book

The Linux Command Line, 3rd Edition

Name: The Linux Command Line, 3rd Edition
Author: William E. Shotts
ISBN: 9781718504523

by William E. Shotts

February 2026

Beginner to intermediate

544 pages

11h 40m

English

No Starch Press

Read now

Unlock full access

Cover Page
Title Page
Copyright Page
About the Author
About the Technical Reviewer
BRIEF CONTENTS
CONTENTS IN DETAIL
ACKNOWLEDGMENTS
INTRODUCTION
Why Use the Command Line?What This Book Is AboutWho Should Read This BookWhat’s in This BookHow to Read This BookPrerequisitesWhat’s New in the Third Print EditionYour Feedback Is Needed!
PART I: LEARNING THE SHELL

1 WHAT IS THE SHELL?
Terminal EmulatorsMaking Your First KeystrokesCommand HistoryCursor MovementTry Some Simple CommandsEnding a Terminal SessionSumming Up
2 NAVIGATION
Understanding the Filesystem TreeThe Current Working DirectoryListing the Contents of a DirectoryChanging the Current Working DirectoryAbsolute PathnamesRelative PathnamesSome Helpful ShortcutsSumming Up
3 EXPLORING THE SYSTEM
More Fun with lsOptions and ArgumentsA Longer Look at Long FormatDetermining a File’s Type with fileViewing File Contents with lessTaking a Guided TourSymbolic LinksHard LinksSumming Up
4 MANIPULATING FILES AND DIRECTORIES
WildcardsDot Filesmkdir—Create Directoriescp—Copy Files and DirectoriesUseful Options and Examplesmv—Move and Rename FilesUseful Options and Examplesrm—Remove Files and DirectoriesUseful Options and Examplesln—Create LinksHard LinksSymbolic LinksLet’s Build a PlaygroundCreating DirectoriesCopying FilesMoving and Renaming FilesCreating Hard LinksCreating Symbolic LinksRemoving Files and DirectoriesSumming Up
5 WORKING WITH COMMANDS
What Exactly Are Commands?Identifying Commandstype—Display a Command’s Typewhich—Display an Executable’s LocationGetting a Command’s Documentationhelp—Get Help for Shell Builtins--help—Display Usage Informationman—Display a Program’s Manual Pageapropos—Display Appropriate Commandswhatis—Display One-Line Manual Page Descriptionsinfo—Display a Program’s Info EntryREADME and Other Program Documentation FilesCreating Our Own Commands with aliasSumming Up
6 REDIRECTION
Standard Input, Output, and ErrorRedirecting Standard OutputGroup CommandsRedirecting Standard ErrorRedirecting Standard Output and Standard Error to One FileDisposing of Unwanted OutputRedirecting Standard Inputcat—Concatenate FilesPipelinesFiltersuniq—Report or Omit Repeated Lineswc—Print Line, Word, and Byte Countsgrep—Print Lines Matching a Patternhead/tail—Print First/Last Part of Filestee—Read from Stdin and Output to Stdout and FilesSumming Up
7 SEEING THE WORLD AS THE SHELL SEES IT
ExpansionPathname ExpansionTilde ExpansionArithmetic ExpansionBrace ExpansionParameter ExpansionCommand SubstitutionQuotingDouble QuotesSingle QuotesEscaping CharactersBackslash Escape SequencesSumming Up
8 ADVANCED KEYBOARD TRICKS
Command Line EditingCursor MovementModifying TextCutting and Pasting (Killing and Yanking) TextCommand CompletionUsing HistorySearching HistoryHistory ExpansionSumming Up
9 PERMISSIONS
Users, Group Members, and Everybody ElseReading, Writing, and Executingchmod—Change File ModeSetting File Mode with the GUIumask—Set Default PermissionsSome Special PermissionsChanging Identitiessu—Run a Shell with Substitute User and Group IDssudo—Execute a Command as Another Userchown—Change File Owner and Groupchgrp—Change Group OwnershipExercising Our PrivilegesChanging Your PasswordSumming Up
10 PROCESSES
How a Process WorksViewing ProcessesViewing Processes Dynamically with topControlling ProcessesInterrupting a ProcessPutting a Process in the BackgroundReturning a Process to the ForegroundStopping (Pausing) a ProcessChanging Process PrioritySignalsSending Signals to Processes with killMaking a Process Hang-Up ProofSending Signals to Multiple Processes with killallShutting Down the SystemMore Process-Related CommandsSumming Up
PART II: CONFIGURATION AND THE ENVIRONMENT
11 THE ENVIRONMENT
What Is Stored in the Environment?Examining the EnvironmentSome Interesting VariablesHow Is the Environment Established?What’s in a Startup File?Exploring How Child Processes Inherit Their EnvironmentsLaunching a Program with a Temporary EnvironmentModifying the EnvironmentWhich Files Should We Modify?Text EditorsUsing a Text EditorActivating Our ChangesSumming Up
