File: gawk.info,  Node: Preface,  Next: Getting Started,  Prev: Foreword4,  Up: Top

Preface
*******

Several kinds of tasks occur repeatedly when working with text files.
You might want to extract certain lines and discard the rest.  Or you
may need to make changes wherever certain patterns appear, but leave the
rest of the file alone.  Such jobs are often easy with 'awk'.  The 'awk'
utility interprets a special-purpose programming language that makes it
easy to handle simple data-reformatting jobs.

   The GNU implementation of 'awk' is called 'gawk'; if you invoke it
with the proper options or environment variables, it is fully compatible
with the POSIX(1) specification of the 'awk' language and with the Unix
version of 'awk' maintained by Brian Kernighan.  This means that all
properly written 'awk' programs should work with 'gawk'.  So most of the
time, we don't distinguish between 'gawk' and other 'awk'
implementations.

   Using 'awk' you can:

   * Manage small, personal databases

   * Generate reports

   * Validate data

   * Produce indexes and perform other document-preparation tasks

   * Experiment with algorithms that you can adapt later to other
     computer languages

   In addition, 'gawk' provides facilities that make it easy to:

   * Extract bits and pieces of data for processing

   * Sort data

   * Perform simple network communications

   * Profile and debug 'awk' programs

   * Extend the language with functions written in C or C++

   This Info file teaches you about the 'awk' language and how you can
use it effectively.  You should already be familiar with basic system
commands, such as 'cat' and 'ls',(2) as well as basic shell facilities,
such as input/output (I/O) redirection and pipes.

   Implementations of the 'awk' language are available for many
different computing environments.  This Info file, while describing the
'awk' language in general, also describes the particular implementation
of 'awk' called 'gawk' (which stands for "GNU 'awk'").  'gawk' runs on a
broad range of Unix systems, ranging from Intel-architecture PC-based
computers up through large-scale systems.  'gawk' has also been ported
to macOS, z/OS, Microsoft Windows (all versions), and OpenVMS.(3)

* Menu:

* History::                     The history of 'gawk' and
                                'awk'.
* Names::                       What name to use to find 'awk'.
* This Manual::                 Using this Info file. Includes sample
                                input files that you can use.
* Conventions::                 Typographical Conventions.
* Manual History::              Brief history of the GNU project and this
                                Info file.
* How To Contribute::           Helping to save the world.
* Acknowledgments::             Acknowledgments.

   ---------- Footnotes ----------

   (1) The 2018 POSIX standard is accessible online at
.

   (2) These utilities are available on POSIX-compliant systems, as well
as on traditional Unix-based systems.  If you are using some other
operating system, you still need to be familiar with the ideas of I/O
redirection and pipes.

   (3) Some other, obsolete systems to which 'gawk' was once ported are
no longer supported and the code for those systems has been removed.