_M_A_W_K(1)                          User commands                         _M_A_W_K(1)

NNAAMMEE
       mawk - pattern scanning and text processing language

SSYYNNOOPPSSIISS
       mmaawwkk  [-WW  _o_p_t_i_o_n]  [-FF _v_a_l_u_e] [-vv _v_a_r_=_v_a_l_u_e] [--] 'program text' [file
       ...]
       mmaawwkk [-WW _o_p_t_i_o_n] [-FF _v_a_l_u_e] [-vv _v_a_r_=_v_a_l_u_e] [-ff _p_r_o_g_r_a_m_-_f_i_l_e] [--] [file
       ...]

DDEESSCCRRIIPPTTIIOONN
       mmaawwkk is an interpreter for  the  AWK  Programming  Language.   The  AWK
       language  is  useful for manipulation of data files, text retrieval and
       processing, and for  prototyping  and  experimenting  with  algorithms.
       mmaawwkk  is a _n_e_w _a_w_k meaning it implements the AWK language as defined in
       Aho, Kernighan and Weinberger, _T_h_e _A_W_K _P_r_o_g_r_a_m_m_i_n_g  _L_a_n_g_u_a_g_e_,  Addison-
       Wesley  Publishing, 1988 (hereafter referred to as the AWK book.)  mmaawwkk
       conforms to the  POSIX  1003.2  (draft  11.3)  definition  of  the  AWK
       language  which  contains a few features not described in the AWK book,
       and mmaawwkk provides a small number of extensions.

       An AWK program is a sequence of _p_a_t_t_e_r_n  _{_a_c_t_i_o_n_}  pairs  and  function
       definitions.   Short  programs  are entered on the command line usually
       enclosed in ' ' to avoid shell interpretation.  Longer programs can  be
       read  in  from a file with the -f option.  Data  input is read from the
       list of files on the command line or from standard input when the  list
       is empty.  The input is broken into records as determined by the record
       separator   variable,  RRSS.   Initially,  RRSS  =  "\n"  and  records  are
       synonymous with lines.  Each record is compared  against  each  _p_a_t_t_e_r_n
       and if it matches, the program text for _{_a_c_t_i_o_n_} is executed.

OOPPTTIIOONNSS
       -FF _v_a_l_u_e       sets the field separator, FFSS, to _v_a_l_u_e.

       -ff _f_i_l_e        Program  text  is  read  from  _f_i_l_e  instead of from the
                      command line.  Multiple --ff options are allowed.

       -vv _v_a_r_=_v_a_l_u_e   assigns _v_a_l_u_e to program variable _v_a_r.

       --             indicates the unambiguous end of options.

       The  above  options  will  be  available  with  any  POSIX   compatible
       implementation  of  AWK.   Implementation specific options are prefaced
       with --WW.  mmaawwkk provides these:

       -WW dump
              writes an assembler like listing of the internal  representation
              of   the   program   to   stdout  and  exits  0  (on  successful
              compilation).

       -WW exec _f_i_l_e
              Program text is read from _f_i_l_e and this is the last option.

              This is a useful alternative to -ff on systems that  support  the
              ##!!   "magic  number"  convention  for executable scripts.  Those
              implicitly pass the pathname of the script itself as  the  final
              parameter,  and  expect  no  more  than one "-" option on the ##!!
              line.  Because mmaawwkk can combine multiple -WW options separated by
              commas, you can use this option when an additional -WW option  is
              needed.

       -WW help
              prints a usage message to stderr and exits (same as "-WW usage").

       -WW interactive
              sets  unbuffered  writes  to stdout and line buffered reads from
              stdin.  Records from stdin are lines regardless of the value  of
              RRSS.

       -WW posix
              modifies mmaawwkk's behavior to be more POSIX-compliant:

              +o   forces mmaawwkk not to consider '\n' to be space.

                  The original "posix_space" is recognized, but deprecated.

              +o   Allow   hexadecimal,  "inf"  (infinity)  and  "nan"  (not-a-
                  number).

                  The Open Group Base Specifications Issue 8 allows  but  does
                  not require these features.

       -WW random=_n_u_m
              calls  ssrraanndd  with  the given parameter (and overrides the auto-
              seeding behavior).

       -WW sprintf=_n_u_m
              adjusts the size of mmaawwkk's internal sprintf buffer to _n_u_m bytes.
              More than rare use of  this  option  indicates  mmaawwkk  should  be
              recompiled.

       -WW traditional
              Omit  features  such  as  interval  expressions  which  were not
              supported by traditional _a_w_k.

       -WW usage
              prints a usage message to stderr and exits (same as "-WW help").

       -WW version
              mmaawwkk writes its version and copyright  to  stdout  and  compiled
              limits to stderr and exits 0.

       mmaawwkk  accepts  abbreviations for any of these options, e.g., "-WW v" and
       "-WWv" both tell mmaawwkk to show its version.

       mmaawwkk allows multiple --WW  options  to  be  combined  by  separating  the
       options  with  commas,  e.g.,  -Wsprint=2000,posix.  This is useful for
       executable ##!!  "magic number" invocations in which only one argument is
       supported, e.g., -WWiinntteerraaccttiivvee,,eexxeecc.

TTHHEE AAWWKK LLAANNGGUUAAGGEE
   11.. PPrrooggrraamm ssttrruuccttuurree
       An AWK program is  a  sequence  of  _p_a_t_t_e_r_n  _{_a_c_t_i_o_n_}  pairs  and  user
       function definitions.

       A pattern can be:
            BBEEGGIINN
            EENNDD
            expression
            expression , expression

       One,  but not both, of _p_a_t_t_e_r_n _{_a_c_t_i_o_n_} can be omitted.  If _{_a_c_t_i_o_n_} is
       omitted it is implicitly { print }.  If _p_a_t_t_e_r_n is omitted, then it  is
       implicitly matched.  BBEEGGIINN and EENNDD patterns require an action.

       Statements  are terminated by newlines, semi-colons or both.  Groups of
       statements such as actions or loop bodies are blocked via { ... } as in
       C.  The last statement in a block doesn't  need  a  terminator.   Blank
       lines  have  no  meaning; an empty statement is terminated with a semi-
       colon.  Long statements can  be  continued  with  a  backslash,  \.   A
       statement  can be broken without a backslash after a comma, left brace,
       &&, ||, ddoo, eellssee,  the  right  parenthesis  of  an  iiff,  wwhhiillee  or  ffoorr
       statement,  and  the  right  parenthesis  of  a function definition.  A
       comment starts with # and extends to, but does not include the  end  of
       line.

