A compendium of shell scripting recipes that can immediately be used, adjusted, and applied
The shell is the primary way of communicating with the Unix and Linux systems, providing a direct way to program by automating simple-to-intermediate tasks. With this book, Linux expert Steve Parker shares a collection of shell scripting recipes that can be used as is or easily modified for a variety of environments or situations. The book covers shell programming, with a focus on Linux and the Bash shell; it provides credible, real-world relevance, as well as providing the flexible tools to get started immediately.
* Shares a collection of helpful shell scripting recipes that can immediately be used for various of real-world challenges
* Features recipes for system tools, shell features, and systems administration
* Provides a host of plug and play recipes for to immediately apply and easily modify so the wheel doesn't have to be reinvented with each challenge faced
Come out of your shell and dive into this collection of tried and tested shell scripting recipes that you can start using right away!
Autorentext
Steve Parker is an IT consultant specializing in Solaris and GNU/Linux. He has been providing consultancy services for more than a decade. He is the author of the popular Bourne Shell Programming/Scripting Tutorial (http://steve-parker.org/sh/sh.shtml), which sees more than one million visitors a year.
Inhalt
Introduction xxix
Part I: About the Ingredients
Chapter 1: The History of Unix, Gnu, and Linux 3
Unix 3
Everything is a File and Pipelines 5
BSD 6
GNU 7
Linux 11
Summary 12
Chapter 2: Getting Started 15
Choosing an OS 15
GNU/Linux 15
The BSDs 17
Proprietary Unix 17
Microsoft Windows 17
Choosing an Editor 18
Graphical Text Editors 18
Terminal Emulation 21
Nongraphical Text Editors 22
Setting Up the Environment 24
The Shell Profile 24
Aliases 26
vim Settings 30
Summary 31
Chapter 3: Variables 33
Using Variables 33
Typing 34
Assigning Values to Variables 35
Positional Parameters 39
Return Codes 42
Unsetting Variables 45
Preset and Standard Variables 47
BASH_ENV 47
BASHOPTS 47
SHELLOPTS 48
BASH_COMMAND 50
BASH_SOURCE, FUNCNAME, LINENO, and BASH_LINENO 51
SHELL 55
HOSTNAME and HOSTTYPE 55
Working Directory 55
PIPESTATUS 55
TIMEFORMAT 56
PPID 57
RANDOM 58
REPLY 58
SECONDS 58
BASH_XTRACEFD 59
GLOBIGNORE 60
HOME 62
IFS 62
PATH 63
TMOUT 64
TMPDIR 65
User Identification Variables 65
Summary 66
Chapter 4: Wildcard Expansion 67
Filename Expansion (Globbing) 67
Bash Globbing Features 70
Shell Options 71
Regular Expressions and Quoting 75
Overview of Regular Expressions 76
Quoting 77
Summary 81
Chapter 5: Conditional Execution 83
If/Then 83
Else 85
elif 85
Test ([) 87
Flags for Test 88
File Comparison Tests 95
String Comparison Tests 96
Regular Expression Tests 98
Numerical Tests 101
Combining Tests 103
Case 105
Summary 109
Chapter 6: Flow Control Using Loops 111
For Loops 111
When to Use for Loops 112
Imaginative Ways of Feeding for with Data 112
C-Style for Loops 118
while Loops 119
When to Use while Loops 119
Ways to Use while Loops 119
Nested Loops 125
Breaking and Continuing Loop Execution 126
while with Case 130
until Loops 131
select Loops 133
Summary 137
Chapter 7: Variables Continued 139
Using Variables 139
Variable Types 141
Length of Variables 142
Special String Operators 144
Stripping Variable Strings by Length 144
Stripping from the End of the String 146
Stripping Strings with Patterns 147
Searching Strings 151
Using Search and Replace 151
Replacing Patterns 153
Deleting Patterns 153
Changing Case 153
Providing Default Values 153
Indirection 157
Sourcing Variables 158
Summary 159
Chapter 8: Functions and Libraries 161
Functions 161
Defining Functions 162
Function Output 162
Writing to a File 164
Redirecting the Output of an Entire Function 167
Functions with Trap 171
Recursive Functions 173
Variable Scope 177
Libraries 181
Creating and Accessing Libraries 183
Library Structures 183
Network Configuration Libr...