Reload a Linux user's group assignments without logging out

From inside a shell, you can issue the following command

su - $USER

id will now list the new group:

id

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.

This nifty trick from this link works great!

exec su -l $USER

I figured I'd post it here as every time I forget how to do this, this is the first link that come up in google.