Linux in a Nutshell, Fifth Edition

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Chapter 11: The gawk Programming Language

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

gawk, which provides a number of additional features. This utility can be invoked

either through the standard name awk or through gawk.

Items described here as “common extensions” are available in gawk and most

versions of awk offered on other operating systems (often called nawk for “new

awk”), but should not be used if strict portability of your programs is important

to you.

With gawk, you can:

• Think of a text file as made up of records and fields in a textual database.

• Perform arithmetic and string operations.

• Use programming constructs, such as loops and conditionals.

• Produce formatted reports.

• Define your own functions.

• Execute Unix commands from a script.

• Process the results of Unix commands.

• Process command-line arguments gracefully.

• Work easily with multiple input streams.

• Flush open output files and pipes.

• Sort arrays.

• Retrieve and format system time values.

• Do bit manipulation.

• Internationalize your gawk programs, allowing strings to be translated into a

local language at runtime.

• Perform two-way I/O to a coprocess.

• Open a two-way TCP/IP connection to a socket.

• Dynamically add built-in functions.

• Profile your gawk programs.

Command-Line Syntax

The syntax for invoking awk has two forms:

awk [options] 'script ...