Hi,

> in Ubuntu defaults are in X11/Xsession.d/60x11-common_xdg_path
> which is shipped by x11-common and sourced by XSession
>
> BTW there is some XDG_* env setting also in X11/Xsession.d/00upstart

Ok, now if only we knew what to actually use as a default for
XDG_RUNTIME_DIR; it is a per-user setting, and defining the
prefix to be /tmp/run is not enough.

Come to think of it, my choice of

    ${XDG_RUNTIME_DIR:-/tmp/run/$USER}

is no good, because, just as an example, if $USER comes from
an AD domain or LDAP it might contain '\'; in the least,
$USER had to undergo some transformation (escaping?) to ensure
that it's filesystem-safe.

No wonder XDG issues no default value, and it all disappears
into implementation code, it's a potato of above-average warmth
- makes me feel sorry i brought it up in the first place :-D

Kind regards,
T.