Reload a Linux user's group assignments without logging out

Solution 1:

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_name>

...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).

Notes:

• This doesn't require you to type your password either, which su will

• Each call to newgrp launches a new shell (as a child of the current shell)

• The current shell can be "replaced" with the exec command

  exec newgrp <new_group_name>
  

• Using exec will resolve the caching issue for the current branch of the pstree

  I.e. if you are logged in to a window manager, every new terminal you launch will be a child of an earlier branch than the one "corrected" by this exercise and will therefore inherit the cached gid map.

Solution 2:

From inside a shell, you can issue the following command

su - $USER

id will now list the new group:

id