Preface

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Linux is thriving. Red Hat is at the forefront of the Linux revolution. And Red Hat Certified Engineers are making it happen.

Even in the current economic recovery, business, education, and governments are cost conscious. They want control of their operating systems. Linux-even Red Hat Enterprise Linux-saves money. The open source nature of Linux allows users to control and customize their operating systems. While there is a price associated with Red Hat Enterprise Linux (RHEL), it includes support and updates. As I describe shortly, there are freely available 'rebuilds' of RHEL 3 that you can get without support from Red Hat.

On The Job 

A 'rebuild' is software that is built by a third party from the same source code. On the other hand, a 'clone' is built from different source code.

Major corporations, from Home Depot to Toyota, and governments such as Germany, the Republic of Korea, and Mexico have made the switch to Linux. When faced with a Microsoft audit for licenses, the Portland, Oregon, school system switched to Linux. Major movie studios such as Disney and Dreamworks use Linux to create the latest motion pictures. IBM has invested more than a billion dollars in this 'free' operating system-just in 2001-and constantly features Linux in its advertising. HP has reported 2.5 billion dollars in Linux-related revenue in 2003.

Security is another reason to move toward Linux. The U.S. National Security Agency has developed its own version of the Linux kernel; RHEL 3 has incorporated many of these improvements.

While there are Linux distributions available from a number of companies, Red Hat is far and away the market leader. Therefore, the RHCE provides the most credibility to you as a Linux professional.

The RHCE exam is difficult. Historically, about 60 percent of the candidates pass this exam. The pass rate is lower for people taking the exam for the first time. But do not be intimidated. While there are no guarantees, this book can help you prepare for and pass the Red Hat Certified Engineer exam.

To study for this exam, you should have a network of at least two Linux or Unix computers. You need to install RHEL 3 on at least one of these computers. That will allow you to configure Linux and test the results. After configuring a service, it's important to be able to check your work from another computer.

Getting Red Hat Enterprise Linux 3

The Red Hat exams are based on your knowledge of Red Hat Enterprise Linux 3. When you take the RHCE exam, it'll be on a 'standard' PC with Intel 32-bit (or compatible) personal computers. The CPU should have a speed of at least 700MHz, and the PC should have at least 256MB of RAM. There are four major versions of this operating system available; the price depends on your hardware and the amount of support you need.

• RHEL 3 Advanced Server (AS) includes varying levels of support for high-end and mission-critical systems.

• RHEL 3 Entry-level Server (ES) includes varying levels of support suitable for smaller or mid-range servers.

• RHEL 3 Workstation (WS) includes varying levels of support suitable for desktop computers and workstations.

• Red Hat Professional Workstation (RHPW) includes all software from RHEL 3 WS, without any support. The difference between RHPW and RHEL 3 ES is minimal. With a few downloadable RPM packages, you can use this to prepare for the RHCE exam fairly inexpensively. I describe the freely available packages that you need shortly.

If you want to prepare for the RHCE exam with the official RHEL 3 server operating system, you can purchase RHEL 3 ES, Basic Edition. This edition allows you to download the four binary CDs associated with this operating system, in ISO format, with quarterly updates, as well as access to downloads through the Red Hat Update Agent. Naturally, as this is the least expensive server option, it does not include any other official level of support.

But you don't have to pay for the operating system to prepare for the RHCE exam. As of this writing, there are four efforts to build freely available 'rebuilds' of Red Hat Enterprise Linux 3. The source code for almost all RHEL 3 RPM packages is released under the Linux General Public License (GPL) or related licenses. This gives anyone the right to build Red Hat Enterprise Linux 3 from the Red Hat released source code.