       The following statements control program flow inside blocks.

            iiff ( _e_x_p_r ) _s_t_a_t_e_m_e_n_t

            iiff ( _e_x_p_r ) _s_t_a_t_e_m_e_n_t eellssee _s_t_a_t_e_m_e_n_t

            wwhhiillee ( _e_x_p_r ) _s_t_a_t_e_m_e_n_t

            ddoo _s_t_a_t_e_m_e_n_t wwhhiillee ( _e_x_p_r )

            ffoorr ( _o_p_t___e_x_p_r ; _o_p_t___e_x_p_r ; _o_p_t___e_x_p_r ) _s_t_a_t_e_m_e_n_t

            ffoorr ( _v_a_r iinn _a_r_r_a_y ) _s_t_a_t_e_m_e_n_t

            ccoonnttiinnuuee

            bbrreeaakk

   22.. DDaattaa ttyyppeess,, ccoonnvveerrssiioonn aanndd ccoommppaarriissoonn
       There  are two basic data types, numeric and string.  Numeric constants
       can be integer like -2, decimal like 1.08, or  in  scientific  notation
       like  -1.1e4 or .28E-3.  All numbers are represented internally and all
       computations are done in floating point arithmetic.   So  for  example,
       the expression 0.2e2 == 20 is true and true is represented as 1.0.

       String constants are enclosed in double quotes.

                   "This is a string with a newline at the end.\n"

       Strings  can  be  continued  across a line by escaping (\) the newline.
       The following escape sequences are recognized.

            \\        \
            \"        "
            \a        alert, ascii 7
            \b        backspace, ascii 8
            \t        tab, ascii 9
            \n        newline, ascii 10
            \v        vertical tab, ascii 11
            \f        formfeed, ascii 12
            \r        carriage return, ascii 13
            \ddd      1, 2 or 3 octal digits for ascii ddd
            \xhh      1 or 2 hex digits for ascii  hh

       If you escape any other character \c, you get \c,  i.e.,  mmaawwkk  ignores
       the escape.

       There are really three basic data types; the third is _n_u_m_b_e_r _a_n_d _s_t_r_i_n_g
       which  has  both  a  numeric value and a string value at the same time.
       User defined variables come into existence when  first  referenced  and
       are  initialized  to  _n_u_l_l, a number and string value which has numeric
       value 0 and string value "".  Non-trivial number and string typed  data
       come from input and are typically stored in fields.  (See section 4).

       The  type  of  an expression is determined by its context and automatic
       type conversion  occurs  if  needed.   For  example,  to  evaluate  the
       statements

            y = x + 2  ;  z = x  "hello"

       The  value  stored  in  variable  y will be typed numeric.  If x is not
       numeric, the value read from x is converted to  numeric  before  it  is
       added  to  2  and  stored in y.  The value stored in variable z will be
       typed string, and the value  of  x  will  be  converted  to  string  if
       necessary  and  concatenated  with  "hello".  (Of course, the value and
       type stored in  x  is  not  changed  by  any  conversions.)   A  string
       expression  is converted to numeric using its longest numeric prefix as
       with aattooff(3).  A numeric expression is converted to string by replacing
       _e_x_p_r with sspprriinnttff((CCOONNVVFFMMTT, _e_x_p_r), unless _e_x_p_r can be represented on the
       host machine as an exact integer then it is converted to  sspprriinnttff("%d",
       _e_x_p_r).   SSpprriinnttff(()) is an AWK built-in that duplicates the functionality
       of sspprriinnttff(3), and CCOONNVVFFMMTT is a built-in  variable  used  for  internal
       conversion  from  number to string and initialized to "%.6g".  Explicit
       type conversions can be  forced,  _e_x_p_r  ""  is  string  and  _e_x_p_r+0  is
       numeric.

       To evaluate, _e_x_p_r1 rreell--oopp _e_x_p_r2, if both operands are numeric or number
       and  string then the comparison is numeric; if both operands are string
       the comparison is string; if one  operand  is  string,  the  non-string
       operand  is  converted  and  the  comparison  is string.  The result is
       numeric, 1 or 0.

       In boolean contexts such as, iiff ( _e_x_p_r ) _s_t_a_t_e_m_e_n_t, a string expression
       evaluates true if and only if it is not the empty  string  "";  numeric
       values if and only if not numerically zero.

   33.. RReegguullaarr eexxpprreessssiioonnss
       In  the  AWK language, records, fields and strings are often tested for
       matching a _r_e_g_u_l_a_r _e_x_p_r_e_s_s_i_o_n.  Regular  expressions  are  enclosed  in
       slashes, and

            _e_x_p_r ~ /_r/

       is  an  AWK  expression  that evaluates to 1 if _e_x_p_r "matches" _r, which
       means a substring of _e_x_p_r is in the set of strings defined by _r.   With
       no  match  the  expression  evaluates  to  0; replacing ~ with the "not
       match" operator, !~ , reverses the meaning.  As  pattern-action pairs,

            /_r/ { _a_c_t_i_o_n }   and   $$00 ~ /_r/ { _a_c_t_i_o_n }

       are the same, and for each input  record  that  matches  _r,  _a_c_t_i_o_n  is
       executed.   In fact, /_r/ is an AWK expression that is equivalent to ($$00
       ~ /_r/) anywhere except when on the right side of a  match  operator  or
       passed  as  an  argument  to a built-in function that expects a regular
       expression argument.

       AWK uses extended regular expressions as with the --EE option of ggrreepp(1).
       The regular expression metacharacters, i.e., those with special meaning
       in regular expressions are

            \ ^ $ . [ ] | ( ) * + ? { }

       If the command line option _-_W _t_r_a_d_i_t_i_o_n_a_l is used, these are omitted:

            { }

       are also regular expression metacharacters, and in this  mode,  require
       escaping to be a literal character.

       Regular expressions are built up from characters as follows:

            _c            matches any non-metacharacter _c.

            \_c           matches  a  character  defined  by  the  same  escape
                         sequences used in string  constants  or  the  literal
                         character _c if \_c is not an escape sequence.

            .            matches any character (including newline).

            ^            matches the front of a string.

            $            matches the back of a string.

            [c1c2c3...]  matches  any  character  in the class c1c2c3... .  An
                         interval of characters  is  denoted  c1-c2  inside  a
                         class [...].

            [^c1c2c3...] matches any character not in the class c1c2c3...

