UNIX Administration: A Comprehensive Sourcebook for Effective Systems & Network Management

730 Pages·2002·5.87 MB·English

by  Bozidar Levi

UNIX
Administration
A Comprehensive Sourcebook
for Effective Systems and
Network Management
© 2002 by CRC Press LLC
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© 2002 by CRC Press LLC
UNIX
Administration
A Comprehensive Sourcebook
for Effective Systems and
Network Management
Bozidar Levi
CRC PR ESS
Boca Raton London New York Washington, D.C.
© 2002 by CRC Press LLC
1351disclaimer Page 1 Thursday, April 18, 2002 1:56 PM
Library of Congress Cataloging-in-Publication Data
Levi, Bozidar.
UNIX administration : a comprehensive sourcebook for effective systems and network management / by
Bozidar Levi.
p. cm. -- (Internet and data comunications series
Includes bibliographical references and index.
ISBN 0-8493-1351-1 (alk. paper)
1. Operating systems (Computers) 2.UNIX System V (Computer file) I. Title. II. Series.
QA76.76.O63 L4853 2002
005.4’82—dc21 2002017438
CIP
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Printed on acid-free paper
© 2002 by CRC Press LLC
TOC.fm Page v Thursday, April 18, 2002 7:02 PM
Preface
Unix Administration: A Comprehensive Sourcebook for Effective Systems and Network Manage-
ment attempts to make UNIX essential and network administrative topics more accessible
to a wide audience, including both academic and professional users. The selected book
title fully reflects this idea: to present UNIX administration in a comprehensive way and
enable effective systems and network management based on the presented text.
To achieve this goal, the book gives equal weight to UNIX systems and network concepts
and their practical implementations. During the many years that I have worked as a
computer hardware designer and programmer, and most recently as a UNIX administrator,
I have tackled many practical UNIX and network problems. Working for different employ-
ers, I faced real-life situations in an academic environment, in the financial industry and
the retail industry, and on the Internet. At the same time, while teaching at New York
University and Columbia University, I met many novices in this field and learned an
optimal and quick way to teach UNIX administration. This accumulated knowledge and
experience have helped me to select UNIX topics that are of the utmost relevance to
successful administration, and those topics served as the basis for this book. Some add-
itional UNIX topics, significant from a historical point of view, or necessary for an overall
presentation of UNIX administration, are also included. In concert, they create a logical
and comprehensive text, easy to read and follow. It is impossible to say that everything
existing in the UNIX administration arena is covered here — it would be impossible to
put it all in a single book. However, the principal and most important UNIX administrative
topics that make a complete UNIX administration environment and a sufficient base for
overall UNIX management are fully explored.
UNIX was developed in two different environments: academic and industrial. Conse-
quently, two main UNIX platforms, Berkeley UNIX (also known as Berkeley Software
Distribution — BSD UNIX) and System V UNIX (also known as AT&T UNIX) have
emerged. Both platforms have coexisted for many years, continuing to develop and pro-
mote UNIX. Simultaneously, many vendors started to develop their own UNIX flavors by
trying to adopt the best from the two main platforms. Today we see a number of vendor-
specific UNIX flavors, all based on these two main platforms. In most cases, it is even
difficult to evaluate which platform is prevailing — each flavor is simply a hybrid of both
platforms, often bringing something new and specific to the UNIX market. However, upon
looking further at specific UNIX segments — for example, file system management,
printing, accounting, etc. — one is more easily able to describe them as mostly Berkeley-
like, or System V-like.
Networking, which appeared later, at a time when UNIX had already developed into
quite a mature product, merged very efficiently into both UNIX platforms and virtually
eliminated their differences in the network area. The TCP/IP protocols became a network
standard, while UNIX provided the main underlying layer of core network services. The
net effect was that UNIX network administration is more or less uniform among many
existing UNIX flavors, although far from identical. Differences in kernels, available com-
mands, and some other details do make a difference in some cases.
