The Linux Command Line by Shotts Jr., William -- Read -- Imperial Library of Trantor

Index

SPECIAL OFFER: Upgrade this ebook with O’Reilly Acknowledgments Introduction

Why Use the Command Line? What This Book Is About Who Should Read This Book What’s in This Book How to Read This Book Prerequisites

I. Learning the Shell

1. What Is the Shell?

Terminal Emulators Your First Keystrokes

Command History Cursor Movement

Try Some Simple Commands Ending a Terminal Session

2. Navigation

Understanding the Filesystem Tree The Current Working Directory Listing the Contents of a Directory Changing the Current Working Directory

Absolute Pathnames Relative Pathnames Some Helpful Shortcuts

3. Exploring the System

More Fun with ls

Options and Arguments A Longer Look at Long Format

Determining a File’s Type with file Viewing File Contents with less A Guided Tour Symbolic Links

4. Manipulating Files and Directories

Wildcards mkdir—Create Directories cp—Copy Files and Directories mv—Move and Rename Files rm—Remove Files and Directories ln—Create Links

Hard Links Symbolic Links

Let’s Build a Playground

Creating Directories Copying Files Moving and Renaming Files Creating Hard Links Creating Symbolic Links Removing Files and Directories

Final Note

5. Working with Commands

What Exactly Are Commands? Identifying Commands

type—Display a Command’s Type which—Display an Executable’s Location

Getting a Command’s Documentation

help—Get Help for Shell Builtins --help—Display Usage Information man—Display a Program’s Manual Page apropos—Display Appropriate Commands whatis—Display a Very Brief Description of a Command info—Display a Program’s Info Entry README and Other Program Documentation Files

Creating Your Own Commands with alias Revisiting Old Friends

6. Redirection

Standard Input, Output, and Error

Redirecting Standard Output Redirecting Standard Error Redirecting Standard Output and Standard Error to One File Disposing of Unwanted Output Redirecting Standard Input

Pipelines

Filters uniq—Report or Omit Repeated Lines wc—Print Line, Word, and Byte Counts grep—Print Lines Matching a Pattern head/tail—Print First/Last Part of Files tee—Read from Stdin and Output to Stdout and Files

Final Note

7. Seeing the World as the Shell Sees It

Expansion

Pathname Expansion Tilde Expansion Arithmetic Expansion Brace Expansion Parameter Expansion Command Substitution

Quoting

Double Quotes Single Quotes Escaping Characters

Final Note

8. Advanced Keyboard Tricks

Command Line Editing

Cursor Movement Modifying Text Cutting and Pasting (Killing and Yanking) Text

Completion Using History

Searching History History Expansion

Final Note

9. Permissions

Owners, Group Members, and Everybody Else Reading, Writing, and Executing

chmod—Change File Mode Setting File Mode with the GUI umask—Set Default Permissions

Changing Identities

su—Run a Shell with Substitute User and Group IDs sudo—Execute a Command as Another User chown—Change File Owner and Group chgrp—Change Group Ownership

Exercising Your Privileges Changing Your Password

10. Processes

How a Process Works

Viewing Processes with ps Viewing Processes Dynamically with top

Controlling Processes

Interrupting a Process Putting a Process in the Background Returning a Process to the Foreground Stopping (Pausing) a Process

Signals

Sending Signals to Processes with kill Sending Signals to Multiple Processes with killall

More Process-Related Commands

II. Configuration and the Environment

11. The Environment

What Is Stored in the Environment?

Examining the Environment Some Interesting Variables

How Is the Environment Established?

Modifying the Environment

Which Files Should We Modify? Text Editors Using a Text Editor Activating Our Changes

Final Note

12. A Gentle Introduction to vi

Why We Should Learn vi A Little Background Starting and Stopping vi Editing Modes

Entering Insert Mode Saving Our Work

Moving the Cursor Around Basic Editing

Appending Text Opening a Line Deleting Text Cutting, Copying, and Pasting Text Joining Lines

Search and Replace

Searching Within a Line Searching the Entire File Global Search and Replace

Editing Multiple Files

Switching Between Files Opening Additional Files for Editing Copying Content from One File into Another Inserting an Entire File into Another

Saving Our Work

13. Customizing the Prompt

Anatomy of a Prompt Trying Some Alternative Prompt Designs Adding Color Moving the Cursor Saving the Prompt Final Note

III. Common Tasks and Essential Tools

14. Package Management

Packaging Systems How a Package System Works

Package Files Repositories Dependencies High- and Low-Level Package Tools

Common Package Management Tasks

Finding a Package in a Repository Installing a Package from a Repository Installing a Package from a Package File Removing a Package Updating Packages from a Repository Upgrading a Package from a Package File Listing Installed Packages Determining Whether a Package Is Installed Displaying Information About an Installed Package Finding Which Package Installed a File

Final Note

15. Storage Media

Mounting and Unmounting Storage Devices

Viewing a List of Mounted Filesystems Determining Device Names

Creating New Filesystems

Manipulating Partitions with fdisk Creating a New Filesystem with mkfs

Testing and Repairing Filesystems Formatting Floppy Disks Moving Data Directly to and from Devices Creating CD-ROM Images

Creating an Image Copy of a CD-ROM Creating an Image from a Collection of Files

Writing CD-ROM Images

Mounting an ISO Image Directly Blanking a Rewritable CD-ROM Writing an Image

Extra Credit

16. Networking

Examining and Monitoring a Network

ping—Send a Special Packet to a Network Host traceroute—Trace the Path of a Network Packet netstat—Examine Network Settings and Statistics

Transporting Files over a Network

ftp—Transfer Files with the File Transfer Protocol lftp—A Better ftp wget—Non-interactive Network Downloader

