Table of Contents, Pro Bash Programming: Scripting the GNU/Linux Shell, by Chris F.A. Johnson

Contents
About the Author	xvii
About the Technical Reviewer	xviii
Introduction	xix
Chapter 1: Hello, World! Your First Shell Program	1
The Code	1
The File	2
The Naming of Scripts	2
Selecting a Directory for the Script	2
Creating the File and Running the Script	3
Choosing and Using a Text Editor	3
Building a Better "Hello, World!"	5
Summary	5
Commands	5
Concepts	6
Variables	6
Exercises	6
Chapter 2: Input, Output, and Throughput	7
Parameter and Variables	7
Positional Parameters	7
Special *@#0$?_!- Parameters	8
Variables	8
Arguments and Options	8
echo, and Why You Should Avoid It	9
printf: Formatting and Printing Data	9
Escape Sequences	10
Format Specifiers	10
Width Specification	11
Printing to a Variable	13
Line Continuation	13
Standard Input/Output Streams and Redirection	13
Redirection: >, >>, and <	13
Reading Input	15
Pipelines	15
Command Substitution	16
Summary	16
Commands	16
Concepts	16
Exercises	17
Chapter 3: Looping and Branching	19
Exit Status	19
Testing an Expression	19
test, aka [ ... ]	20
[[ ... ]]: Evaluate an Expression	21
(( ... )): Evaluate an Arithmetic Expression	22
Lists	22
Conditional execution	22
if	22
Conditional Operators, && and \|\|	23
case	24
Looping	25
while	25
until	26
for	26
break	26
continue	27
Summary	27
Commands	27
Concepts	28
Exercises	28
Chapter 4: Command-Line Parsing and Expansion	29
Quoting	30
Brace Expansion	31
Tilde Expansion	32
Parameter and Variable Expansion	33
Arithmetic Expansion	33
Command Substitution	35
Word Splitting	36
Pathname Expansion	37
Process Substitution	37
Parsing Options	38
Summary	41
Commands	41
Exercises	41
Chapter 5: Parameters and Variables	43
The Scope of a Variable: Can You See It from Here?	43
Shell Variables	44
The Naming of Variables	46
Parameter Expansion	46
Bourne Shell	46
POSIX Shell	49
Bash	51
Bash-4.0	52
Positional Parameters	53
Arrays	54
Integer-Indexed Arrays	54
Associative Arrays	56
Summary	56
Commands	56
Concepts	57
Exercises	57
Chapter 6: Shell Functions	59
Definition Syntax	59
Compound Commands	61
Getting Results	62
Set Different Exit Codes	62
Print the Result	63
Place Results in One or More Variables	63
Function Libraries	64
Using Functions from Libraries	64
Sample Script	64
Summary	66
Commands	66
Exercises	66
Chapter 7: String Manipulation	67
Concatenation	67
Repeat Character to a Given Length	68
Processing Character by Character	69
Reversal	70
Case Conversion	70
Comparing Contents Without Regard to Case	72
Check for Valid Variable Name	73
Insert One String into Another	74
Examples	74
Overlay	74
Examples	75
Trim Unwanted Characters	75
Examples	76
Index	77
Summary	78
Commands	78
Functions	78
Exercises	78
Chapter 8: File Operations and Commands	79
Reading a File	79
External Commands	81
cat	81
head	82
touch	83
ls	83
cut	84
wc	85
Regular Expressions	85
grep	86
sed	87
awk	88
File Name Expansion Options	89
nullglob	90
failglob	91
dotglob	91
extglob	91
nocaseglob	93
globstar	93
Summary	94
Shell Options	94
External Commands	94
Exercises	95
Chapter 9: Reserved Words and Builtin Commands	97
help, Display Information About Builtin Commands	97
time, Print Time Taken for Execution of a Command	98
read, Read a Line from an Input Stream	99
-r, Read Backslashes Literally	99
-e, Get Input with the readline Library	100
-a, Read Words into an Array	100
-d DELIM, Read Until DELIM Instead of a Newline	101
-n NUM, Read a Maximum of NUM Characters	101
-s, Do Not Echo Input Coming from a Terminal	101
-p PROMPT:, Output PROMPT Without a Trailing Newline	101
-t TIMEOUT, Only Wait TIMEOUT Seconds for Complete Input	102
-u FD: Read from File Descriptor FD Instead of the Standard Input	102
-i TEXT, Use TEXT as the Initial Text for readline	103
eval, Expand Arguments and Execute Resulting Command	103
Poor Man's Arrays	104
Setting Multiple Variables from One Command	106
type, Display Information About Commands	106
builtin, Execute a Builtin Command	108
command, Execute a Command or Display Information About Commands	108
pwd, Print the Current Working Directory	108
unalias, Remove One or More Aliases	109
Deprecated Builtins	109
Dynamically Loadable Builtins	109
Summary	110
Commands and Reserved Words	110
Deprecated Commands	111
Exercises	111
Chapter 10: Writing Bug-Free Scripts and Debugging the Rest	113
Prevention Is Better Than Cure	113
Structure Your Programs	113
Document Your Code	116
Format Your Code Consistently	117
The K.I.S.S. Principle	117
Test As You Go	118
Debugging a Script	120
Summary	123
Exercises	123
Chapter 11: Programming for the Command Line	125
Manipulating the Directory Stack	125
cd	125
pd	126
cdm	127
menu	128
Filesystem Functions	129
l	129
lsr	130
cp, mv	131
md	131
Miscellaneous Functions	132
pr1	132
calc	133
Managing Man Pages	133
sman	133
sus	134
k	134
Games	134
The Fifteen Puzzle	136
Summary	140
Exercises	140
Chapter 12: Runtime Configuration	141
Defining Variables	141
Command-Line Options and Arguments	141
Menus	142
Q&A Dialogue	143
Configuration Files	143
Scripts with Several Names	144
Environment Variables	146
All Together Now	146
## Script Information	147
## Default Configuration	147
## Screen Variables	148
## Function Definitions	148
## Parse Command-Line Options	154
## Bits and Pieces	155
Summary	156
Exercises	156
Chapter 13: Data Processing	157
Arrays	157
Holes in an Indexed Array	157
Using an Array for Sorting	158
Two-Dimensional Grids	163
Data File Formats	171
Line-Based Records	172
Block File Formats	175
Summary	176
Exercises	177
Chapter 14: Scripting the Screen	179
Teletypewriter vs. Canvas	179
Stretching the Canvas	180
CSI: Command Sequence Introducer	180
Priming the Canvas	181
Moving the Cursor	181
Changing Rendition Modes and Colors	182
Placing a Block of Text on the Screen	183
Scrolling Text	186
Rolling Dice	187
Summary	189
Exercises	189
Chapter 15: Entry-Level Programming	191
Single-Key Entry	191
Function Library, key-funcs	191
History in Scripts	197
Sanity Checking	198
Form Entry	199
Reading the Mouse	200
Summary	204
Exercises	204
Appendix: Shell Variables	205
Index	219

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