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I'm using Ubuntu 16.04. When I use LightDM to login and start X, I see that my secondary groups aren't loaded (running "groups" reports that I belong only to my primary group). If I log in via console or if I su in a term in X, the groups command works normally, reporting my primary and all of my secondary groups.

Curiously, even though "groups" does not report that I'm a member of sudoers, I can still sudo. Similarly, I can run mythfrontend, even though I'm not reportedly a member of mythtv. It seems as if the OS recognizes my secondary groups, even if the groups command does not.

So, it doesn't seem to cause a real problem, but I'm curious if anyone else has seen this behavior. I have three other machines running Ubuntu 16.04, but groups works normally on each of them.

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    what does id show? – ivanivan Jul 11 '18 at 1:59
  • id also reports that I am a member of my primary group and no other. – Jesse Hughes Jul 11 '18 at 2:11
  • Are you saying that your user isn't in the /etc/sudoers file? Also if you reboot the system it still reports the same way? Please post your /etc/nsswitch.conf as well. Specifically we want to see the group: ... line. – slm♦ Jul 11 '18 at 3:33
  • My user is a member of the group sudo, which has access to all commands, per the default Ubuntu sudoers file. But this problem isn't about sudo, really. To test it out, I created a new user and added him to a test group. When I logged in as that user, "groups" reported only his primary group, not the test (secondary) group. When I su'ed to the same user, his test group was listed under "groups". – Jesse Hughes Jul 11 '18 at 11:55
  • nsswitch.conf found <a href="phiwumbda.org/~jesse/tmp/nsswitch.conf">here</a>. – Jesse Hughes Jul 11 '18 at 11:59
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I've got my exact problem fixed, thanks to the defect reported here https://bugzilla.redhat.com/show_bug.cgi?id=1581495

I had errors logged into the /var/log/auth.log which made me suspect problems around this.

These Ubuntu package was updated yesterday, libpam-kwallet4:amd64 (4:5.5.5-0ubuntu1.2, 4:5.5.5-0ubuntu1.3), libpam-kwallet5:amd64 (4:5.5.5-0ubuntu1.2, 4:5.5.5-0ubuntu1.3) and this must have caused the trouble. I just commented out the following lines in /etc/pam.d/lightdm

auth    optional        pam_kwallet.so
auth    optional        pam_kwallet5.so

and a reboot saved my day

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  • I wouldn't mind understanding what those lines were supposed to do, mind you. I've a very meager understanding of pam. – Jesse Hughes Jul 11 '18 at 20:09
  • @JesseHughes - It was supposed to get my KDE wallet unlocked automatically. It doesn't happen anymore, but that's okay. It pops up a prompt for me once I log in. – roby Jul 17 '18 at 12:46

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