Discrepancies in `groups` output

Question

why is it that when I execute groups the output doesn't contain the adm group, while the output of groups $USER has it? The user is supposed to be in that group.

Answer 1

If you have just added a user to a group, you will need a log out and log back in in order to acquire the new credentials. For example:

$ id
uid=500(lars) gid=500(lars) 
$ groups
lars
$ sudo usermod -G wheel,libvirt,mock lars
$ groups
lars
$ groups lars
lars : lars wheel libvirt mock

And if I log out and log back in:

$ groups
lars wheel libvirt mock