The AWK Programming Language

Originally developed by Alfred Aho, Brian Kernighan, and Peter Weinberger in 1977, AWK is a pattern-matching language for writing short programs to perform common data-manipulation tasks. In 1985, a new version of the language was developed, incorporating additional features such as multiple input files, dynamic regular expressions, and user-defined functions. This new version is available for both UNIX and MS-DOS.

This is the first book on AWK. It begins with a tutorial that shows how easy AWK is to use. The tutorial is followed by a comprehensive manual for the new version of AWK.

Subsequent chapters illustrate the language by a range of useful applications, such as:

• Retrieving, transforming, reducing, and validating dtata
• Managing small, personal databases
• Text processing
• Little languages
• Experimenting with algorithms

The examples illustrate the book's three themes: showing how to use AWK well, demonstrating AWK's versatility, and explaining how common computing operations are done. In addition, the book contains two appendixes: a summary of the language, and answers to selected exercises.

1. An AWK Tutorial
1. Getting Started
• The Structure of an AWK Program
• Running an AWK Program
• Errors
2. Simple Output
• Printing Every Line
• Printing Certain Fields
• NF, the Number of Fields
• Computing and Printing
• Printing Line Numbers
• Putting Text in the Output
3. Fancier Output
• Lining Up Fields
• Sorting the Output
4. Selection
• Selection by Comparison
• Selection by Computation
• Selection by Text Content
• Combination of Patterns
• Data Validation
• BEGIN and END
5. Computing with AWK
• Counting
• Computing Sums and Averages
• Handling Text
• String Concatenation
• Printing the Last Input Line
• Built-in Functions
• Counting Lines, Words, and Characters
6. Control-Flow Statements
• If-Else Statement
• While Statement
• For Statement
7. Arrays
8. A Handful of Useful "One-liners"
9. What Next?
2. The AWK Language
• The Input File Countries
• Program Format
1. Patterns
• BEGIN and END
• Expressions as Patterns
• String-Matching Patters
• Regular Expressions
• Compound Patterns
• Range Patterns
• Summary of Patterns
2. Actions
• Expressions
• Control-Flow Statements
• Empty Statements
• Arrays
3. User-Defined Functions
4. Output
• The print statement
• Output Separators
• The printf statement
• Output into Files
• Output into Pipes
• Closing Files and Pipes
5. Input
• Input Separators
• Multiline Records
• The getline Function
• Command-Line Variable Assignments
• Command-Line Arguments
6. Interaction with Other Programs
• The system Function
• Making a Shell Command from an AWK Program
7. Summary
3. Data Processing
1. Data Transformation and Reduction
• Summing Columns
• Computing Percentages and Quantiles
• Number with Commas
• Fixed-Field Input
• Program Cross-Reference Checking
• Formatted Output
2. Data Validation
• Balanced Delimiters
• Password-File Checking
• Generating Data-Validation Programs
• Which Version of AWK?
3. Bundle and Unbundle
4. Multiline Records
• Records Separated by Blank Lines
• Processing Multiline Records
• Records witth Headers and Trailers
• Name-Value Data
5. Summary
4. Reports and Databases
1. Generating Reports
• A Simple Report
• A More Complex Report
2. Packaged Queries and Reports
• Form Letters
3. A Relational Database System
• Natural Joins
• The relfile
• q, and awk-like query language
• qawk, a q-to-awk translator
4. Summary
5. Processing Words
1. Random Text Generation
• Random Choices
• Cliche Generation
• Random Sentences
2. Interactive Text Manipulation
• Skills Testing: Arithmetic
• Skills Testing: Quiz
3. Text Processing
• Word Counts
• Text Formatting
• Maintaining Cross-References in Manuscripts
• Making a KWIC Index
• Making Indexes
4. Summary
6. Little Languages
1. An Assembler and Interpreter
2. A Language for Drawing Graphs
3. A Sort Generator
4. A Reverse-Polish Calculator
5. An Infix Calculator
6. Recursive-Descent Parsing
7. Summary
7. Experiments with Algorithms
1. Sorting
• Insertion Sort
• Quicksort
• Heapsort
2. Profiling
3. Topological Sorting
• Breadth-First Topological Sort
• Depth-First Search
• Depth-First Topological Sort
4. Make: A File Updating Program
5. Summary
8. Epilog
1. AWK as a Language
2. Performance
3. Conclusion

1. AWK Summary
2. Answers to Selected Exercises

Check the authors and you'll understand where it got its name from. The defining document for AWK.