- •Preface
- •History of awk
- •GNU GENERAL PUBLIC LICENSE
- •Preamble
- •TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
- •How to Apply These Terms to Your 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
- •Controlling Numeric Output with print
- •Using printf Statements for Fancier Printing
- •Introduction to the printf Statement
- •Format-Control Letters
- •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
- •Patterns
- •Kinds of Patterns
- •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
- •The Empty Pattern
- •Overview of Actions
- •Expressions as Action Statements
- •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
- •Numeric and String Values
- •Conditional Expressions
- •Function Calls
- •Operator Precedence (How Operators Nest)
- •Control Statements in Actions
- •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
- •Using Numbers to Subscript Arrays
- •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
- •The return Statement
- •Built-in Variables
- •Built-in Variables that Control awk
- •Built-in Variables that Convey Information
- •Invoking awk
- •Command Line Options
- •Other Command Line Arguments
- •Index
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How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest to attach them to the start of each source le to most e ectively convey the exclusion of warranty; and each le should have at least the \copyright" line and a pointer to where the full notice is found.
one line to give the program's name and a brief idea of what it does.
Copyright (C) 19yy name of author
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) 19yy name of author Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items|whatever suits your program.
You should also get your employer (if you work as a programmer) or your school, if any, to sign a \copyright disclaimer" for the program, if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers) written by James Hacker.
signature of Ty Coon, 1 April 1989 Ty Coon, President of Vice
GNU GENERAL PUBLIC LICENSE |
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This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License.
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