For the logout :
/usr/lib/indicator-session/gtk-logout-helper --logout prompts the logout applet and clicking on Logout ends the sessions and gets you back to the Lightdm greeter.
Same behavior when you click on Logout button from the user system button.
For the logout : indicator- session/ gtk-logout- helper --logout prompts the logout applet and clicking on Logout ends the sessions and gets you back to the Lightdm greeter.
/usr/lib/
Same behavior when you click on Logout button from the user system button.