


 |
UNIX® Unleashed,
System Administrator's Edition
Robin Burk and David B. Horvath, CCP, et al
Dedication
To Stephen P. Kowalchuk, who provided an IS manager and practicing network
administrator's point of view.
----Robin Burk
This edition is dedicated to my parents and grandparents. Education and doing
one's best was always important to them.
----David B. Horvath
Acknowledgments
Special thanks to Roger for support and grocery shopping. Also to the Laurelwood
English Cockers, who intuitively understand how to negotiate a communications session
(beg), allocate resources (if it's on the counter, it's ours!), and travel in encapsulated
cells (show crates) over broadband highway networks.
----Robin Burk
As with all the other projects I get involved with, my wife and muse, Mary, has
been tremendously supportive. Even when I spent my evenings and weekends at the keyboard.
Of course, she filled her time by shopping (she said this, not me).
My parents, brothers, and the rest of family, who always wondered about the time
I spent with computers, are now seeing the concrete results of it all.
I've been involved with this project for close to a year now. The development
staff were very helpful and have certainly kept it interesting. I want to thank them
and the other authors (especially those that I talked into helping out). This certainly
turned out to be a bigger project (and resulting book) than any of us expected. I
hope and expect that people will be looking at these two volumes as the
definitive reference!
After I take a short rest, I will be looking for the next project. Although these
things are really tiring, especially with the effort this one entailed, I miss them
when I'm not working on one.
---- David B. Horvath
About the Authors
Robin Burk has over 25 years' experience in advanced software, computer,
and data communications technologies. She has provided technical and managerial leadership
for the development of language tools, communications software, operating systems,
and multimedia applications. A successful executive in entrepreneurial companies,
she consults on software product development and the use of the Internet for business
success. Robin's undergraduate degree is in physics and math. She also holds an MBA
in finance and operations. Robin's other passion is breeding, training, and showing
dogs. She moderates an e-mail list for English Cocker Spaniel fanciers and can be
reached at robink@wizard.net.
David B. Horvath, CCP, is a Senior Consultant with CGI Systems, Inc., an
IBM Company, in the Philadelphia, Pennsylvania area. He has been a consultant for
over twelve years and is also a part-time Adjunct Professor at local colleges teaching
topics that include C Programming, UNIX, and Database Techniques. He is currently
pursuing an M.S. degree in Dynamics of Organization at the University of Pennsylvania.
He has provided seminars and workshops to professional societies and corporations
on an international basis. David is the author of "UNIX for the Mainframer"
and numerous magazine articles.
When not at the keyboard, he can be found working in the garden or soaking in
the hot tub. He has been married for over ten years and has several dogs and cats.
David can be reached at unx2@cobs.com
for questions related to this book. No Spam please!
Fred Trimble holds a master's degree in computer science from Villanova
University. In his nine years with Unisys Corporation, he held many positions, including
UNIX system administrator, C programmer, and Oracle database administrator. Currently,
he is a senior consultant and instructor with Actium Corporation in Conshohocken,
Pennsylvania, specializing in C++, Java, and the Brio data warehousing product line.
He is currently pursuing a master's degree in software engineering from Drexel University.
Sanjiv Guha has 14 years of experience in managing and developing financial
and other application systems. He specializes in C, UNIX, C++, Windows, and COBOL.
Sanjiv holds a Master of Technology Degree from Indian Institute of Technology, New
Delhi, India.
William A. Farra's computer career started in the summer of 1978, working
in a time sharing shop on a IBM 365. It had 768 KB, 8 disk packs totaling 125 MB
and a cost of 10 million dollars. That fall, Mr. Farra went to the University of
Delaware for electrical engineering and worked part time at Radio Shack playing with
the trash 80's. He continued to work for the Shack until he met a bright guy who
was writing custom programs for the larger computers the Shack sold. Bill took a
full time job with him in September of 1983, working on Microsoft's first versions
of UNIX (called Xenix at the time) and writing BASIC and C code.
