I'm not looking for shutdown or reboot or the like. I want to know how to shut down Xubuntu from the terminal, by executing a command that would have the same effect as clicking the "Shutdown" button in a menu.
Similar to this question, but for Xubuntu/XFCE.
I think what you want is xfce4-session-logout (online manpage).
Excerpt from the manpage (reformatted, filtered):
The xfce4-session-logout command allows you to programmatically logout
from your Xfce session. It requests the session manager to display the
logout confirmation screen, or, if given one of the command-line
options below, causes the session manager to take the requested action
immediately.
OPTIONS:
--logout Log out without displaying the logout dialog.
--halt Halt without displaing the logout dialog.
--reboot Reboot without displaying the logout dialog.
--suspend Suspend without displaying the logout dialog.
--hibernate Hibernate without displaying the logout dialog.
--fast Do a fast shutdown. This instructs the session manager not to
save the session, but instead to quit everything quickly.
So to shut down, use
xfce4-session-logout --halt
and to reboot, use
xfce4-session-logout --reboot
If you just want to get the dialogue where you can pick an action manually, run it without arguments:
xfce4-session-logout