The source code is released in Source RPM package format, which means the RPM packages can be built using the rpm commands described in Chapter 4. The four groups have all revised the source code to remove Red Hat trademarks. Some have used and added different versions of a limited number of RPM packages. As of this writing, the first three groups have consolidated the RHEL 3 software in three CDs. You can select and download the rebuild that most closely meets your needs. I have only tried the rebuild as developed by the cAos group. However, there are good reports about all of these rebuilds. These rebuilds are free; however, you should have a high-speed Internet connection. These rebuilds do not use 100 percent RHEL 3 software, so be careful:

• Community Linux The rebuild developed by the cAos group at www.caosity.org appears solid. As of this writing, this seems closest to the original RHEL 3 software.

• TaoLinux The folks behind TaoLinux are based at Alfred University. You can find out more about TaoLinux at www.taolinux.org.

• White Box Linux This group was first with a 'final' rebuild of RHEL 3. As of this writing, they've documented the different sources that they've used on their first CD. You can find out more about this distribution at www.beau.org/~jmorris/linux/whitebox/.

• RHEL-Rebuild This group is based out of the University of Innsbruck, Austria. While their rebuild of RHEL 3 is not available as of this writing, they have a complete HOWTO for rebuilding RHEL from source at www2.uibk.ac.at/zid/software/unix/linux/rhel-rebuild.htm.

Alternatively, you can work from RHEL 3 WS or RHPW. There are four binary CDs associated with RHEL 3 ES and RHEL 3 WS (or RHPW). The software on the final three CDs are identical. The first RHEL 3 ES CD includes 22 additional RPM packages, naturally related to a number of servers. Thus you can install RHPW, without support or updates from Red Hat, and then build the software for the following servers from the source code:

• Domain Name Service (DNS)

• Dynamic Host Configuration Protocol (DHCP)

• Very Secure FTP (vsFTP)

• Network Information Service (NIS)

Using the techniques described in Chapter 4, you can download the Red Hat Enterprise Linux source RPMs at ftp.redhat.com, process them into binary RPMs, and then install them on your computer.

In This Book

This book is organized to serve as an in-depth review for the RHCE exam for both experienced Linux and Unix professionals. Each chapter covers a major aspect of the exam, with an emphasis on the 'why' as well as the 'how to' of working with and supporting RHEL 3 as a systems administrator or engineer. As the actual RHCE study points change with every release of RHEL, refer to www.redhat.com for the latest information.

This book includes relevant information from Red Hat Enterprise Linux 3 (RHEL 3). There are more than 100 major new features when compared to Red Hat Enterprise Linux 2.1. A few of the key features of RHEL 3 include:

• A strong stable Linux kernel. While the version is 2.4.21-4.EL, it includes features 'backported' from the latest 2.6 kernel, as well as features that improve stability of the operating system environment.

• A new NPTL (Native Posix Threading Library) which improves the performance of multi-threaded applications.

• Improved support for Logical Volume Management (LVM).

• Performance and stability improvements for NFS.

• Support in high-performance enterprise computing environments.

• Tight integration and support of a number of enterprise-level applications by IBM, Oracle, Veritas, and more.

• Samba version 3.0, which allows Linux to act as a Microsoft Windows PDC, as well as a member server on an Active Directory network.

• A substantial number of GUI configuration utilities developed by Red Hat.

There are many more key features; those that I believe are relevant to the RHCE exam are also included in this book.

While it's not the best practice in service, it is fastest to administer RHEL 3 during the exam by logging into the root user account. The command prompt and PATH assumes use of that account. When you're logged into the root account, you'll see a command line prompt similar to:

[root@Enterprise3 root]#

As the length of this prompt would lead to a number of broken and wrapped code lines throughout this book, I've normally abbreviated the root account prompt as:

#

Be careful. The hash mark (#) is also used as a comment character in Linux scripts and programs; for example, here is an excerpt from /etc/inittab:

# Default runlevel. The runlevels used by RHS are:

When logged in as a regular user, the prompt is slightly different; for user michael, it would typically look like the following:

[michael@Enterprise3 michael]$

Similarly, I've abbreviated this as:

$

There are a number of command lines and code interspersed throughout the chapters.

