First, thanks for informing about "su -" needed for /sbin commands to be used rather than just "su", indeed it fixed my problem.
So after installing the daily image,tasksel, selected "Debian Desktop environment", "dpkg-reconfigure x11-common xserver-xorg-legacy" as described in https://www.debian.org/ports/hurd/hurd-install , startx, left-clicking lower-right icon of a folder, choosing "Open in Terminal" in the menu, I get a popup window that say: Failed to execute child process "bash": Failed to fdwalk: Too many open files in the system. Searching the web for similar message have revealed: https://gitlab.gnome.org/GNOME/vte/-/issues/296 ... but since it is for Gnome rather than XFCE... I don't know if it apply. Also reading the man page for https://docs.oracle.com/cd/E19683-01/816-0213/6m6ne37ud/index.html I am learning first that fdwalk allows to call a function for all open file descriptors... that it is link to /proc/self/fd which does not seems to exist in Hurd Debian. But since bash run in "normal" console but not in Xorg... I kind of suspect it is probably more linked to rlimit setting in Xorg. I guess I should write a function in C to use fdwalk, and see if I can get it to run in normal console, than in Xorg... but it feels hard work to me.
