groupadd

Dit deel is nog niet vertaald. Je ziet de Engelse tekst.

Wat het doet

Groups give the same rights to many users, for example write access to a shared folder. The groups are in /etc/group and /etc/gshadow. The GID comes from the range in /etc/login.defs (GID_MIN … GID_MAX) unless you give one.

groupmod renames a group or changes its GID. groupdel removes a group, but not if it is the primary group of a user.

Add members with usermod -aG GROUP USER or gpasswd -a USER GROUP.

Zo schrijf je het

groupadd [OPTION]... GROUP
groupmod [OPTION]... GROUP
groupdel [OPTION]... GROUP

Opties 17

Meest gebruikt

-g, --gid GID: Use this GID.
-r, --system: Create a system group (GID under 1000).
-f, --force: Exit with success if the group already exists (and pick another GID if -g is used).
-o, --non-unique: Allow a GID that is used already (with -g).
-U, --users USER1[,USER2...]: Add these users as members right away.
-K, --key KEY=VALUE: Override a value of /etc/login.defs (like GID_MIN).
-p, --password HASH: Set a hashed group password (not recommended).
-R, --root DIR: Work in this chroot folder.
-P, --prefix DIR: Use the files under this prefix folder.
-h, --help: Show help.

groupmod

-n, --new-name NEW_GROUP: Rename the group.
-g, --gid GID: Change the GID (files keep the old number; fix them with find).
-a, --append: With -U: add the users to the members (do not replace).
-U, --users USER1[,USER2...]: Set the member list.
-o, --non-unique: Allow a GID that is used already.
-p, --password HASH: Change the hashed group password.

groupdel

-f, --force: Delete the group even if it is the primary group of a user.

Voorbeelden 11

$ als gewone gebruiker# als root (of met sudo)

1Create a group
```
#groupadd webadmins
```
Gets the next free GID.
2Create a group with a fixed GID
```
#groupadd -g 3000 sales
```
Same GID on all servers for NFS shares.
3Create a system group for a service
```
#groupadd -r appsvc
```
GID under 1000.
4Create a group with members
```
#groupadd -U anna,bob projectx
```
Newer versions only; else use gpasswd -a.
5Rename a group
```
#groupmod -n web-admins webadmins
```
Members and files keep working: they use the GID.
6Change the GID and fix the files
```
#groupmod -g 3100 sales
#find / -xdev -gid 3000 -exec chgrp -h sales {} +
```
Files still have the old number until you change them.
7Delete a group
```
#groupdel projectx
```
Fails if it is the primary group of a user.
8Set up a shared team folder
```
#groupadd sales
#mkdir /srv/sales
#chgrp sales /srv/sales; chmod 2770 /srv/sales
```
2 = setgid: new files get the group sales (see the permissions chapter).
9Do not fail when the group exists (scripts)
```
#groupadd -f sales
```
Safe to run twice, for example in Ansible-like scripts.
10Check the group
```
$getent group sales
sales:x:3000:anna,bob
```
Name, password placeholder, GID, members.
11Find groups with no members (cleanup)
```
#awk -F: '$4 == "" && $3 >= 1000 {print $1}' /etc/group
```
Private groups of users are listed too; they are normal.

Let op

groupdel does not change files: they then show the old GID number.
A user gets new groups only after a new login.

Bestanden

/etc/group, /etc/gshadow: The group data.
/etc/login.defs: GID_MIN, GID_MAX, SYS_GID_MIN, SYS_GID_MAX.

Exitcodes

`0`	Done.
`2`	Wrong syntax.
`3`	Wrong value for an option.
`4`	The GID is used already.
`6`	The group does not exist (groupmod, groupdel).
`8`	Cannot delete the primary group of a user (groupdel).
`9`	The group name is used already.
`10`	Could not update the group file.

`groupadd`

Wat het doet

Zo schrijf je het

Opties 17

groupadd

groupmod

groupdel

Voorbeelden 11

1Create a group

2Create a group with a fixed GID

3Create a system group for a service

4Create a group with members

5Rename a group

6Change the GID and fix the files

7Delete a group

8Set up a shared team folder

9Do not fail when the group exists (scripts)

10Check the group

11Find groups with no members (cleanup)

Let op

Bestanden

Exitcodes

Volledige handleiding

groupadd

Wat het doet

Zo schrijf je het

Opties 17

groupadd

groupmod

groupdel

Voorbeelden 11

1Create a group

2Create a group with a fixed GID

3Create a system group for a service

4Create a group with members

5Rename a group

6Change the GID and fix the files

7Delete a group

8Set up a shared team folder

9Do not fail when the group exists (scripts)

10Check the group

11Find groups with no members (cleanup)

Let op

Bestanden

Exitcodes

Verwante commando's

Gebruikt in deze lessen

Gebruikt in deze labs

Volledige handleiding

`groupadd`