Table of Contents

1 A Quick Review of the Basics

    Some Basic Commands

        Displaying the Date and Time: The date Command

        Finding Out Who’s Logged In: The who Command

        Echoing Characters: The echo Command

    Working with Files

        Listing Files: The ls Command

        Displaying the Contents of a File: The cat Command

        Counting the Number of Words in a File: The wc Command

        Command Options

        Making a Copy of a File: The cp Command

        Renaming a File: The mv Command

        Removing a File: The rm Command

    Working with Directories

        The Home Directory and Pathnames

        Displaying Your Working Directory: The pwd Command

        Changing Directories: The cd Command

        More on the ls Command

        Creating a Directory: The mkdir Command

        Copying a File from One Directory to Another

        Moving Files Between Directories

        Linking Files: The ln Command

        Removing a Directory: The rmdir Command

    Filename Substitution

        The Asterisk

        Matching Single Characters

    Filename Nuances

        Spaces in Filenames

        Other Weird Characters

    Standard Input/Output, and I/O Redirection

        Standard Input and Standard Output

        Output Redirection

        Input Redirection

    Pipes

        Filters

    Standard Error

    More on Commands

        Typing More Than One Command on a Line

        Sending a Command to the Background

        The ps Command

    Command Summary

2 What Is the Shell?

    The Kernel and the Utilities

    The Login Shell

    Typing Commands to the Shell

    The Shell’s Responsibilities

        Program Execution

        Variable and Filename Substitution

        I/O Redirection

        Hooking up a Pipeline

        Environment Control

        Interpreted Programming Language

3 Tools of the Trade

    Regular Expressions

        Matching Any Character: The Period (.)

        Matching the Beginning of the Line: The Caret (&hat;)

        Matching the End of the Line: The Dollar Sign $

        Matching a Character Set: The [...] Construct

        Matching Zero or More Characters: The Asterisk (*)

        Matching a Precise Number of Subpatterns: \{...\}

        Saving Matched Characters: \(...\)

    cut

        The -d and -f Options

    paste

        The -d Option

        The -s Option

    sed

        The -n Option

        Deleting Lines

    tr

        The -s Option

        The -d Option

    grep

        Regular Expressions and grep

        The -v Option

        The -l Option

        The -n Option

    sort

        The -u Option

        The -r Option

        The -o Option

        The -n Option

        Skipping Fields

        The -t Option

        Other Options

    uniq

        The -d Option

        Other Options

4 And Away We Go

    Command Files

        Comments

    Variables

        Displaying the Values of Variables

        Undefined Variables Have the Null Value

        Filename Substitution and Variables

        The ${variable} Construct

    Built-in Integer Arithmetic

5 Can I Quote You on That?

    The Single Quote

    The Double Quote

    The Backslash

        Using the Backslash for Continuing Lines

        The Backslash Inside Double Quotes

    Command Substitution

        The Back Quote

        The $(...) Construct

        The expr Command

6 Passing Arguments

    The $# Variable

    The $* Variable

    A Program to Look Up Someone in the Phone Book

    A Program to Add Someone to the Phone Book

    A Program to Remove Someone from the Phone Book

        ${n}

    The shift Command

7 Decisions, Decisions

    Exit Status

        The $? Variable

    The test Command

        String Operators

        An Alternative Format for test

        Integer Operators

        File Operators

        The Logical Negation Operator !

        The Logical AND Operator -a

        Parentheses

        The Logical OR Operator -o

    The else Construct

    The exit Command

        A Second Look at the rem Program

    The elif Construct

        Yet Another Version of rem

    The case Command

        Special Pattern-Matching Characters

        The -x Option for Debugging Programs

        Back to the case

    The Null Command :

    The && and Constructs

8 'Round and 'Round She Goes

    The for Command

        The $@ Variable

        The for Without the List

    The while Command

    The until Command

    More on Loops

        Breaking Out of a Loop

        Skipping the Remaining Commands in a Loop

        Executing a Loop in the Background

        I/O Redirection on a Loop

        Piping Data into and out of a Loop

        Typing a Loop on One Line

    The getopts Command

9 Reading and Printing Data

    The read Command

        A Program to Copy Files

        Special echo Escape Characters

        An Improved Version of mycp

        A Final Version of mycp

        A Menu-Driven Phone Program

        The $$ Variable and Temporary Files

        The Exit Status from read

    The printf Command

10 Your Environment

    Local Variables

        Subshells

    Exported Variables

        export -p

    PS1 and PS2

    HOME

    PATH

    Your Current Directory

        CDPATH

    More on Subshells

        The .Command

        The exec Command

        The (...) and { ...; } Constructs

        Another Way to Pass Variables to a Subshell

    Your .profile File

    The TERM Variable

    The TZ Variable

11 More on Parameters

    Parameter Substitution

        ${parameter}

        ${parameter:-value}

        ${parameter:=value}

        ${parameter:?value}

        ${parameter:+value}

        Pattern Matching Constructs

        ${#variable}

    The $0 Variable

    The set Command

        The -x Option

        set with No Arguments

        Using set to Reassign Positional Parameters

        The -- Option

        Other Options to set

    The IFS Variable

        The readonly Command

        The unset Command

12 Loose Ends

    The eval Command

    The wait Command

        The $! Variable

    The trap Command

        trap with No Arguments

        Ignoring Signals

        Resetting Traps

    More on I/O

        <&- and >&-

        In-line Input Redirection

        Shell Archives

    Functions

        Removing a Function Definition

        The return Command

    The type Command

13 Rolo Revisited

    Data Formatting Considerations

    rolo

    add

    lu

    display

    rem

    change

    listall

    Sample Output

14 Interactive and Nonstandard Shell Features

    Getting the Right Shell

    The ENV File

    Command-Line Editing

    Command History

    The vi Line Edit Mode

        Accessing Commands from Your History

    The emacs Line Edit Mode

        Accessing Commands from Your History

    Other Ways to Access Your History

        The history Command

        The fc Command

        The r Command

    Functions

        Local Variables

        Automatically Loaded Functions

    Integer Arithmetic

        Integer Types

        Numbers in Different Bases

    The alias Command

        Removing Aliases

    Arrays

    Job Control

        Stopped Jobs and the fg and bg Commands

    Miscellaneous Features

        Other Features of the cd Command

        Tilde Substitution

        Order of Search

    Compatibility Summary

Appendixes    

A Shell Summary

B For More Information