(gawk.info)SVR4

Changes between SVR3.1 and SVR4
===============================

   The System V Release 4 version of Unix `awk' added these features
(some of which originated in `gawk'):

   * The `ENVIRON' variable (Note: Built-in Variables.).

   * Multiple `-f' options on the command line (Note: Command Line
     Options.).

   * The `-v' option for assigning variables before program execution
     begins (Note: Command Line Options.).

   * The `--' option for terminating command line options.

   * The `\a', `\v', and `\x' escape sequences (Note: Escape
     Sequences.).

   * A defined return value for the `srand' built-in function (Note:
     Numeric Built-in Functions.).

   * The `toupper' and `tolower' built-in string functions for case
     translation (*note Built-in Functions for String Manipulation:
     String Functions.).

   * A cleaner specification for the `%c' format-control letter in the
     `printf' function (Note: Format-Control Letters.).

   * The ability to dynamically pass the field width and precision
     (`"%*.*d"') in the argument list of the `printf' function (Note:
     Format-Control Letters.).

   * The use of regexp constants such as `/foo/' as expressions, where
     they are equivalent to using the matching operator, as in `$0 ~
     /foo/' (Note: Using Regular Expression Constants.
).