You have to log out and log back in after adding yourself to a group
Suppose you add yourself to a group with:
sudo usermod -aG examplegroup $USER
You might expect that you can immediately view all files with the new
permissions afforded to you by your membership in examplegroup. Alas, no.
Your group memberships are cached in your session. To see what groups you are
effectively a part of (for the current session) with:
id
To see what groups you're in globally (as stored in /etc/group), use:
groups $USER
You can "remove" yourself from a group with:
sudo gpasswd --delete $USER examplegroup
but you'll still have permissions associated with examplegroup (due to the session cache).
The easiest way to update your effective groups is to log out and log back in. If you want to make sure there aren't any processes around with the stale groups info, you can kill them all:
sudo pkill -u $USER
If you just added yourself to a new group, you can update your membership in that group with:
newgrp examplegroup
However, it has side-effects. It starts a new shell, and changes the current real group ID to the specified group, meaning any files you create will be associated with that group. So I think it's better to log out and log back in.
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Posted December 27, 2024.
Tags: #linux