Book Image

Linux Utilities Cookbook

By : James Kent Lewis
Book Image

Linux Utilities Cookbook

By: James Kent Lewis

Overview of this book

<p>Linux is a stable, reliable and extremely powerful operating system. It has been around for many years, however, most people still don't know what it can do and the ways it is superior to other operating systems. Many people want to get started with Linux for greater control and security, but getting started can be time consuming and complicated. <br /><br />A practical, hands-on guide that provides you with a number of clear step-by-step examples to help you solve many of the questions that crop up when using an operating system you may not be familiar with.</p> <p>Presenting solutions to the most common Linux problems in a clear and concise way, this helpful guide starts with spicing up the terminal sessions by command retrieval and line editing, and shell prompt variables. We will then get to know the different desktops (GUIs) available for Linux systems and which is the best fit for you. We will then explore the world of managing files and directories, connectivity, and what to do when it goes wrong. We will also learn a range of skills, from creating and managing user accounts to securing your system, managing and limiting processes, and letting information flow from one process to another using pipes. Later, we will master disk management, working with scripts and automating tasks quickly, and finally, understand the need for a custom kernel and tips on how to build one.</p> <p><br />Based on the author's extensive experience, there is a section on best practices that every Linux user should be familiar with.</p>
Table of Contents (19 chapters)
Linux Utilities Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Understanding processes


Every process has a unique identifier called a Process Identifier (PID). Also, every process has a Parent Process Identifier (PPID). There is an exception, init (or systemd). The init process starts all other processes and has a PID of 1. This process is special because it cannot be killed (and any attempt to do so is often fatal).

Similar to files, a process also has access permissions. These are referred to as the Real user and Group IDs. This provides a level of protection by not allowing unprivileged users to access critical operating system tasks. Memory, open files, and other resources are owned by the process and are kept separate from other processes (in most cases).

From the user’s perspective, a process is typically started from the command line or desktop. Take editing a file with vi, for example. The user starts the session and works interactively with the editor. He can save the file or edit another one. As long as the session is active, there is a PID...