add group without logout
# Horribly hacky, but you could use two layers of newgrp to achieve this for a particular group: id -g # ...will give you the current primary group ID. We'll call this orig_group for the purposes of this example. Then: newgrp <new group name> # ...will switch you to that group as the primary and add it to the list of groups returned by groups or id -G. Now, a further: newgrp <orig_group> # ...will get you a shell in which you can see the new group and the primary is the original one. # This is horrible and will only get you one group added at a time, but it has helped me out a couple of times to get groups added without logging out/in my whole X session (e.g. to get fuse added as a group to a user so that sshfs will work). # Edit : This doesn't require you to type your password either, which su will.