Question

3

Why can you add a user to a group with usermod, but you cant remove a user from a group with usermod?

rated 0 times [ 3] [ 0] / answers: 1 / hits: 581 / 2 Years ago, sat, april 30, 2022, 9:14:44

Uhy can you add a user to a group with usermod, but you cant remove a user from a group with usermod? Am I wrong?

I got a user I want to remove from the sudo group. I put this user in with usermod, now I have to use deluser to remove the user from the group?

On a test box, I ran sudo usermod -G "" user (bad advice form some thread I read) which removed all the groups, glad I didn't run that on the server.

From the man page, I see a -W option that mentions removing a list of gids. Are gids groups?

Answers

Only authorized users can answer the question. Please sign in first, or register a free account.

mentpengu

Add To Favorites

Follow

Total Points: 148

Total Questions: 114

Total Answers: 119

Location: Anguilla

Member since Sun, Aug 7, 2022

2 Years ago

mentpengu questions

1 Mounting "/run" as noexec

Sun, Apr 17, 22, 18:09, 2 Years ago

1 Duplicate mount-points for external disks after 22.04.1 upgrade

Tue, Dec 20, 22, 04:48, 1 Year ago

1 Set default visible columns for Files

Fri, Aug 12, 22, 01:35, 2 Years ago

1 Ubuntu 20.04 Dell XPS Laptop Audio not working

Tue, Jul 26, 22, 14:52, 2 Years ago

1 Color picker doesn't work

Wed, Jun 30, 21, 02:28, 3 Years ago

View All

answered 2 Years ago afisird · Accepted Answer

Although I wouldn't necessarily recommend it, you can in fact remove a user from a supplementary group with usermod - by passing a list of groups to keep to the -G command. From man usermod:

   -G, --groups GROUP1[,GROUP2,...[,GROUPN]]]

       .

       .

       .



       If the user is currently a member of a group which is not listed,

       the user will be removed from the group. This behaviour can be

       changed via the -a option, which appends the user to the current

       supplementary group list.

Ex.

$ id testuser

uid=1001(testuser) gid=1001(testuser) groups=1001(testuser),27(sudo),33(www-data),100(users)



$ sudo usermod -G users,www-data testuser



$ id testuser

uid=1001(testuser) gid=1001(testuser) groups=1001(testuser),33(www-data),100(users)