In 1985, Bill went out on his own for six years, writing UNIX-based data processing
systems for various clients in the Philadelphia area including "Dan Peter Kopple
and Associates," the architects who renovated 30th Station. Since 1991, Bill
has returned to employment, developing and/or enhancing various systems including
"Fraud Detection Delivery System" for MBNA and Settlement systems for EPS
"MAC card ATM processor." Recently he got away from the "Big Cities"
and is living at the Jersey Shore. He is a lead developer for National Freight Industries,
working with various UNIX based systems including real-time tracking of vehicles
using national transportation satellite and ground-based networks. Always keeping
an eye on the future, Bill is just having more fun doing it now.
Richard E. Rummel, CDP, is the president of ASM Computing, Jacksonville,
Florida, which specializes in UNIX software development and end user training. He
has been actively employed in the computer industry for over 20 years. Married for
25 years, he is the father of two children, a dog, and a cat.
Sriranga Veeraraghavan is earning his B.E. from UC Berkeley in 1997. He
is a GUI designer on UNIX, and currently uses Java for multiple Web-based applications.
He is currently working at Cisco Systems. Sriranga amuses himself with Perl, Marathon
and MacsBugs.
Christopher Johnson is currently studying at Sheffield Hallam University
in the UK for a degree in Electronic and Information Engineering. He is mostly self
taught in the computer field, with experience being gained from helping other students,
people on Usenet, and colleagues at work. He is part of a team that administers a
Linux server on the university's network, and administers a web server on it. When
not working, his interests include cycling and music, and he enjoys traveling.
John Valley lives in Richmond, Virginia with his wife Terri and his Labrador
retriever, Brandon. Mr. Valley currently operates a small practice as an independent
consultant for UNIX and Windows tools and applications. With more than 20 years of
experience in the computer industry, his background ranges from Cobol business applications
and mainframe operating system development to UNIX tools and Windows programming.
He teaches courses in C/C++ programming and UNIX fundamentals.
Mr. Valley has published three books on UNIX topics and was a contributing author
for the first edition of UNIX Unleashed.
Sydney S. Weinstein, CDP, CCP, is a consultant, columnist, lecturer, author,
professor, and president of Myxa Corporation, an Open Systems technology company
specializing in helping companies move to and work with Open Systems. He has 20 years
experience with UNIX dating all the way back to Version 6.
Sean Drew is a distributed object software developer, working primarily
with UNIX, C++, and CORBA. Sean is married to his college sweetheart Sheri and together
they have two children, Dylan Thomas and Terran Caitlin. At the time of this writing
a third child is on the way, and depending on the gender will probably be named Erin
Nichole, Brenna Nichole, or Ryan Patrick. When Sean is not busy with his family or
church, he likes to brew beer. Anybody up for a nice imperial stout? Sean can be
reached at ninkasi@worldnet.att.net.
Eric Goebelbecker has been working with market data and trading room systems
in the New York City area for the past six years. He is currently the Director for
Systems Development with MXNet Inc, a subsidiary of the Sherwood Group in Jersey
City, New Jersey, where he is responsible for developing new market data and transaction
distribution systems.
Ron Rose is an international management consultant with over 20 years of
data processing management experience. He has led large-scale data processing installations
in Asia, Europe, and the United States, and he has managed several software product
start-up efforts. He completed a master's in information systems from Georgia Institute
of Technology after completing undergraduate work at Tulane University and the University
of Aberdeen, Scotland.
Lance Cavener is co-founder of Senarius. His function is to provide support
to employers in Eastern Canada. Tasks such as payroll, work force deployment, and
more are part of his business. He is also the President and Senior Network Administrator
of ASCIO Communications, a subsidiary of Senarius. He provides the public and businesses
with Internet related services. Lance has been actively involved in UNIX since 1990,
as an administrator for corporate networks at various companies in Eastern Canada.
His work includes working with BIND/DNS, Sendmail, Usenet setup, web servers, and
UNIX security. He has also written various programs for SunOS, MS-DOS, MS-Windows,
and VMS.
