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diff --git a/doc/gawk.texi b/doc/gawk.texi index f7b04d7d..fd411745 100644 --- a/doc/gawk.texi +++ b/doc/gawk.texi @@ -708,7 +708,7 @@ particular records in a file and perform operations upon them. record. * Nextfile Statement:: Stop processing the current file. * Exit Statement:: Stop execution of @command{awk}. -* Built-in Variables:: Summarizes the built-in variables. +* Built-in Variables:: Summarizes the predefined variables. * User-modified:: Built-in variables that you change to control @command{awk}. * Auto-set:: Built-in variables where @command{awk} @@ -906,7 +906,6 @@ particular records in a file and perform operations upon them. * Extension API Description:: A full description of the API. * Extension API Functions Introduction:: Introduction to the API functions. * General Data Types:: The data types. -* Requesting Values:: How to get a value. * Memory Allocation Functions:: Functions for allocating memory. * Constructor Functions:: Functions for creating values. * Registration Functions:: Functions to register things with @@ -919,6 +918,7 @@ particular records in a file and perform operations upon them. * Two-way processors:: Registering a two-way processor. * Printing Messages:: Functions for printing messages. * Updating @code{ERRNO}:: Functions for updating @code{ERRNO}. +* Requesting Values:: How to get a value. * Accessing Parameters:: Functions for accessing parameters. * Symbol Table Access:: Functions for accessing global variables. @@ -957,9 +957,9 @@ particular records in a file and perform operations upon them. processor. * Extension Sample Read write array:: Serializing an array to a file. * Extension Sample Readfile:: Reading an entire file into a string. -* Extension Sample API Tests:: Tests for the API. * Extension Sample Time:: An interface to @code{gettimeofday()} and @code{sleep()}. +* Extension Sample API Tests:: Tests for the API. * gawkextlib:: The @code{gawkextlib} project. * Extension summary:: Extension summary. * Extension Exercises:: Exercises. @@ -1570,7 +1570,7 @@ for getting most things done in a program. @ref{Patterns and Actions}, describes how to write patterns for matching records, actions for -doing something when a record is matched, and the built-in variables +doing something when a record is matched, and the predefined variables @command{awk} and @command{gawk} use. @ref{Arrays}, @@ -3656,8 +3656,8 @@ The @option{-v} option can only set one variable, but it can be used more than once, setting another variable each time, like this: @samp{awk @w{-v foo=1} @w{-v bar=2} @dots{}}. -@cindex built-in variables, @code{-v} option@comma{} setting with -@cindex variables, built-in, @code{-v} option@comma{} setting with +@cindex predefined variables, @code{-v} option@comma{} setting with +@cindex variables, predefined @code{-v} option@comma{} setting with @quotation CAUTION Using @option{-v} to set the values of the built-in variables may lead to surprising results. @command{awk} will reset the @@ -6142,7 +6142,7 @@ standard input (by default, this is the keyboard, but often it is a pipe from an command) or from files whose names you specify on the @command{awk} command line. If you specify input files, @command{awk} reads them in order, processing all the data from one before going on to the next. -The name of the current input file can be found in the built-in variable +The name of the current input file can be found in the predefined variable @code{FILENAME} (@pxref{Built-in Variables}). @@ -6190,9 +6190,9 @@ used with it do not have to be named on the @command{awk} command line @cindex @code{FNR} variable @command{awk} divides the input for your program into records and fields. It keeps track of the number of records that have been read so far from -the current input file. This value is stored in a built-in variable +the current input file. This value is stored in a predefined variable called @code{FNR} which is reset to zero every time a new file is started. -Another built-in variable, @code{NR}, records the total number of input +Another predefined variable, @code{NR}, records the total number of input records read so far from all @value{DF}s. It starts at zero, but is never automatically reset to zero. @@ -6210,7 +6210,7 @@ Records are separated by a character called the @dfn{record separator}. By default, the record separator is the newline character. This is why records are, by default, single lines. A different character can be used for the record separator by -assigning the character to the built-in variable @code{RS}. +assigning the character to the predefined variable @code{RS}. @cindex newlines, as record separators @cindex @code{RS} variable @@ -6596,7 +6596,7 @@ field. @cindex @code{NF} variable @cindex fields, number of -@code{NF} is a built-in variable whose value is the number of fields +@code{NF} is a predefined variable whose value is the number of fields in the current record. @command{awk} automatically updates the value of @code{NF} each time it reads a record. No matter how many fields there are, the last field in a record can be represented by @code{$NF}. @@ -6954,7 +6954,7 @@ is split into three fields: @samp{m}, @samp{@bullet{}g}, and Note the leading spaces in the values of the second and