       Regular  expressions  are  built  up  from other regular expressions as
       follows:

            _r1_r2         matches    _r1    followed    immediately    by     _r2
                         (_c_o_n_c_a_t_e_n_a_t_i_o_n).


            _r1 | _r2      matches _r1 or _r2 (_a_l_t_e_r_n_a_t_i_o_n).


            _r*           matches _r repeated zero or more times.

            _r+           matches _r repeated one or more times.

            _r?           matches _r zero or once.  (_r_e_p_e_t_i_t_i_o_n).

            (_r)          matches _r (_g_r_o_u_p_i_n_g).


            _r{n}         matches _r exactly n times.

            _r{n,}        matches _r repeated n or more times.

            _r{n,m}       matches _r repeated n to m (inclusive) times.

            _r{,m}        matches  _r  repeated  0  to  m  times (a non-standard
                         option).

       The increasing pprreecceeddeennccee ooff ooppeerraattoorrss is:

       alternation concatenation repetition grouping


       For example,

            /^[_a-zA-Z][_a-zA-Z0-9]*$/  and
            /^[-+]?([0-9]+\.?|\.[0-9])[0-9]*([eE][-+]?[0-9]+)?$/

       are matched by AWK identifiers and AWK numeric constants  respectively.
       Note  that  "."  has to be escaped to be recognized as a decimal point,
       and that metacharacters are not special inside character classes.

       Any expression can be used on the right  hand  side  of  the  ~  or  !~
       operators  or  passed  to a built-in that expects a regular expression.
       If needed, it is converted to string, and then interpreted as a regular
       expression.  For example,

            BEGIN { identifier = "[_a-zA-Z][_a-zA-Z0-9]*" }

            $0 ~ "^" identifier

       prints all lines that start with an AWK identifier.

       mmaawwkk recognizes the empty regular expression,  //,  which  matches  the
       empty  string and hence is matched by any string at the front, back and
       between every character.  For example,

            echo  abc | mawk '{ gsub(//, "X")' ; print }
            XaXbXcX


   44.. RReeccoorrddss aanndd ffiieellddss
       Records are read in one at a time, and stored in the _f_i_e_l_d variable $$00.
       The record is split into _f_i_e_l_d_s which are stored in $$11, $$22,  ...,  $$NNFF.
       The built-in variable NNFF is set to the number of fields, and NNRR and FFNNRR
       are incremented by 1.  Fields above $$NNFF are set to "".

       Assignment to $$00 causes the fields and NNFF to be recomputed.  Assignment
       to  NNFF or to a field causes $$00 to be reconstructed by concatenating the
       $$ii''ss separated by OOFFSS.  Assignment to a field with index  greater  than
       NNFF, increases NNFF and causes $$00 to be reconstructed.

       Data  input  stored  in  fields  is string, unless the entire field has
       numeric form and then the type is number and string.  For example,

            echo 24 24E |
            mawk '{ print($1>100, $1>"100", $2>100, $2>"100") }'
            0 1 1 1

       $$00 and $$22 are string and $$11 is number and string.  The first comparison
       is numeric, the second is string, the third is string (100 is converted
       to "100"), and the last is string.

   55.. EExxpprreessssiioonnss aanndd ooppeerraattoorrss
       The expression syntax is similar to C.  Primary expressions are numeric
       constants, string constants, variables,  fields,  arrays  and  function
       calls.   The  identifier  for  a  variable,  array or function can be a
       sequence of letters, digits and underscores, that does not start with a
       digit.  Variables are not declared; they exist  when  first  referenced
       and are initialized to _n_u_l_l.

       New  expressions  are composed with the following operators in order of
       increasing precedence.

            _a_s_s_i_g_n_m_e_n_t          =  +=  -=  *=  /=  %=  ^=
            _c_o_n_d_i_t_i_o_n_a_l         ?  :
            _l_o_g_i_c_a_l _o_r          ||
            _l_o_g_i_c_a_l _a_n_d         &&
            _a_r_r_a_y _m_e_m_b_e_r_s_h_i_p    iinn
            _m_a_t_c_h_i_n_g       ~   !~
            _r_e_l_a_t_i_o_n_a_l          <  >   <=  >=  ==  !=
            _c_o_n_c_a_t_e_n_a_t_i_o_n       (no explicit operator)
            _a_d_d _o_p_s             +  -
            _m_u_l _o_p_s             *  /  %
            _u_n_a_r_y               +  -
            _l_o_g_i_c_a_l _n_o_t         !
            _e_x_p_o_n_e_n_t_i_a_t_i_o_n      ^
            _i_n_c _a_n_d _d_e_c         ++ -- (both post and pre)
            _f_i_e_l_d               $

       Assignment, conditional and exponentiation associate right to left; the
       other operators  associate  left  to  right.   Any  expression  can  be
       parenthesized.

   66.. AArrrraayyss
       Awk  provides  one-dimensional arrays.  Array elements are expressed as
       _a_r_r_a_y[_e_x_p_r].  _E_x_p_r is internally converted  to  string  type,  so,  for
       example,  A[1]  and A["1"] are the same element and the actual index is
       "1".   Arrays  indexed  by  strings  are  called  associative   arrays.
       Initially  an  array  is empty; elements exist when first accessed.  An
       expression, _e_x_p_r iinn _a_r_r_a_y evaluates to 1 if _a_r_r_a_y[_e_x_p_r] exists, else to
       0.

       There is a form of the ffoorr statement that loops over each index  of  an
       array.

            ffoorr ( _v_a_r iinn _a_r_r_a_y ) _s_t_a_t_e_m_e_n_t

       sets _v_a_r to each index of _a_r_r_a_y and executes _s_t_a_t_e_m_e_n_t.  The order that
       _v_a_r transverses the indices of _a_r_r_a_y is not defined.

       The  statement,  ddeelleettee  _a_r_r_a_y[_e_x_p_r],  causes _a_r_r_a_y[_e_x_p_r] not to exist.
       mmaawwkk supports the ddeelleettee _a_r_r_a_y feature, which deletes all  elements  of
       _a_r_r_a_y.

       Multidimensional  arrays  are  synthesized with concatenation using the
       built-in  variable  SSUUBBSSEEPP.   _a_r_r_a_y[_e_x_p_r1,_e_x_p_r2]   is   equivalent   to
       _a_r_r_a_y[_e_x_p_r1 SSUUBBSSEEPP _e_x_p_r2].  Testing for a multidimensional element uses
       a parenthesized index, such as

            if ( (i, j) in A )  print A[i, j]


   77.. BBuuiillttiinn--vvaarriiaabblleess
       The  following  variables  are  built-in and initialized before program
       execution.

