Usermod

carlosinfl · 09-14-2006, 12:04 PM

Yesterday my user name "carlwill" was a part of 2 groups on this server (RHEL4).

"ctia" & "wheel"

I created a new group on the server called "ctia_admin" with specific read/write access to folders.

I then gave the following command:

Code:

#usermod -G ctia_admin cwilliams

Now I am no longer a member of wheel. I am now a member of ctia & ctia_admin. Why did this command not add a 3rd group rather than replace my wheel group. I could not for the life of me understand why I no longer had sudo access.

I did "man" the usermod page and am still confused.

Thanks!

mcmillan · 09-14-2006, 03:17 PM

usermod -G changes the groups so your only part of the groups you specify. A better command to use is adduser <name> <group>

carlosinfl · 09-14-2006, 03:24 PM

Quote:

Originally Posted by mcmillan

A better command to use is adduser <name> <group>

I am not sure if "adduser" would be good considering the user already exist on the system. I would just be modifying their groups and not adding an entire new person to the system unless I am misunderstanding you...

mcmillan · 09-14-2006, 04:35 PM

Sorry about that. I knew there was a different command from usermod that doesn't remove all the preexisting groups, but I gave the wrong one. gpasswd was the one I was thinking of. It's used gpasswd -a <user> <group>

fudam · 09-14-2006, 06:53 PM

Or quite simply edit /etc/group as root. Much easier to remember and manage IMO.

JrLz · 09-14-2006, 08:23 PM

Quote:

Originally Posted by man usermod

-G group,[...]
A list of supplementary groups which the user is also a member
of. Each group is separated from the next by a comma, with no
intervening whitespace. The groups are subject to the same
restrictions as the group given with the -g option. If the
user is currently a member of a group which is not listed, the
user will be removed from the group

you need to list all of the groups(wheel,ctia,etc) for that user in usermod -G parameters, and put the user's initial group with -g parameter

carlosinfl · 09-15-2006, 07:32 AM

So just to avoid confusion, can you post an example of how this scenario would look.

User = Jim
Group(s) = ctia wheel

Jim needs to also be a member of admin so in total Jim will be a member of ctia wheel admin

How would this command look?

mcmillan · 09-15-2006, 01:26 PM

To use usermod -G ctia_admin,wheel,ctia cwilliams

gpasswd would be gpasswd -a cwilliams ctia_admin for what you originally wanted, just adding the group. Since now you're just missing wheel it would be gpasswd -a cwilliams wheel.

As for directly editing the files, I don't remember the syntax and I'm currently on windows and trying to figure out how to get my wireless working on Linux so I'm not much help right now.

JrLz · 09-19-2006, 08:26 PM

Quote:

Originally Posted by Carlwill

So just to avoid confusion, can you post an example of how this scenario would look.

User = Jim
Group(s) = ctia wheel

Jim needs to also be a member of admin so in total Jim will be a member of ctia wheel admin

How would this command look?

usermod -g admin -G admin,ctia,wheel Jim
with admin as the initial group, ctia and wheel supplementary groups
Jim will be a member of admin,ctia and wheel
you can check it by using id command, or groups command (as Jim)

files to edit are /etc/passwd(note the GID there) and /etc/group