third fields. @cindex troubleshooting, @command{awk} uses @code{FS} not @code{IFS} -The field separator is represented by the built-in variable @code{FS}. +The field separator is represented by the predefined variable @code{FS}. Shell programmers take note: @command{awk} does @emph{not} use the name @code{IFS} that is used by the POSIX-compliant shells (such as the Unix Bourne shell, @command{sh}, or Bash). @@ -7199,7 +7199,7 @@ an uppercase @samp{F} instead of a lowercase @samp{f}. The latter option (@option{-f}) specifies a file containing an @command{awk} program. The value used for the argument to @option{-F} is processed in exactly the -same way as assignments to the built-in variable @code{FS}. +same way as assignments to the predefined variable @code{FS}. Any special characters in the field separator must be escaped appropriately. For example, to use a @samp{\} as the field separator on the command line, you would have to type: @@ -8185,7 +8185,7 @@ from the file @var{file}, and put it in the variable @var{var}. As above, @var{file} is a string-valued expression that specifies the file from which to read. -In this version of @code{getline}, none of the built-in variables are +In this version of @code{getline}, none of the predefined variables are changed and the record is not split into fields. The only variable changed is @var{var}.@footnote{This is not quite true. @code{RT} could be changed if @code{RS} is a regular expression.} @@ -8347,7 +8347,7 @@ BEGIN @{ @} @end example -In this version of @code{getline}, none of the built-in variables are +In this version of @code{getline}, none of the predefined variables are changed and the record is not split into fields. However, @code{RT} is set. @ifinfo @@ -8409,7 +8409,7 @@ When you use @samp{@var{command} |& getline @var{var}}, the output from the coprocess @var{command} is sent through a two-way pipe to @code{getline} and into the variable @var{var}. -In this version of @code{getline}, none of the built-in variables are +In this version of @code{getline}, none of the predefined variables are changed and the record is not split into fields. The only variable changed is @var{var}. However, @code{RT} is set. @@ -8512,9 +8512,9 @@ know that there is a string value to be assigned. @ref{table-getline-variants} summarizes the eight variants of @code{getline}, -listing which built-in variables are set by each one, +listing which predefined variables are set by each one, and whether the variant is standard or a @command{gawk} extension. -Note: for each variant, @command{gawk} sets the @code{RT} built-in variable. +Note: for each variant, @command{gawk} sets the @code{RT} predefined variable. @float Table,table-getline-variants @caption{@code{getline} Variants and What They Set} @@ -8974,7 +8974,7 @@ of items separated by commas. In the output, the items are normally separated by single spaces. However, this doesn't need to be the case; a single space is simply the default. Any string of characters may be used as the @dfn{output field separator} by setting the -built-in variable @code{OFS}. The initial value of this variable +predefined variable @code{OFS}. The initial value of this variable is the string @w{@code{" "}}---that is, a single space. The output from an entire @code{print} statement is called an @@ -9050,7 +9050,7 @@ more fully in @cindexawkfunc{sprintf} @cindex @code{OFMT} variable @cindex output, format specifier@comma{} @code{OFMT} -The built-in variable @code{OFMT} contains the format specification +The predefined variable @code{OFMT} contains the format specification that @code{print} uses with @code{sprintf()} when it wants to convert a number to a string for printing. The default value of @code{OFMT} is @code{"%.6g"}. @@ -10227,7 +10227,7 @@ retval = close(command) # syntax error in many Unix awks The return value is @minus{}1 if the argument names something that was never opened with a redirection, or if there is a system problem closing the file or process. -In these cases, @command{gawk} sets the built-in variable +In these cases, @command{gawk} sets the predefined variable @code{ERRNO} to a string describing the problem. In @command{gawk}, @@ -10283,7 +10283,7 @@ retval = close(command) # syntax error in many Unix awks The return value is @minus{}1 if the argument names something that was never opened with a redirection, or if there is a system problem closing the file or process. -In these cases, @command{gawk} sets the built-in variable +In these cases, @command{gawk} sets the predefined variable @code{ERRNO} to a string describing the problem. In @command{gawk}, @@ -10776,10 +10776,10 @@ array parameters. @xref{String Functions}. @cindex variables, initializing A few variables have special built-in meanings, such as @code{FS} (the field separator), and @code{NF} (the number of fields in the current input -record). @xref{Built-in Variables}, for a list of the built-in variables. -These built-in variables can be used and assigned just like all other +record). @xref{Built-in Variables}, for a list of the predefined variables. +These predefined variables can be used and assigned just like all other variables, but their values are also used or changed automatically by -@command{awk}. All built-in variables' names are entirely