How to Add a User to a Group in Linux

In Linux, groups are small subsets of the larger user population who have access to a set of files. Groups can also be used to indicate which users can execute certain commands. A single user must be a member of one primary group, but can also be a member of one or several secondary groups.
The usermod command is used to change or modify the system account of an existing user, including changing a user's primary group and adding the user to secondary groups.

Things You'll Need

• Linux Root Privileges

Instructions

Instructions

1. Open a terminal window.
   The terminal window will be found under Application-> Utilities (GNOME) or Start-> Utilities (KDE).

2. Switch to root.
   su
   You must have administrator privileges to change or add user groups.

3. Add the user to the group. The usermod command has the following syntax to add a user to a group:
   usermod -aG group user
   For example, if you wanted to add "mary" to the "Others" group, the command would be:
   usermod -aG Others mary
   You must execute this command for each user you wish to add to the group.

4. Exit from the root session by typing "exit".

Tips & Warnings

• The usermod command has two options for adding users to groups. The "-g" option changes the user's primary group. The "-G" option adds users to secondary groups. With the "-G" option, more than one group can be specified by placing a comma (,) between the group names.

• If you do not specify the "-a" (append) option with "-G", the user will be removed from all secondary groups except the groups listed.