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A Practical Guide to Linux Commands, Editors, and Shell Programming, Fourth Edition

Name: A Practical Guide to Linux Commands, Editors, and Shell Programming, Fourth Edition
ISBN: 9780134774626

by Mark G. Sobell, Matthew Helmke

November 2017

Intermediate to advanced

1232 pages

36h 16m

English

Pearson

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Cover Page
About This E-Book
Title Page
Copyright Page
Dedication
Brief Contents
Contents
Preface
Chapter 1: Welcome to Linux and macOS
The History of UNIX and GNU–LinuxThe Heritage of Linux: UNIXFade to 1983Next Scene, 1991The Code Is FreeHave Fun!What Is So Good About Linux?Why Linux Is Popular with Hardware Companies and DevelopersLinux Is PortableThe C Programming LanguageOverview of LinuxLinux Has a Kernel Programming InterfaceLinux Can Support Many UsersLinux Can Run Many TasksLinux Provides a Secure Hierarchical FilesystemThe Shell: Command Interpreter and Programming LanguageA Large Collection of Useful UtilitiesInterprocess CommunicationSystem AdministrationAdditional Features of LinuxGUIs: Graphical User Interfaces(Inter)Networking UtilitiesSoftware DevelopmentChapter SummaryExercises
Part I The Linux and macOS Operating Systems