uppercase. +@command{awk}. All predefined variables' names are entirely uppercase. Variables in @command{awk} can be assigned either numeric or string values. The kind of value a variable holds can change over the life of a program. @@ -10905,7 +10905,7 @@ Strings that can't be interpreted as valid numbers convert to zero. @cindex @code{CONVFMT} variable The exact manner in which numbers are converted into strings is controlled -by the @command{awk} built-in variable @code{CONVFMT} (@pxref{Built-in Variables}). +by the @command{awk} predefined variable @code{CONVFMT} (@pxref{Built-in Variables}). Numbers are converted using the @code{sprintf()} function with @code{CONVFMT} as the format specifier @@ -12936,7 +12936,7 @@ program, and occasionally the format for data read as input. As you have already seen, each @command{awk} statement consists of a pattern with an associated action. This @value{CHAPTER} describes how you build patterns and actions, what kinds of things you can do within -actions, and @command{awk}'s built-in variables. +actions, and @command{awk}'s predefined variables. The pattern-action rules and the statements available for use within actions form the core of @command{awk} programming. @@ -12951,7 +12951,7 @@ building something useful. * Action Overview:: What goes into an action. * Statements:: Describes the various control statements in detail. -* Built-in Variables:: Summarizes the built-in variables. +* Built-in Variables:: Summarizes the predefined variables. * Pattern Action Summary:: Patterns and Actions summary. @end menu @@ -14360,11 +14360,11 @@ results across different operating systems. @c ENDOFRANGE accs @node Built-in Variables -@section Built-in Variables +@section Predefined Variables @c STARTOFRANGE bvar -@cindex built-in variables +@cindex predefined variables @c STARTOFRANGE varb -@cindex variables, built-in +@cindex variables, predefined Most @command{awk} variables are available to use for your own purposes; they never change unless your program assigns values to @@ -14375,8 +14375,8 @@ to tell @command{awk} how to do certain things. Others are set automatically by @command{awk}, so that they carry information from the internal workings of @command{awk} to your program. -@cindex @command{gawk}, built-in variables and -This @value{SECTION} documents all of @command{gawk}'s built-in variables, +@cindex @command{gawk}, predefined variables and +This @value{SECTION} documents all of @command{gawk}'s predefined variables, most of which are also documented in the @value{CHAPTER}s describing their areas of activity. @@ -14391,7 +14391,7 @@ their areas of activity. @node User-modified @subsection Built-in Variables That Control @command{awk} @c STARTOFRANGE bvaru -@cindex built-in variables, user-modifiable +@cindex predefined variables, user-modifiable @c STARTOFRANGE nmbv @cindex user-modifiable variables @@ -14628,9 +14628,9 @@ The default value of @code{TEXTDOMAIN} is @code{"messages"}. @subsection Built-in Variables That Convey Information @c STARTOFRANGE bvconi -@cindex built-in variables, conveying information +@cindex predefined variables, conveying information @c STARTOFRANGE vbconi -@cindex variables, built-in, conveying information +@cindex variables, predefined conveying information The following is an alphabetical list of variables that @command{awk} sets automatically on certain occasions in order to provide information to your program. @@ -15305,7 +15305,7 @@ immediately. You may pass an optional numeric value to be used as @command{awk}'s exit status. @item -Some built-in variables provide control over @command{awk}, mainly for I/O. +Some predefined variables provide control over @command{awk}, mainly for I/O. Other variables convey information from @command{awk} to your program. @item @@ -16099,7 +16099,7 @@ An important aspect to remember about arrays is that @emph{array subscripts are always strings}. When a numeric value is used as a subscript, it is converted to a string value before being used for subscripting (@pxref{Conversion}). -This means that the value of the built-in variable @code{CONVFMT} can +This means that the value of the predefined variable @code{CONVFMT} can affect how your program accesses elements of an array. For example: @example @@ -17283,8 +17283,8 @@ for @code{match()}, the order is the same as for the @samp{~} operator: @cindex @code{RSTART} variable, @code{match()} function and @cindex @code{RLENGTH} variable, @code{match()} function and @cindex @code{match()} function, @code{RSTART}/@code{RLENGTH} variables -The @code{match()} function sets the built-in variable @code{RSTART} to -the index. It also sets the built-in variable @code{RLENGTH} to the +The @code{match()} function sets the predefined variable @code{RSTART} to +the index. It also sets the predefined variable @code{RLENGTH} to the length in characters of the matched substring. If no match is found, @code{RSTART} is set to zero, and @code{RLENGTH} to @minus{}1. @@ -19273,7 +19273,7 @@ the call. A function cannot have two parameters with the same name, nor may it have a parameter with the same name as the function itself. In addition, according to the POSIX standard, function parameters -cannot have the same name as one of the special built-in variables +cannot have the same name as