12 A GENTLE INTRODUCTION TO VI(M)
Why We Should Learn viA Little BackgroundStarting and Stopping viEditing ModesEntering Insert ModeSaving Our WorkMoving the Cursor AroundBasic EditingAppending TextOpening a LineDeleting TextCutting, Copying, and Pasting TextJoining LinesSearch-and-ReplaceSearching Within a LineSearching the Entire FileGlobal Search-and-ReplaceEditing Multiple FilesSwitching Between FilesOpening Additional Files for EditingCopying Content from One File into AnotherInserting an Entire File into AnotherSaving Our Workbash Does vi TooSumming Up
13 CUSTOMIZING THE PROMPT
Anatomy of a PromptTrying Some Alternative Prompt DesignsAdding ColorMoving the CursorSaving the PromptSumming Up
PART III: COMMON TASKS AND ESSENTIAL TOOLS
14 PACKAGE MANAGEMENT
Packaging SystemsHow a Package System WorksPackage FilesRepositoriesDependenciesHigh- and Low-Level Package ToolsCommon Package Management TasksFinding a Package in a RepositoryInstalling a Package from a RepositoryInstalling a Package from a Package FileRemoving a PackageUpdating Packages from a RepositoryUpgrading a Package from a Package FileListing Installed PackagesDetermining Whether a Package Is InstalledDisplaying Information About an Installed PackageFinding Which Package Installed a FileSumming Up
15 STORAGE MEDIA
Mounting and Unmounting Storage DevicesViewing a List of Mounted FilesystemsDetermining Device NamesCreating New FilesystemsManipulating Partitions with partedCreating a New Filesystem with mkfsTesting and Repairing FilesystemsMoving Data Directly to and from DevicesCreating CD-ROM ImagesCreating an Image Copy of a CD-ROMCreating an Image from a Collection of FilesWriting CD-ROM ImagesMounting an ISO Image DirectlyBlanking a Rewritable CD-ROMWriting an ImageVerifying DataSumming Up
16 NETWORKING
Examining and Monitoring a NetworkpingtracerouteipTransporting Files Over a Networkftplftp—A Better ftpcurl—Transfer a URLwget—Non-Interactive Network DownloaderSecure Communication with Remote Hostssshscp and sftpSumming Up
17 SEARCHING FOR FILES
locate—Find Files the Easy Wayfind—Find Files the Hard WayTestsOperatorsPredefined ActionsUser-Defined ActionsImproving EfficiencyxargsA Return to the PlaygroundOptionsSumming Up
18 ARCHIVING AND BACKUP
Compressing Filesgzipbzip2Archiving FilestarzipSynchronizing Files and DirectoriesUsing rsync Over a NetworkSumming Up
19 REGULAR EXPRESSIONS
What Are Regular Expressions?grepMetacharacters and LiteralsThe Any CharacterAnchorsBracket Expressions and Character ClassesNegationTraditional Character RangesPOSIX Character ClassesPOSIX Basic vs. Extended Regular ExpressionsAlternationQuantifiers?—Match an Element Zero or One Time*—Match an Element Zero or More Times+—Match an Element One or More Times{ }—Match an Element a Specific Number of TimesPutting Regular Expressions to WorkValidating a Phone List with grepFinding Ugly Filenames with findSearching for Files with locateSearching for Text with less and vimSumming Up
20 TEXT PROCESSING
Applications of TextDocumentsWeb PagesEmailPrinter OutputProgram Source CodeRevisiting Some Old FriendscatsortuniqSlicing and DicingcutpastejointacrevComparing TextcommdiffpatchEditing on the FlytrsedaspellSumming UpExtra Credit
21 FORMATTING OUTPUT
Simple Formatting Toolsnl—Number Linesfold—Wrap Each Line to a Specified Lengthfmt—A Simple Text Formatterpr—Format Text for Printingprintf—Format and Print DataDocument Formatting SystemsgroffSumming Up
22 PRINTING
A Brief History of PrintingPrinting in the Dim TimesCharacter-Based PrintersGraphical PrintersPrinting with LinuxPreparing Files for Printingpr—Convert Text Files for PrintingSending a Print Job to a Printerlpr—Print Files (Berkeley Style)lp—Print Files (System V Style)Another Option: a2psMonitoring and Controlling Print Jobslpstat—Display Print System Statuslpq—Display Printer Queue Statuslprm/cancel—Cancel Print JobsSumming Up
23 COMPILING PROGRAMS
What Is Compiling?Are All Programs Compiled?Compiling a C ProgramObtaining the Source CodeExamining the Source TreeBuilding the ProgramInstalling the ProgramSumming Up
PART IV: WRITING SHELL SCRIPTS
24 WRITING YOUR FIRST SCRIPT
What Are Shell Scripts?How to Write a Shell ScriptScript File FormatExecutable PermissionsScript File LocationGood Locations for ScriptsMore Formatting TricksLong Option NamesIndentation and Line-ContinuationSumming Up
