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Foreword
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   Arnold Robbins and I are good friends. We were introduced 11 years
ago by circumstances--and our favorite programming language, AWK.  The
circumstances started a couple of years earlier. I was working at a new
job and noticed an unplugged Unix computer sitting in the corner.  No
one knew how to use it, and neither did I.  However, a couple of days
later it was running, and I was `root' and the one-and-only user.  That
day, I began the transition from statistician to Unix programmer.

   On one of many trips to the library or bookstore in search of books
on Unix, I found the gray AWK book, a.k.a. Aho, Kernighan and
Weinberger, `The AWK Programming Language', Addison-Wesley, 1988.
AWK's simple programming paradigm--find a pattern in the input and then
perform an action--often reduced complex or tedious data manipulations
to few lines of code.  I was excited to try my hand at programming in
AWK.

   Alas,  the `awk' on my computer was a limited version of the
language described in the AWK book.  I discovered that my computer had
"old `awk'" and the AWK book described "new `awk'."  I learned that
this was typical; the old version refused to step aside or relinquish
its name.  If a system had a new `awk', it was invariably called
`nawk', and few systems had it.  The best way to get a new `awk' was to
`ftp' the source code for `gawk' from `prep.ai.mit.edu'.  `gawk' was a
version of new `awk' written by David Trueman and Arnold, and available
under the GNU General Public License.

   (Incidentally, it's no longer difficult to find a new `awk'. `gawk'
ships with Linux, and you can download binaries or source code for
almost any system; my wife uses `gawk' on her VMS box.)

   My Unix system started out unplugged from the wall; it certainly was
not plugged into a network.  So, oblivious to the existence of `gawk'
and the Unix community in general, and desiring a new `awk', I wrote my
own, called `mawk'.  Before I was finished I knew about `gawk', but it
was too late to stop, so I eventually posted to a `comp.sources'
newsgroup.

   A few days after my posting, I got a friendly email from Arnold
introducing himself.   He suggested we share design and algorithms and
attached a draft of the POSIX standard so that I could update `mawk' to
support language extensions added after publication of the AWK book.

   Frankly, if our roles had been reversed, I would not have been so
open and we probably would have never met.  I'm glad we did meet.  He
is an AWK expert's AWK expert and a genuinely nice person.  Arnold
contributes significant amounts of his expertise and time to the Free
Software Foundation.

   This book is the `gawk' reference manual, but at its core it is a
book about AWK programming that will appeal to a wide audience.  It is
a definitive reference to the AWK language as defined by the 1987 Bell
Labs release and codified in the 1992 POSIX Utilities standard.

   On the other hand, the novice AWK programmer can study a wealth of
practical programs that emphasize the power of AWK's basic idioms: data
driven control-flow, pattern matching with regular expressions, and
associative arrays.  Those looking for something new can try out
`gawk''s interface to network protocols via special `/inet' files.

   The programs in this book make clear that an AWK program is
typically much smaller and faster to develop than a counterpart written
in C.  Consequently, there is often a payoff to prototype an algorithm
or design in AWK to get it running quickly and expose problems early.
Often, the interpreted performance is adequate and the AWK prototype
becomes the product.

   The new `pgawk' (profiling `gawk'), produces program execution
counts.  I recently experimented with an algorithm that for n lines of
input, exhibited ~ C n^2 performance, while theory predicted ~ C n log n
behavior. A few minutes poring over the `awkprof.out' profile
pinpointed the problem to a single line of code.  `pgawk' is a welcome
addition to my programmer's toolbox.

   Arnold has distilled over a decade of experience writing and using
AWK programs, and developing `gawk', into this book.  If you use AWK or
want to learn how, then read this book.

     Michael Brennan
     Author of `mawk'