book

Pro Bash Programming : Scripting the GNU/Linux Shell, Second Edition

by Chris F. A. Johnson, Jayant Varma

June 2015

Beginner to intermediate

256 pages

4h 48m

English

Apress

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The CodeThe FileThe Naming of ScriptsSelecting a Directory for the ScriptCreating the File and Running the ScriptChoosing and Using a Text EditorBuilding a Better “Hello, World!”SummaryCommandsConceptsVariablesExercises
Parameter and VariablesPositional ParametersSpecial*@#0$?_!- ParametersVariablesArguments and Optionsecho, and Why You Should Avoid Itprintf: Formatting and Printing DataEscape SequencesFormat SpecifiersWidth SpecificationPrinting to a VariableLine ContinuationStandard Input /Output Streams and RedirectionRedirection: >, >>, and <Reading InputPipelinesCommand SubstitutionSummaryCommandsConceptsExercises

Exit StatusTesting an Expressiontest, a.k.a. [ … ][[ … ]]: Evaluate an Expression(( … )): Evaluate an Arithmetic ExpressionConditional ExecutionifConditional Operators, & and ||caseLoopingwhileuntilforbreakcontinueSummaryCommandsConceptsExercises
QuotingBrace ExpansionTilde ExpansionParameter and Variable ExpansionArithmetic ExpansionCommand SubstitutionWord SplittingPathname ExpansionProcess SubstitutionParsing OptionsSummaryCommandsExercises
The Naming of VariablesThe Scope of a Variable: Can You See It from Here?Shell VariablesParameter ExpansionBourne ShellPOSIX ShellBashBash-4.0Positional ParametersArraysInteger-Indexed ArraysAssociative ArraysSummaryCommandsConcepts
Definition SyntaxCompound CommandsGetting ResultsSet Different Exit CodesPrint the ResultPlace Results in One or More VariablesFunction LibrariesUsing Functions from LibrariesSample ScriptSummaryCommandsExercises
ConcatenationRepeat Character to a Given LengthProcessing Character by CharacterReversalCase ConversionComparing Contents Without Regard to CaseCheck for Valid Variable NameInsert One String into AnotherExamplesOverlayExamplesTrim Unwanted CharactersExamplesIndexSummaryCommandsFunctionsExercises
Reading a FileExternal CommandscatheadtouchlscutwcRegular ExpressionsgrepsedawkFile Name Expansion OptionsnullglobfailglobdotglobextglobnocaseglobglobstarSummaryShell OptionsExternal CommandsExercises
help, Display Information About Built-In Commandstime, Print Time Taken for Execution of a Commandread, Read a Line from an Input Stream-r, Read Backslashes Literally-e, Get Input with the readline Library-a, Read Words into an Array-d DELIM, Read Until DELIM Instead of a Newline-n NUM, Read a Maximum of NUM Characters-s, Do Not Echo Input Coming from a Terminal-p PROMPT:, Output PROMPT Without a Trailing Newline-t TIMEOUT, Only Wait TIMEOUT Seconds for Complete Input-u FD: Read from File Descriptor FD Instead of the Standard Input-i TEXT, Use TEXT as the Initial Text for Readlineeval, Expand Arguments and Execute Resulting CommandPoor Man’s ArraysSetting Multiple Variables from One Commandtype, Display Information About Commandsbuiltin, Execute a Built-In Commandcommand, Execute a Command or Display Information About Commandspwd, Print the Current Working Directoryunalias, Remove One or More AliasesDeprecated Built-InsDynamically Loadable Built-InsSummaryCommands and Reserved WordsDeprecated CommandsExercise
Prevention Is Better Than CureStructure Your ProgramsDocument Your CodeFormat Your Code ConsistentlyThe K.I.S.S. PrincipleTest as You GoDebugging a ScriptSummaryExercises
Manipulating the Directory StackcdpdcdmmenuFilesystem Functionsllsrcp, mvmdMiscellaneous Functionspr1calcManaging Man PagessmansuskGamesThe fifteen PuzzleSummaryExercises
Defining VariablesCommand-Line Options and ArgumentsMenusQ&A DialogueConfiguration FilesScripts with Several NamesEnvironment VariablesAll Together NowScript InformationDefault ConfigurationScreen VariablesFunction DefinitionsParse Command-Line OptionsBits and PiecesSummaryExercises
ArraysHoles in an Indexed ArrayUsing an Array for SortingTwo-Dimensional GridsData File FormatsLine-Based RecordsBlock File FormatsSummaryExercises
Teletypewriter vs. CanvasStretching the CanvasCommand Sequence IntroducerPriming the CanvasMoving the CursorChanging Rendition Modes and ColorsPlacing a Block of Text on the ScreenScrolling TextRolling DiceSummaryExercises
Single-Key EntryFunction Library, key-funcsHistory in ScriptsSanity CheckingForm EntryReading the MouseSummaryExercises
BASHBASHPIDBASH_ALIASESBASH_ARGCBASH_ARGVBASH_CMDSBASH_COMMANDBASH_EXECUTION_STRINGBASH_LINENOBASH_REMATCHBASH_SOURCEBASH_SUBSHELLBASH_VERSINFOBASH_VERSIONCOMP_CWORDCOMP_KEYCOMP_LINECOMP_POINTCOMP_TYPECOMP_WORDBREAKSCOMP_WORDSDIRSTACKEUIDFUNCNAMEGROUPSHISTCMDHOSTNAMEHOSTTYPELINENOMACHTYPEOLDPWDOPTARGOPTINDOSTYPEPIPESTATUSPPIDPWDRANDOMREPLYSECONDSSHELLOPTSSHLVLUIDBASH_ENVCDPATHCOLUMNSCOMPREPLYEMACSFCEDITFIGNOREGLOBIGNOREHISTCONTROLHISTFILEHISTFILESIZEHISTIGNOREHISTSIZEHISTTIMEFORMATHOMEHOSTFILEIFSIGNOREEOFINPUTRCLANGLC_ALLLC_COLLATELC_CTYPELC_MESSAGESLC_NUMERICLINESMAILMAILCHECKMAILPATHOPTERRPATHPOSIXLY_CORRECTPROMPT_COMMANDPROMPT_DIRTRIMPS1PS2PS3PS4SHELLTIMEFORMATTMOUTTMPDIRauto_resumehistchars

Overview

Pro Bash Programming teaches you how to effectively utilize the Bash shell in your programming. The Bash shell is a complete programming language, not merely a glue to combine external Linux commands. By taking full advantage of Shell internals, Shell programs can perform as snappily as utilities written in C or other compiled languages. And you will see how, without assuming Unix lore, you can write professional Bash 4.3 programs through standard programming techniques.

This second edition has updated for Bash 4.3, and many scripts have been rewritten to make them more idiomatically Bash, taking better advantage of features specific to Bash. It is easy to read, understand, and will teach you how to get to grips with Bash programming without drowning you in pages and pages of syntax.

Using this book you will be able to use the shell efficiently, make scripts run faster using expansion and external commands, and understand how to overcome many common mistakes that cause scripts to fail. This book is perfect for all beginning Linux and Unix system administrators who want to be in full control of their systems, and really get to grips with Bash programming.