sed & awk, 2nd Edition

Chapter 7. Writing Scripts for awk

As mentioned in the preface, this book describes POSIX awk; that is, the awk language as specified by the POSIX standard. Before diving into the details, we’ll provide a bit of history.

The original awk was a nice little language. It first saw the light of day with Version 7 UNIX, around 1978. It caught on, and people used it for significant programming.

In 1985, the original authors, seeing that awk was being used for more serious programming than they had ever intended, decided to beef up the language. (See Chapter 11, for a description of the original awk, and all the things it did not have when compared to the new one.) The new version was finally released to the world at large in 1987, and it is this version that is still found on SunOS 4.1.x systems.

In 1989, for System V Release 4, awk was updated in some minor ways.^[1] This version became the basis for the awk feature list in the POSIX standard. POSIX clarified a number of things about awk, and added the CONVFMT variable (to be discussed later in this chapter).

As you read the rest of this book, bear in mind that the term awk refers to POSIX awk, and not to any particular implementation, whether the original one from Bell Labs, or any of the others discussed in Chapter 11. However, in the few cases where different versions have fundamental differences of behavior, that will be pointed out in the main body of the discussion.

^[1] The -v option and tolower( ) and toupper( ) functions were added, ...