Book Image

Mastering Ubuntu Server - Second Edition

By : Jay LaCroix
Book Image

Mastering Ubuntu Server - Second Edition

By: Jay LaCroix

Overview of this book

Ubuntu Server has taken the data centers by storm. Whether you're deploying Ubuntu for a large-scale project or for a small office, it is a stable, customizable, and powerful Linux distribution that leads the way with innovative and cutting-edge features. For both simple and complex server deployments, Ubuntu's flexible nature can be easily adapted to meet to the needs of your organization. With this book as your guide, you will learn all about Ubuntu Server, from initial deployment to creating production-ready resources for your network. The book begins with the concept of user management, group management, and filesystem permissions. Continuing into managing storage volumes, you will learn how to format storage devices, utilize logical volume management, and monitor disk usage. Later, you will learn how to virtualize hosts and applications, which will cover setting up KVM/QEMU, as well as containerization with both Docker and LXD. As the book continues, you will learn how to automate configuration with Ansible, as well as take a look at writing scripts. Lastly, you will explore best practices and troubleshooting techniques when working with Ubuntu Server that are applicable to real-world scenarios. By the end of the book, you will be an expert Ubuntu Server administrator who is well-versed in its advanced concepts.
Table of Contents (21 chapters)

Understanding the /etc/passwd and /etc/shadow files

Now that we know how to create (and delete) user accounts on our server, we are well on our way to being able to manage our users. But where exactly is this information stored? We know that users store their personal files in /home, but is there some kind of database somewhere that keeps track of which user accounts are on our system? Actually, user account information is stored in two special text files:

  • /etc/passwd
  • /etc/shadow

You can display the contents of each of those two files with the following commands. Take note that any user can look at the contents of /etc/passwd, while only root has access to /etc/shadow:

cat /etc/passwd 
sudo cat /etc/shadow

Go ahead and take a look at these two files (just don't make any changes), and I will help you understand them. First, let's go over the /etc/passwd file. What follows...