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

Environment variables and shells


One thing that comes up a lot during system administration is the monitoring of several machines. It's not uncommon to have 5 or 6 ssh sessions open at a time, more if you have multiple monitors. It's crucial to know which session is running on which machine, as typing the right command on the wrong machine can be a disaster. For this reason and others, I recommend using a custom PS1 variable when logging into a remote machine.

This was mentioned in Chapter 1, Using the Terminal / Command Line, during the discussion of environment variables. The following is what my PS1 variable looks like on my machine running Fedora 17:

Big2 /temp/linuxbook/chapA # echo $PS1
Big2 \w #
Big2 /temp/linuxbook/chapA #

Simple, and not too cluttered. The following is what PS1 looks like on my other machine when I log into it:

BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 /temp # echo $PS1
BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 \w #
BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 BIG4 /temp #

It should be pretty hard to mix those up.

While we are on the subject of environment variables, there is something else to keep in mind. When you make a change to your .bashrc file and source it, the changes are only visible in that session (as well as any newly opened sessions). In order to see the change in other existing sessions you must source it in them as well. It would be rather cool if there was a way to make the changes visible in every session with just one command, however, I do not believe that is possible. Of course, one could argue that shutdown -r now will do it.