This book basically follows a historical UNIX path, i.e., it addresses UNIX administration
with an eye to the two main UNIX platforms, Berkeley and System V. For easier conceptual
understanding of administrative topics, Berkeley UNIX seems more convenient. This is
© 2002 by CRC Press LLC
TOC.fm Page vi Thursday, April 18, 2002 7:02 PM
probably the case, because it was primarily developed in academia. By following that
pattern for each individual UNIX topic, the Berkeley platform is discussed first and
afterward its System V counterpart. A practical implementation of a specific UNIX topic
is accomplished through many real-life examples from different vendor-specific UNIX
flavors. Now, at the start of a new millennium, Solaris, HP-UX, Linux, and AIX and SGI
IRIX are the most dominant flavors, and thus, this book mainly addresses them. SunOS,
as a dominant UNIX flavor for many years, is also occasionally quoted, especially because
SunOS is a typical representive of Berkeley UNIX, and is still widely in use. In combination,
the book is an instrumental source of the information needed to learn UNIX administration
and efficiently perform the most essential and network-related UNIX administrative tasks.
This book presents a reliable UNIX administration reference book for practical UNIX
implementation. However, it could be easily used for educational purposes, as a textbook,
due to its education-related organization, conceptual clarifications, as well as an appro-
priate selection of administrative topics. Not many books of this kind are on the market
that are so diverse and detailed oriented at the same time. Many practical examples and
specific administrative procedures, logically connected to theoretical issues, strongly sup-
port the educational significance of this book.
UNIX Administration Sourcebook started as handouts prepared for the course "UNIX
System Administration" at NYU’s School of Continuous and Professional Studies and has
been in full use for quite some time with very encouraging feedback from students. During
this time, a number of text improvements and updates have been made, until this version
was reached. UNIX is changing continually (supposedly always better) and this text
presents an up-to-date version organized in a logical and comprehensive way. It can be
easily used by beginners, as well as experienced administrators.
There are many books related to UNIX systems and network administration, and they
all contribute to this complex arena in some way. This book contains elements that make
it different from others:
(cid:127) The comprehensive organization and presentation of the text
(cid:127) The condensed explanation of concepts and their practical implementations
(cid:127) The inclusion of both UNIX systems and network administration, in full detail
(cid:127) The choice of crucial administrative topics and their full coverage
(cid:127) The discussion of the most common UNIX flavors
(cid:127) The text is self-sufficient for successful administration on a daily basis
(cid:127) The coverage of all basic and many advanced UNIX administrative topics
(cid:127) The coverage of X window system, a complex administrative topic almost always
excluded from UNIX administration books
(cid:127) Up-to-date text with coverage of the latest main UNIX flavors and releases
(cid:127) Usefulness as a reference book as well as a textbook
(cid:127) A careful selection of relevant examples based on many years of professional
experience in this field
(cid:127) And last but not least, many years use of the initial book text in a handout form
demonstrates high usability of the text by students and professionals.
The book consists of four parts: UNIX Administration, Network Administration, Sup-
plemental UNIX Topics, and Case Studies. A total of 82 figures fully support the existing
text. Such an organization is logical, comprehensive, and easy to read.
© 2002 by CRC Press LLC
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UNIX Administration covers essential UNIX administration and contains 13 chapters.
The first three chapters are an introduction to the UNIX operating system, an overview
of a certain number of selected UNIX topics important for the administration, and an
overview of the UNIX administration itself. The remaining chapters cover UNIX system
startup and shutdown, detailed UNIX filesystem management and layout, user account
management and system security, logging and printing subsystems, terminals, system
backup and recovery, and time-related UNIX facilities. In combination they provide suf-
ficient material for a successful “out-of-network” UNIX administration, which can also be
called stand-alone UNIX administration.
Network Administration covers network-related UNIX administration and contains
eight chapters. The first two chapters present an introduction to networking and, more
specifically, to TCP/IP networks. Other chapters cover the main network services: domain
name system (DNS), network information system (NIS), network filesystem (NFS), UNIX
remote commands and secure shell, electronic mail, and the most common network appli-
cations such as telnet and ftp. Selected network topics present core network services with
which each networked UNIX system has to comply.
