When I add myself "vboxusers" group I an no longer in the "admins" group

Solution 1:

Your second command is right.

By default, usermod -G replaces all supplementary groups the user is in (the primary group is generally named the same as your username, and specified separately; don't mess with that though). By also using -a it appends the groups you give.

So this should work (and does, for me, just tried it):

usermod -aG vboxusers myusername

If running that command takes you out of any other group then you've found a bug. Note you have to relogin to see the effects.

Solution 2:

Alternatively:

gpasswd --add myusername vboxusers

Solution 3:

According to the usermod man page the correct command to add a user to a group is

sudo usermod -G group -a username

or in your case since you want to add your self to the vboxusers group that will be

sudo usermod -G vboxusers -a $USER

Solution 4:

Never use the top method to add a user to vboxusers by using the usermod -G vboxusers myusername command. This will make you lose your sudo privileges!

If you have lost your sudo privileges, you can use the method described here to recover them. It boils down to executing the following command:

usermod -G adm,cdrom,sudo,dip,plugdev,lpadmin,guoshicheng,vboxusers myusername