Chapter 2: Getting Started
Conventions Used in This BookLogging In from a Terminal (Emulator)Working from the Command LineWhich Shell Are You Running?Correcting MistakesRepeating/Editing Command Linessu/sudo: Curbing Your Power (root Privileges)Where to Find Documentationman: Displays the System Manualapropos: Searches for a Keywordinfo: Displays Information About UtilitiesThe ––help OptionThe bash help CommandGetting HelpMore About Logging In and PasswordsWhat to Do If You Cannot Log InLogging In Remotely: Terminal Emulators, ssh, and Dial-Up ConnectionsUsing Virtual ConsolesLogging OutChanging Your PasswordChapter SummaryExercisesAdvanced Exercises
Chapter 3: The Utilities
Special CharactersBasic Utilitiesls: Lists the Names of Filescat: Displays a Text Filerm: Deletes a Fileless Is more: Display a Text File One Screen at a Timehostname: Displays the System NameWorking with Filescp: Copies a Filemv: Changes the Name of a Filelpr: Prints a Filegrep: Searches for a Stringhead: Displays the Beginning of a Filetail: Displays the End of a Filesort: Displays a File in Orderuniq: Removes Duplicate Lines from a Filediff: Compares Two Filesfile: Identifies the Contents of a File| (Pipeline): Communicates Between ProcessesFour More Utilitiesecho: Displays Textdate: Displays the Time and Datescript: Records a Shell Sessionunix2dos: Converts Linux Files to Windows and macOS FormatCompressing and Archiving Filesbzip2: Compresses a Filebzcat and bunzip2: Decompress a Filegzip: Compresses a Filetar: Packs and Unpacks ArchivesLocating Utilitieswhich and whereis: Locate a Utilitylocate: Searches for a FileDisplaying User and System Informationwho: Lists Users on the Systemfinger: Lists Users on the Systemuptime: Displays System Load and Duration Informationw: Lists Users on the Systemfree: Displays Memory Usage InformationCommunicating with Other Userswrite: Sends a Messagemesg: Denies or Accepts MessagesEmailChapter SummaryExercisesAdvanced Exercises
Chapter 4: The Filesystem
The Hierarchical FilesystemDirectory Files and Ordinary FilesFilenamesThe Working DirectoryYour Home DirectoryPathnamesAbsolute PathnamesRelative PathnamesWorking with Directoriesmkdir: Creates a Directorycd: Changes to Another Working Directoryrmdir: Deletes a DirectoryUsing Pathnamesmv, cp: Move or Copy Filesmv: Moves a DirectoryImportant Standard Directories and FilesAccess Permissionsls –l: Displays Permissionschmod: Changes Access PermissionsSetuid and Setgid PermissionsDirectory Access PermissionsACLs: Access Control ListsEnabling ACLsWorking with Access RulesSetting Default Rules for a DirectoryLinksHard LinksSymbolic Linksrm: Removes a LinkDereferencing Symbolic LinksChapter SummaryExercisesAdvanced Exercises
Chapter 5: The Shell
Special CharactersOrdinary Files and Directory FilesThe Working DirectoryYour Home DirectoryThe Command LineA Simple CommandSyntaxSimple CommandsProcessing the Command LineExecuting a CommandEditing the Command LineStandard Input and Standard OutputThe Screen as a FileThe Keyboard and Screen as Standard Input and Standard OutputRedirectionPipelinesListsRunning a Command in the BackgroundFilename Generation/Pathname ExpansionThe ? Special CharacterThe * Special CharacterThe [ ] Special CharactersBuiltinsChapter SummaryUtilities and Builtins Introduced in This ChapterExercisesAdvanced Exercises
Part II The Editors
Chapter 6: The vim Editor
HistoryTutorial: Using vim to Create and Edit a FileStarting vimCommand and Input ModesEntering TextGetting HelpEnding the Editing SessionThe compatible ParameterIntroduction to vim FeaturesOnline HelpTerminologyModes of OperationThe DisplayCorrecting Text as You Insert ItWork BufferLine Length and File SizeWindowsFile LocksAbnormal Termination of an Editing SessionRecovering Text After a CrashCommand Mode: Moving the CursorMoving the Cursor by CharactersMoving the Cursor to a Specific CharacterMoving the Cursor by WordsMoving the Cursor by LinesMoving the Cursor by Sentences and ParagraphsMoving the Cursor Within the ScreenViewing Different Parts of the Work BufferInput ModeInserting TextAppending TextOpening a Line for TextReplacing TextQuoting Special Characters in Input ModeCommand Mode: Deleting and Changing TextUndoing ChangesDeleting CharactersDeleting TextChanging TextReplacing TextChanging CaseSearching and SubstitutingSearching for a CharacterSearching for a StringSubstituting One String for AnotherMiscellaneous CommandsJoinStatus. (Period)Copying, Moving, and Deleting TextThe General-Purpose BufferNamed BuffersNumbered BuffersReading and Writing FilesReading FilesWriting FilesIdentifying the Current FileSetting ParametersSetting Parameters from Within vimSetting Parameters in a Startup FileThe .vimrc Startup FileParametersAdvanced Editing TechniquesUsing MarkersEditing Other FilesMacros and ShortcutsExecuting Shell Commands from Within vimUnits of MeasureCharacterWordBlank-Delimited WordLineSentenceParagraphScreen (Window)Repeat FactorChapter SummaryExercisesAdvanced Exercises
