Linux Unleashed, Third Edition:Introduction

Debugging Exception HandlersSummary of gdb C Specific CommandsGNU C Class LibrariesStreamsStringsRandom NumbersData CollectionLinked ListsPlex ClassesStacksQueuesSetsSummaryChapter 28—PerlWhat Is Perl?Creating and Executing Perl ProgramsHandling Data in PerlVariablesNumbersStringsFile OperatorsArraysPerl Programming ConstructsStatement Blocksif Statementsunless Statementsfor Statementsforeach Statementswhile Statementsuntil StatementsFunctionsPassing Arguments to FunctionsUsing Return ValuesPerl OperatorsConverting Programs to PerlSummaryChapter 29—Introduction to Tcl and TkWhat Is Tcl?

What Is Tk?The Tcl LanguageTcl Variables and Variable SubstitutionTcl Command SubstitutionQuotesThe if CommandThe for CommandThe while CommandThe switch CommandCommentsThe Tk Language ExtensionsFramesButtonsMenus and Menu buttonsList BoxesScrollbarsSummaryChapter 30—Other CompilersAdaCOBOLDSPEiffelFORTRANLISPModula-3OGI Speech ToolsSchemeScilabSummaryChapter 31—Smalltalk/XWhat Is Smalltalk/X?How to Install Smalltalk/XInvoking Smalltalk/XGetting Around in ST/XThe Browsers OptionThe System BrowserThe Class Hierarchy BrowserImplementors

SendersThe Changes BrowserDirectory BrowserThe Workspace OptionThe File Browser OptionThe Projects OptionThe Utilities OptionThe Goodies OptionThe Games & Demos OptionEditing in BrowsersUsing the InspectorUsing the DebuggerSummaryPart VI—Linux for System AdministratorsChapter 32—System Administration BasicsThe root AccountStarting and Stopping the SystemBooting from a FloppyUsing LILO to BootShutting Down LinuxMounting File SystemsMounting a FloppyCreating a New File SystemUnmounting File SystemsChecking File SystemsUsing a File as Swap SpaceCompressing Files with gzip and compressUsing tarBackupsSetting Up Your SystemSetting the System NameUsing a Maintenance DiskForgetting the root PasswordSetting the Login MessageSummaryChapter 33—DevicesCharacter and Block Mode Devices

Major and Minor Device NumbersThe mknod CommandPrinter AdministrationThe lpd Printing DaemonFollowing a Print RequestThe /etc/printcap File and Spooling DirectoriesAdding Printer Devices with mknodManaging Printers with lpcManaging the Printer Queue with lpq and lprmTerminalsUsing Multiport CardsAdding Serial Port TerminalsThe Login ProcessWhat Are /sbin/getty and /etc/gettydefs?Terminal Files: /etc/ttys and /etc/inittabTerminal Definitions: The /etc/termcap FileAdding a TerminalUsing stty and tsetResetting a Screwy TerminalAdding a ModemSummaryChapter 34—ProcessesWhat You Need to Know About ProcessesTypes of ProcessesUsing the ps Commandps Command OutputLogin ShellsFor the SuperuserUseful ps optionsUsing killKilling Child ProcessesKilling RightsSummaryChapter 35—Users and LoginsThe Superuser AccountUser Accounts: /etc/passwdUsernamesPasswords

User IDGroup IDCommentsHome DirectoryLogin CommandDefault System UsernamesAdding UsersDeleting UsersGroupsDefault System GroupsAdding a GroupAdding a User to New GroupsDeleting a GroupThe su CommandSummaryChapter 36—SCSI Device SupportNewer SCSI StandardsSupported SCSI DevicesSCSI Device DriversHard DrivesCD-ROM DevicesTape DrivesOther DevicesTroubleshooting SCSI DevicesSummaryChapter 37—NetworkingWhat Is TCP/IP?Hardware RequirementsConfiguring Linux FilesWhat You Need Before You StartSetting Up the Dummy InterfaceConfiguration FilesTesting and TroubleshootingThe netstat CommandpingSummaryChapter 38—SLIP and PPPSetting Up the Dummy Interface

