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gawk: 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'
    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 Mac OS X, Microsoft Windows (all versions), and OpenVMS.(3)


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