$ cat -net /etc/group | tail -n 3 67 vboxusers:x:127:hannu$ 68 nvidia-persistenced:x:128:$ 69 $ $
a) With the lines as shown I get the profiling (System Settings > Color > Calibrate) for the MAIN DISPLAY ONLY (I have four of them! i.e. not full functionality) loaded as I log in. The group on line 68 is vital for xorg-edgers nvidia driver (nvidia-337 and nvidia-settings installed)
b) if I swap lines 67 and 68 I WILL NOT get to access USB devices in Virtualbox 4.3 (.12 has a remedied "Shared cliboard" compared to 4.3.10 - which is availble in U.S.C. - I have tried both).
From this I conclude that the LAST line in the /etc/groups file isn't read / used as it should. The empty line (#69) doesn't matter as it seems to me.
$ groups --version groups (GNU coreutils) 8.21 Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later . This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Written by David MacKenzie and James Youngman.