O que você tem no meu sistema.
user:~$ groups test;
test : test
user:~$ groups
user adm cdrom sudo dip www-data plugdev lpadmin sambashare davfs2 wireshark
user:~$ sudo usermod -a -G $(id -Gn | tr " " ",") test
user:~$ groups test
test : test adm cdrom sudo dip www-data plugdev lpadmin user sambashare davfs2 wireshark