mike@acer64:~$ sudo adduser test
[sudo] password for mike:
Adding user `test' ...
Adding new group `test' (1001) ...
Adding new user `test' (1001) with group `test' ...
Creating home directory `/home/test' ...
Copying files from `/etc/skel' ...
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for test
Enter the new value, or press ENTER for the default
        Full Name []: test
        Room Number []:
        Work Phone []:
        Home Phone []:
        Other []:
Is the information correct? [Y/n] y
mike@acer64:~$ sudo grep test /etc/group
test:x:1001:
mike@acer64:~$ su -l test
Password:
test@acer64:~$ groups
test
test@acer64:~$