            AARRGGCC   number of command line arguments.

            AARRGGVV   array of command line arguments, 0..ARGC-1.

            CCOONNVVFFMMTT
                   format  for  internal  conversion  of  numbers  to  string,
                   initially = "%.6g".

            EENNVVIIRROONN
                   array  indexed  by  environment  variables.  An environment
                   string, _v_a_r_=_v_a_l_u_e is stored as EENNVVIIRROONN[_v_a_r] = _v_a_l_u_e.

            FFIILLEENNAAMMEE
                   name of the current input file.

            FFNNRR    current record number in FFIILLEENNAAMMEE.

            FFSS     splits records into fields as a regular expression.

            NNFF     number of fields in the current record.

            NNRR     current record number in the total input stream.

            OOFFMMTT   format for printing numbers; initially = "%.6g".

            OOFFSS    inserted between fields on output, initially = " ".

            OORRSS    terminates each record on output, initially = "\n".

            RRLLEENNGGTTHH
                   length set by the  last  call  to  the  built-in  function,
                   mmaattcchh(()).

            RRSS     input record separator, initially = "\n".

            RRSSTTAARRTT index set by the last call to mmaattcchh(()).

            SSUUBBSSEEPP used  to  build  multiple  array  subscripts,  initially  =
                   "\034".

   88.. BBuuiilltt--iinn ffuunnccttiioonnss
       SSttrriinngg ffuunnccttiioonnss

            gsub(_r_,_s_,_t)  gsub(_r_,_s)
                   Global substitution, every match of regular expression _r in
                   variable  _t  is  replaced  by  string  _s.   The  number  of
                   replacements is returned.  If _t is omitted, $$00 is used.  An
                   _&  in  the  replacement string _s is replaced by the matched
                   substring  of  _t.   \&  and  \\  put   literal  &  and   \,
                   respectively, in the replacement string.

            index(_s_,_t)
                   If  _t is a substring of _s, then the position where _t starts
                   is returned, else 0 is returned.  The first character of  _s
                   is in position 1.

            length(_s)
                   Returns the length of string or array _s.

            match(_s_,_r)
                   Returns  the  index  of  the first longest match of regular
                   expression _r in string _s.  Returns 0 if  no  match.   As  a
                   side effect, RRSSTTAARRTT is set to the return value.  RRLLEENNGGTTHH is
                   set  to  the length of the match or -1 if no match.  If the
                   empty string is matched, RRLLEENNGGTTHH is set  to  0,  and  1  is
                   returned  if  the match is at the front, and length(_s)+1 is
                   returned if the match is at the back.

            split(_s_,_A_,_r)  split(_s_,_A)
                   String _s is split into fields by regular expression  _r  and
                   the  fields  are loaded into array _A.  The number of fields
                   is returned.  See section 11 below for more detail.   If  _r
                   is omitted, FFSS is used.

            sprintf(_f_o_r_m_a_t_,_e_x_p_r_-_l_i_s_t)
                   Returns  a  string  constructed from _e_x_p_r_-_l_i_s_t according to
                   _f_o_r_m_a_t.  See the description of printf() below.

            sub(_r_,_s_,_t)  sub(_r_,_s)
                   Single substitution, same as  gsub()  except  at  most  one
                   substitution.

            substr(_s_,_i_,_n)  substr(_s_,_i)
                   Returns  the substring of string _s, starting at index _i, of
                   length _n.  If _n is omitted, the suffix of _s, starting at  _i
                   is returned.

            tolower(_s)
                   Returns  a  copy  of  _s  with  all  upper  case  characters
                   converted to lower case.

            toupper(_s)
                   Returns  a  copy  of  _s  with  all  lower  case  characters
                   converted to upper case.

       TTiimmee ffuunnccttiioonnss

       These are available on systems which support the corresponding C mmkkttiimmee
       and ssttrrffttiimmee functions:

            mktime(_s_p_e_c_i_f_i_c_a_t_i_o_n)
                   converts  a date specification to a timestamp with the same
                   units as ssyyssttiimmee.   The  date  specification  is  a  string
                   containing the components of the date as decimal integers:

                   YYYYYYYY
                      the year, e.g., 2012

                   MMMM the month of the year starting at 1

                   DDDD the day of the month starting at 1

                   HHHH hour (0-23)

                   MMMM minute (0-59)

                   SSSS seconds (0-59)

                   DDSSTT
                      tells  how  to  treat  timezone  versus daylight savings
                      time:

                        positive
                           DST is in effect

                        zero (default)
                           DST is not in effect

                        negative
                           mktime()  should  (use  timezone  information   and
                           system  databases to) attempt  to determine whether
                           DST is in effect at the specified time.

            strftime([_f_o_r_m_a_t [, _t_i_m_e_s_t_a_m_p [, _u_t_c ]]])
                   formats the given timestamp using the format (passed to the
                   C ssttrrffttiimmee function):

                   +o   If the _f_o_r_m_a_t parameter is missing, "%c" is used.

                   +o   If the _t_i_m_e_s_t_a_m_p  parameter  is  missing,  the  current
                       value from ssyyssttiimmee is used.

                   +o   If the _u_t_c parameter is present and nonzero, the result
                       is in UTC.  Otherwise local time is used.

            systime()
                   returns  the  current  time of day as the number of seconds
                   since the Epoch (1970-01-01 00:00:00 UTC on POSIX systems).

       AArriitthhmmeettiicc ffuunnccttiioonnss

            atan2(_y_,_x)
                   Arctan of _y/_x between -pi and pi.

            cos(_x) Cosine function, _x in radians.

            exp(_x) Exponential function.

            int(_x) Returns _x truncated towards zero.

            log(_x) Natural logarithm.

            rand() Returns a random number between zero and one.

            sin(_x) Sine function, _x in radians.

            sqrt(_x)
                   Returns square root of _x.

            srand(_e_x_p_r)

            srand()
                   Seeds the random number generator, using the clock if  _e_x_p_r
                   is  omitted,  and  returns  the value of the previous seed.
                   Srand(_e_x_p_r)  is  useful   for   repeating   pseudo   random
                   sequences.

                   Note: mmaawwkk is normally configured to seed the random number
                   generator  from the clock at startup, making it unnecessary
                   to call  srand().   This  feature  can  be  suppressed  via
                   conditional  compile,  or  overridden  using  the  --WWrraannddoomm
                   option.