25 STARTING A PROJECT
First Stage: Minimal DocumentSecond Stage: Adding a Little DataVariables and ConstantsAssigning Values to Variables and ConstantsHere DocumentsSumming Up
26 TOP-DOWN DESIGN
Shell FunctionsLocal VariablesShell Functions and RedirectionKeep Scripts RunningSumming Up
27 FLOW CONTROL: BRANCHING WITH IF
if StatementsExit StatusUsing testFile ExpressionsString ExpressionsInteger ExpressionsA More Modern Version of test(( ))—Designed for IntegersCombining ExpressionsControl Operators: Another Way to BranchSumming Up
28 READING KEYBOARD INPUT
read—Read Values from Standard InputOptionsIFSValidating InputMenusSumming UpExtra Credit
29 FLOW CONTROL: LOOPING WITH WHILE/UNTIL
Loopingwhilebreak and continueselectuntilReading Files with LoopsSumming Up
30 TROUBLESHOOTING
Syntactic ErrorsMissing QuotesMissing or Unexpected TokensUnanticipated ExpansionsLogical ErrorsDefensive Programmingset -e, set -u, and set -o pipefailShellCheck Is Your FriendWatch Out for FilenamesVerifying InputTestingTest CasesDebuggingFinding the Problem AreaTracingExamining Values During ExecutionSumming Up
31 FLOW CONTROL: BRANCHING WITH CASE
casePatternsPerforming Multiple ActionsSumming Up
32 POSITIONAL PARAMETERS
Accessing the Command LineDetermining the Number of Argumentsshift—Getting Access to Many ArgumentsSimple ApplicationsUsing Positional Parameters with Shell FunctionsHandling Positional Parameters en MasseA More Complete ApplicationThe getopts OptionInteractive ModeFile OutputSumming Up
33 FLOW CONTROL: LOOPING WITH FOR
for—Traditional Shell Formfor—C Language FormSumming Up
34 STRINGS AND NUMBERS
Parameter ExpansionBasic ParametersExpansions to Manage Empty VariablesExpansions That Return Variable NamesString OperationsCase ConversionArithmetic Evaluation and ExpansionNumber BasesUnary OperatorsSimple ArithmeticAssignmentBit OperationsLogicThe Comma Operatorbc—An Arbitrary Precision Calculator LanguageUsing bcAn Example ScriptSumming UpExtra Credit
35 ARRAYS
What Are Arrays?Creating an ArrayAssigning Values to an ArrayAccessing Array ElementsArray OperationsOutputting the Entire Contents of an ArrayDetermining the Number of Array ElementsFinding the Subscripts Used by an ArrayAssigning Array Elements with read -aAdding Elements to the End of an ArrayReading a File Into an ArraySlicing an ArraySorting an ArrayDeleting an ArrayAssociative ArraysUsing Associative Arrays to Simulate Multiple DimensionsSumming Up
36 EXOTICA
Group Commands and SubshellsProcess SubstitutionConstructing Commands with evalA Wordle HelperTrapsAsynchronous ExecutionwaitNamed PipesSetting Up a Named PipeUsing Named PipesSumming Up
INDEX

Content preview from The Linux Command Line, 3rd Edition

21FORMATTING OUTPUT

In this chapter, we continue our look at text-related tools, focusing on programs that are used to format text output, rather than changing the text itself. These tools are often used to prepare text for eventual printing, a subject that we will cover in the next chapter. We will cover the following programs in this chapter:

nl Number lines.
fold Wrap each line to a specified length.
fmt A simple text formatter.
pr Prepare text for printing.
printf Format and print data.
groff A document formatting system.

Simple Formatting Tools

We’ll look at some of the simple formatting tools first. These are mostly single-purpose ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.

Read now

Unlock full access

More than 5,000 organizations count on O’Reilly

O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.

Julian F.

Head of Cybersecurity

I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.

Addison B.

Field Engineer

I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.

Amir M.

Data Platform Tech Lead

I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.

Mark W.

Embedded Software Engineer

Publisher Resources

ISBN: 0642572230227Errata Page

Cloud Computing

Data Engineering

Data Science

AI & ML

Programming Languages

Software Architecture

IT/Ops

Security

Design

Business

Soft Skills

The Linux Command Line, 3rd Edition

by William E. Shotts

21FORMATTING OUTPUT

Simple Formatting Tools

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.