Usermod and history output

Question

I used usermod -G without the -a option, now the main user has only 2 groups. I want to restore all the previous groups but the problem is that i need to list all the groups before the changes

I am trying to use

locate /etc/groups

and grep username in the previous version of the file to get all the previous group

How can I access to the file from the db and read them ?

Possible duplicate of [Default groups for user in Ubuntu?](https://askubuntu.com/questions/219083/default-groups-for-user-in-ubuntu) — muru, May 15 '18 at 15:46
And you'll probably need https://askubuntu.com/q/70442/158442 as well to get back your lost sudo rights. — muru, May 15 '18 at 15:46
Possible duplicate of [How do I add myself back as a sudo user?](https://askubuntu.com/questions/70442/how-do-i-add-myself-back-as-a-sudo-user) — karel, May 15 '18 at 21:03

score 1 · Accepted Answer · answered May 15 '18 at 16:04

There is no /etc/groups. There's /etc/group and /etc/group- (the backup). To get results for your user from the backup, you can do:

grep username /etc/group-

Or, to get just the groups, using awk:

awk -F: -v u=username '$NF ~ u {print $1}' /etc/group-

To then add those groups back, as root:

awk -F: -v u=username '$NF ~ u {print $1}' /etc/group- |
  xargs -n1 gpasswd -a username

Usermod and history output

1 Answers1