Linux system administrator's survival guide

1049 Pages·1996·1.946 MB·English

by  Tim Parker

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Linux System Administrator's Survival Guide new buy it
Imprint: SAMS.net
Author: Timothy Parker
Publication Date: Jan-96
ISBN: 0-672-30850-9
Acknowledgments
About the Author
Introduction
Part I: Installation and Configuration
Chapter 1: Introduction to Linux
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Chapter 2: Linux Hardware and Software
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Chapter 3: Installing and Updating Linux
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Chapter 4: LILO
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Chapter 5: Installing and Configuring XFree86
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Part II: Expanding Your System
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Chapter 6: Devices and Device Drivers
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Chapter 7: SCSI Devices
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Chapter 8: Hard Disks
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Chapter 9: CD-ROM Drives
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Chapter 10: Sound Cards
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Chapter 11: Terminals and term
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Chapter 12: Tape Drives
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Chapter 13:Modems
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Chapter 14: Other Devices
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Part III: Managing Your Linux System
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Chapter 15: Booting, init, and Shutdown
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Chapter 16: Users and Logins
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Chapter 17: System Names and Access Permissions
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Chapter 18: Filesystems and Disks
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Chapter 19: Printers and Print Spoolers
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Chapter 20: Managing Processes
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Chapter 21: Managing Resources
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Chapter 22: Backup, Backup, Backup!
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Chapter 23: The cron and at Programs
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Chapter 24: Security
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Chapter 25: Modifying the Kernel
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Chapter 26: Shell Programming
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Part IV: Networking
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Chapter 27: UUCP
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Chapter 28: TCP/IP and Networks
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Chapter 29: Configuring Hardware and the Kernel for Networking
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Chapter 30: Configuring TCP/IP
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Chapter 31: Configuring SLIP and PPP
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Chapter 32: TCP/IP Utilities
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Chapter 33: NFS and NIS
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Part V: E-Mail and News
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Chapter 34: E-mail and Linux
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Chapter 35: Configuring sendmail
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Chapter 36: Using smail
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Chapter 37: Configuring Elm and Pine
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Chapter 38: USENET and Netnews
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Chapter 39: NNTP and INN
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Chapter 40: C News
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Chapter 41: Configuring Newsreaders trn and tin
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Part VI: The Internet
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Chapter 42: Setting Up an Internet Site
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Chapter 43: Setting up an FTP and Anonymous FTP Site
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Chapter 44: Configuring a WAIS Site
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Chapter 45: Setting Up a Gopher Service
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Chapter 46: Configuring a WWW Site
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Part VII: Appendixes
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Appendix A: Linux FTP Sites and Newsgroups
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Appendix B: Commercial Vendors for Linux
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Appendix C: The Linux Documentation Project
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Appendix D: The GNU General Public License
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Appendix E: Copyright Information
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Appendix F: Hardware Compatibility
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Appendix G: Glossary
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Appendix H: What's on the CD-ROM
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Linux System Administrator's Survival Guide lsgfm.htm
Acknowledgments
This book, unlike our popular Linux Unleashed, was conceived as a solo effort and as such meant an
awful lot of my time was taken away from others. This book took a while to write because it contains a
lot of technical information. To my parents and close friends, thanks for understanding why I couldn't
visit. In particular, thanks to Yvonne who understood why I had to spend evenings and weekends at the
computer, muttering veiled curses about deadlines, Linux, and applications that crashed at the most
inopportune times. Of course, I never said anything bad about my editors!
At Sams, those editors were Rosemarie Graham, who drove deadlines, tolerated changes, and generally
tried to bear with me as I struggled to submit this material on time. Thanks also to Todd Bumbalough,
who rode shotgun over the technical completeness of the material. To the production editors and
technical reviewers, thanks are also due. Also at Sams, Grace Buechlein gracefully bore changes to her
own schedules in order to fit this book in.
Finally, thanks to Rick McMullin, who graciously allowed me to steal some of his material for the shell
programming chapter and some details of the gcc C compiler.
About the Author
Tim Parker is a well-known author with over 800 feature articles and reviews published in many
different magazines. In addition, Dr. Parker has written or contributed to two dozen books. He is
currently Technical Editor of SCO World Magazine, Contributing Editor of Canadian Computer
Reseller, and a frequent contributor to UNIX Review Magazine. Dr. Parker is president of TPCI, based
in Kanata, Ontario. TPCI provides technical writing, training, investigative, and consulting services to
many large corporations, military installations, and law enforcement organizations.
