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

Examining processes using top


The top program is similar to ps except that it shows the state of the system in real time. You can control how it operates using command line switches and/or its interactive interface. It can also use a configuration file. You can do quite a bit with top. The following are some examples of what is possible.

Getting ready

No special setup is needed. These commands will be run as root.

To get help for top, you can run the following command line:

      top -h or -v

These are equivalent and show the library version and usage.

The general syntax for top is as follows:

      top -bcHisS -d delay -n iterations -p pid [,pid...]

The following is a screenshot of top running on Fedora 17:

How to do it...

Following are some examples using the command line switches:

  1. To update the screen every 2 seconds:

    top -d 2
    
  2. To update the screen every half second:

    top -d 0.5
    
  3. To update 10 times and then quit:

    top -n 10
    
  4. To do both:

    top -d 0.5 -n 10
    
  5. To update the screen immediately, press Spacebar...