gawk: Foreword3
Foreword to the Third Edition
*****************************
Arnold Robbins and I are good friends. We were introduced in 1990 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. Alfred V. Aho, Brian W.
Kernighan, and Peter J. Weinberger's '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 a 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 gray book. I discovered that my computer had "old
'awk'" and the 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 GNU/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
Programming Language'.
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
Laboratories 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 prototyping 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'
March 2001
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