Chapter 7: The emacs Editor
HistoryEvolutionemacs Versus vimTutorial: Getting Started with emacsStarting emacsExitingInserting TextDeleting CharactersMoving the CursorEditing at the Cursor PositionSaving and Retrieving the BufferBasic Editing CommandsKeys: Notation and UseKey Sequences and CommandsMETA-x: Running a Command Without a Key BindingNumeric ArgumentsPoint and the CursorScrolling Through a BufferErasing TextSearching for TextUsing the Menubar from the KeyboardOnline HelpAdvanced EditingUndoing ChangesPoint, Mark, and RegionCut and Paste: Yanking Killed TextInserting Special CharactersGlobal Buffer CommandsVisiting and Saving FilesBuffersWindowsForeground Shell CommandsBackground Shell CommandsMajor Modes: Language-Sensitive EditingSelecting a Major ModeHuman-Language ModesC ModeCustomizing IndentionCommentsSpecial-Purpose ModesCustomizing emacsThe .emacs Startup FileRemapping KeysA Sample .emacs FileMore InformationAccess to emacsChapter SummaryExercisesAdvanced Exercises
Part III The Shells
Chapter 8: The Bourne Again Shell (bash)
BackgroundStartup FilesLogin ShellsInteractive Nonlogin ShellsNoninteractive ShellsSetting Up Startup Files. (Dot) or source: Runs a Startup File in the Current ShellCommands That Are SymbolsRedirecting Standard ErrorWriting and Executing a Simple Shell Scriptchmod: Makes a File Executable#! Specifies a Shell# Begins a CommentExecuting a Shell ScriptControl Operators: Separate and Group Commands; and NEWLINE Separate Commands| and & Separate Commands and Do Something Else&& and || Boolean Control Operators( ) Groups Commands\ Continues a CommandJob Controljobs: Lists Jobsfg: Brings a Job to the ForegroundSuspending a Jobbg: Sends a Job to the BackgroundManipulating the Directory Stackdirs: Displays the Stackpushd: Pushes a Directory on the Stackpopd: Pops a Directory Off the StackParameters and VariablesUser-Created VariablesVariable AttributesKeyword VariablesSpecial CharactersLocaleTime
Processes
Process StructureProcess IdentificationExecuting a CommandHistoryVariables That Control HistoryReexecuting and Editing CommandsThe Readline LibraryAliasesSingle Versus Double Quotation Marks in AliasesExamples of AliasesFunctionsControlling bash: Features and Optionsbash Command-Line OptionsShell FeaturesProcessing the Command LineHistory ExpansionAlias SubstitutionParsing and Scanning the Command LineCommand-Line ExpansionChapter SummaryExercisesAdvanced Exercises
Chapter 9: The TC Shell (tcsh)
Shell ScriptsEntering and Leaving the TC ShellStartup FilesFeatures Common to the Bourne Again and TC ShellsCommand-Line Expansion (Substitution)Job ControlFilename SubstitutionManipulating the Directory StackCommand SubstitutionRedirecting Standard ErrorWorking with the Command LineWord CompletionEditing the Command LineCorrecting SpellingVariablesVariable SubstitutionString VariablesArrays of String VariablesNumeric VariablesBracesSpecial Variable Formstcsh VariablesControl StructuresifgotoInterrupt Handlingif...then...elseforeachwhilebreak and continueswitchBuiltinsChapter SummaryExercisesAdvanced Exercises
Part IV Programming Tools
Chapter 10: Programming the Bourne Again Shell (bash)
Control Structuresif...thenif...then...elseif...then...eliffor...inforwhileuntilbreak and continuecaseselectHere DocumentFile DescriptorsOpening a File DescriptorDuplicating a File DescriptorFile Descriptor ExamplesDetermining Whether a File Descriptor Is Associated with the TerminalParametersPositional ParametersSpecial ParametersVariablesShell Variables
Environment, Environment Variables, and Inheritance
Expanding Null and Unset VariablesArray VariablesVariables in FunctionsBuiltin Commandstype: Displays Information About a Commandread: Accepts User Inputexec: Executes a Command or Redirects File Descriptorstrap: Catches a Signalkill: Aborts a Processeval: Scans, Evaluates, and Executes a Command Linegetopts: Parses OptionsA Partial List of BuiltinsExpressionsArithmetic EvaluationLogical Evaluation (Conditional Expressions)String Pattern MatchingArithmetic OperatorsImplicit Command-Line ContinuationShell ProgramsA Recursive Shell ScriptThe quiz Shell ScriptChapter SummaryExercisesAdvanced Exercises
Chapter 11: The Perl Scripting Language
Introduction to PerlMore InformationHelpperldocTerminologyRunning a Perl ProgramSyntaxVariablesScalar VariablesArray VariablesHash VariablesControl Structuresif/unlessif...elseif...elsif...elseforeach/forlast and nextwhile/untilWorking with FilesSortSubroutinesRegular ExpressionsSyntax and the =~ OperatorCPAN ModulesExamplesChapter SummaryExercisesAdvanced Exercises