David Gumkowski currently is a senior systems analyst for Digital Systems
Group, Inc., Warminster, PA. Nineteen years ago, he emerged from his computing womb
at Purdue University and cut his system administration teeth using Control Data and
Texas Instruments machines. For the last 11 years, he developed his UNIX skills prodding
Sun, Hewlett Packard, Digital Equipment and Silicon Graphics machines to behave for
approximately 3,000 users. He would publicly like to thank his wife and children
for their support when trying new things like writing chapters for this book.
John Semencar is a senior software analyst for Thomas Jefferson University,
Philadelphia, PA. Beginning system administration on Control Data legacy systems
10 years ago, and with a background that also includes DEC and SGI, he presently
surrounds himself with Hewlett Packard 9000 servers running HP-UX v10.x. He would
like to thank his wife Georgia and little Buster for their support.
Steve Shah is a systems administrator for the Center of Environmental Research
and Technology at the University of California, Riverside. He received his B.S. in
Computer Science with a minor in Creative Writing from UCR and is currently working
on his M.S. there as well. In his copious spare time, he enjoys writing fiction,
DJing, and spending time with his friends, family, and sweet, Heidi.
Daniel Wilson currently performs UNIX Systems Administration and Database
Administration work for the Defense Finance and Accounting Services Financial Systems
Organization, which is a financial organization within the Department of Defense.
William D. Wood currently works at Software Artistry, Inc as a support
specialist on UNIX systems. He supports the Expert Advisor software it runs on SUN
OS, HP-UX and IBM AIX. He has specialized in multi-systems and remote systems support
since 1985, when he started work at the Pentagon. He has solely supported infrastructures
that span the world and just the U.S. He has also supported up to 80 UNIX machines
at one time.
William G. Pierce currently performs UNIX Systems Administration and is
the Technical Lead for the MidTier Management Operation at the Defense Finance and
Accounting Services, Financial Services Organization, Indianapolis, Indiana.
Salim M. Douba (Salim_Douba@ott.usconnect.com)
is a senior computer network consultant mainly specializing in UNIX, NetWare, and
mainframe connectivity. He also designs and implements TCP/IP-based networks and
enterprise network management solutions. Salim holds a master's degree in electrical
engineering from the American University of Beirut. His experience and main career
interests have primarily been in internetworking, multiplatform integration, and
network analysis and management.
Chris Byers is a systems administrator for a financial securities firm
in Philadelphia. As a former consultant and disaster recovery specialist, he has
many years of experience in the UNIX world with its many different variants. He lives
in South Jersey with his wife, his son, and his cat. He can be reached at southst@voicenet.com.
Jeff Smith is a psychology major who took a wrong turn and ended up working
with computers. Jeff has worked with UNIX systems since 1982 as a programmer and
systems administrator. He has administered mail, news, security, and the domain name
system on several varieties of UNIX including 2.9 BSD, 4.3 BSD, Dynix, SunOS, and
AIX.
James C. Armstrong, Jr. is a software engineer with more than ten years
of industry experience with UNIX and C.
James Edwards (jamedwards@deloitte.ca)
is an IT professional experienced in data communications, network integration, and
systems design in both North America and Europe. He holds an M.S. in information
technology from the University of London and a B.A. (Hons) from Middlesex University,
both in the United Kingdom. James currently resides in Toronto, Canada, where he
is employed as a manager with the Deloitte & Touche Consulting Group. His spare
time is taken up with his girls, Denise, Lauren, and Poppy.
Tell Us What You Think!
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value your opinion and want to know what we're doing right, what we could do better,
what areas you'd like to see us publish in, and any other words of wisdom you're
willing to pass our way. You can help us make strong books that meet your needs and
give you the computer guidance you require.
Do you have access to the World Wide Web? Then check out our site at http://www.mcp.com.
NOTE: If you have a technical question about this book, call the
technical support line at 317-581-3833 or send e-mail to support@mcp.com.
As the team leader of the group that created this book, I welcome your comments.
