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 Extensions in `gawk' Not in POSIX `awk'
 =======================================
 
    The GNU implementation, `gawk', adds a number of features.  This
 sections lists them in the order they were added to `gawk'.  They can
 all be disabled with either the `--traditional' or `--posix' options
 ( Command Line Options Options.).
 
    Version 2.10 of `gawk' introduced these features:
 
    * The `AWKPATH' environment variable for specifying a path search for
      the `-f' command line option ( Command Line Options
      Options.).
 
    * The `IGNORECASE' variable and its effects ( Case-sensitivity
      in Matching Case-sensitivity.).
 
    * The `/dev/stdin', `/dev/stdout', `/dev/stderr', and `/dev/fd/N'
      file name interpretation ( Special File Names in `gawk'
      Special Files.).
 
    Version 2.13 of `gawk' introduced these features:
 
    * The `FIELDWIDTHS' variable and its effects ( Reading
      Fixed-width Data Constant Size.).
 
    * The `systime' and `strftime' built-in functions for obtaining and
      printing time stamps ( Functions for Dealing with Time
      Stamps Time Functions.).
 
    * The `-W lint' option to provide source code and run time error and
      portability checking ( Command Line Options Options.).
 
    * The `-W compat' option to turn off these extensions ( Command
      Line Options Options.).
 
    * The `-W posix' option for full POSIX compliance ( Command
      Line Options Options.).
 
    Version 2.14 of `gawk' introduced these features:
 
    * The `next file' statement for skipping to the next data file
      ( The `nextfile' Statement Nextfile Statement.).
 
    Version 2.15 of `gawk' introduced these features:
 
    * The `ARGIND' variable, that tracks the movement of `FILENAME'
      through `ARGV'  ( Built-in Variables).
 
    * The `ERRNO' variable, that contains the system error message when
      `getline' returns -1, or when `close' fails ( Built-in
      Variables).
 
    * The ability to use GNU-style long named options that start with
      `--' ( Command Line Options Options.).
 
    * The `--source' option for mixing command line and library file
      source code ( Command Line Options Options.).
 
    * The `/dev/pid', `/dev/ppid', `/dev/pgrpid', and `/dev/user' file
      name interpretation ( Special File Names in `gawk' Special
      Files.).
 
    Version 3.0 of `gawk' introduced these features:
 
    * The `next file' statement became `nextfile' ( The `nextfile'
      Statement Nextfile Statement.).
 
    * The `--lint-old' option to warn about constructs that are not
      available in the original Version 7 Unix version of `awk' (
      Major Changes between V7 and SVR3.1 V7/SVR3.1.).
 
    * The `--traditional' option was added as a better name for
      `--compat' ( Command Line Options Options.).
 
    * The ability for `FS' to be a null string, and for the third
      argument to `split' to be the null string ( Making Each
      Character a Separate Field Single Character Fields.).
 
    * The ability for `RS' to be a regexp ( How Input is Split into
      Records Records.).
 
    * The `RT' variable ( How Input is Split into Records
      Records.).
 
    * The `gensub' function for more powerful text manipulation (
      Built-in Functions for String Manipulation String Functions.).
 
    * The `strftime' function acquired a default time format, allowing
      it to be called with no arguments ( Functions for Dealing
      with Time Stamps Time Functions.).
 
    * Full support for both POSIX and GNU regexps ( Regular
      Expressions Regexp.).
 
    * The `--re-interval' option to provide interval expressions in
      regexps ( Regular Expression Operators Regexp Operators.).
 
    * `IGNORECASE' changed, now applying to string comparison as well as
      regexp operations ( Case-sensitivity in Matching
      Case-sensitivity.).
 
    * The `-m' option and the `fflush' function from the Bell Labs
      research version of `awk' ( Command Line Options Options.;
      also  Built-in Functions for Input/Output I/O Functions.).
 
    * The use of GNU Autoconf to control the configuration process
      ( Compiling `gawk' for Unix Quick Installation.).
 
    * Amiga support ( Installing `gawk' on an Amiga Amiga
      Installation.).
 
 

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