xfce4-session -V (return code: 1)
xfce4-session: Cannot open display: .
Type 'xfce4-session --help' for usage.
xfce4-session --help (return code: 0)
Usage:
xfce4-session [OPTION?]
Help Options:
-h, --help Show help options
--help-all Show all help options
--help-gtk Show GTK+ Options
Application Options:
--disable-tcp Disable binding to TCP ports
-V, --version Print version information and exit
--display=DISPLAY X display to use