Learning the Korn Shell by Robbins, Arnold -- Read -- Imperial Library of Trantor

Index

Learning the Korn Shell, 2nd Edition Dedication A Note Regarding Supplemental Files Preface

Korn Shell Versions Summary of Korn Shell Features Intended Audience Code Examples Chapter Summary Conventions Used in This Handbook About the Second Edition We’d Like to Hear From You Acknowledgments Acknowledgments from the First Edition

1. Korn Shell Basics

What Is a Shell? Scope of This Book History of Unix Shells

The Korn Shell Features of the Korn Shell

Getting the 1993 Korn Shell Interactive Shell Use

Commands, Arguments, and Options Built-in Help

Files

Directories

The working directory Tilde notation Changing working directories Symbolic links to directories

Filenames and Wildcards

Input and Output

Standard I/O I/O Redirection Pipelines

Background Jobs

Background I/O Background Jobs and Priorities

nice

Special Characters and Quoting

Quoting Backslash-Escaping Quoting Quotation Marks Continuing Lines Control Keys

2. Command-Line Editing

Enabling Command-Line Editing The History File Emacs Editing Mode

Basic Commands Word Commands Line Commands Moving Around in the History File Filename and Variable Completion and Expansion Miscellaneous Commands Macro Expansion with Aliases

Vi Editing Mode

Simple Control Mode Commands Entering and Changing Text Deletion Commands Moving Around in the History File Character-Finding Commands Filename and Variable Completion and Expansion Miscellaneous Commands Macro Expansion with Aliases

The hist Command Finger Habits

3. Customizing Your Environment

The .profile File

The /etc/profile File

Aliases Options Shell Variables

Variables and Quoting Built-in Variables

Editing mode variables Mail variables Prompting variables Using history command numbers Terminal types Command search path PATH security considerations PATH and tracked aliases Directory search path Miscellaneous variables

Customization and Subprocesses

Environment Variables The Environment File

Customization Hints

4. Basic Shell Programming

Shell Scripts and Functions

Functions

Automatically loading functions POSIX functions

Shell Variables

Positional Parameters

Positional parameters in functions Changing the positional parameters

More on Variable Syntax Appending to a Variable

Compound Variables

Compound Variable Assignment

Indirect Variable References (namerefs) String Operators

Syntax of String Operators Patterns and Regular Expressions

Regular expression basics POSIX character class additions Korn shell versus awk/egrep regular expressions Pattern matching with regular expressions

Pattern-Matching Operators Pattern Substitution Operators

Greedy versus non-greedy matching

Variable Name Operators Length Operators The .sh.match Variable

Command Substitution Advanced Examples: pushd and popd

5. Flow Control

if/else

Exit Status and Return

Return Advanced example: overriding a built-in command Pipeline exit status Interpreting exit status values

Combinations of Exit Statuses Reversing the Sense of a Test Condition Tests

String comparisons About C compilers File attribute checking Arithmetic conditionals

for case

Merging Cases

select while and until

break and continue

6. Command-Line Options and Typed Variables

Command-Line Options

shift Options with Arguments getopts

More about C compilers

Numeric Variables and Arithmetic

Built-in Arithmetic Functions Arithmetic Conditionals Arithmetic Variables and Assignment

Arithmetic for Arrays

Indexed Arrays Associative Arrays Array Name Operators

typeset

Local Variables in Functions String Formatting Options Type and Attribute Options Function Options

7. Input/Output and Command-Line Processing

I/O Redirectors

Here-Documents Here-Strings File Descriptors

Redirector ordering

Special Filenames

String I/O

print escape sequences Options to print

printf

Additional Korn shell printf specifiers

read

Reading lines from files I/O redirection and multiple commands Code blocks Reading user input Options to read

Command-Line Processing

Brace Expansion and Process Substitution Substitution Order Quoting

Extended quoting

eval

The C compiler as pipeline

8. Process Handling

Process IDs and Job Numbers Job Control

Foreground and Background Suspending a Job Disowning a Job

Signals

Control-Key Signals kill ps

System V BSD

kill: The Full Story

trap

Traps and Functions Process ID Variables and Temporary Files Ignoring Signals Resetting Traps

Coroutines

wait Advantages and Disadvantages of Coroutines Parallelization Coroutines with Two-Way Pipes Two-Way Pipes Versus Standard Pipes

Shell Subprocesses and Subshells

Shell Subprocess Inheritance Subshells

9. Debugging Shell Programs

Basic Debugging Aids

Set Options Fake Signals

EXIT ERR DEBUG Signal delivery order

Discipline Functions

A Korn Shell Debugger

Structure of the Debugger

The driver script exec

The Preamble Debugger Functions

Commands Stepping Breakpoints Break conditions Execution tracing Watchpoints Limitations

A Sample kshdb Session Exercises

10. Korn Shell Administration

Installing the Korn Shell as the Standard Shell Environment Customization

umask ulimit Types of Global Customization

Customizing the Editing Modes System Security Features

Tips for Secure Shell Scripts Restricted Shell Trojan Horses Setuid and Privileged Mode

A. Related Shells

The Bourne Shell The 1988 Korn Shell The IEEE 1003.2 POSIX Shell Standard dtksh tksh pdksh bash zsh

Extended Globbing Completion Command-Line Editor Prompts and Prompt Themes Differences Between zsh and ksh

Workalikes on PC Platforms

Cygwin DJGPP MKS Toolkit Thompson Automation Software Toolkit AT&T UWIN

B. Reference Information

Invocation Options Built-in Commands and Keywords Predefined Aliases Built-in Shell Variables Test Operators Options Typeset Options Arithmetic Emacs Mode Commands vi Control Mode Commands Using getopts

C. Building ksh from Source Code

Korn Shell Web Sites What You Can Download Building ksh

D. AT&T ast Source Code License Agreement Index About the Authors Colophon Copyright

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