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Add Users to Groups: A Comprehensive Guide

Understanding User and Group Permissions

In Linux systems, users are organized into groups to assign permissions and manage access. Only root users or those with sudo privileges can add users to groups.

Adding an Existing User to a Group

To add an existing user to a secondary group, use the following syntax: ```Bash usermod -aG groupname username ``` For example: ```Bash usermod -aG developers alice ```

Adding Multiple Users to a Group Simultaneously

You can add multiple users to a group simultaneously by separating group names with commas: ```Bash usermod -aG developers,testers bob charlie ```

Adding a New User and Assigning Groups

If the user doesn't exist, use `useradd` to create it and assign groups: ```Bash useradd username usermod -aG groupname username ``` Example: ```Bash useradd john usermod -aG engineers john ```

Creating a New Group and Adding Users

To create a new group and add users: ```Bash groupadd groupname usermod -aG groupname username ``` Example: ```Bash groupadd designers usermod -aG designers sarah ```

Note: Remember to replace `groupname` and `username` with the actual group and user names you wish to use.

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