02. Creating and Modifying Groups

Creating a Group

To create a group, use the groupadd command.

$ groupadd family
-g
Specify group id (else, system will make one for you).
-f
Force create a group, even if it already exists.
-n
Change name of the group.
-o
Allow duplicate groupnames to be created.
-r
Create a system group ID (gid < 500).

Notice that there's an option to set the group ID to less than 500 with the -r option. All group ID's in this range are known a system processes and not real user-populated groups. You may check all current groups within the /etc/group file, which we'll go over in detail shortly.

Modifying a Group

To modify a group, use the groupmod command. Let's try renaming our family group to cousins.

$ groupmod -n cousins family

Deleting groups

To delete a group, simply use the groupdel command.

$ groupdel cousins

Here's some extra practice for using the above commands and options.

$ groupadd developers
# Check to see that the new group has been added
$ cat /etc/group
# Let's say we have a group with GID 1010 already
$ groupadd -g 1010 developers
# This should error out. Now let's allow duplicates
$ groupmod -o -g 1040 developers
# Rename 
$ groupmod -n cool-kids developers

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