   99.. IInnppuutt aanndd oouuttppuutt
       There are two output statements, pprriinntt and pprriinnttff.

            print  writes $$00  OORRSS to standard output.

            print _e_x_p_r1, _e_x_p_r2, ..., _e_x_p_rn
                   writes _e_x_p_r1 OOFFSS  _e_x_p_r2  OOFFSS  ...  _e_x_p_rn  OORRSS  to  standard
                   output.   Numeric  expressions are converted to string with
                   OOFFMMTT.

            printf _f_o_r_m_a_t_, _e_x_p_r_-_l_i_s_t
                   duplicates  the  printf  C  library  function  writing   to
                   standard output.  The complete ANSI C format specifications
                   are recognized with conversions %c, %d, %e, %E, %f, %g, %G,
                   %i,  %o, %s, %u, %x, %X and %%, and conversion qualifiers h
                   and l.

       The argument list to print or printf  can  optionally  be  enclosed  in
       parentheses.   Print  formats  numbers  using  OOFFMMTT  or  "%d" for exact
       integers.  "%c" with a numeric argument prints the corresponding 8  bit
       character,  with a string argument it prints the first character of the
       string.  The output of print and printf can be redirected to a file  or
       command  by  appending  >  _f_i_l_e, >> _f_i_l_e or | _c_o_m_m_a_n_d to the end of the
       print  statement.   Redirection  opens  _f_i_l_e  or  _c_o_m_m_a_n_d  only   once,
       subsequent   redirections  append  to  the  already  open  stream.   By
       convention, mmaawwkk associates the filename

          +o   "/dev/stderr" with stderr,

          +o   "/dev/stdout" with stdout,

          +o   "-" and "/dev/stdin" with stdin.

       The association with stderr is  especially  useful  because  it  allows
       print  and  printf to be redirected to stderr.  These names can also be
       passed to functions.

       The input function ggeettlliinnee has the following variations.

            getline
                   reads into $$00, updates the fields, NNFF, NNRR and FFNNRR.

            getline < _f_i_l_e
                   reads into $$00 from _f_i_l_e, updates the fields and NNFF.

            getline _v_a_r
                   reads the next record into _v_a_r, updates NNRR and FFNNRR.

            getline _v_a_r < _f_i_l_e
                   reads the next record of _f_i_l_e into _v_a_r.

            _c_o_m_m_a_n_d | getline
                   pipes a record from _c_o_m_m_a_n_d into $$00 and updates the  fields
                   and NNFF.

            _c_o_m_m_a_n_d | getline _v_a_r
                   pipes a record from _c_o_m_m_a_n_d into _v_a_r.

       Getline returns 0 on end-of-file, -1 on error, otherwise 1.

       Commands on the end of pipes are executed by /bin/sh.

       The  function cclloossee(_e_x_p_r) closes the file or pipe associated with _e_x_p_r.
       Close returns 0 if _e_x_p_r is an open file, the exit status if _e_x_p_r  is  a
       piped  command,  and  -1  otherwise.  Close is used to reread a file or
       command, make sure the other end of  an  output  pipe  is  finished  or
       conserve file resources.

       The  function  fffflluusshh(_e_x_p_r)  flushes the output file or pipe associated
       with _e_x_p_r.  Fflush returns 0 if _e_x_p_r is an open output stream else  -1.
       Fflush  without  an  argument  flushes  stdout.   Fflush  with an empty
       argument ("") flushes all open output.

       The function ssyysstteemm(_e_x_p_r) uses the C runtime  ssyysstteemm  call  to  execute
       _e_x_p_r  and  returns  the  corresponding  wait  status  of the command as
       follows:

       +o   if the ssyysstteemm call failed, setting the status to -1,  mmaawwkk  returns
           that value.

       +o   if the command exited normally, mmaawwkk returns its exit-status.

       +o   if  the command exited due to a signal such as SSIIGGHHUUPP, mmaawwkk returns
           the signal number plus 256.

       Changes made to the EENNVVIIRROONN array are not passed to  commands  executed
       with ssyysstteemm or pipes.

   1100.. UUsseerr ddeeffiinneedd ffuunnccttiioonnss
       The syntax for a user defined function is

            ffuunnccttiioonn name( _a_r_g_s ) { _s_t_a_t_e_m_e_n_t_s }

       The function body can contain a return statement

            rreettuurrnn _o_p_t___e_x_p_r

       A  return  statement  is not required.  Function calls may be nested or
       recursive.  Functions are passed expressions by  value  and  arrays  by
       reference.    Extra   arguments   serve  as  local  variables  and  are
       initialized to _n_u_l_l.  For example, csplit(_s_,_A) puts each character of _s
       into array _A and returns the length of _s.

            function csplit(s, A,    n, i)
            {
              n = length(s)
              for( i = 1 ; i <= n ; i++ ) A[i] = substr(s, i, 1)
              return n
            }

       Putting extra space between passed arguments  and  local  variables  is
       conventional.  Functions can be referenced before they are defined, but
       the  function  name  and  the  '(' of the arguments must touch to avoid
       confusion with concatenation.

       A function parameter is normally a scalar value (number or string).  If
       there is a forward  reference  to  a  function  using  an  array  as  a
       parameter, the function's corresponding parameter will be treated as an
       array.

   1111.. SSpplliittttiinngg ssttrriinnggss,, rreeccoorrddss aanndd ffiilleess
       Awk  programs  use the same algorithm to split strings into arrays with
       split(), and records into fields on FFSS.  mmaawwkk uses essentially the same
       algorithm to split files into records on RRSS.

       Split(_e_x_p_r_,_A_,_s_e_p) works as follows:

          (1)  If _s_e_p is omitted, it  is  replaced  by  FFSS.   _S_e_p  can  be  an
               expression  or  regular  expression.  If it is an expression of
               non-string type, it is converted to string.

          (2)  If _s_e_p = " " (a single space), then <SPACE> is trimmed from the
               front and back of _e_x_p_r, and _s_e_p becomes <SPACE>.  mmaawwkk  defines
               <SPACE> as the regular expression /[ \t\n]+/.  Otherwise _s_e_p is
               treated  as  a  regular expression, except that meta-characters
               are ignored for a string of length 1, e.g.,  split(x,  A,  "*")
               and split(x, A, /\*/) are the same.

