xfce4-display-settings -V (return code: 1)
xfce4-display-settings: Cannot open display: .
Type 'xfce4-display-settings --help' for usage.
xfce4-display-settings --help (return code: 0)
Usage:
xfce4-display-settings [OPTION?]
Help Options:
-h, --help Show help options
--help-all Show all help options
--help-gtk Show GTK+ Options
Application Options:
-s, --socket-id=SOCKET ID Settings manager socket
-v, --version Version information
-m, --minimal Minimal interface to set up an external output
--display=DISPLAY X display to use