How To Add User To Group.
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.
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 liviu to the sudo group, you would run the following command:
sudo usermod -a -G sudo liviu
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 -G option.
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 , (commas):
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 -d option.
In the following example, we are removing the user username from the group groupname:
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 -g option:
sudo usermod -g groupname username
In the following example, we are changing the primary group of the user liviu to developers:
sudo usermod -g developers liviu
How to Create a New User and Assign Groups in One Command
The following 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:
id username
If you omit the username, the command will print the information about the currently logged-in user. Let’s check the user liviu:
id liviu
uid=0(root) gid=0(root) groups=0(root)
From the output above, we see that the primary group of the user is users and it belongs to wheel, storage, libvirt, docker, and kvm supplementary groups.
Use the groups command to display the user’s supplementary groups:
groups liviu
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.
Conclusion
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,
