MAWK(1)                          USER COMMANDS                         MAWK(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 lan-
       guage is useful for manipulation of data files, text retrieval and pro-
       cessing,  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  con-
       forms  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 synony-
       mous 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 com-
                      mand 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 implemen-
       tation  of  AWK.  Implementation specific options are prefaced with --WW.
       mmaawwkk provides these:

       -WW dump        writes an assembler like listing of the internal  repre-
                      sentation  of the program to stdout and exits 0 (on suc-
                      cessful 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 sup-
                      port 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_space forces mmaawwkk not to consider '\n' to be space.

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

       -WW version     mmaawwkk writes its version and copyright to stdout and com-
                      piled 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 func-
       tion 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 state-
       ment  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  state-
       ments

            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  neces-
       sary  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 op-
       erand 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  exe-
       cuted.   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

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

       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 fol-
       lows:

            _r1_r2         matches  _r1  followed  immediately  by _r2 (concatena-
                         tion).

            _r1 | _r2      matches _r1 or _r2 (alternation).

            _r*           matches _r repeated zero or more times.

            _r+           matches _r repeated one or more times.

            _r?           matches _r zero or once.

            (_r)          matches _r, providing grouping.

       The increasing precedence of operators  is  alternation,  concatenation
       and unary (*, + or ?).

       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 !~ opera-
       tors 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  paren-
       thesized.

   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.   Ini-
       tially  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 an extension, ddeelleettee _a_r_r_a_y, 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
       String functions

            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 replace-
                   ments  is  returned.  If _t is omitted, $$00 is used.  An & in
                   the replacement string _s is replaced by  the  matched  sub-
                   string 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 sub-
                   stitution.

            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 con-
                   verted to lower case.

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

       Time functions

       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 con-
                   taining the components of the date as decimal integers:

                   YYYY
                      the year, e.g., 2012

                   MM the month of the year starting at 1

                   DD the day of the month starting at 1

                   HH hour (0-23)

                   MM minute (0-59)

                   SS seconds (0-59)

                   DST
                      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 sys-
                           tem 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).

       Arithmetic functions

            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 condi-
                   tional 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 out-
                   put.  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 stan-
                   dard 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  inte-
       gers.   "%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, subse-
       quent 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 con-
       serve 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  argu-
       ment ("") 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  fol-
       lows:

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

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

       +o   if the command exited due to a signal such as SSIIGGHHUUPP, _m_a_w_k  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  initial-
       ized  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 con-
       fusion 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  parame-
       ter,  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 expres-
               sion  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 separa-
       tor.  (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 separa-
       tors.

            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   Changing FFSS = "\n", gives two fields "a b" and "c";

            +o   changing 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 = "" regard-
       less 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  execu-
       tion  phase  of the program.  AARRGGVV[[00]] is set the name of the AWK inter-
       preter and 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  sec-
       tion  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 pat-
           tern 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.

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
            }


CCOOMMPPAATTIIBBIILLIITTYY IISSSSUUEESS
   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 Sys-
       temVR4 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 func-
              tion, an environment variable MAWKBINMODE and a  built-in  vari-
              able  BINMODE.   The  bits of the BINMODE value tell _m_a_w_k 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  conven-
       tion, 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  deter-
       mines 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  sim-
       plified 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 pro-
       grams 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 pro-
       vide 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.  The
       built-in fffflluusshh first appeared in a recent (1993) AT&T awk released  to
       netlib, and is not part of the POSIX standard.  Aggregate deletion with
       ddeelleettee _a_r_r_a_y is not part of the POSIX standard.

       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.

   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
       NNeexxttffiillee  is a ggaawwkk extension (also implemented by BWK awk), is not yet
       part of the POSIX standard (as of October 2012), although it  has  been
       accepted for the next revision of the standard.

       MMkkttiimmee, ssttrrffttiimmee and ssyyssttiimmee are ggaawwkk extensions.

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

   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.

EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS
       MMaawwkk recognizes these variables:

          MAWKBINMODE
             (see CCOOMMPPAATTIIBBIILLIITTYY IISSSSUUEESS)

          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.

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

               ignore MMaawwkk ignores the option.

               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  an  undocumented  ggaawwkk  feature.  It tells mmaawwkk to sort
             array indices before it starts to iterate over the elements of an
             array.

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.

BBUUGGSS
       mmaawwkk implements printf() and sprintf() 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 imagi-
       nation when naming their programs.

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



Version 1.3.4                     2019-12-31                           MAWK(1)