AWK is an interpreted programming language that is included in most versions of Unix. The name is derived from the initials of its creators--Alfred Aho, Peter Weinberger, and Brian Kernighan--who developed the language in 1977. The language is particularly designed for filtering and manipulating textual data. In this respect, it is similar to Perl, though Perl is more powerful. There are many variants of AWK, including gawk, which is the GNU version.
Effective AWK Programming was published by the Free Software Foundation (FSF) and distributed in electronic form with the GNU AWK source code. It was also published by SSC to help make it more widely available in book form, and is now offered by O'Reilly & Associates.
Effective AWK Programming covers every aspect of the AWK 3.0.3 and 3.0.4 language. It offers the most up-to-date coverage of the POSIX standard for AWK available anywhere, and clearly distinguishes standard AWK features from GNU AWK-specific features. The author sheds light on many of the "dark corners" of the language (areas to watch out for when programming), devotes two full chapters to example programs, and includes a summary of how the AWK language evolved.