On the CD

For more information on the CD-ROM, please see Appendix A.

Exam Readiness Checklist

At the end of the Introduction, you will find an Exam Readiness Checklist. This table has been constructed to allow you to cross-reference the official exam objectives with the objectives as they are presented and covered in this book. The checklist also allows you to gauge your level of expertise on each objective at the outset of your studies. This should allow you to check your progress and make sure you spend the time you need on more difficult or unfamiliar sections. References have been provided for the objective exactly as the vendor presents it, the section of the study guide that covers that objective, and a chapter and page reference.

In Every Chapter

We've created a set of chapter components that call your attention to important items, reinforce important points, and provide helpful exam-taking hints. Take a look at what you'll find in every chapter:

• Every chapter begins with the Certification Objectives-what you need to know in order to pass the section on the exam dealing with the chapter topic. The Objective headings identify the objectives within the chapter, so you'll always know an objective when you see it.

• Exam Watch notes call attention to information about, and potential pitfalls in, the exam. These helpful hints are written by authors who have taken the exams and received their certification-who better to tell you what to worry about? They know what you're about to go through!

• Practice Exercises are interspersed throughout the chapters. These are step-by-step exercises that allow you to get the hands-on experience you need in order to pass the exams. They help you master skills that are likely to be an area of focus on the exam. Don't just read through the exercises; they are hands-on practice that you should be comfortable completing. Learning by doing is an effective way to increase your competency with a product. Remember, the RHCE exam is entirely 'hands-on;' there are no longer any multiple choice questions on this exam.

  On The Job 

  On the Job notes describe the issues that come up most often in real-world settings. They provide a valuable perspective on certification- and product-related topics. They point out common mistakes and address questions that have arisen from on-the-job discussions and experience.

• Inside the Exam sidebars highlight some of the most common and confusing problems that students encounter when taking a live exam. Designed to anticipate what the exam will emphasize, getting inside the exam will help ensure you know what you need to know to pass the exam. You can get a leg up on how to respond to those difficult-to-understand labs by focusing extra attention on these sidebars.

• Scenario & Solution sections lay out potential problems and solutions in a quick-to-read format.

• The Certification Summary is a succinct review of the chapter and a restatement of salient points regarding the exam.

• The Two-Minute Drill at the end of every chapter is a checklist of the main points of the chapter. It can be used for last-minute review.

• The Self Test offers questions similar to those found on the certification exams. The answers to these questions, as well as explanations of the answers, can be found at the end of each chapter. By taking the Self Test after completing each chapter, you'll reinforce what you've learned from that chapter while becoming familiar with the structure of the exam questions.

• The Lab Questions at the end of the Self Test section offers a unique and challenging question format that requires the reader to understand multiple chapter concepts to answer correctly. These questions are more complex and more comprehensive than the other questions, as they test your ability to take all the knowledge you have gained from reading the chapter and apply it to complicated, real-world situations. Most importantly, the RHCE exam contains only lab type questions. I've tried to make these questions a bit more difficult than what you will find on the exam. If you can answer these questions, you have proven that you know the subject!

Some Pointers

Once you've finished reading this book, set aside some time to do a thorough review. You might want to return to the book several times and make use of all the methods it offers for reviewing the material:

1. Reread all the Exam Watch notes. Remember that these notes are written by authors who have taken the exam and passed. They know what you should expect-and what you should be on the lookout for.

2. Review all the Scenario & Solution sections for quick problem solving.

3. Retake the Self Tests. Taking the tests right after you've read the chapter is a good idea. Focus on the labs, as there are no multiple choice questions on the RHCE exam. I've included multiple choice questions just to test your mastery of the practical material in each chapter.

4. Complete the exercises. Did you do the exercises when you read through each chapter? If not, do them! These exercises are designed to cover exam topics, and there's no better way to get to know this material than by practicing. Be sure you understand why you are performing each step in each exercise. If there is something you are not clear on, reread that section in the chapter.

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