one of the special predefined variables (@pxref{Built-in Variables}). Not all versions of @command{awk} enforce this restriction. @@ -20521,7 +20521,7 @@ example, @code{getopt()}'s @code{Opterr} and @code{Optind} variables (@pxref{Getopt Function}). The leading capital letter indicates that it is global, while the fact that the variable name is not all capital letters indicates that the variable is -not one of @command{awk}'s built-in variables, such as @code{FS}. +not one of @command{awk}'s predefined variables, such as @code{FS}. @cindex @option{--dump-variables} option, using for library functions It is also important that @emph{all} variables in library @@ -23435,7 +23435,7 @@ and the file transition library program The program begins with a descriptive comment and then a @code{BEGIN} rule that processes the command-line arguments with @code{getopt()}. The @option{-i} (ignore case) option is particularly easy with @command{gawk}; we just use the -@code{IGNORECASE} built-in variable +@code{IGNORECASE} predefined variable (@pxref{Built-in Variables}): @cindex @code{egrep.awk} program @@ -30287,7 +30287,7 @@ results. With the @option{-M} command-line option, all floating-point arithmetic operators and numeric functions can yield results to any desired precision level supported by MPFR. -Two built-in variables, @code{PREC} and @code{ROUNDMODE}, +Two predefined variables, @code{PREC} and @code{ROUNDMODE}, provide control over the working precision and the rounding mode. The precision and the rounding mode are set globally for every operation to follow. @@ -30563,7 +30563,7 @@ $ @kbd{gawk -f pi2.awk} the precision or accuracy of individual numbers. Performing an arithmetic operation or calling a built-in function rounds the result to the current working precision. The default working precision is 53 bits, which you can -modify using the built-in variable @code{PREC}. You can also set the +modify using the predefined variable @code{PREC}. You can also set the value to one of the predefined case-insensitive strings shown in @ref{table-predefined-precision-strings}, to emulate an IEEE 754 binary format. @@ -31264,13 +31264,13 @@ This (rather large) @value{SECTION} describes the API in detail. @menu * Extension API Functions Introduction:: Introduction to the API functions. * General Data Types:: The data types. -* Requesting Values:: How to get a value. * Memory Allocation Functions:: Functions for allocating memory. * Constructor Functions:: Functions for creating values. * Registration Functions:: Functions to register things with @command{gawk}. * Printing Messages:: Functions for printing messages. * Updating @code{ERRNO}:: Functions for updating @code{ERRNO}. +* Requesting Values:: How to get a value. * Accessing Parameters:: Functions for accessing parameters. * Symbol Table Access:: Functions for accessing global variables. @@ -31289,6 +31289,9 @@ API function pointers are provided for the following kinds of operations: @itemize @value{BULLET} @item +Allocating, reallocating, and releasing memory. + +@item Registration functions. You may register: @itemize @value{MINUS} @item @@ -31321,9 +31324,6 @@ Symbol table access: retrieving a global variable, creating one, or changing one. @item -Allocating, reallocating, and releasing memory. - -@item Creating and releasing cached values; this provides an efficient way to use values for multiple variables and can be a big performance win. @@ -32534,7 +32534,7 @@ Return false if the value cannot be retrieved. @item awk_bool_t sym_update_scalar(awk_scalar_t cookie, awk_value_t *value); Update the value associated with a scalar cookie. Return false if the new value is not of type @code{AWK_STRING} or @code{AWK_NUMBER}. -Here too, the built-in variables may not be updated. +Here too, the predefined variables may not be updated. @end table It is not obvious at first glance how to work with scalar cookies or @@ -33399,7 +33399,7 @@ This variable is true if @command{gawk} was invoked with @option{--traditional} @end table The value of @code{do_lint} can change if @command{awk} code -modifies the @code{LINT} built-in variable (@pxref{Built-in Variables}). +modifies the @code{LINT} predefined variable (@pxref{Built-in Variables}). The others should not change during execution. @node Extension API Boilerplate @@ -33974,7 +33974,16 @@ for success: @} @end example -Finally, here is the @code{do_stat()} function. It starts with +The third argument to @code{stat()} was not discussed previously. This +argument is optional. If present, it causes @code{do_stat()} to use +the @code{stat()} system call instead of the @code{lstat()} system +call. This is done by using a function pointer: @code{statfunc}. +@code{statfunc} is initialized to point to @code{lstat()} (instead +of @code{stat()}) to get the file information, in case the file is a +symbolic link. However, if there were three arguments, @code{statfunc} +is set point to @code{stat()}, instead. + +Here is the @code{do_stat()} function. It starts with variable declarations and argument checking: @ignore @@ -34005,16 +34014,10 @@ do_stat(int nargs, awk_value_t *result) @} @end example -The third argument to @code{stat()} was not discussed previously. This argument -is optional. If present, it causes @code{stat()} to use the @code{stat()} -system call instead of the @code{lstat()} system call. - Then comes the actual work. First, the function gets the arguments. -Next, it gets the information for the file. -The code use @code{lstat()} (instead of @code{stat()}) -to get the file information, -in case the file is a symbolic link. -If there's an error, it sets @code{ERRNO} and returns: +Next, it gets the information for the file. If the called function +(@code{lstat()} or @code{stat()}) returns an error, the code sets +@code{ERRNO} and returns: @example /* file is first arg, array to hold results is second */ @@ -34043,7 +34046,7 @@ If there's an error, it sets @code{ERRNO} and returns: @end example The tedious work is done by @code{fill_stat_array()}, shown -earlier. When done, return the result from @code{fill_stat_array()}: +earlier. When done, the function returns the result from @code{fill_stat_array()}: @example ret = fill_stat_array(name, array, & sbuf); @@ -34106,7 +34109,7 @@ of the @file{gawkapi.h} header file, the following steps@footnote{In practice, you would probably want to use the GNU Autotools---Automake, Autoconf, Libtool, and @command{gettext}---to configure and build your libraries. Instructions for doing so are beyond -the scope of this @value{DOCUMENT}. @xref{gawkextlib}, for WWW links to +the scope of this @value{DOCUMENT}. @xref{gawkextlib}, for Internet links to the tools.} create a GNU/Linux shared library: @example @@ -34134,14 +34137,14 @@ BEGIN @{ for (i in data) printf "data[\"%s\"] = %s\n", i, data[i] print "testff.awk modified:", - strftime("%m %d %y %H:%M:%S", data["mtime"]) + strftime("%m %d %Y %H:%M:%S", data["mtime"]) print "\nInfo for JUNK" ret = stat("JUNK", data) print "ret =", ret for (i in data) printf "data[\"%s\"] = %s\n", i, data[i] - print "JUNK modified:", strftime("%m %d %y %H:%M:%S", data["mtime"]) + print "JUNK modified:", strftime("%m %d %Y %H:%M:%S", data["mtime"]) @} @end example @@ -34155,25 +34158,26 @@ $ @kbd{AWKLIBPATH=$PWD gawk -f testff.awk} @print{} Info for testff.awk @print{} ret = 0 @print{} data["blksize"] = 4096 -@print{} data["mtime"] = 1350838628 +@print{} data["devbsize"] = 512 +@print{} data["mtime"] = 1412004710 @print{} data["mode"] = 33204 @print{} data["type"] = file @print{} data["dev"] = 2053 @print{} data["gid"] = 1000 -@print{} data["ino"] = 1719496 -@print{} data["ctime"] = 1350838628 +@print{} data["ino"] = 10358899 +@print{} data["ctime"] = 1412004710 @print{} data["blocks"] = 8 @print{} data["nlink"] = 1 @print{} data["name"] = testff.awk -@print{} data["atime"] = 1350838632 +@print{} data["atime"] = 1412004716 @print{} data["pmode"] = -rw-rw-r-- -@print{} data["size"] = 662 +@print{} data["size"] = 666 @print{} data["uid"] = 1000 -@print{} testff.awk modified: 10 21 12 18:57:08 -@print{} +@print{} testff.awk modified: 09 29 2014 18:31:50 +@print{} @print{} Info for JUNK @print{} ret = -1 -@print{} JUNK modified: 01 01 70 02:00:00 +@print{} JUNK modified: 01 01 1970 02:00:00 @end example @node Extension Samples @@ -34198,9 +34202,9 @@ Others mainly provide example code that shows how to use the extension API. * Extension Sample Rev2way:: Reversing data sample two-way processor. * Extension Sample Read write array:: Serializing an array to a file. * Extension Sample Readfile:: Reading an entire file into a string. -* Extension Sample API Tests:: Tests for the API. * Extension Sample Time:: An interface to @code{gettimeofday()} and @code{sleep()}. +* Extension Sample API Tests:: Tests for the API. @end menu @node Extension Sample File Functions @@ -34210,7 +34214,7 @@ The @code{filefuncs} extension provides three different functions, as follows: The usage is: @table @asis -@item @@load "filefuncs" +@item @code{@@load "filefuncs"} This is how you load the extension. @cindex @code{chdir()} extension function @@ -34273,7 +34277,7 @@ Not all systems support all file types. @tab All @itemx @code{result = fts(pathlist, flags, filedata)} Walk the file trees provided in @code{pathlist} and fill in the @code{filedata} array as described below. @code{flags} is the bitwise -OR of several predefined constant values, also described below. +OR of several predefined values, also described below. Return zero if there were no errors, otherwise return @minus{}1. @end table @@ -34318,10 +34322,10 @@ Immediately follow a symbolic link named in @code{pathlist}, whether or not @code{FTS_LOGICAL} is set. @item FTS_SEEDOT -By default, the @code{fts()} routines do not return entries for @file{.} (dot) -and @file{..} (dot-dot). This option causes entries for dot-dot to also -be included. (The extension always includes an entry for dot, -see below.) +By default, the C library @code{fts()} routines do not return entries for +@file{.} (dot) and @file{..