You can fax, e-mail, or write me directly to let me know what you did or didn't like
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Introduction
by Robin Burk and David B. Horvath, CCP
Welcome to UNIX Unleashed, System Administrator's Edition.
Who Should Read This Book
Our highly popular first edition brought comprehensive, up-to-date information
on UNIX to a wide audience. That original edition was already 1,600 pages. The new
topics covered in this edition have obliged us to split the second edition into two
volumes, namely, the System Administrator's Edition and the Internet Edition,
which we'll refer to jointly as "the new" or the second edition. Though
each volume can stand alone and may be read independently of the other, they form
a complementary set with frequent cross-references. This new edition is written for:
- People new to UNIX
- Anyone using UNIX who wants to learn more about the system and its utilities
- Programmers looking for a tutorial and reference guide to C, C++, Perl, awk,
and the UNIX shells
- System administrators concerned about security and performance on their machines
- Webmasters and Internet server administrators
- Programmers who want to write Web pages and implement gateways to server databases
- Anyone who wants to bring his or her UNIX skills and knowledge base up-to-date
A lot has happened in the UNIX world since the first edition of UNIX Unleashed
was released in 1994. Perhaps the most important change is the tremendous growth
of the Internet and the World Wide Web. Much of the public Internet depends on UNIX-based
servers. In addition, many corporations of all sizes have turned to UNIX as the environment
for network and data servers. As UNIX fans have long known, the original open operating
system is ideal for connecting heterogeneous computers and networks into a seamless
whole.
What's New in UNIX Unleashed, Second Edition
This edition of UNIX Unleashed includes a substantial amount of new information
describing Internet and World Wide Web technologies in UNIX. New topics include:
- Programming Web pages with HTML
- Object-oriented programming in C++
- Programming Common Gateway Interfaces (CGI) using Perl, C/C++, HTML, and the
UNIX shells
- MIME, the Multipurpose Internet Mail Extension
- HTTP, the HyperText Transfer Protocol
- Web servers and server performance
As UNIX becomes the platform of choice for critical network and data applications,
UNIX vendors have placed increased emphasis on system maturity, ease-of-use, and
security capabilities. Even with the growth of Microsoft Windows NT, UNIX still has
a place in the industry. It is more mature, more stable, more scaleable, and has
a wider array of applications than NT. Many people claim that NT is the open operating
system of the future; that may be true (I have my own personal opinion), but
for now, UNIX holds that place.
We've also updated this edition of UNIX Unleashed to bring you current
information regarding:
- Frequently Asked Questions (FAQs) about the most popular variants of UNIX
- Security issues and the technologies you can use to protect your system and its
information against intruders and malicious users
- The most popular Graphical User Interfaces (GUIs)
As with the original edition, we set out to bring users the most comprehensive,
useful, and up-to-date UNIX guide. To meet this goal, we've added nearly two dozen
new chapters and have revised much of the original material in the book. The resulting
book is so large that it is now divided into two volumes. The System Administrator's
Edition introduces UNIX and contains much of the information required for basic
users and for systems administrators. The Internet Edition includes advanced
information for programmers, Internet/Web developers, and those who need detailed
information regarding specific UNIX flavors.
Coverage of Popular UNIX Variants
Based on input from some of the experts, application developers, consultants,
and system administrators working in industry, we have provided information about
a number of the UNIX variants. We split the variants into two categories: major and
minor. This is not a comment on the quality or capabilities of the variant, but on
the penetration in the marketplace (popularity).
We consider AIX, HP-UX, Solaris, and SVR4 to be major and BSD, IRIX, Linux, and
SunOS to be minor players in the marketplace. There are other variants; the next
edition may cover them as they become more popular.
You can identify where something specific to a variant is discussed by the icon
next to it:
- AIX--major--IBM's version that runs on the RS/6000 series of RISC systems and
mainframes. Over 500,000 RS/6000 systems have been sold!
- BSD--minor--This version has a lesser presence in the marketplace. Although many
variants can trace their heritage to BSD, it is not that popular as a product.