When not busy writing books or articles, Dr. Parker can be found outdoors. He is a semi-professional
photographer, white-water kayaker, and hiker. He is also a scuba diving instructor and licensed pilot.
Introduction
UNIX system administration used to be a skill learned by watching others, trying many things on spec,
and scouring obscure magazine articles, obtuse man pages, and e-mail from others. In short, system
administration was a skill that was learned over the years with no single reference to the role and
functions a system administrator plays. UNIX, especially, was a tough system to administer properly
because there were many versions of the software, a disparate support base, and few solid working
applications. Luckily, time has changed these conditions.
With the popularity of computers in general, system administrators started writing down the details of
their tasks. Publishers realized that there was a distinct and eager, albeit small, market for system
administration books. The market grew as the number of systems and LANs expanded. The stabilization
of the UNIX operating system in two, and now one, major version helped enormously as well.
Linux became a dominant UNIX product about two years ago when it started receiving worldwide
acclaim as a reasonably stable PC version of UNIX. As more and more programmers got involved and
started producing software for Linux, the attraction of the operating system continued to grow. Soon, PC
users who didn't know anything about UNIX at all were running Linux and starting to deal with shells,
filesystems, and devices.
After helping to write Linux Unleashed (a great book, definitely worth buying if you haven't already got
a copy!), I realized that many users used that book and CD-ROM to get started with Linux, but they
needed more advanced material on managing their systems and setting up network systems. That's when
the Linux System Administrator's Survival Guide was born. This book expands on the Linux Unleashed
material, providing more detail on many aspects of the operating system. Although some overlap exists
between Linux Unleashed and this book, it has been minimized as much as possible. Relative
newcomers to Linux will still find that that book is very readable, however.
Many Linux books are available, but to date there are no complete books on administering a Linux
system. A few books do cover specific aspects of the task, such as networking or device drivers, but
none cover the entire gamut. That's the task I set for myself when this book was born: give readers
enough information to help them get their Linux systems running smoothly. The next problem was how
to condense 20 years of UNIX system administration experience into a single book. It took a while, but I
hope I've managed to include enough information on every aspect of system administration to keep you
going.
Bear in mind that this book was written for the system administrator, although the material will certainly
be applicable (and hopefully interesting) to any user who has mastered the basics of Linux. I cover
practically every aspect of system administration in this book. When dealing with subjects, like security,
that have entire books written on them, I cover only the basics. Also, I don't include all the details about
the more obscure topics that aren't relevant to most readers.
This book should provide you with everything you need, from setting up filesystems to installing servers
for popular Internet utilities. The book was not written for the advanced user; it was written for those
just starting in system administration. I hope you find a lot of useful information in this book.
A note about the CD-ROM accompanying this book. You probably already have a Linux system up and
running. Just in case you don't or you want the latest versions of some of the Linux software, this book
comes with the latest Slackware Linux CD-ROM distribution. You don't have to use this version of
Linux to use the material covered in these pages. I've tried to make the material in each chapter relevant
to as many versions as possible, and I usually give several possible pathnames and (in some cases)
filenames when they may differ across versions or distributions. If your Linux system doesn't have a file
or package in the location mentioned in this book, search your directory structure for the filenames given
and substitute the pathname as necessary.
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Linux System Administrator's Survival Guide lsgpt01.htm
Part I
Installation and Configuration
Introduction to Linux
Linux Hardware and Software
Installing and Updating Linux
LILO
Installing and Configuring XFree86
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Linux System Administrator's Survival Guide lsg01.htm
What Is Linux?
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Linux's Kernel
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GNU software
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X
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DOS Interface
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TCP/IP
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Linux's History
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Copyrights
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Sources of Help
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Documentation
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USENET Newsgroups
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World Wide Web Sites
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Linux Journal
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Recent Linux Distributions
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Summary
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Chapter 1
Introduction to Linux
The Linux operating system has become immensely popular. USENET newsgroups dedicated to the
Linux operating system have hundreds of messages a day, CD-ROMs of Linux archives are sold by the
thousands, and even more DOS users are wandering around trying to figure out UNIX syntax and Linux
installation problems. In many ways, the interest in Linux brings back the heady hacker days and the
excitement of CP/M and early DOS machines.