Chapter 12: The Python Programming Language
IntroductionInvoking PythonMore InformationWriting to Standard Output and Reading from Standard InputFunctions and MethodsScalar Variables, Lists, and DictionariesScalar VariablesListsDictionariesControl Structuresifif...elseif...elif...elsewhileforReading from and Writing to FilesFile Input and OutputException HandlingPickleRegular ExpressionsDefining a FunctionUsing LibrariesStandard LibraryNonstandard LibrariesSciPy and NumPy LibrariesNamespaceImporting a ModuleExample of Importing a FunctionLambda FunctionsList ComprehensionsChapter SummaryExercisesAdvanced Exercises
Chapter 13: The MariaDB SQL Database Management System
HistoryNotesSyntax and ConventionsMore InformationInstalling a MariaDB Server and ClientFedora/RHEL (Red Hat Enterprise Linux)Debian/Ubuntu/MintopenSUSEmacOSClient OptionsSetting Up MariaDBAssigning a Password to the MariaDB User Named rootRemoving Anonymous UsersRunning the Secure Installation Script~/.my.cnf: Configures a MariaDB Client~/.mysql_history: Stores Your MariaDB HistoryCreating a DatabaseAdding a UserExamplesLogging InCreating a TableAdding DataRetrieving DataBacking Up a DatabaseModifying DataCreating a Second TableJoinsChapter SummaryExercises
Chapter 14: The AWK Pattern Processing Language
SyntaxArgumentsOptionsNotesLanguage BasicsPatternsActionsCommentsVariablesFunctionsArithmetic OperatorsAssociative ArraysprintfControl StructuresExamplesAdvanced gawk Programminggetline: Controlling InputCoprocess: Two-Way I/OGetting Input from a NetworkChapter SummaryExercisesAdvanced Exercises
Chapter 15: The sed Editor
SyntaxArgumentsOptionsEditor BasicsAddressesInstructionsControl StructuresThe Hold SpaceExamplesChapter SummaryExercises
Part V Secure Network Utilities
Chapter 16: The rsync Secure Copy Utility
SyntaxArgumentsOptionsNotesMore InformationExamplesUsing a Trailing Slash ( / ) on source-fileRemoving FilesCopying Files to and from a Remote SystemMirroring a DirectoryMaking BackupsRestoring a FileChapter SummaryExercises
Chapter 17: The OpenSSH Secure Communication Utilities
Introduction to OpenSSHFilesMore InformationRunning the ssh, scp , and sftp OpenSSH ClientsPrerequisitesJumpStart I: Using ssh and scp to Connect to an OpenSSH ServerConfiguring OpenSSH Clientsssh: Logs in or Executes Commands on a Remote Systemscp: Copies Files to and from a Remote Systemsftp: A Secure FTP Client~/.ssh/config and /etc/ssh/ssh_config Configuration FilesSetting Up an OpenSSH Server (sshd)PrerequisitesNoteJumpStart II: Starting an OpenSSH ServerAuthorized Keys: Automatic LoginRandomart Imagessh-agent: Holds Your Private KeysCommand-Line Options/etc/ssh/sshd_config Configuration FileTroubleshootingTunneling/Port ForwardingForwarding X11Port ForwardingChapter SummaryExercisesAdvanced Exercises
Part VI Command Reference
Utilities That Display and Manipulate Files
Network UtilitiesUtilities That Display and Alter StatusUtilities That Are Programming ToolsMiscellaneous UtilitiesStandard Multiplicative SuffixesCommon OptionsThe sample Utilitysample Brief description of what the utility does aspell Checks a file for spelling errorsat Executes commands at a specified timebusybox Implements many standard utilitiesbzip2 Compresses or decompresses filescal Displays a calendarcat Joins and displays filescd Changes to another working directorychgrp Changes the group associated with a filechmod Changes the access mode (permissions) of a filechown Changes the owner of a file and/or the group the file is associated withcmp Compares two filescomm Compares sorted filesconfigure Configures source code automaticallycp Copies filescpio Creates an archive, restores files from an archive, or copies a directory hierarchycrontab Maintains crontab filescut Selects characters or fields from input linesdate Displays or sets the system time and datedd Converts and copies a filedf Displays disk space usagediff Displays the differences between two text filesdiskutil Checks, modifies, and repairs local volumes
ditto Copies files and creates and unpacks archives
dmesg Displays kernel messagesdscl Displays and manages Directory Service information du Displays information on disk usage by directory hierarchy and/or fileecho Displays a messageexpand/unexpand Converts TABs to SPACEs and SPACEs to TABsexpr Evaluates an expressionfile Displays the classification of a filefind Finds files based on criteriafinger Displays information about usersfmt Formats text very simplyfsck Checks and repairs a filesystemftp Transfers files over a networkgawk Searches for and processes patterns in a filegcc Compiles C and C++ programsGetFileInfo Displays file attributes grep Searches for a pattern in filesgzip Compresses or decompresses fileshead Displays the beginning of a file
join Joins lines from two files based on a common field