- HP-UX--major--Hewlett Packard's (HP) version with a strong hardware presence
in the marketplace and a strong future growth path.
- IRIX--minor--While the Silicon Graphics (SGI) machines are wonderful for graphics,
they have not found wide acceptance in business environments.
- Linux--minor--Although this is a very nice and free variant, it has little commercial
presence in the marketplace (probably because corporations do not want to run their
mission-critical applications without a vendor they can sue when there is a problem).
See the SAMS Linux Unleashed series books (Red Hat and Slackware) for detailed information.
- Solaris--major--Sun Microsystems' version with a strong hardware presence in
the marketplace and a strong future growth path.
- SunOs--minor--Largely being superseded by Solaris installations. A good variant,
but it is difficult for a company to support two versions of UNIX at a time.
- SVR4--major--This version has a strong presence in the marketplace. In addition,
many variants can trace their heritage to System V Release 4.
CD-ROM Contents
We've also enhanced our CD-ROM with a C compiler, the most popular Web server
software, and megabytes of other useful tools and information. The CD-ROM packaged
with each volume contains exactly the same software and materials. Here are some
of the noteworthy inclusions:
- The entire text of both volumes in HTML format
- Listings and code examples from various chapters in the volume
- FreeBSD 2.2.5, full binary release
- Linux RedHat 4.2, full binary release [x86 platform only]
- BASH, sources and documentation.
- sendmail version 8.7
- RFCs 821, 822, 1425, 1123, 976, 977, 1036
- latest version of INN source code
- GNU findutils 4.1
- GNU fileutils 3.16
- xv-3.10a
- disktool (v2.0)
- tcl/tk
- screen
- xarchie
- xrn
- SATAN
- Crack (or equivalent)
- Perl 5.x
- LaTeX
- Lynx
- elm and pine
- pico
- UNIX sort utility
- GNU awk, gawk
- APACHE web server
- GNU C compiler
- emacs editor
- gtar
- gzip
- gcc
- gmake
- NCSA Web Server
- asWedit
- missinglink
- Weblint
- Isearch and Isearch-cgi
- @cgi.pm
- LessTif 0.80 sources Linux & FreeBSD bins
- fvwm window manager
- Enlightenment window manager
- libg 2.7.2 (useful companion to C compiler)
- acroread, Adobe Acrobat PDF reader (for Linux and FreeBSD)
To make use of the CD-ROM easier, whenever a reference in print is made to the
CD-ROM, you will see an icon. You can also scan through the text to find the CD-ROM
icons to find more information the disk contents.
Enjoy!
How These Volumes are Organized
The books are divided into parts (detailed information about each volume is in
the next sections). Each volume also contains a glossary of terms and an index.
Whenever there is special information you should pay attention to, it will be
placed in a blocks to grab your attention. There are three types of special blocks:
note, tip, and caution.
NOTE: A note is used to provide you with information that you may
want to pay attention to but is not critical. It provides you with information that
can be critical but should not cause too much trouble.
TIP: A tip is used to make your life easier. It provides you with
information so you do not have to go digging for information to solve a problem.
These are based on real-life exposure to problems (and how they were solved).
CAUTION: A caution is used to grab your attention to prevent you
from doing something that would cause problems. Pay close attention to cautions!
The icons shown in the CD-ROM Contents and Coverage of Popular UNIX Variants sections
also provide a quick means of referencing information.
How the System Administrator's Edition Is Organized
The first volume, UNIX Unleashed, Systems Administrator Edition, consists
of three major sections or parts. The general focus is getting you started using
UNIX, working with the shells, and then administering the system.
Part I, Introduction to UNIX, is designed to get you started using UNIX. It provides
you with the general information on the organization of the UNIX operating system,
how and where to find files, and the commands a general user would want to use. Information
is also provided on how to get around the network and communicating with other users
on the system.
Part II, UNIX Shells, provides you the information on how to choose which shell
to use and how to use that shell. The most popular shells: Bourne, Bourne Again (BASH),
Korn, and C, are covered as well as a comparison between them. Under UNIX, the shell
is what provides the user interface to the operating system.