Supplemental UNIX Topics covers several more subjects, which, by implementing cer-
tain criteria, make UNIX administration complete. These administrative topics are often
handled separately, out of basic UNIX administration. Four chapters include X window
system, kernel reconfiguration, modems and related UNIX facilities, and intranet technol-
ogies. X windowing, with its quite complex administration, is almost always handled
separately, as well as most of the advanced intranet technologies.
Finally, Case Studies are presented in three chapters on subjects extremely important to
practical UNIX implementation: UNIX installation, disk space upgrade, and several emer-
gency situations that every UNIX administrator should expect to face at some point. Most
administrators have experienced a need to bypass a “forgotten root password,” and while
this routine bypassing task varies among different flavors, the general hints presented can
be helpful in any case.
Finally, I would like to point out that during many years of active UNIX administration,
I was always thinking how nice it would be to have a single book in front of me, which
together with standard UNIX online documentation (UNIX manual pages) would be
sufficient for effective usual daily systems and network management. This book is a
response to that idea.
Dr. Bozidar Levi
New York City
October 2001
© 2002 by CRC Press LLC
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About the Author
Dr. Bozidar Levi is an electronics engineer by education, a hardware designer and pro-
grammer by evocation, and an UNIX administration expert by profession. He received
his education at the University of Belgrade, Yugoslavia, and was awarded B.S., M.S., and
Ph.D. degrees in electronics and computer science. Dr. Levi joined Belgrade’s Pupin
Institute and had a successful career path from a junior associate to a top senior scientist,
dealing with many challenging projects — mostly as a project leader. A majority of the
devices and equipment he designed are still operational worldwide.
UNIX was a logical continuation of Dr. Levi’s rich and extensive IT background. He has
focused with enthusiasm and strength on system and network administration issues.
Again, Dr. Levi made a full circle by working in academia (Hunter College of the City
University of New York), in the financial industry (New York Stock Exchange), retail
industry (J. Crew), and currently the Internet (Linkshare Corporation). Such a wide work-
ing range has resulted in accumulated administrative expertise and experience.
Dr. Levi has also fully exercised his educational mission: first by teaching at the Uni-
versity of Belgrade, and now at Columbia and New York University. His teaching has
always been a rational balance between theory and practice, with strong emphasis on real-
life problems. Many of his former students are employed as IT professionals in various
industrial and non-industrial segments nationwide. UNIX Administration: A Comprehensive
Sourcebook for Effective Systems and Network Management is an extended and updated version
of his UNIX administration course syllabi, which are appreciated and highly rated by his
students. The book merges the required theoretical background with the practical needs
for a successful UNIX administration in almost any environment.
Dr. Levi has also appeared as an author or co-author in more than 60 published and
presented articles and papers and has received several awards for excellence and
achievement.
© 2002 by CRC Press LLC
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Contents
Section I UNIX Administration
1 UNIX — Introductory Notes
1.1 UNIX Operating System
1.2 User’s View of UNIX
1.3 The History of UNIX
1.3.1 Berkeley Standard Distribution — BSD UNIX
1.3.2 System V or ATT UNIX
1.4 UNIX System and Network Administration
1.4.1 System Administrator’s Job
1.4.2 Computing Policies
1.4.3 Administration Guidelines
1.4.3.1 Legal Acts
1.4.3.2 Code of Ethics
1.4.3.3 Organizations
1.4.3.4 Standardization
1.4.4 In This Book
2 The UNIX Model — Selected Topics
2.1 Introduction
2.2 Files
2.2.1 File Ownership
2.2.2 File Protection/File Access
2.2.2.1 Access Classes
2.2.2.2 Setting a File Protection
2.2.2.3 Default File Mode
2.2.2.4 Additional Access Modes
2.2.3 Access Control Lists (ACLs)
2.2.4 File Types
2.2.4.1 Plain (Regular) File
2.2.4.2 Directory
2.2.4.3 Special Device File
2.2.4.4 Link
2.2.4.5 Socket
2.2.4.6 Named Pipe
2.2.4.7 Conclusion
2.3 Devices and Special Device Files
2.3.1 Special File Names
2.3.2 Special File Creation
2.4 Processes
2.4.1 Process Parameters
2.4.1.1 Process Types
2.4.1.2 Process Attributes
© 2002 by CRC Press LLC