In this tutorial, we will explain how to add a user to a group in Linux systems. We will also show you how to remove a user from a group and how to create, delete, and list groups.
Linux groups are organization units that are used to organize and administer user accounts in Linux. The primary purpose of groups is to define a set of privileges such as reading, writing, or executing permission for a given resource that can be shared among the users within the group.
There are two types of groups in Linux operating systems:
- Primary group – When a user creates a file, the file’s group is set to the user’s primary group. Usually, the name of the group is the same as the name of the user. The information about the user’s primary group is stored in the
- Secondary or supplementary group - Useful when you want to grant certain file permissions to a set of users who are members of the group. For example, if you add a specific user to the
dockergroup, the user will inherit the access rights from the group, and be able to run docker commands.
Each user can belong to exactly one primary group and zero or more secondary groups.
Only root or users with
sudo access can add a user to a group.
How to Add an Existing User to a Group
To add an existing user to a secondary group, use the
usermod -a -G command followed the name of the group and the user:
sudo usermod -a -G groupname username
For example, to add the user
black to the
sudo group you would run the following command:
sudo usermod -a -G sudo black
Always use the
-a (append) option when adding a user to a new group. If you omit the
-a option, the user will be removed from any groups not listed after the
On success, the
usermod command does not display any output. It warns you only if the user or group doesn’t exist.
How to Add an Existing User to Multiple Groups in One Command
If you want to add an existing user to multiple secondary groups in one command, use the
usermod command followed by the
-G option name of the group separated by
sudo usermod -a -G group1,group2 username
How to Remove a User From a Group
To remove a user from a group, use the
gpasswd command wit the
In the following example we are removing the user
username from the group
sudo gpasswd -d username groupname
How to Create a Group
To create a new group, use the
groupadd command followed by the group name:
sudo groupadd groupname
How to Delete a Group
To delete an existing group, use the
groupdel command followed by the group name:
sudo groupdel groupname
How to Change a User’s Primary Group
To change a user primary group, use the
usermod command followed by the
sudo usermod -g groupname username
In the following example, we are changing the primary group of the user
sudo usermod -g developers black
How to Create a New User and Assign Groups in One Command
useradd command creates a new user named
nathan with primary group
users and secondary groups wheel and developers.
sudo useradd -g users -G wheel,developers nathan
Display User Groups
To display complete user information including all the groups of which a user is a member of, use the
id command followed by the username:
If you omit the username, the command will print the information about the currently logged in user. Let’s check the user
uid=1000(black) gid=100(users) groups=100(users),10(wheel),95(storage),98(power),990(libvirt),993(docker),999(kvm)
From the output above, we see that the primary group of the user is
users and it belongs to
kvm supplementary groups.
groups command to display the user’s supplementary groups:
wheel storage power users libvirt docker kvm
If no username is passed to the
groups command, it will print the currently logged in user’s groups.
In this tutorial, we have shown you how to add a user to a group.
The same commands apply for any Linux distribution, including Ubuntu, CentOS, RHEL, Debian, and Linux Mint.
Feel free to leave a comment if you have any questions.