Part III, System Administration, gets you started and keeps you going with the
tasks required to administer a UNIX system. From installation through performance
and tuning, the important topics are covered. The general duties of the system administrator
are described (so you can build a job description to give to your boss). In case
you are working on a brand-new UNIX system, the basics of UNIX installation are covered.
Other topics covered in this section include: starting and stopping UNIX, user administration,
file system and disk administration, configuring the kernel (core of the operating
system), networking UNIX systems, accounting for system usage, device (add-on hardware)
administration, mail administration, news (known as netnews or UseNet) administration,
UUCP (UNIX to UNIX Copy Program, an early networking method still in wide use today)
administration, FTP (File Transfer Protocol) administration, and finally, backing
up and restoring files.
How the Internet Edition Is Organized
The second volume, UNIX Unleashed, Internet Edition, consists of seven major parts.
The general focus is programming (GUI, application languages, and the Internet),
text formatting (which involves embedding commands in your text and then processing
it), security considerations (advanced system administration), developing for the
Internet, "programming," getting you started using UNIX, working with the
shells, and source code control and configuration management, and Frequently Asked
Questions (FAQ) for the different variants of UNIX.
Part I, Graphical User Interfaces, provides you with information about using and
writing GUI applications. When the operating system is UNIX, the GUI is the X-windowing
system.
Part II, Programming, introduces the most popular program development tools in
the UNIX environment. The most important part is how to enter your program (editing
with vi and emacs)! The awk, Perl, C, and C++ programming languages are covered.
Awk and Perl are interpreted languages designed for quick program development. C
is the compiled language developed by Kernighan and Ritchie--UNIX is written in this
language. C++ is an enhancement to the C language that supports object oriented programming.
The final chapter in this section discusses the make utility, which provides
a rule-based method to control program compilation.
Part III, Text Formatting and Printing, covers the tools that support the development,
formatting, and printing of documents in the UNIX environment. These tools were much
of the original justification for hardware that was used to develop UNIX. The formatting
programs, nroff and troff, the standard macro packages, and many
of the other document preparation tools are covered. In addition, developing your
own text formatting macros is discussed.
Part IV, Security, is an advanced area of systems administration. One of the criticisms
of UNIX is that it is not secure. It was developed in an environment where the individuals
were trusted and sharing information was important. UNIX is capable of being very
secure; you just have to know how to set it up. This section provides that information.
The risks, available tools, and helpful organizations are covered.
Part V, UNIX and the Internet, introduces the tools used with the world wide web
and the transmission of binary files via email (MIME). The web page definition language,
HTML, is introduced, along with the methods of developing CGI (Common Gateway Interface--programs
that run on the web server processing data from web pages) programs in shell scripting
languages, Perl, and C/C++. Administrative information is provided in chapters on
HTTP (HyperText Transport Protocol) and monitoring server activity.
Part VI, Source Control, covers the tools that UNIX provides to maintain control
of your source code as different versions (and revisions) are created. The three
major tools are RCS, CVS, and SCCS.
Part VII, Frequently Asked Questions, provides answers, as the name implies, to
the most frequently asked questions about the various variants of UNIX. AIX, BSD,
HP-UX, Linux, Solaris, SVR4, and IRIX are covered in individual chapters.
Conventions Used in This Volume
This book uses the following typographical conventions:
- Menu names are separated from the individual menu options with a vertical bar
(|). For example, "File|Save" means "Select the File menu and then
choose the Save option."
- New terms appear in italic.
- All code appears in monospace. This includes pseudocode that is used
to show a general format rather than a specific example.
- Words that you are instructed to type appear in monospace bold.
- Placeholders (words that stand for what you actually type) appear in italic
monospace.
- Lines of code that are too long to fit on only one line of this book are broken
at a convenient place and continued on the next line. A code continuation character
(
) precedes
the new line. Any code that contains this character should be entered as one long
line without a line break.
- An ellipsis (...) in code indicates that some code has been omitted for the sake
of brevity.
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