Setting Up SLIPConfiguring SLIPdipSetting Up PPPSetting Up a PPP AccountDialing Out with chatRunning pppdChecking ProblemsPPP AuthenticationUsing DNS with SLIP and PPPSummaryChapter 39—UUCPUUCP ConfigurationTaylor UUCP ConfigurationHDB UUCP ConfigurationA UUCP ConnectionDirect ConnectionsLogin ScriptsChanging Access TimesUUCP SecurityUsing UUCPSending Email with UUCPTransferring Files with UUCPChecking on TransfersSummaryChapter 40—Configuring Linux for MailHow Email WorksConfiguring sendmailThe sendmail.cf FileConfiguration Table LocationsBuilding sendmail.cf from sendmail.m4Using sendmail Version 8smailSetting Up smailConfiguring smail for UUCPModifying Behavior of smailSummaryChapter 41—Configuring Linux for News

Usenet and NewsNNTPInstalling the NNTP Server ProgramConfiguring nntpdConfiguring NewsreadersConfiguring trnConfiguring tinSummaryChapter 42—Network SecurityWeak PasswordsFile SecurityModem AccessCallback ModemsModem-Line ProblemsHow a Modem Handles a CallUUCPLocal Area Network AccessTracking IntrudersPreparing for the WorstSummaryChapter 43—NFSConfiguring Linux for NFSConfiguring Linux ServersConfiguring Other Linux ServersSetting Up a Linux ClientSummaryChapter 44—NIS and YPSetting Up the NIS DomainNIS DaemonsSetting Up the NIS MasterSetting Up NIS SlavesSetting Up NIS ClientsSummaryChapter 45—BackupsWhy Make Backups?Backup MediaSetting a Backup ScheduleBackup Logs

Using tar for BackupsSummaryChapter 46—cron and atUsing cronCreating a crontab FileSubmitting and Managing crontab FilesComplex cron CommandsThe at ProgramSummaryPart VII—Setting up an Internet SiteChapter 47—Setting up an Internet SiteConnecting to the InternetServices You NeedDirect Connection Through a GatewayConnecting Through Another GatewayUsing a Service ProviderSummaryChapter 48—Setting Up an FTP and Anonymous FTP SiteWhat Is FTP?Using FTPHow FTP Uses TCPConfiguring FTPSetting Up ftpdFTP LoginsSetting Up the DirectoriesSetting PermissionsTest the SystemA More Secure FTPProtecting an Anonymous FTP SystemSummaryChapter 49—Configuring a WAIS SiteCompiling and Installing freeWAISSetting Up freeWAISStarting freeWAISBuilding Your WAIS IndexesWAIS Index FilesThe waisindex Command

Getting FancySummaryChapter 50—Setting up a Gopher ServiceGopher and LinuxConfiguring GopherThe gopherd.conf FileThe gopherdlocal.conf FileSetting Up the MakefileWAIS and GopherSetting Up Your Gopher DirectoriesStarting GopherLetting the World KnowSummaryChapter 51—Configuring a WWW SiteWeb Server SoftwareUnpacking the Web FilesCompiling the Web SoftwareConfiguring the Web SoftwareStarting the Web SoftwareApacheUsing make with Apache SoftwareEditing the Configuration FileApache httpd Command FlagsSetting Up Apache for a Simple Web SiteSummaryChapter 52—CGI ScriptsWhat Is CGI?CGI and HTMLCGI and PerlSummaryChapter 53—HTML Programming BasicsHTML Authoring ToolsDeveloping Web Pages on WindowsHTML Development on LinuxMaintaining HTMLHTML Programming BasicsWhat Does HTML Look Like?Starting an HTML Document

ParagraphsHyperlinksListsChanging Character AppearancesA Few Other TagsSummaryChapter 54—Java and JavaScript BasicsWhat You NeedThe Java LanguageJavaScript and HTMLSummaryChapter 55—Creating a Solid Web SiteSystem ResponseKeep Your Web Pages CleanGet Your Message Across at the Top of the PageUsing Multiple PagesUsing IconsUse Links ProperlyUsing HTML Tags ProperlySummaryPart VIII—Advanced Programming TopicsChapter 56—Source Code ControlmakeA Sample makefileBasic makefile FormatBuilding Different Versions of ProgramsForcing RecompilesMacrosSuffix RulesRCSDeltasCreating an RCS fileRetrieving an RCS FileUsing KeywordsRetrieving Version Information from an RCS FileAdministering AccessComparing and Merging Revisions

