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

Redirection and piping


Suppose you run a command, say route, and want to save the output in a file. The redirection (>) operator is used to do this instead of sending the output to the screen.

How to do it...

Let's try some redirection:

  1. Enter ifconfig > file1.txt. You won't see anything, because the output went into the file.

  2. Run cat file1.txt. You should now see the output.

  3. This works the other direction as well, to read from a file run the following command:

    sort < file1.txt
    
  4. You can even do both in one step:

    sort < file1.txt > output-file.txt
    
  5. You can also send the output to another command using the pipe operator. For example, run route | grep eth0. The above command would display only the lines from route that contain the phrase eth0.

There's more...

Here is something that I use all the time. Say I have written a program in C a long time ago, have several versions, and want to find the latest one. I could run locate to find them all:

locate crc.c

This might return quite a few lines. How can I run ls on each file to find the latest one? By piping the output into the xargs command and then ls:

locate crc.c | xargs ls -la

This will now show the time and date of each file.

This might seem a bit complicated at first, but if you experiment a little it will become second nature to you.