Adding user to the group:
`gpasswd -a <username> <group_name>`
Removing user from the group:
`gpasswd -d <username> <group_name>`
### See also
1. [[RHCSA]]
### Reference
1. [Red Hat Docs - Attaching Users to Groups](https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/html/deployment_guide/cl-tools-gpasswd)