GNU Info

(gawk.info)POSIX/GNU

---

Next: Contributors Prev: BTL Up: Language History

---

Enter node , (file) or (file)node

Extensions in `gawk' Not in POSIX `awk'
=======================================

   The GNU implementation, `gawk', adds a large number of features.
This minor node lists them in the order they were added to `gawk'.
They can all be disabled with either the `--traditional' or `--posix'
options (Note: Command-Line Options.).

   Version 2.10 of `gawk' introduced the following features:

   * The `AWKPATH' environment variable for specifying a path search for
     the `-f' command-line option (*note Command-Line Options:
     Options.).

   * The `IGNORECASE' variable and its effects (Note: Case Sensitivity
     in Matching.).

   * The `/dev/stdin', `/dev/stdout', `/dev/stderr' and `/dev/fd/N'
     special file names (Note: Special File Names in `gawk'.
).

   Version 2.13 of `gawk' introduced the following features:

   * The `FIELDWIDTHS' variable and its effects (Note: Reading
     Fixed-Width Data.).

   * The `systime' and `strftime' built-in functions for obtaining and
     printing timestamps (*note Using `gawk''s Timestamp Functions:
     Time Functions.).

   * The `-W lint' option to provide error and portability checking for
     both the source code and at runtime (*note Command-Line Options:
     Options.).

   * The `-W compat' option to turn off the GNU extensions (Note:
     Command-Line Options.).

   * The `-W posix' option for full POSIX compliance (Note:
     Command-Line Options.).

   Version 2.14 of `gawk' introduced the following feature:

   * The `next file' statement for skipping to the next data file
     (Note: Using `gawk''s `nextfile' Statement.).

   Version 2.15 of `gawk' introduced the following features:

   * The `ARGIND' variable, which tracks the movement of `FILENAME'
     through `ARGV'  (Note: Built-in Variables).

   * The `ERRNO' variable, which contains the system error message when
     `getline' returns -1 or when `close' fails (Note: Built-in
     Variables).

   * The `/dev/pid', `/dev/ppid', `/dev/pgrpid', and `/dev/user' file
     name interpretation (Note: Special File Names in `gawk'.
).

   * The ability to delete all of an array at once with `delete ARRAY'
     (Note: The `delete' Statement.).

   * The ability to use GNU-style long-named options that start with
     `--' (Note: Command-Line Options.).

   * The `--source' option for mixing command-line and library file
     source code (Note: Command-Line Options.).

   Version 3.0 of `gawk' introduced the following features:

   * `IGNORECASE' changed, now applying to string comparison as well as
     regexp operations (*note Case Sensitivity in Matching:
     Case-sensitivity.).

   * The `RT' variable that contains the input text that matched `RS'
     (Note: How Input Is Split into Records.).

   * Full support for both POSIX and GNU regexps (Note: Regular
     Expressions.).

   * The `gensub' function for more powerful text manipulation (Note:
     String Manipulation Functions.).

   * The `strftime' function acquired a default time format, allowing
     it to be called with no arguments (Note: Using `gawk''s Timestamp
     Functions.).

   * The ability for `FS' and for the third argument to `split' to be
     null strings (Note: Making Each Character a Separate Field.
).

   * The ability for `RS' to be a regexp (Note: How Input Is Split into
     Records.).

   * The `next file' statement became `nextfile' (Note: Using `gawk''s
     `nextfile' Statement.).

   * The `--lint-old' option to warn about constructs that are not
     available in the original Version 7 Unix version of `awk' (Note:
     Major Changes Between V7 and SVR3.1.1.).

   * The `-m' option and the `fflush' function from the Bell
     Laboratories research version of `awk' (Note: Command-Line
     Options.; also Note: Input/Output Functions.
).

   * The `--re-interval' option to provide interval expressions in
     regexps (Note: Regular Expression Operators.).

   * The `--traditional' option was added as a better name for
     `--compat' (Note: Command-Line Options.).

   * The use of GNU Autoconf to control the configuration process
     (Note: Compiling `gawk' for Unix.).

   * Amiga support (Note: Installing `gawk' on an Amiga.
).


   Version 3.1 of `gawk' introduced the following features:

   * The `BINMODE' special variable for non-POSIX systems, which allows
     binary I/O for input and/or output files (Note: Using `gawk' on PC
     Operating Systems.).

   * The `LINT' special variable, which dynamically controls lint
     warnings (Note: Built-in Variables).

   * The `PROCINFO' array for providing process-related information
     (Note: Built-in Variables).

   * The `TEXTDOMAIN' special variable for setting an application's
     internationalization text domain (Note: Built-in Variables, and
     Note: Internationalization with `gawk'.

   * The ability to use octal and hexadecimal constants in `awk'
     program source code (*note Octal and Hexadecimal Numbers:
     Non-decimal-numbers.).

   * The `|&' operator for two-way I/O to a coprocess (Note: Two-Way
     Communications with Another Process.).

   * The `/inet' special files for TCP/IP networking using `|&' (Note:
     Using `gawk' for Network Programming.).

   * The optional second argument to `close' that allows closing one end
     of a two-way pipe to a coprocess (Note: Two-Way Communications
     with Another Process.).

   * The optional third argument to the `match' function for capturing
     text-matching subexpressions within a regexp (Note: String
     Manipulation Functions.).

   * Positional specifiers in `printf' formats for making translations
     easier (Note: Rearranging `printf' Arguments.).

   * The `asort' function for sorting arrays (Note: Sorting Array
     Values and Indices with `gawk'.).

   * The `bindtextdomain' and `dcgettext' functions for
     internationalization (*note Internationalizing `awk' Programs:
     Programmer i18n.).

   * The `extension' built-in function and the ability to add new
     built-in functions dynamically (Note: Adding New Built-in
     Functions to `gawk'.).

   * The `mktime' built-in function for creating timestamps (Note:
     Using `gawk''s Timestamp Functions.).

   * The `and', `or', `xor', `compl', `lshift', `rshift', and
     `strtonum' built-in functions (Note: Using `gawk''s Bit
     Manipulation Functions.).

   * The support for `next file' as two words was removed completely
     (Note: Using `gawk''s `nextfile' Statement.).

   * The `--dump-variables' option to print a list of all global
     variables (Note: Command-Line Options.).

   * The `--gen-po' command-line option and the use of a leading
     underscore to mark strings that should be translated (Note:
     Extracting Marked Strings.).

   * The `--non-decimal-data' option to allow non-decimal input data
     (Note: Allowing Non-Decimal Input Data.).

   * The `--profile' option and `pgawk', the profiling version of
     `gawk', for producing execution profiles of `awk' programs (Note:
     Profiling Your `awk' Programs.).

   * The `--enable-portals' configuration option to enable special
     treatment of pathnames that begin with `/p' as BSD portals (Note:
     Using `gawk' with BSD Portals.).

   * The use of GNU Automake to help in standardizing the configuration
     process (Note: Compiling `gawk' for Unix.).

   * The use of GNU `gettext' for `gawk''s own message output (Note:
     `gawk' Can Speak Your Language.).

   * BeOS support (Note: Installing `gawk' on BeOS.).

   * Tandem support (Note: Installing `gawk' on a Tandem.
).

   * The Atari port became officially unsupported (Note: Installing
     `gawk' on the Atari ST.).

   * The source code now uses new-style function definitions, with
     `ansi2knr' to convert the code on systems with old compilers.