          (3)  If  _e_x_p_r  is not string, it is converted to string.  If _e_x_p_r is
               then the empty string "", split() returns 0 and _A is set empty.
               Otherwise, all non-overlapping, non-null and longest matches of
               _s_e_p in _e_x_p_r, separate _e_x_p_r into fields which are loaded into _A.
               The fields are placed in A[1],  A[2],  ...,  A[n]  and  split()
               returns  n, the number of fields which is the number of matches
               plus one.  Data placed in _A that looks numeric is typed  number
               and string.

       Splitting  records  into  fields  works  the same except the pieces are
       loaded into $$11, $$22,..., $$NNFF.  If $$00 is empty, NNFF is set to 0 and all $$ii
       to "".

       mmaawwkk splits files into records by the  same  algorithm,  but  with  the
       slight  difference  that  RRSS  is  really  a  terminator  instead  of  a
       separator.  (OORRSS is really a terminator too).

            E.g., if FFSS = ":+" and $$00 = "a::b:" , then NNFF = 3 and $$11 = "a", $$22
            = "b" and $$33 = "", but if "a::b:" is the contents of an input file
            and RRSS = ":+", then there are two records "a" and "b".

       RRSS = " " is not special.

       If FFSS = "", then mmaawwkk breaks the  record  into  individual  characters,
       and,  similarly,  split(_s_,_A_,"")  places  the individual characters of _s
       into _A.

   1122.. MMuullttii--lliinnee rreeccoorrddss
       Since mmaawwkk interprets RRSS as a regular  expression,  multi-line  records
       are easy.  Setting RRSS = "\n\n+", makes one or more blank lines separate
       records.  If FFSS = " " (the default), then single newlines, by the rules
       for   <SPACE>  above,  become  space  and  single  newlines  are  field
       separators.

            For example, if

            +o   a file is "a b\nc\n\n",

            +o   RRSS = "\n\n+" and

            +o   FFSS = " ",

            then there is one record "a b\nc" with three fields "a",  "b"  and
            "c":

            +o   using FFSS = "\n", gives two fields "a b" and "c";

            +o   using FFSS = "", gives one field identical to the record.

       If  you want lines with spaces or tabs to be considered blank, set RRSS =
       "\n([ \t]*\n)+".  For compatibility with other awks, setting  RRSS  =  ""
       has  the  same effect as if blank lines are stripped from the front and
       back of files and then records are  determined  as  if  RRSS  =  "\n\n+".
       POSIX  requires  that  "\n"  always  separates  records  when  RRSS  = ""
       regardless of the value of FFSS.  mmaawwkk does not support this  convention,
       because defining "\n" as <SPACE> makes it unnecessary.

       Most  of  the  time when you change RRSS for multi-line records, you will
       also want to change OORRSS to "\n\n" so the record spacing is preserved on
       output.

   1133.. PPrrooggrraamm eexxeeccuuttiioonn
       This section describes the order of program execution.  First  AARRGGCC  is
       set  to  the  total  number  of  command  line  arguments passed to the
       execution phase of the program.

       +o   AARRGGVV[[00]] is set to the name of the AWK interpreter and

       +o   AARRGGVV[[11]]  ...   AARRGGVV[[AARRGGCC--11]]  holds  the  remaining   command   line
           arguments exclusive of options and program source.

       For example, with

            mawk  -f  prog  v=1  A  t=hello  B

       AARRGGCC = 5 with
              AARRGGVV[[00]] = "mawk",
              AARRGGVV[[11]] = "v=1",
              AARRGGVV[[22]] = "A",
              AARRGGVV[[33]] = "t=hello" and
              AARRGGVV[[44]] = "B".

       Next,  each  BBEEGGIINN block is executed in order.  If the program consists
       entirely of BBEEGGIINN blocks, then  execution  terminates,  else  an  input
       stream  is opened and execution continues.  If AARRGGCC equals 1, the input
       stream is set to stdin, else  the command line  arguments  AARRGGVV[[11]]  ...
       AARRGGVV[[AARRGGCC--11]] are examined for a file argument.

       The  command  line  arguments  divide  into three sets: file arguments,
       assignment arguments and empty strings "".  An assignment has the  form
       _v_a_r=_s_t_r_i_n_g.   When  an AARRGGVV[[ii]] is examined as a possible file argument,
       if it is empty it is skipped; if it  is  an  assignment  argument,  the
       assignment  to  _v_a_r  takes place and ii skips to the next argument; else
       AARRGGVV[[ii]] is opened for input.  If it fails to open, execution terminates
       with exit code 2.  If no command line argument is a file argument, then
       input comes from stdin.  Getline in a BBEEGGIINN action opens input.  "-" as
       a file argument denotes stdin.

       Once an input stream is open, each input record is tested against  each
       _p_a_t_t_e_r_n,  and  if  it  matches,  the associated _a_c_t_i_o_n is executed.  An
       expression pattern matches if it  is  boolean  true  (see  the  end  of
       section  2).   A  BBEEGGIINN pattern matches before any input has been read,
       and an EENNDD pattern matches after all input  has  been  read.   A  range
       pattern,  _e_x_p_r1,_e_x_p_r2 , matches every record between the match of _e_x_p_r1
       and the match _e_x_p_r2 inclusively.

       When end of file occurs on the input stream, the remaining command line
       arguments are examined for a file argument, and if there is one  it  is
       opened,  else the EENNDD _p_a_t_t_e_r_n is considered matched and all EENNDD _a_c_t_i_o_n_s
       are executed.

       In the example, the assignment v=1 takes place after the BBEEGGIINN  _a_c_t_i_o_n_s
       are  executed,  and  the  data  placed in v is typed number and string.
       Input is then read from file A.  On end of file A,  t  is  set  to  the
       string  "hello",  and B is opened for input.  On end of file B, the EENNDD
       _a_c_t_i_o_n_s are executed.

       Program flow at the _p_a_t_t_e_r_n _{_a_c_t_i_o_n_} level can be changed with the

            nneexxtt
            nneexxttffiillee
            eexxiitt  _o_p_t___e_x_p_r

       statements:

       +o   A nneexxtt statement causes the  next  input  record  to  be  read  and
           pattern  testing to restart with the first _p_a_t_t_e_r_n _{_a_c_t_i_o_n_} pair in
           the program.

       +o   A nneexxttffiillee statement tells mmaawwkk  to  stop  processing  the  current
           input  file.   It  then updates FILENAME to the next file listed on
           the command line, and resets FNR to 1.

       +o   An eexxiitt statement causes immediate execution of the EENNDD actions  or
           program  termination  if there are none or if the eexxiitt occurs in an
           EENNDD action.  The _o_p_t___e_x_p_r sets the exit value of the program unless
           overridden by a later eexxiitt or subsequent error.

