Это работает 14.04. Обновленный вариант предыдущего IMO, правильный ответ Flimm.
sudo mkdir -p /etc/polkit-1/localauthority/50-local.d
sudoedit /etc/polkit-1/localauthority/50-local.d/allow_all_users_to_shutdown_reboot_suspend.pkla
Вставить это внутри:
[Allow all users to shutdown]
Identity=unix-user:*
Action=org.freedesktop.login1.power-off-multiple-sessions
ResultActive=yes
[Allow all users to reboot]
Identity=unix-user:*
Action=org.freedesktop.login1.reboot-multiple-sessions
ResultActive=yes
[Allow all users to suspend]
Identity=unix-user:*
Action=org.freedesktop.login1.suspend-multiple-sessions
ResultActive=yes
[Allow all users to ignore inhibit of shutdown]
Identity=unix-user:*
Action=org.freedesktop.login1.power-off-ignore-inhibit
ResultActive=yes
[Allow all users to ignore inhibit of reboot]
Identity=unix-user:*
Action=org.freedesktop.login1.reboot-ignore-inhibit
ResultActive=yes
[Allow all users to ignore inhibit of suspend]
Identity=unix-user:*
Action=org.freedesktop.login1.suspend-ignore-inhibit
ResultActive=yes