kill Terminates a process by PIDkillall Terminates a process by namelaunchctl Controls the launchd daemon less Displays text files, one screen at a timeln Makes a link to a filelpr Sends files to printersls Displays information about one or more filesmake Keeps a set of programs currentman Displays documentation for utilitiesmc Manages files in a textual environment (aka Midnight Commander)mkdir Creates a directorymkfs Creates a filesystem on a devicemv Renames or moves a filenice Changes the priority of a commandnl Numbers lines from a filenohup Runs a command that keeps running after you log outod Dumps the contents of a fileopen Opens files, directories, and URLs otool Displays object, library, and executable files paste Joins corresponding lines from filespax Creates an archive, restores files from an archive, or copies a directory hierarchyplutil Manipulates property list files pr Paginates files for printingprintf Formats string and numeric dataps Displays process statusrenice Changes the priority of a process
rm Removes a file (deletes a link)
rmdir Removes directoriesrsync Securely copies files and directory hierarchies over a networkscp Securely copies one or more files to or from a remote systemscreen Manages several textual windowssed Edits a file noninteractivelySetFile Sets file attributes sleep Creates a process that sleeps for a specified intervalsort Sorts and/or merges filessplit Divides a file into sectionsssh Securely runs a program or opens a shell on a remote systemsshfs/curlftpfs Mounts a directory on an OpenSSH or FTP server as a local directorystat Displays information about filesstrings Displays strings of printable characters from filesstty Displays or sets terminal parameterssysctl Displays and alters kernel variables at runtimetail Displays the last part (tail) of a filetar Stores or retrieves files to/from an archive filetee Copies standard input to standard output and one or more filestelnet Connects to a remote computer over a networktest Evaluates an expressiontop Dynamically displays process statustouch Creates a file or changes a file’s access and/or modification timetr Replaces specified characterstty Displays the terminal pathnametune2fs Changes parameters on an ext2, ext3, or ext4 filesystemumask Specifies the file-creation permissions maskuniq Displays unique lines from a filew Displays information about local system userswc Displays the number of lines, words, and bytes in one or more fileswhich Shows where in PATH a utility is locatedwho Displays information about logged-in usersxargs Converts standard input to command lines
Part VII Appendixes
Appendix A Regular Expressions
CharactersDelimitersSimple StringsSpecial CharactersPeriodsBracketsAsterisksCarets and Dollar SignsQuoting Special CharactersRulesLongest Match PossibleEmpty Regular ExpressionsBracketing ExpressionsThe Replacement StringAmpersandQuoted DigitExtended Regular ExpressionsAppendix Summary
Appendix B Help
Solving a ProblemFinding Linux and macOS Related InformationMailing ListsSpecifying a Terminal
Appendix C Keeping the System Up-to-Date
Using dnfUsing dnf to Install, Remove, and Update PackagesOther dnf Commandsdnf GroupsDownloading rpm Package Files Using dnf downloadConfiguring dnfUsing apt-getUsing apt-get to Install, Remove, and Update PackagesUsing apt-get to Upgrade the SystemOther apt-get CommandsUsing apt CommandsRepositoriessources.list: Specifies Repositories for apt-get to SearchBitTorrent
Appendix D macOS Notes
Open DirectoryFilesystemsNondisk FilesystemsCase Sensitivity/VolumesExtended AttributesFile ForksFile AttributesACLsActivating the Terminal META KeyStartup FilesRemote LoginsMany Utilities Do Not Respect Apple Human Interface GuidelinesInstalling Xcode and MacPortsmacOS Implementation of Linux Features
Glossary
File Tree Index
Utility Index
Main Index

Content preview from A Practical Guide to Linux Commands, Editors, and Shell Programming, Fourth Edition

Environment, Environment Variables, and Inheritance

This section explains the concepts of the command execution environment and inheritance.

Environment

When the Linux kernel invokes a program, the kernel passes to the program a list comprising an array of strings. This list, called the command execution environment or simply the environment, holds a series of name-value pairs in the form name=value.

Environment Variables

When bash is invoked, it scans its environment and creates parameters for each name-value pair, assigning the corresponding value to each name. Each of these parameters is an environment variable; these variables are in the shell’s environment. Environment variables are sometimes referred to as global variables or exported variables. ...

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