Tying It All Together: Working with make and RCSSummaryChapter 57—Working with the KernelUpgrading and Installing New Kernel SoftwareCompiling the Kernel from Source CodeAdding Drivers to the KernelUpgrading LibrariesThe Linux C CompilerDebugging and Profiling OptionsDebugging gcc Programs with gdbSummaryChapter 58—Writing Device DriversDevice DriversInterruptsAnatomy of a Linux Device DriverHeadersOpening the DeviceClosing the Devicestrategy Functionswrite() Functionsread() Functionsstart and ioctl RoutinesUsing a New Device DriverSummaryChapter 59—The Wine ProjectCurrent Status of WineSetting Up WineSystem RequirementsWhere to Get Wine DistributionHow to Install WineHow to Configure Wine Before BuildingHow to Build WineUsing WineSpecifying Configuration ParametersUsing Command-Line OptionsThe Wine DebuggerHow Wine WorksHow Wine Loads Programs

The Wine LibraryWhere Does Wine End and MS-Windows Begin?Limitations of WineSoftware That WorksUsing winestat to Analyze Windows ProgramsMajor Pieces That Are Missing from WineSoftware Unlikely to Ever WorkSummaryChapter 60—HylaFAXInstalling HylaFAXCompiling HylaFAXAdding ModemsSending a FaxThe sendfax OptionsCover PagesReceiving a FaxSummaryChapter 61—GamesWhich Games Have You Installed?X GamesGames in the xdm Root MenuCharacter-based GamesText Adventure GamesWord GamesCard GamesBoard GamesSimulations”Video” GamesMath Games and UtilitiesMultiplayer Game: HuntFull Graphics Game: SasteroidsOther Thinking GamesMiscellaneous Demos and UtilitiesSummaryChapter 62—Adabas-D and other DatabasesdBASE-Compatible DatabasesWhat Is xBase?What Is FlagShip?

Installing FlagShipUsing FlagShipPorting Existing ApplicationsdbManAdabas-DInstalling Adabas-DLINCKSOther Database ProductsSummaryChapter 63—StarOfficeInstalling StarOfficeStarting StarOfficeStarWriterStarCalcStarImpressImporting and Exporting FilesSummaryChapter 64—Lone Star Software’s Lone-TarWhat Is Lone-Tar?Using Lone-Tar’s InterfaceInstalling Lone-TarBacking Up with Lone-TarVerifying FilesRestoring FilesUtilities and Environment: Tweaking Lone-TarSummaryAppendix AAppendix BAppendix CAppendix DAppendix EAppendix FIndex

-- Table of ContentsAbout the AuthorDr. Tim Parker has written more than 40 books covering many aspects of the computer business. He isthe technical editor of SCO World Magazine, as well as a frequent contributor to dozens of magazines,including UNIX Review, Canadian Computer Reseller, UNIQUE: The UNIX Systems InformationSource, Windows NT Systems, and others. Dr. Parker is the most widely published UNIX author in theworld. When not putting up with temperamental computers, he spends his time flying, diving, and ridinghis favorite motorcycle.DedicationThis one is for Yvonne. What more can I say? Amor vincit omnia.AcknowledgmentsAs with the previous versions of Linux Unleashed, this book has been superbly managed by the finefolks at Sams. Both Jane Brownlow and Mark Cierzniak worked with me to produce another tome weare all proud of. Thanks to the technical reviewers who took the time to make excellent suggestions forimprovements and to the copy editors who made sure every sentence made sense. Without all thesepeople working under very tight deadlines, we would have a much weaker book.Thanks to the staff at Caldera for providing not only multiple versions of their Linux distribution, butalso several applications for inclusion. Thanks also to Lone Star and Cactus for their Lone-Tar product.On a personal level, thanks to my parents for tolerating yet another few months when I couldn’t visit.Thanks to “the boys” for the delightful deviations on Thursday nights. Finally, thanks to Yvonne forunderstanding why I had to, yet again, spend my mornings, days, and evenings in front of my computersinstead of with her.Tell Us What You Think!As the reader of this book, you are our most important critic and commentator. We value your opinionand want to know what we’re doing right, what we could do better, what areas you’d like to see uspublish in, and any other words of wisdom you’re willing to pass our way.As the Executive Editor for the Operating Systems team at Macmillan Computer Publishing, I welcomeyour comments. You can fax, email, or write me directly to let me know what you did or didn’t likeabout this book—as well as what we can do to make our books stronger.

