GAWK: Effective AWK Programming

Appendix A: The Evolution of the awk Language 261• The ‘--source’ option for mixing command-line and library-file source code (seeSection 11.2 [Command-Line Options], page 177).Version 3.0 of gawk introduced the following features:• IGNORECASE changed, now applying to string comparison as well as regexp operations(see Section 2.6 [Case Sensitivity in Matching], page 32).• The RT variable that contains the input text that matched RS (see Section 3.1 [HowInput Is Split into Records], page 36).• Full support for both POSIX and GNU regexps (see Chapter 2 [Regular Expressions],page 24).• The gensub function for more powerful text manipulation (see Section 8.1.3 [String-Manipulation Functions], page 132).• The strftime function acquired a default time format, allowing it to be called withno arguments (see Section 8.1.5 [Using gawk’s Timestamp Functions], page 146).• The ability for FS and for the third argument to split to be null strings (seeSection 3.5.2 [Making Each Character a Separate Field], page 45).• The ability for RS to be a regexp (see Section 3.1 [How Input Is Split into Records],page 36).• The next file statement became nextfile (see Section 6.4.9 [Using gawk’s nextfileStatement], page 109).• The ‘--lint-old’ option to warn about constructs that are not available in the originalVersion 7 Unix version of awk (see Section A.1 [Major Changes Between V7 andSVR3.1], page 257).• The ‘-m’ option and the fflush function from the Bell Laboratories research versionof awk (see Section 11.2 [Command-Line Options], page 177; also see Section 8.1.4[Input/Output Functions], page 143).• The ‘--re-interval’ option to provide interval expressions in regexps (see Section 2.3[Regular Expression Operators], page 27).• The ‘--traditional’ option was added as a better name for ‘--compat’ (seeSection 11.2 [Command-Line Options], page 177).• The use of GNU Autoconf to control the configuration process (see Section B.2.1 [Compilinggawk for Unix], page 268).Version 3.1 of gawk introduced the following features:• The BINMODE special variable for non-POSIX systems, which allows binary I/O forinput and/or output files (see Section B.3.1.4 [Using gawk on PC Operating Systems],page 273).• The LINT special variable, which dynamically controls lint warnings (see Section 6.5[Built-in Variables], page 110).• The PROCINFO array for providing process-related information (see Section 6.5 [Built-inVariables], page 110).• The TEXTDOMAIN special variable for setting an application’s internationalization textdomain (see Section 6.5 [Built-in Variables], page 110, and Chapter 9 [Internationalizationwith gawk], page 160).