Linux does have its problems though. One problem is the wide variety of Linux versions available, some
of which are not very stable. The quality of the installation and configuration utilities also varies widely
from Linux version to Linux version. Another problem is supporting documentation. Although this
problem is decreasing as more people get involved, most available Linux documentation can be
intimidating for first-time users (and some veterans). Commercial books dedicated to beginning Linux
users are helping by offering a smoother explanation, but most books are simply rehashed Linux
documents.
Although this book also uses the Linux documentation as a basis, it also uses almost two decades of
UNIX system administration experience, years of working with Linux, and a lot of advice from other
users. This book is not designed for a new Linux user who can't find their way around a filesystem,
although readers with any knowledge of UNIX will feel quite at home. Instead, this book is for Linux
users who want to expand their systems, optimize them, and learn more about system administration.
Two schools of thought exist on pronouncing Linux. Because Linux is
similar to UNIX and was originally developed by a programmer with the
first name Linus, many assume the long i, as in line-ucks, is correct. On the
other hand, Linux was developed to replace a UNIX workalike called Minix
(with a short i), so the rest of the Linux community calls the operating
system lih-nicks. Which is correct? The original developers used the latter
pronunciation, while most North Americans prefer the former. Choose
whichever you wish.
What Is Linux?
Linux is a freely distributed, multitasking, multiuser operating system that behaves like UNIX. Designed
specifically for the PC, Linux takes advantage of the PC's architecture to give you performance similar
to UNIX workstations of a couple of years ago. Linux isn't a small, simple operating system like DOS
(even in its latest incarnations). The development of UNIX has resulted in a mish-mash of files and
directories, all of which are carried over to Linux for compatibility and programming reasons.
Linux includes a bunch of files for the operating system itself (called the kernel), a ton of utility
programs, documentation files, add-on emulators for other operating systems, and much more. The
following sections explain what you get when you install Linux on your system. Future chapters expand
on these topics.
Linux's Kernel
Linux is a complete multitasking, multiuser operating system that behaves like the UNIX operating
system in terms of kernel behavior and peripheral support. Linux has all the features of UNIX, plus
several recent extensions that add new versatility to Linux. All source code for Linux and its utilities is
freely available.
The Linux kernel was originally developed for the Intel 80386 CPU's protected mode. The 80386 was
designed with multitasking in mind (despite the fact that most of the Intel CPUs are used with single-
tasking DOS), and Linux makes good use of the advanced features built into the CPU's instruction set.
Memory management is especially strong with the 80386 (compared to earlier CPUs). A floating-point
emulation routine allows Linux to function on machines that do not have math coprocessors (such as the
SX series of Intel CPUs).
Linux allows shared executables so that if more than one copy of a particular application is loaded
(either by one user running several identical tasks, or several users running the same task), all the tasks
can share the same memory. This process, called copy-on-write pages, makes for much more efficient
use of RAM.
The Linux kernel also supports demand paging, which means that only sections of a program that are
necessary are read into RAM. To further optimize memory usage, Linux uses a unified memory pool.
This pool enables all free memory on the system to be used as disk cache, effectively speeding up access
to frequently used programs and data. As memory usage increases, the amount of cache is automatically
adjusted.
To support large memory requirements when only small amounts of physical RAM are available, Linux
supports swap space. Swap space enables pages of memory to be written to a reserved area of a disk and
treated as an extension of physical memory. By moving pages back and forth between the swap space
and RAM, Linux can effectively behave as if it had more physical RAM than it does, albeit at the cost of
some speed due to the hard drive's slower access.
Linux uses dynamically shared libraries extensively. Dynamically shared libraries use a common library
section for many different applications, effectively reducing the size of each application. Linux does
allow full library linking (called statically linked libraries) for portability to machines that may not have
the dynamic libraries.
To make Linux widely acceptable, it supports a number of different filesystems, including those
compatible with DOS and OS/2. Linux's own primary filesystem, called ext2fs, is designed for optimal
use of the disk.
Linux is ideally suited for application development and experimentation with new languages. Several
different compilers, including C, C++, Fortran, Pascal, Modula-2, LISP, Ada, Basic, and Smalltalk,
come with the distribution software. Many of the Linux compilers, tools, debuggers, and editors are
from the Free Software Foundation's GNU project.
GNU software
GNU (a recursive acronym for Gnu's Not UNIX) was developed by the Free Software Foundation(FSF)
to provide royalty-free software to programmers and developers. Since it was created, many programmer