Secure Communication with Remote Hosts

ssh—Securely Log in to Remote Computers scp and sftp—Securely Transfer Files

17. Searching for Files

locate—Find Files the Easy Way find—Find Files the Hard Way

Tests Actions A Return to the Playground Options

18. Archiving and Backup

Compressing Files

gzip—Compress or Expand Files bzip2—Higher Compression at the Cost of Speed

Archiving Files

tar—Tape Archiving Utility zip—Package and Compress Files

Synchronizing Files and Directories

rsync—Remote File and Directory Synchronization Using rsync over a Network

19. Regular Expressions

What Are Regular Expressions? grep—Search Through Text Metacharacters and Literals The Any Character Anchors Bracket Expressions and Character Classes

Negation Traditional Character Ranges POSIX Character Classes

POSIX Basic vs. Extended Regular Expressions Alternation Quantifiers

?—Match an Element Zero Times or One Time *—Match an Element Zero or More Times +—Match an Element One or More Times { }—Match an Element a Specific Number of Times

Putting Regular Expressions to Work

Validating a Phone List with grep Finding Ugly Filenames with find Searching for Files with locate Searching for Text with less and vim

Final Note

20. Text Processing

Applications of Text

Documents Web Pages Email Printer Output Program Source Code

Revisiting Some Old Friends

cat—Concatenate Files and Print on Standard Output sort—Sort Lines of Text Files uniq—Report or Omit Repeated Lines

Slicing and Dicing

cut—Remove Sections from Each Line of Files paste—Merge Lines of Files join—Join Lines of Two Files on a Common Field

Comparing Text

comm—Compare Two Sorted Files Line by Line diff—Compare Files Line by Line patch—Apply a diff to an Original

Editing on the Fly

tr—Transliterate or Delete Characters sed—Stream Editor for Filtering and Transforming Text aspell—Interactive Spell Checker

Final Note Extra Credit

21. Formatting Output

Simple Formatting Tools

nl—Number Lines fold—Wrap Each Line to a Specified Length fmt—A Simple Text Formatter pr—Format Text for Printing printf—Format and Print Data

Document Formatting Systems

The roff Family and TEX groff—A Document Formatting System

Final Note

22. Printing

A Brief History of Printing

Printing in the Dim Times Character-Based Printers Graphical Printers

Printing with Linux Preparing Files for Printing

pr—Convert Text Files for Printing

Sending a Print Job to a Printer

lpr—Print Files (Berkeley Style) lp—Print Files (System V Style) Another Option: a2ps

Monitoring and Controlling Print Jobs

lpstat—Display Print System Status lpq—Display Printer Queue Status lprm and cancel—Cancel Print Jobs

23. Compiling Programs

What Is Compiling?

Are All Programs Compiled?

Compiling a C Program

Obtaining the Source Code Examining the Source Tree Building the Program Installing the Program

Final Note

IV. Writing Shell Scripts

24. Writing Your First Script

What Are Shell Scripts? How to Write a Shell Script

Script File Format Executable Permissions Script File Location Good Locations for Scripts

More Formatting Tricks

Long Option Names Indentation and Line Continuation

Final Note

25. Starting a Project

First Stage: Minimal Document Second Stage: Adding a Little Data Variables and Constants

Creating Variables and Constants Assigning Values to Variables and Constants

Here Documents Final Note

26. Top-Down Design

Shell Functions Local Variables Keep Scripts Running Final Note

27. Flow Control: Branching with if

Using if Exit Status Using test

File Expressions String Expressions Integer Expressions

A More Modern Version of test (( ))—Designed for Integers Combining Expressions Control Operators: Another Way to Branch Final Note

28. Reading Keyboard Input

read—Read Values from Standard Input

Options Separating Input Fields with IFS

Validating Input Menus Final Note Extra Credit

29. Flow Control: Looping with while and until

Looping while Breaking out of a Loop until Reading Files with Loops Final Note

30. Troubleshooting

Syntactic Errors

Missing Quotes Missing or Unexpected Tokens Unanticipated Expansions

Logical Errors

Defensive Programming Verifying Input

Testing

Stubs Test Cases

Debugging

Finding the Problem Area Tracing Examining Values During Execution

Final Note

31. Flow Control: Branching with case

case

Patterns Combining Multiple Patterns

Final Note

32. Positional Parameters

Accessing the Command Line

Determining the Number of Arguments shift—Getting Access to Many Arguments Simple Applications Using Positional Parameters with Shell Functions

Handling Positional Parameters En Masse A More Complete Application Final Note

33. Flow Control: Looping with for

for: Traditional Shell Form for: C Language Form Final Note

34. Strings and Numbers

Parameter Expansion

Basic Parameters Expansions to Manage Empty Variables Expansions That Return Variable Names String Operations

Arithmetic Evaluation and Expansion

Number Bases Unary Operators Simple Arithmetic Assignment Bit Operations Logic

bc—An Arbitrary-Precision Calculator Language

Using bc An Example Script

Final Note Extra Credit

35. Arrays

What Are Arrays? Creating an Array Assigning Values to an Array Accessing Array Elements Array Operations

Outputting the Entire Contents of an Array Determining the Number of Array Elements Finding the Subscripts Used by an Array Adding Elements to the End of an Array Sorting an Array Deleting an Array

Final Note

36. Exotica

Group Commands and Subshells

Performing Redirections Process Substitution

Traps Asynchronous Execution

wait

Named Pipes

Setting Up a Named Pipe Using Named Pipes

Final Note

Index A. Updates SPECIAL OFFER: Upgrade this ebook with O’Reilly

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