Understanding users and groups is essential for becoming an effective Linux user.
How to assign a user to a group
Assigning a user to an existing group. first you can see which groups the user is part of
For example the root user is part of the root group
root : root
To add a user to an excising group
usermod -a -G <group name> <user name>
How to create a new group
To add a new group in Linux use the “groupadd” command. Note: adding groups requires root privileges.
sudo groupadd GroupName