Expert Shell Scripting

1430218436......Page 1
Contents......Page 6
About the Author......Page 13
About the Technical Reviewer......Page 14
Acknowledgments......Page 15
Introduction......Page 16
PART 1: Basic Scripting Techniques......Page 18
Shell Trace Options......Page 19
Simple Output Statements......Page 22
Controlling Output with Debug Levels......Page 24
Simplifying Error Checking with a Function......Page 25
Manual Stepping......Page 27
The Library File......Page 29
Some Useful Functions......Page 30
Using Your Library......Page 32
Date in Days......Page 34
Evaluating for the Current Day and Time......Page 37
The Basics of Comparisons......Page 40
CHAPTER 5: Accepting Command-Line Options, Switches,and Parameters......Page 45
Setting Defaults......Page 50
Variable Substitution......Page 51
Log File Monitoring with Indirect Variables......Page 56
The Main Monitor Loop......Page 57
CHAPTER 8: Shell Process Tree......Page 61
Process Tree Implemented Using Arrays......Page 62
Process Tree Implemented Using Indirect Variables......Page 67
Bourne Shell Implementation of a Process Tree......Page 68
Avoiding Confusion......Page 71
Common Redirection......Page 72
Access to User-Specified File Handles......Page 74
Descriptor Access from the Shell......Page 76
CHAPTER 10: Piping Input to read......Page 77
Line-by-Line Option 1......Page 78
Line-by-Line Option 2......Page 79
Line-by-Line Option 4......Page 80
Process Input Word-by-Word......Page 82
PART 2: System Interaction and Advanced Techniques......Page 84
expr......Page 85
Internal Shell Math......Page 86
dc......Page 88
crontab Entries......Page 90
Environment Problems......Page 91
Output Redirection......Page 93
CHAPTER 13: Self-Linked Scripts......Page 95
CHAPTER 14: Throttling Parallel Processes......Page 98
Parallel Processing with ksh......Page 99
Parallel Processing with bash......Page 104
CHAPTER 15: Command-Line Editing and History......Page 106
Setting Up vi Editing......Page 107
Command and File Completion......Page 108
A Few Examples......Page 109
CHAPTER 17: Automating User Input with expect......Page 112
A Shell Script to Customize Parameters for an expect Script......Page 113
Manual Timeout Method......Page 120
Timeout Using stty......Page 122
General Timeout Utility......Page 123
CHAPTER 19: Instant Keyboard Response......Page 125
Using cp......Page 129
Using find......Page 130
Using rsync......Page 131
The Display......Page 134
X Applications Through a Third-Party System......Page 136
User-Profile Entry......Page 138
Root-Profile Entry......Page 140
Throw a Temporary Root Window......Page 141
Navigation Window Usage......Page 144
Navigation Setup......Page 145
Navigation Window......Page 148
uuencode......Page 153
MIME Encoding......Page 155
Displaying Specific Fields......Page 158
Simple Pattern-Matching......Page 159
Determining the Last Field......Page 160
Passing Variables to awk......Page 161
Displaying a Range of Fields (Main Method)......Page 162
Displaying a Range of Fields (Alternate Method)......Page 163
Displaying a Substring with awk......Page 164
Disregarding Blank and Commented Lines from a File......Page 165
Filtering Lines with sed......Page 166
A Clean Method of Searching the Process Table......Page 167
Generating Random Numbers Using awk......Page 168
Displaying Character-Based Fields with sed......Page 169
Escaping Special Characters......Page 170
Returning Trailing Lines from a Pattern Match Using grep......Page 171
Returning Preceding Lines to a Pattern Match Using grep......Page 172
CHAPTER 25: Editing Files in Place......Page 174
Search and Replace Using ed, Dissected......Page 175
Examples of ed Commands......Page 176
Escaping Special Characters in a File......Page 179
CHAPTER 26: Evaluating Variables in a Flat File......Page 182
CHAPTER 27: Read Piped Input......Page 184
CHAPTER 28: Free-Format Output Using cat......Page 186
CHAPTER 29: Automating Interactive Processes......Page 188
PART 3: Useful Scripts......Page 191
CHAPTER 30: Automating E-mail with procmail......Page 192
The .procmailrc File......Page 193
The Code......Page 195
CHAPTER 31: Process-Management Monitor......Page 199
File-Count Monitor......Page 208
Testing File-Count Methods......Page 210
CHAPTER 33: Processes Running from inittab......Page 211
CHAPTER 34: Automatic RCS......Page 214
CHAPTER 35: Colorful /proc Reporting......Page 217
CHAPTER 36: Password-Aging Notification......Page 224
Script Initialization......Page 225
Processing Begins......Page 227
Determine Password Age......Page 229
CHAPTER 37: A Pseudo–shadow File......Page 234
CHAPTER 38: Linux Gold-System Build......Page 238
CHAPTER 39: System Snapshots......Page 244
Snapshot Script......Page 246
Snapshot Promotion......Page 248
Final Thoughts......Page 251
CHAPTER 40: Removing Large Files and Log Rolling......Page 253
CHAPTER 41: Core Finder......Page 256
CHAPTER 42: Network Adapter Failover......Page 258
Check the Network......Page 261
Switch the Interfaces......Page 262
APPENDIX A: Test Switches......Page 263
APPENDIX C: Other Shell-Scripting Resources......Page 265
Books......Page 267
Shell Resources......Page 268
Online Resources......Page 269
A......Page 270
C......Page 271
D......Page 272
F......Page 273
H......Page 274
L......Page 275
N......Page 276
P......Page 277
S......Page 278
T......Page 280
W......Page 281
Z......Page 282