Please note that I cannot help you with technical problems related to the topic of this book, and that dueto the high volume of mail I receive, I might not be able to reply to every message.When you write, please be sure to include this book’s title and author’s name, as well as your name andphone or fax number. I will carefully review your comments and share them with the author and editorswho worked on the tive EditorOperating SystemsMacmillan Computer Publishing201 West 103rd StreetIndianapolis, IN 46290 USATable of Contents

-- Previous Table of Contents NextPart IIntroductionIn This Part Introduction to Linux Types of Linux Installing Linux Using LILO Wrapping Up the InstallationChapter 1Introduction to Linuxby Tim ParkerIn This Chapter What is Linux? Linux’s history What Linux can do for you What you need to run Linux Minimum system requirements Copyrights Getting help Usenet newsgroups What’s in this book?You’ve seen dozens of books about it. You’ve read magazine articles about it. There are Usenetnewsgroups with hundred of messages a day, CD-ROMs of Linux archives sold by the thousands, andeven more Windows users wandering around trying to figure out what to make of this Linuxphenomenon. Despite the popularity of this operating system, there are still thousands, if not millions, ofusers who are curious about Linux but are afraid to take the first steps: installing and playing with thesystem. That’s what this book is intended to help with. We’ll guide you step-by-step through theinstallation procedure, show you how to use Linux, and generally introduce you to this wonderful worldof UNIX.Before we start, though, a quick word on pronouncing “Linux.” There are two schools of thought about

the i sound in “Linux”; because Linux is similar to UNIX and was originally developed by aprogrammer with the first name Linus, many assume that the long i, as in “line-ucks,” is the correctpronunciation. On the other hand, Linux was actually developed to replace a UNIX workalike calledMinix (with a short i), so the rest of the Linux community calls the operating system “lih-nicks.” Whichis correct? The original developers use the latter pronunciation, while most North Americans prefer theformer. Choose whichever you prefer. Either way, we know what you mean.What Is Linux?Linux, for those who haven’t figured it out by now, is a freely distributed multitasking multiuseroperating system that behaves like UNIX. Linux was designed specifically for the PC (Intel CPU)platform and takes advantage of its architecture to give you performance similar to high-end UNIXworkstations. A number of ports of Linux to other hardware platforms have also appeared, and theywork much like the PC version that we’ll concentrate on here.To begin, let’s look at the Linux operating system as a package. When you install Linux, what do youget? Here’s a quick list, most of which is expanded in future chapters.Linux’s KernelLinux is a complete multitasking, multiuser operating system that behaves like the UNIX operatingsystem in terms of kernel behavior and peripheral support. Linux has all the features of UNIX, plusseveral recent extensions that add new versatility to Linux. All source code for Linux and its utilities isfreely available.The Linux kernel was originally developed for the Intel 80386 CPU’s protected mode. The 80386 wasoriginally designed with multitasking in mind (despite the fact that most of the Intel CPUs are used withsingle-tasking DOS), and Linux makes good use of the advanced features built into the CPU’sinstruction set. Memory management is especially strong with the 80386 (compared to earlier CPUs). Afloating point emulation routine allows Linux to function on machines that do not have mathcoprocessors.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 taskscan share the same memory. This process, called copy-on-write pages, makes for much more efficientuse of RAM.The Linux kernel also supports demand paging, which means that only the sections of a program that arenecessary are read into RAM. To further optimize memory usage, Linux uses a unified memory pool.This enables all free memory on the system to be used as disk cache, effectively speeding access tofrequently used programs and data. As memory usage increases, the amount of cache is automaticallyadjusted.

To support large memory requirements when only small amounts of physical RAM are available, Linuxsupports swap space. Swap space (which is somewhat of a misnomer) allows pages of memory to bewritten to a reserved area of a disk and treated as an extension of physical memory. By moving pagesback and forth between the swap space and RAM, Linux can effectively behave as if it had much morephysical 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 librarysection for many different applications, effectively reducing the size of each application. Linux doesallow full library linking (called statically linked libraries) for portability to machines that may not havethe dynamic libraries.To make Linux widely acceptable, it supports a number of different file systems, including thosecompatible with DOS and OS/2. Linux’s own file system, called ext2fs, is designed for optimal use ofthe disk.Linux is ideally suited for application development and experimentation with new languages. As part ofthe distribution software there are several different compilers, including C, C , Fortran, Pascal, LISP,Ada, BASIC, and Smalltalk. Many of the Linux compilers, tools, debuggers, and editors are from theFree Software Foundation’s GNU project.GNU SoftwareGNU (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 programmerpackages and toolkits have been developed and assigned to FSF for distribution. Most of the GNUsoftware mirrors commerc

GNU Software X DOS and Windows Interface TCP/IP Linux’s History What Linux Can Do for You Learning UNIX Through Linux Running a Business Internet Servers What You Need to Run Linux Minimum System Requirements Motherboard Requirements Hard Disks Video System Mouse Tape Drives CD-ROM