Linux Accounts & Groups (Users & Permissions) - Page

Introduction

Linux is a multi-user operating system. Multiple users can access the same machine while keeping their files, processes, and permissions isolated. This is achieved through user accounts, groups, and permissions.

These concepts are fundamental for Linux administration, cloud computing, and DevOps.

What is it?

A user is an identity that can log in and run processes.

A group is a collection of users that share common permissions.

Instead of assigning permissions individually to every user, Linux allows permissions to be assigned to groups, making administration much easier.

Why is it important?

Users and groups help:

• Secure systems
• Prevent unauthorized access
• Organize users
• Simplify permission management
• Support collaboration
• Enforce the Principle of Least Privilege

Every Linux server in production relies on users and groups.

How it Works

When a user logs in:

1. Linux verifies the username. Note: users are stored in /etc/passwd