usermod

[Steve Buehler]

At 08:50 AM 3/30/2005, McDougall, Marshall (FSH) wrote:
>> >>I know you can use "usermod" on RedHat Linux to add a user to another
>>group
>> >>by typing:
>> >>usermod -G sam,frank steve
>> >>This would effectively add steve to the "frank" and "sam" group.  How do
>> >>you remove them from those groups without editing the /etc/group file
>> >>manually?  I can do:
>> >>usermod -G steve steve
>> >>That will remove him from "sam" and "frank" groups but would add steve to
>> >>his own group so the /etc/group file would look like:
>> >>steve:x:590:steve
>> >>instead of just:
>> >>steve:x:590:
>> >>For the life of me, I can't figure this one out.  Does anybody know?
>>
>> >If you "usermod -G sam,frank steve" and realize that you shouldn't have put
>> >steve in the frank group, just "usermod -G sam steve" and by omission, will
>> >remove the user from the group.  HTH
>>
>>Yes, but what if I want to remove him from both groups.  You can't type
>>"usermod -G steve".  Basically, I am wanting to remove him from ALL groups
>>except for his initial group.  And "usermod -g steve steve" will not do it
>>either.  The "-G" must have atleast one group as an
>>option..................................I just tried something that seems
>>to work, but not sure if it is suppose to work this way.  I typed:
>>usermod -G "" steve
>>and that removed steve from all extra groups.  So either my problem is
>>solved, or there is another "proper" way of doing it.
>
>"usermod -Gsteve steve" should remove him from all groups except steve.  If
>the group is in the list, then the user is added to the group.  If the group
>is not in the list, then the user is removed from any groups not in the
>list.  This is the way I go about it.  We all know that with *nix, there is
>always more than 1 way to accomplish it.

I know it shouldn't hurt to do that, but if you do, it actually adds steve 
to his own group again.  So instead of the line in the /etc/group file 
looking like the following which is how it should look if they are not in 
any other group:
steve:x:590:
it would then look like the following if you run "usermod -Gsteve steve":
steve:x:590:steve

Thanks
Steve