Group membership disappears with tmux

Question

I have a weird problem in that my user (on Linux Mint 18.3 Sylvia) is part of group docker, which I verify by starting a terminal:

$ groups
me adm cdrom sudo dip plugdev lpadmin sambashare docker

Now, when I fire up tmux, and run the same command, suddenly my docker membership disappears:

$ tmux
$ groups
me adm cdrom sudo dip plugdev lpadmin sambashare

The weird thing is, when I attempt to forcibly add my user to the group docker when in tmux, it says I'm already in it!

$ sudo adduser me docker
The user `me' is already a member of `docker'.

I'm stumped -- why would being in tmux make a difference? For reference, I use fish shell and this is my .tmux.conf:

$ cat ~/config/.tmux.conf 
new-session
set -g default-terminal "screen-256color"
set -g history-limit 10000
setw -g mode-keys vi
set-option -g default-shell /usr/bin/fish
set-option -g default-command /usr/bin/fish

EDIT

When I restarted my computer, everything worked again (both tmux and "normal" shells showed my docker membership). I'm still curious -- why did this happen?

Are you using the same version of groups in both shell environments? Have you tried using other commands to show group membership, such as the getent or id commands? — igal, Mar 15 '18 at 12:34
Your example shows you creating a new tmux session. Are you sure you didn't do tmux attach instead? — Andy Dalton, Mar 15 '18 at 14:12
@AndyDalton I don't think I did tmux attach, I just ran tmux and it's not aliased to anything as far as I can tell. — rxmnnxfpvg, Mar 15 '18 at 15:11
It seems to be duplicate of https://stackoverflow.com/questions/18673016/in-tmux-i-only-have-2-groups. — Kuldip Nanda, Aug 27 '19 at 11:51
Does this answer your question? I added a user to a group, but group permissions on files still have no effect — ilkkachu, Aug 18 '21 at 07:18
adduser just edits a file (the /etc/groups file. It does not add a process to a group. — ctrl-alt-delor, Nov 29 '21 at 17:30

score 3 · Answer 1 · answered Aug 18 '21 at 07:41

3

The most likely explanation for this is that the tmux session was started before you added your user to the docker group. Note that you can log out without terminating an active tmux session, but that this session would not be affected by changes in group memberships when you re-attach to it after logging in again later.

In your edit to the question you say that when you started a new tmux session (after a reboot), the user shows up as member of the docker group. This is expected as you now have a tmux session started from an environment where the group memberships had been altered.

answered Aug 18 '21 at 07:41

Kusalananda

333,661

yes try newgrp to create a new shell in the new group. – ctrl-alt-delor Nov 29 '21 at 17:31
for me tmux kill-session -t mysession and then tmux new -s mysession and tmux attach -t mysession didn't resolve the problem :( – Mona Jalal Dec 16 '21 at 00:10
@MonaJalal No, because you did not log out before starting a new tmux session. – Kusalananda Dec 16 '21 at 08:31

score 2 · Answer 2 · answered Nov 29 '21 at 16:11

2

I just had the same issue. I had to close all existing tmux sessions. After that, all new tmux sessions inherited the correct groups.

answered Nov 29 '21 at 16:11

schreon

121

this answer worked for me while https://unix.stackexchange.com/a/665147/72728 didn't – Mona Jalal Dec 16 '21 at 00:23

score 0 · Answer 3 · answered Jun 15 '23 at 11:11

0

You can delete your tmux session file:

rm /tmp/tmux-1000 # example for uid 1000

Then start a new session and see that you are a member of the group.

answered Jun 15 '23 at 11:11

owenthewizard

66

Loner · Answer 4 · 2023-10-13T07:58:03.887

0

Killing the tmux-server and then starting a new session fixed it for me.
tmux kill-server
tmux new -s ...
Also ensure you exit the current terminal session and start a new terminal after modifying a user/group for the changes to take effect.

edited Oct 13 '23 at 07:58

answered Oct 13 '23 at 07:55

Loner

1
1

Group membership disappears with tmux

4 Answers4