The term awk refers to a particular program, and to the language you
use to tell this program what to do. When we need to be careful, we call
the program "the awk utility" and the language "the awk
language." The term gawk refers to a version of awk developed
as part the GNU project. The purpose of this book is to explain
both the awk language and how to run the awk utility.
The main purpose of the book is to explain the features
of awk, as defined in the POSIX standard. It does so in the context
of one particular implementation, gawk. While doing so, it will also
attempt to describe important differences between gawk and other
awk implementations. Finally, any gawk features that
are not in the POSIX standard for awk will be noted.
This book has the difficult task of being both tutorial and reference. If you are a novice, feel free to skip over details that seem too complex. You should also ignore the many cross references; they are for the expert user, and for the on-line Info version of the document.
The term awk program refers to a program written by you in
the awk programming language.
See section Getting Started with awk, for the bare
essentials you need to know to start using awk.
Some useful "one-liners" are included to give you a feel for the
awk language (see section Useful One Line Programs).
Many sample awk programs have been provided for you
(see section A Library of awk Functions; also
see section Practical awk Programs).
The entire awk language is summarized for quick reference in
section gawk Summary. Look there if you just need
to refresh your memory about a particular feature.
If you find terms that you aren't familiar with, try looking them up in the glossary (see section Glossary).
Most of the time complete awk programs are used as examples, but in
some of the more advanced sections, only the part of the awk program
that illustrates the concept being described is shown.
While this book is aimed principally at people who have not been
exposed
to awk, there is a lot of information here that even the awk
expert should find useful. In particular, the description of POSIX
awk, and the example programs in
section A Library of awk Functions, and
section Practical awk Programs,
should be of interest.
Who opened that window shade?!? Count Dracula
Until the POSIX standard (and The Gawk Manual),
many features of awk were either poorly documented, or not
documented at all. Descriptions of such features
(often called "dark corners") are noted in this book with
"(d.c.)".
They also appear in the index under the heading "dark corner."
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