The GAWK Manual

• Preface
  • History of awk and gawk
• GNU General Public License
  • Preamble
  • TERMS AND CONDITIONS
  • Appendix: Using These Terms in New Programs
• Using This Manual
  • Data Files for the Examples
• Getting Started With awk
  • A Very Simple Example
  • An Example with Two Rules
  • A More Complex Example
  • How to Run awk Programs
    • One-shot Throw-away awk Programs
    • Running awk without Input Files
    • Running Long Programs
    • Executable awk Programs
  • Comments in awk Programs
  • awk Statements versus Lines
  • When to Use awk
• Reading Input Files
  • How Input is Split into Records
  • Examining Fields
  • Non-constant Field Numbers
  • Changing the Contents of a Field
  • Specifying How Fields Are Separated
  • Multiple-Line Records
  • Explicit Input with getline
  • Closing Input Files and Pipes
• Printing Output
  • The print Statement
  • Examples of print Statements
  • Output Separators
  • Using printf Statements For Fancier Printing
    • Introduction to the printf Statement
    • Format-Control Letters
    • Modifiers for printf Formats
    • Examples of Using printf
  • Redirecting Output of print and printf
    • Redirecting Output to Files and Pipes
    • Closing Output Files and Pipes
  • Standard I/O Streams
• Useful "One-liners"
• Patterns
  • Kinds of Patterns
  • The Empty Pattern
  • Regular Expressions as Patterns
    • How to Use Regular Expressions
    • Regular Expression Operators
    • Case-sensitivity in Matching
  • Comparison Expressions as Patterns
  • Boolean Operators and Patterns
  • Expressions as Patterns
  • Specifying Record Ranges With Patterns
  • BEGIN and END Special Patterns
• Actions: Overview
• Actions: Expressions
  • Constant Expressions
  • Variables
    • Assigning Variables on the Command Line
  • Arithmetic Operators
  • String Concatenation
  • Comparison Expressions
  • Boolean Expressions
  • Assignment Expressions
  • Increment Operators
  • Conversion of Strings and Numbers
  • Conditional Expressions
  • Function Calls
  • Operator Precedence: How Operators Nest
• Actions: Control Statements
  • The if Statement
  • The while Statement
  • The do-while Statement
  • The for Statement
  • The break Statement
  • The continue Statement
  • The next Statement
  • The exit Statement
• Arrays in awk
  • Introduction to Arrays
  • Referring to an Array Element
  • Assigning Array Elements
  • Basic Example of an Array
  • Scanning All Elements of an Array
  • The delete Statement
  • Multi-dimensional Arrays
  • Scanning Multi-dimensional Arrays
• Built-in Functions
  • Calling Built-in Functions
  • Numeric Built-in Functions
  • Built-in Functions for String Manipulation
  • Built-in Functions For Input/Output
• User-defined Functions
  • Syntax of Function Definitions
  • Function Definition Example
  • Calling User-defined Functions
  • The return Statement
• Built-in Variables
  • Built-in Variables That Control awk
  • Built-in Variables That Convey Information to You
• Invocation of awk
  • Command Line Options
  • Other Command Line Arguments
  • The AWKPATH Environment Variable
• The Evolution of the awk Language
  • Major Changes Between V7 and S5R3.1
  • Minor Changes between S5R3.1 and S5R4
  • Extensions In gawk Not In S5R4
• gawk Summary
  • Command Line Options Summary
  • Language Summary
  • Variables and Fields
    • Fields
    • Built-in Variables
    • Arrays
    • Data Types
  • Patterns and Actions
    • Patterns
    • Regular Expressions
    • Actions
      • Operators
      • Control Statements
      • I/O Statements
      • printf Summary
      • Special File Names
      • Numeric Functions
      • String Functions
      • String Constants
  • Functions
• Sample Program
• Implementation Notes
  • Downwards Compatibility and Debugging
  • Probable Future Extensions
  • Suggestions for Improvements
• Glossary
• Index