Contents
PART 1 Basic Scripting Techniques
CHAPTER 1 Shell Script Debugging
Controlling Output with Debug Levels
Simplifying Error Checking with a Function
CHAPTER 2 Standard Function Library
CHAPTER 3 Date and Time Manipulation
Alternatives for Finding the Date in Seconds
Evaluating for the Current Day and Time
CHAPTER 4 Comparisons and Tests
CHAPTER 5 Accepting Command-Line Options, Switches, and Parameters
CHAPTER 6 Testing Variables and Assigning Defaults
CHAPTER 7 Indirect Reference Variables
Log File Monitoring with Indirect Variables
Process Tree Implemented Using Arrays
Process Tree Implemented Using Indirect Variables
Bourne Shell Implementation of a Process Tree
Access to User-Specified File Handles
Descriptor Access from the Shell
CHAPTER 10 Piping Input to read
PART 2 System Interaction and Advanced Techniques
CHAPTER 11 Math from the Shell
CHAPTER 13 Self-Linked Scripts
CHAPTER 14 Throttling Parallel Processes
CHAPTER 15 Command-Line Editing and History
CHAPTER 16 Scripting from the Command Line
CHAPTER 17 Automating User Input with expect
A Shell Script to Customize Parameters for an expect Script
An expect Script to Automate telnet
CHAPTER 19 Instant Keyboard Response
CHAPTER 21 A Brief Tour of the X Display Environment
X Applications Through a Third-Party System
CHAPTER 22 X Navigation Window
CHAPTER 23 Command-Line E-mail Attachments
CHAPTER 24 Text-Processing One-Liners
Specifying the Field Separator
Matching Fields Against Several Values
Determining the Number of Fields
Determining the Second-to-Last Field
Using a Variable Passed to awk in a Condition
Displaying a Range of Fields (Main Method)
Displaying a Range of Fields (Alternate Method)
Determining the Length of a String Using awk
Determining the Length of a String Using expr
Displaying a Substring with awk
Displaying a Substring with expr
Conducting Simple Search and Replace with sed
Disregarding Blank and Commented Lines from a File
Conducting Dual Search and Replace with sed
Searching for Multiple Strings with egrep
A Clean Method of Searching the Process Table
Generating Random Numbers Using awk
Generating Random Numbers from the Shell
Displaying Character-Based Fields with sed
Returning Trailing Lines from a Pattern Match Using grep
Returning Preceding Lines to a Pattern Match Using grep
CHAPTER 25 Editing Files in Place
Simple Search and Replace with ed
Search and Replace Using ed, Dissected
Escaping Special Characters in a File
CHAPTER 26 Evaluating Variables in a Flat File
CHAPTER 28 Free-Format Output Using cat
CHAPTER 29 Automating Interactive Processes
PART 3 Useful Scripts
CHAPTER 30 Automating E-mail with procmail
CHAPTER 31 Process-Management Monitor
CHAPTER 32 Managing File Counts
CHAPTER 33 Processes Running from inittab
CHAPTER 35 Colorful /proc Reporting
CHAPTER 36 Password-Aging Notification
CHAPTER 37 A Pseudo–shadow File
CHAPTER 38 Linux Gold-System Build
CHAPTER 40 Removing Large Files and Log Rolling
CHAPTER 42 Network Adapter Failover