EENNVVIIRROONNMMEENNTT
       MMaawwkk recognizes these variables:

          MAWKBINMODE
             (see CCOOMMPPAATTIIBBIILLIITTYY)

          MAWK_LONG_OPTIONS
             If this is set, mmaawwkk uses its value to decide  what  to  do  with
             GNU-style long options:

               allow  MMaawwkk allows the option to be checked against the (small)
                      set of long options it recognizes.

                      The  long names from the --WW option are recognized, e.g.,
                      ----vveerrssiioonn is derived from --WWvveerrssiioonn.

               error  MMaawwkk prints an error message and  exits.   This  is  the
                      default.

               ignore MMaawwkk  ignores the option, unless it happens to be one of
                      the one it recognizes.

               warn   Print  an  warning  message  and  otherwise  ignore  the
                      option.

             If the variable is unset, mmaawwkk prints an error message and exits.

          WHINY_USERS
             This  is  a ggaawwkk 3.1.0 feature, removed in the 4.0.0 release.  It
             tells mmaawwkk to sort array indices before it starts to iterate over
             the elements of an array.

CCOOMMPPAATTIIBBIILLIITTYY
   MMAAWWKK 11..33..33 vveerrssuuss PPOOSSIIXX 11000033..22 DDrraafftt 1111..33
       The POSIX 1003.2(draft 11.3) definition of the AWK language is  AWK  as
       described  in  the  AWK  book  with  a  few extensions that appeared in
       SystemVR4 nawk.  The extensions are:

          +o   New functions: toupper() and tolower().

          +o   New variables: ENVIRON[] and CONVFMT.

          +o   ANSI C conversion specifications for printf() and sprintf().

          +o   New command options:  -v  var=value,  multiple  -f  options  and
              implementation options as arguments to -W.

          +o   For   systems  (MS-DOS  or  Windows)  which  provide  a  _s_e_t_m_o_d_e
              function, an environment variable  MAWKBINMODE  and  a  built-in
              variable  BINMODE.  The bits of the BINMODE value tell mmaawwkk  how
              to modify the RRSS and OORRSS variables:

              0  set standard input to binary mode, and if BIT-2 is unset, set
                 RRSS to "\r\n" (CR/LF) rather than "\n" (LF).

              1  set standard output to binary mode, and if  BIT-2  is  unset,
                 set OORRSS to "\r\n" (CR/LF) rather than "\n" (LF).

              2  suppress  the  assignment  to  RRSS and OORRSS of CR/LF, making it
                 possible to run scripts and generate output  compatible  with
                 Unix line-endings.

       POSIX  AWK is oriented to operate on files a line at a time.  RRSS can be
       changed from "\n" to another single character, but it is hard  to  find
       any  use  for  this  --  there  are  no  examples  in the AWK book.  By
       convention, RRSS = "", makes one or more blank  lines  separate  records,
       allowing  multi-line  records.   When  RRSS  = "", "\n" is always a field
       separator regardless of the value in FFSS.

       mmaawwkk, on the other hand, allows RRSS to be a  regular  expression.   When
       "\n"  appears  in  records,  it  is  treated  as  space,  and FFSS always
       determines fields.

       Removing the line at a time paradigm can make some programs simpler and
       can often improve performance.  For example,  redoing  example  3  from
       above,

            BEGIN { RS = "[^A-Za-z]+" }

            { word[ $0 ] = "" }

            END { delete  word[ "" ]
              for( i in word )  cnt++
              print cnt
            }

       counts  the  number  of  unique words by making each word a record.  On
       moderate size files, mmaawwkk  executes  twice  as  fast,  because  of  the
       simplified inner loop.

       The  following  program  replaces each comment by a single space in a C
       program file,

            BEGIN {
              RS = "/\*([^*]|\*+[^/*])*\*+/"
                 # comment is record separator
              ORS = " "
              getline  hold
              }

              { print hold ; hold = $0 }

              END { printf "%s" , hold }

       Buffering one record is needed to avoid  terminating  the  last  record
       with a space.

       With mmaawwkk, the following are all equivalent,

            x ~ /a\+b/    x ~ "a\+b"     x ~ "a\\+b"

       The  strings  get  scanned  twice,  once  as string and once as regular
       expression.  On the string scan, mmaawwkk ignores the escape on  non-escape
       characters  while  the  AWK  book advocates _\_c be recognized as _c which
       necessitates the double escaping of meta-characters in strings.   POSIX
       explicitly  declines  to  define  the  behavior  which passively forces
       programs that must run under a variety of awks to use the more portable
       but less readable, double escape.

       POSIX AWK does  not  recognize  "/dev/std{in,out,err}".   Some  systems
       provide an actual device for this, allowing AWKs which do not implement
       the feature directly to support it.

       POSIX  AWK  does  not  recognize  \x  hex  escape sequences in strings.
       Unlike ANSI C, mmaawwkk limits the number of digits that follows \x to  two
       as the current implementation only supports 8 bit characters.

       POSIX explicitly leaves the behavior of FFSS = "" undefined, and mentions
       splitting  the record into characters as a possible interpretation, but
       currently this use is not portable across implementations.

       Some features were not part of the  POSIX  standard  until  long  after
       their  introduction  in  mmaawwkk  and  other  implementations.  These were
       published in IEEE 1003.1-2024 (The Open Group Base Specifications Issue
       8):

       +o   The built-in fffflluusshh first appeared in a 1993 AT&T awk  released  to
           netlib.  It was approved for the POSIX standard in 2012.

       +o   The  built-in  nneexxttffiillee first appeared in gawk in 1988, was adopted
           by BWK in 1996, and by mawk in 2012.  It was approved for the POSIX
           standard in 2012.

       +o   Aggregate deletion with ddeelleettee _a_r_r_a_y was approved in 2018.

   RRaannddoomm nnuummbbeerrss
       POSIX does not prescribe a method for initializing  random  numbers  at
       startup.

       In practice, most implementations do nothing special, which makes ssrraanndd
       and rraanndd follow the C runtime library, making the initial seed value 1.
       Some  implementations  (Solaris XPG4 and Tru64) return 0 from the first
       call to ssrraanndd, although the results from rraanndd behave as if the  initial
       seed is 1.  Other implementations return 1.

       While  mmaawwkk  can  call ssrraanndd at startup with no parameter (initializing
       random numbers from the clock), this feature may  be  suppressed  using
       conditional compilation.

