What is a Primary Group?

How to change the primary group of a user in Linux?

In Linux, every user is associated with a primary group. The primary group is a fundamental concept in Unix-like operating systems, including Linux, and it determines the initial group ownership of files created by the user. When a user creates a file, it is owned by the user’s primary group by default. Each user is a member of one primary group specified in the user’s entry in the /etc/passwd file. The primary group is important because it dictates the default group ownership of files and directories created by the user.

Difference Between Primary Group vs Secondary Group

Basic	Primary Group	Secondary Group
Definition	The major group to which a user belongs is known as the primary group. There is exactly one main group for each user.	In addition to the primary group, a user may also belong to other groups known as secondary groups. Users may be a part of several secondary groupings.
Default Group Ownership	By default, the user’s primary group owns any files and directories that are created by the user.	The ownership of files and folders by default is unaffected by secondary groups.
Group Permissions	Establishes the initial group permissions for the user’s generated files and folders.	Secondary groups don’t affect permissions in that way. The user’s default group and specific file permissions regulate permissions.
Changing Groups	Users can change their primary group using the usermod command.	Users can add themselves to secondary groups using the usermod or useradd commands.
In /etc/passwd	Specified in the user’s entry in the /etc/passwd file under the group ID (GID) field.	secondary group information is stored in the /etc/group file.
File Creation	The default ownership setting for files and folders created by the user is the primary group.	Secondary groups do not affect the user-created files’ default ownership.
Purpose	designed to specify the user’s primary affiliation and is frequently applied to collaborative project work.	used to grant specific permissions or access rights over and beyond what the main group offers.
Examples	A primary group named “users” for all regular users	Secondary groups like “wheel” for administrative access or “audio” for sound-related permissions.

How to Change The Primary Group of a User in Linux?

In the field of Linux system administration, learning the modification of the primary group is essential. In this article, we are going to deliver concise details about user groups and how to manage them.