Adjusting a users groups

[meggin]

Hello,

Being a newbie to Gentoo I have made some mistakes with what users may access.

I can type groups username and see what the user can access but I don't understand some of the abreviations.

So can someone please tell me -

1/ Is there a site I can visit to read what each of the "access" abreviations allow access to?

2 / How does one go about amending a users access ?

thanks

[atreyu]

do you mean like the output from "ls -l"? e.g.:

-rw-r--r--  1 joebob users       4 Aug 21 18:19 myfile
drwxr-xr-x  2 joebob users    4096 Aug 19 17:27 foo

Here are a couple articles that describes linux permissions pretty well:

Linux Files and File Permissions

Linux file permissions

if that's not what you mean, then post what command you are running to get the output, and the output itself.

[meggin]

it seems I have not made myself clear
I type
@$ groups dragon
and get the response
root bin disk lp wheel uucp console audio cdrom usb users games scanner cron mysql kdm dragon
Now I do know what root, games, usb, cdrom
But what site can I visit to understand what the rest allow acess to?
And then how do I add and subtact from this list?

[atreyu]

it seems I have not made myself clear
I type
@$ groups dragon
and get the response
root bin disk lp wheel uucp console audio cdrom usb users games scanner cron mysql kdm dragon
Now I do know what root, games, usb, cdrom
But what site can I visit to understand what the rest allow acess to?

ah, yeah, misunderstood you.

Try this site for an explanation for some of those groups:

https://wiki.archlinux.org/index.php/Users_and_Groups

What you need to understand is how groups work. This can be explained in the links I gave you originally, but here is a simple example. Take this text file, "/tmp/foo.txt", which I will list using "ls -l /tmp/foo.txt":

-rw-rw-r--  1 joeblow admins 0 2012-08-30 00:51 /tmp/test.txt

in the above example, the permissions are divided into three categories: owner (red), group (blue), other (green). therefore, user "joeblow" has read and write perms, all users belonging to the group "admins" also have read and write perms, and anyone else (not joeblow and not in admins and not root) have only read access to the file.

Therefore, to know what membership in all those groups means might best be explained by knowing what files and directories are group-owned by that group.

you could do that with a find command, but it would output a bunch of stuff. here's an example:

#!/bin/bash
for group in users wheel lp uucp; do
  echo "Group $group:"
  find / -group $group 2>/dev/null
done

And then how do I add and subtact from this list?

you can use the usermod command. instead of deleting groups one by one, you'd just give it the new list of groups, including only the ones you really want the user in. here's an example:

usermod -g users -G wheel,usb joeblow

here, joeblow's main group is "users" and he's also been added to the groups "wheel", and "usb". read the man page for usermod for more details.

[meggin]

I was getting most irritated by not being able to find the information I wanted

thanks for your time and trouble