} (dot-dot). This option causes entries for +dot-dot to also be included. (The extension always includes an entry +for dot, see below.) @item FTS_XDEV During a traversal, do not cross onto a different mounted filesystem. @@ -34375,8 +34379,8 @@ Otherwise it returns @minus{}1. @quotation NOTE The @code{fts()} extension does not exactly mimic the interface of the C library @code{fts()} routines, choosing instead to -provide an interface that is based on associative arrays, which should -be more comfortable to use from an @command{awk} program. This includes the +provide an interface that is based on associative arrays, which is +more comfortable to use from an @command{awk} program. This includes the lack of a comparison function, since @command{gawk} already provides powerful array sorting facilities. While an @code{fts_read()}-like interface could have been provided, this felt less natural than simply @@ -34384,7 +34388,8 @@ creating a multidimensional array to represent the file hierarchy and its information. @end quotation -See @file{test/fts.awk} in the @command{gawk} distribution for an example. +See @file{test/fts.awk} in the @command{gawk} distribution for an example +use of the @code{fts()} extension function. @node Extension Sample Fnmatch @subsection Interface To @code{fnmatch()} @@ -34592,7 +34597,7 @@ indicating the type of the file. The letters are file types are shown in @ref{table-readdir-file-types}. @float Table,table-readdir-file-types -@caption{File Types Returned By @code{readdir()}} +@caption{File Types Returned By The @code{readdir} Extension} @multitable @columnfractions .1 .9 @headitem Letter @tab File Type @item @code{b} @tab Block device @@ -34684,6 +34689,9 @@ The @code{rwarray} extension adds two functions, named @code{writea()} and @code{reada()}, as follows: @table @code +@item @@load "rwarray" +This is how you load the extension. + @cindex @code{writea()} extension function @item ret = writea(file, array) This function takes a string argument, which is the name of the file @@ -34759,17 +34767,6 @@ if (contents == "" && ERRNO != "") @{ @} @end example -@node Extension Sample API Tests -@subsection API Tests -@cindex @code{testext} extension - -The @code{testext} extension exercises parts of the extension API that -are not tested by the other samples. The @file{extension/testext.c} -file contains both the C code for the extension and @command{awk} -test code inside C comments that run the tests. The testing framework -extracts the @command{awk} code and runs the tests. See the source file -for more information. - @node Extension Sample Time @subsection Extension Time Functions @@ -34800,6 +34797,17 @@ Implementation details: depending on platform availability, this function tries to use @code{nanosleep()} or @code{select()} to implement the delay. @end table +@node Extension Sample API Tests +@subsection API Tests +@cindex @code{testext} extension + +The @code{testext} extension exercises parts of the extension API that +are not tested by the other samples. The @file{extension/testext.c} +file contains both the C code for the extension and @command{awk} +test code inside C comments that run the tests. The testing framework +extracts the @command{awk} code and runs the tests. See the source file +for more information. + @node gawkextlib @section The @code{gawkextlib} Project @cindex @code{gawkextlib} @@ -34815,8 +34823,7 @@ As of this writing, there are five extensions: @itemize @value{BULLET} @item -XML parser extension, using the @uref{http://expat.sourceforge.net, Expat} -XML parsing library. +GD graphics library extension. @item PDF extension. @@ -34825,17 +34832,14 @@ PDF extension. PostgreSQL extension. @item -GD graphics library extension. - -@item MPFR library extension. This provides access to a number of MPFR functions which @command{gawk}'s native MPFR support does not. -@end itemize -The @code{time} extension described earlier (@pxref{Extension Sample -Time}) was originally from this project but has been moved in to the -main @command{gawk} distribution. +@item +XML parser extension, using the @uref{http://expat.sourceforge.net, Expat} +XML parsing library. +@end itemize @cindex @command{git} utility You can check out the code for the @code{gawkextlib} project @@ -34926,6 +34930,9 @@ API function pointers are provided for the following kinds of operations: @itemize @value{BULLET} @item +Allocating, reallocating, and releasing memory. + +@item Registration functions. You may register extension functions, exit callbacks, @@ -34949,9 +34956,6 @@ Symbol table access: retrieving a global variable, creating one, or changing one. @item -Allocating, reallocating, and releasing memory. - -@item Creating and releasing cached values; this provides an efficient way to use values for multiple variables and can be a big performance win. @@ -34983,7 +34987,7 @@ treated as read-only by the extension. @item @emph{All} memory passed from an extension to @command{gawk} must come from the API's memory allocation functions. @command{gawk} takes responsibility for -the memory and will release it when appropriate. +the memory and releases it when appropriate. @item The API provides information about the running version of @command{gawk} so @@ -35000,7 +35004,7 @@ The @command{gawk} distribution includes a number of small but useful sample extensions. The @code{gawkextlib} project includes several more, larger, extensions. If you wish to write an extension and contribute it to the community of @command{gawk} users, the @code{gawkextlib} project -should be the place to do so. +is the place to do so. @end itemize @@ -35082,7 +35086,7 @@ which follows the POSIX specification. Many long-time @command{awk} users learned @command{awk} programming with the original @command{awk} implementation in Version 7 Unix. (This implementation