktopNames key in the session file (which is intentionally omitted from sway.desktop and results in an empty variable)

Apparently, DESKTOP_SESSION is also supposed to be obsoleted by the XDG_SESSION_DESKTOP, but in a wonderful mess of undocumented XDG-but-not-really variables I can't even find a reliable source for that :weary:

I think I'll add a conditional pass through (only if set) for DESKTOP_SESSION as the working one and XDG_SESSION_DESKTOP as the standard one. But I really hope that nothing important relies on these variables.

Edit: Both systemd import-environment and dbus-update-activation-environment are ignoring unset variables, so was safe to add the vars into the VARIABLES list without any checks.