(gawk.info)V7/SVR3.1

Major Changes between V7 and SVR3.1
===================================

   The `awk' language evolved considerably between the release of
Version 7 Unix (1978) and the new version first made generally
available in System V Release 3.1 (1987).  This section summarizes the
changes, with cross-references to further details.

   * The requirement for `;' to separate rules on a line (Note: `awk'
     Statements Versus Lines.).

   * User-defined functions, and the `return' statement (Note:
     User-defined Functions.).

   * The `delete' statement (Note: The `delete' Statement.).

   * The `do'-`while' statement (Note: The `do'-`while' Statement.
).

   * The built-in functions `atan2', `cos', `sin', `rand' and `srand'
     (Note: Numeric Built-in Functions.).

   * The built-in functions `gsub', `sub', and `match' (Note: Built-in
     Functions for String Manipulation.).

   * The built-in functions `close', and `system' (Note: Built-in
     Functions for Input/Output.).

   * The `ARGC', `ARGV', `FNR', `RLENGTH', `RSTART', and `SUBSEP'
     built-in variables (Note: Built-in Variables.).

   * The conditional expression using the ternary operator `?:' (Note:
     Conditional Expressions.).

   * The exponentiation operator `^' (*note Arithmetic Operators:
     Arithmetic Ops.) and its assignment operator form `^=' (Note:
     Assignment Expressions.).

   * C-compatible operator precedence, which breaks some old `awk'
     programs (*note Operator Precedence (How Operators Nest):
     Precedence.).

   * Regexps as the value of `FS' (Note: Specifying How Fields are
     Separated.), and as the third argument to the
     `split' function (Note: Built-in Functions for String
     Manipulation.).

   * Dynamic regexps as operands of the `~' and `!~' operators (Note:
     How to Use Regular Expressions.).

   * The escape sequences `\b', `\f', and `\r' (Note: Escape
     Sequences.).  (Some vendors have updated their old versions of
     `awk' to recognize `\r', `\b', and `\f', but this is not something
     you can rely on.)

   * Redirection of input for the `getline' function (Note: Explicit
     Input with `getline'.).

   * Multiple `BEGIN' and `END' rules (Note: The `BEGIN' and `END'
     Special Patterns.).

   * Multi-dimensional arrays (*note Multi-dimensional Arrays:
     Multi-dimensional.).