was the basis for @command{awk} in Berkeley Unix, through 4.3-Reno. Subsequent versions -of Berkeley Unix, and some systems derived from 4.4BSD-Lite, used various +of Berkeley Unix, and, for a while, some systems derived from 4.4BSD-Lite, used various versions of @command{gawk} for their @command{awk}.) This @value{CHAPTER} briefly describes the evolution of the @command{awk} language, with cross-references to other parts of the @value{DOCUMENT} where you can @@ -35155,7 +35159,7 @@ The built-in functions @code{close()} and @code{system()} @item The @code{ARGC}, @code{ARGV}, @code{FNR}, @code{RLENGTH}, @code{RSTART}, -and @code{SUBSEP} built-in variables (@pxref{Built-in Variables}). +and @code{SUBSEP} predefined variables (@pxref{Built-in Variables}). @item Assignable @code{$0} (@pxref{Changing Fields}). @@ -35186,14 +35190,11 @@ of @code{FS}. @item Dynamic regexps as operands of the @samp{~} and @samp{!~} operators -(@pxref{Regexp Usage}). +(@pxref{Computed Regexps}). @item The escape sequences @samp{\b}, @samp{\f}, and @samp{\r} (@pxref{Escape Sequences}). -(Some vendors have updated their old versions of @command{awk} to -recognize @samp{\b}, @samp{\f}, and @samp{\r}, but this is not -something you can rely on.) @item Redirection of input for the @code{getline} function @@ -35232,7 +35233,7 @@ The @option{-v} option for assigning variables before program execution begins @c GNU, Bell Laboratories & MKS together @item -The @option{--} option for terminating command-line options. +The @option{--} signal for terminating command-line options. @item The @samp{\a}, @samp{\v}, and @samp{\x} escape sequences @@ -35255,7 +35256,7 @@ A cleaner specification for the @code{%c} format-control letter in the @item The ability to dynamically pass the field width and precision (@code{"%*.*d"}) -in the argument list of the @code{printf} function +in the argument list of @code{printf} and @code{sprintf()} (@pxref{Control Letters}). @item @@ -35290,8 +35291,8 @@ The concept of a numeric string and tighter comparison rules to go with it (@pxref{Typing and Comparison}). @item -The use of built-in variables as function parameter names is forbidden -(@pxref{Definition Syntax}. +The use of predefined variables as function parameter names is forbidden +(@pxref{Definition Syntax}). @item More complete documentation of many of the previously undocumented @@ -35386,7 +35387,7 @@ in the current version of @command{gawk}. @itemize @value{BULLET} @item -Additional built-in variables: +Additional predefined variables: @itemize @value{MINUS} @item @@ -35470,14 +35471,6 @@ The @code{BEGINFILE} and @code{ENDFILE} special patterns. (@pxref{BEGINFILE/ENDFILE}). @item -The ability to delete all of an array at once with @samp{delete @var{array}} -(@pxref{Delete}). - -@item -The @code{nextfile} statement -(@pxref{Nextfile Statement}). - -@item The @code{switch} statement (@pxref{Switch Statement}). @end itemize @@ -35492,7 +35485,7 @@ of a two-way pipe to a coprocess (@pxref{Two-way I/O}). @item -POSIX compliance for @code{gsub()} and @code{sub()}. +POSIX compliance for @code{gsub()} and @code{sub()} with @option{--posix}. @item The @code{length()} function accepts an array argument @@ -35520,6 +35513,20 @@ Additional functions only in @command{gawk}: @itemize @value{MINUS} @item +The @code{gensub()}, @code{patsplit()}, and @code{strtonum()} functions +for more powerful text manipulation +(@pxref{String Functions}). + +@item +The @code{asort()} and @code{asorti()} functions for sorting arrays +(@pxref{Array Sorting}). + +@item +The @code{mktime()}, @code{systime()}, and @code{strftime()} +functions for working with timestamps +(@pxref{Time Functions}). + +@item The @code{and()}, @code{compl()}, @@ -35533,30 +35540,15 @@ functions for bit manipulation @c In 4.1, and(), or() and xor() grew the ability to take > 2 arguments @item -The @code{asort()} and @code{asorti()} functions for sorting arrays -(@pxref{Array Sorting}). +The @code{isarray()} function to check if a variable is an array or not +(@pxref{Type Functions}). @item The @code{bindtextdomain()}, @code{dcgettext()} and @code{dcngettext()} functions for internationalization (@pxref{Programmer i18n}). - -@item -The @code{fflush()} function from BWK @command{awk} -(@pxref{I/O Functions}). - -@item -The @code{gensub()}, @code{patsplit()}, and @code{strtonum()} functions -for more powerful text manipulation -(@pxref{String Functions}). - -@item -The @code{mktime()}, @code{systime()}, and @code{strftime()} -functions for working with timestamps -(@pxref{Time Functions}). @end itemize - @item Changes and/or additions in the command-line options: @@ -35679,7 +35671,7 @@ GCC for VAX and Alpha has not been tested for a while. @item Support for the following obsolete systems was removed from the code -and the documentation for @command{gawk} @value{PVERSION} 4.1: +for @command{gawk} @value{PVERSION} 4.1: @c nested table @itemize @value{MINUS} @@ -36316,33 +36308,29 @@ The dynamic extension interface was completely redone @cindex extensions, Brian Kernighan's @command{awk} @cindex extensions, @command{mawk} -This @value{SECTION} summarizes the common extensions supported +The following table summarizes the common extensions supported by @command{gawk}, Brian Kernighan's @command{awk}, and @command{mawk}, the three most widely-used freely available versions of @command{awk} (@pxref{Other Versions}). -@multitable {@file{/dev/stderr} special file} {BWK Awk} {Mawk} {GNU Awk} -@headitem Feature @tab BWK Awk @tab Mawk @tab GNU Awk -@item @samp{\x} Escape sequence @tab X @tab X @tab X -@item @code{FS} as null string @tab X @tab X @tab X -@item @file{/dev/stdin} special file @tab X @tab X @tab X -@item @file{/dev/stdout} special file @tab X @tab X @tab X -@item @file{/dev/stderr} special file @tab X @tab X @tab X -@item @code{delete} without subscript @tab X @tab X @tab X -@item @code{fflush()} function @tab X @tab X @tab X -@item @code{length()} of an array @tab X @tab X @tab X -@item @code{nextfile} statement @tab X @tab X @tab X -@item @code{**} and @code{**=} operators @tab X @tab @tab X -@item @code{func} keyword @tab X @tab @tab X -@item @code{BINMODE} variable @tab @tab X @tab X -@item @code{RS} as regexp @tab @tab X @tab X -@item Time related functions @tab @tab X @tab X +@multitable {@file{/dev/stderr} special file} {BWK Awk} {Mawk} {GNU Awk} {Now standard} +@headitem Feature @tab BWK Awk @tab Mawk @tab GNU Awk @tab Now standard +@item @samp{\x} Escape sequence @tab X @tab X @tab X @tab +@item @code{FS} as null string @tab X @tab X @tab X @tab +@item @file{/dev/stdin} special file @tab X @tab X @tab X @tab +@item @file{/dev/stdout} special file @tab X @tab X @tab X @tab +@item @file{/dev/stderr} special file @tab X @tab X @tab X @tab +@item @code{delete} without subscript @tab X @tab X @tab X @tab X +@item @code{fflush()} function @tab X @tab X @tab X @tab X +@item @code{length()} of an array @tab X @tab X @tab X @tab +@item @code{nextfile} statement @tab X @tab X @tab X @tab X +@item @code{**} and @code{**=} operators @tab X @tab @tab X @tab +@item @code{func} keyword @tab X @tab @tab X @tab +@item @code{BINMODE} variable @tab @tab X @tab X @tab +@item @code{RS} as regexp @tab @tab X @tab X @tab +@item Time related functions @tab @tab X @tab X @tab @end multitable -(Technically speaking, as of late 2012, @code{fflush()}, @samp{delete @var{array}}, -and @code{nextfile} are no longer extensions, since they have been added -to POSIX.) - @node Ranges and Locales @appendixsec Regexp Ranges and Locales: A Long Sad Story @@ -36379,6 +36367,7 @@ In the @code{"C"} and @code{"POSIX"} locales, a range expression like But outside those locales, the ordering was defined to be based on @dfn{collation order}. +What does that mean? In many locales, @samp{A} and @samp{a} are both less than @samp{B}. In other words, these locales sort characters in dictionary order, and @samp{[a-dx-z]} is typically not equivalent to @samp{[abcdxyz]}; @@ -36386,7 +36375,7 @@ instead it might be equivalent to @samp{[ABCXYabcdxyz]}, for example. This point needs to be emphasized: Much literature teaches that you should use @samp{[a-z]} to match a lowercase character. But on systems with -non-ASCII locales, this also matched all of the uppercase characters +non-ASCII locales, this also matches all of the uppercase characters except @samp{A} or @samp{Z}! This was a continuous cause of confusion, even well into the twenty-first century. @@ -36692,6 +36681,11 @@ The development of the extension API first released with Arnold Robbins and Andrew Schorr, with notable contributions from the rest of the development team. +@cindex Malmberg, John E. +@item +John Malmberg contributed significant improvements to the +OpenVMS port and the related documentation. + @item @cindex Colombo, Antonio Antonio Giovanni Colombo rewrote a number of examples in the early @@ -39215,7 +39209,7 @@ Pat Rankin suggested the solution that was adopted. @appendixsubsec Other Design Decisions As an arbitrary design decision, extensions can read the values of -built-in variables and arrays (such as @code{ARGV} and @code{FS}), but cannot +predefined variables and arrays (such as @code{ARGV} and @code{FS}), but cannot change them, with the exception of @code{PROCINFO}. The reason for this is to prevent an extension function from affecting @@ -39956,11 +39950,11 @@ See ``Free Documentation License.'' @item Field When @command{awk} reads an input record, it splits the record into pieces separated by whitespace (or by a separator regexp that you can -change by setting the built-in variable @code{FS}). Such pieces are +change by setting the predefined variable @code{FS}). Such pieces are called fields. If the pieces are of fixed length, you can use the built-in variable @code{FIELDWIDTHS} to describe their lengths. If you wish to specify the contents of fields instead of the field -separator, you can use the built-in variable @code{FPAT} to do so. +separator, you can use the predefined variable @code{FPAT} to do so. (@xref{Field Separators}, @ref{Constant Size}, and @@ -39979,7 +39973,7 @@ See also ``Double Precision'' and ``Single Precision.'' Format strings control the appearance of output in the @code{strftime()} and @code{sprintf()} functions, and in the @code{printf} statement as well. Also, data conversions from numbers to strings -are controlled by the format strings contained in the built-in variables +are controlled by the format strings contained in the predefined variables @code{CONVFMT} and @code{OFMT}. (@xref{Control Letters}.) @item Free Documentation License |