   EExxtteennssiioonnss aaddddeedd ffoorr ccoommppaattiibbiilliittyy ffoorr GGAAWWKK aanndd BBWWKK
       MMkkttiimmee, ssttrrffttiimmee and ssyyssttiimmee are ggaawwkk extensions.

       The   "/dev/stdin"   feature   was  added  to  mmaawwkk  after  1.3.4,  for
       compatibility with ggaawwkk and BWK awk.  The corresponding "-" (alias  for
       /dev/stdin) was present in mmaawwkk 1.3.3.

       Interval   expressions,   e.g.,  a  range  _{_m_,_n_}  in  Extended  Regular
       Expressions (EREs), were not supported in awk  (or  even  the  original
       "nawk"):

       +o   Gawk provided this feature in 1991 (and later, in 1998, options for
           turning it off, for compatibility with "traditional awk").

       +o   Interval  expressions, were introduced into _a_w_k regular expressions
           in IEEE 1003.1-2001 (also  known  as  Unix  03),  along  with  some
           internationalization features.

       +o   Apple  modified  its copy of the original awk in April 2006, making
           this version of awk support interval expressions.

           The updated source provides for compatibility with  older  "legacy"
           versions  using  an  environment  variable, making this "Unix 2003"
           feature (perhaps meant as Unix 03) the default.

       +o   NetBSD developers copied this change in January 2018, omitting  the
           compatibility option, and then applied it to BWK awk.

       +o   The  interval expression implementation in mmaawwkk is based on changes
           proposed by James Parkinson in April 2016.

       MMaawwkk also recognizes a  few  gawk-specific  command  line  options  for
       script compatibility:

            ----hheellpp, ----ppoossiixx, --rr, ----rree--iinntteerrvvaall, ----ttrraaddiittiioonnaall, ----vveerrssiioonn

   SSuubbttllee DDiiffffeerreenncceess nnoott iinn PPOOSSIIXX oorr tthhee AAWWKK BBooookk
       Finally,  here  is  how mmaawwkk handles exceptional cases not discussed in
       the AWK book or the POSIX draft.  It is unsafe  to  assume  consistency
       across awks and safe to skip to the next section.

          +o   substr(s,  i, n) returns the characters of s in the intersection
              of the closed interval [1, length(s)] and the half-open interval
              [i, i+n).  When this intersection is empty, the empty string  is
              returned; so substr("ABC", 1, 0) = "" and substr("ABC", -4, 6) =
              "A".

          +o   Every  string,  including  the  empty  string, matches the empty
              string at the front so, s ~ // and s ~ "", are always  1  as  is
              match(s, //) and match(s, "").  The last two set RRLLEENNGGTTHH to 0.

          +o   index(s,  t)  is always the same as match(s, t1) where t1 is the
              same as t with metacharacters escaped.  Hence  consistency  with
              match  requires  that  index(s,  "") always returns 1.  Also the
              condition, index(s,t) != 0 if and only t is a  substring  of  s,
              requires index("","") = 1.

          +o   If  getline  encounters  end  of  file,  getline var, leaves var
              unchanged.  Similarly, on entry to  the  EENNDD  actions,  $$00,  the
              fields and NNFF have their value unaltered from the last record.

BBUUGGSS
       mmaawwkk  implements  pprriinnttff(()) and sspprriinnttff(()) using the C library functions,
       printf and sprintf, so full  ANSI  compatibility  requires  an  ANSI  C
       library.   In practice this means the h conversion qualifier may not be
       available.

       Also mmaawwkk inherits any bugs or limitations of the library functions.

       Implementors of the AWK  language  have  shown  a  consistent  lack  of
       imagination when naming their programs.

EEXXAAMMPPLLEESS
       1. emulate cat.

            { print }

       2. emulate wc.

            { chars += length($0) + 1  # add one for the \n
              words += NF
            }

            END{ print NR, words, chars }

       3. count the number of unique "real words".

            BEGIN { FS = "[^A-Za-z]+" }

            { for(i = 1 ; i <= NF ; i++)  word[$i] = "" }

            END { delete word[""]
                  for ( i in word )  cnt++
                  print cnt
            }

       4. sum the second field of every record based on the first field.

            $1 ~ /credit|gain/ { sum += $2 }
            $1 ~ /debit|loss/  { sum -= $2 }

            END { print sum }

       5. sort a file, comparing as string

            { line[NR] = $0 "" }  # make sure of comparison type
                            # in case some lines look numeric

            END {  isort(line, NR)
              for(i = 1 ; i <= NR ; i++) print line[i]
            }

            #insertion sort of A[1..n]
            function isort( A, n,    i, j, hold)
            {
              for( i = 2 ; i <= n ; i++)
              {
                hold = A[j = i]
                while ( A[j-1] > hold )
                { j-- ; A[j+1] = A[j] }
                A[j] = hold
              }
              # sentinel A[0] = "" will be created if needed
            }


AAUUTTHHOORRSS
       Mike Brennan (brennan@whidbey.com).
       Thomas E. Dickey <dickey@invisible-island.net>.

SSEEEE AALLSSOO
       ggrreepp(1)

       Aho,  Kernighan  and Weinberger, _T_h_e _A_W_K _P_r_o_g_r_a_m_m_i_n_g _L_a_n_g_u_a_g_e, Addison-
       Wesley Publishing, 1988, (the AWK book), defines the language,  opening
       with  a  tutorial and advancing to many interesting programs that delve
       into issues of software design and analysis relevant to programming  in
       any language.

       _T_h_e  _G_A_W_K _M_a_n_u_a_l, The Free Software Foundation, 1991, is a tutorial and
       language reference that does not attempt the depth of the AWK book  and
       assumes  the  reader  may  be  a novice programmer.  The section on AWK
       arrays is excellent.  It also discusses POSIX requirements for AWK.

       mmaawwkk--aarrrraayyss(7) discusses mmaawwkk's implementation of arrays.

       mmaawwkk--ccooddee(7) gives more information on the --WW dduummpp option.

       _a_w_k _- _p_a_t_t_e_r_n _s_c_a_n_n_i_n_g _a_n_d _p_r_o_c_e_s_s_i_n_g _l_a_n_g_u_a_g_e
       The Open Group Base Specifications Issue 8
       IEEE Std 1003.1-2024
       https://pubs.opengroup.org/onlinepubs/9799919799/utilities/awk.html

Version 1.3.4                     2026-01-28                           _M_A_W_K(1)