Provided by: libmawk1_1.0.2-1_amd64 bug

NAME

       lmawk - pattern scanning and text processing language

SYNOPSIS

       lmawk [-W option] [-F value] [-v var=value] [--] 'program text' [file ...]
       lmawk [-W option] [-F value] [-v var=value] [-f program-file] [--] [file ...]

DESCRIPTION

       lmawk  is  an  interpreter  for  the  AWK Programming Language derived from mawk.  The AWK
       language is useful for manipulation of data files, text retrieval and processing, and  for
       prototyping  and  experimenting with algorithms.  lmawk is a new awk meaning it implements
       the AWK language as  defined  in  Aho,  Kernighan  and  Weinberger,  The  AWK  Programming
       Language, Addison-Wesley Publishing, 1988.  (Hereafter referred to as the AWK book.)  mawk
       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  mawk  provides a small number of
       extensions.

       An AWK program is a sequence of pattern {action} 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, RS.  Initially, RS = "\n" and records are synonymous with lines.  Each record is
       compared against each pattern and  if  it  matches,  the  program  text  for  {action}  is
       executed.

OPTIONS

       -F value       sets the field separator, FS, to value.

       -f file        Program  text is read from file instead of from the command line.  Multiple
                      -f options are allowed. As a libmawk extension, if file  name  starts  with
                      plus  ('+'), it is not loaded if the same file has been loaded already by a
                      previous -f or include from any of the scripts already loaded.

       -b file        Program bytecode is read from file  .  Multiple  -b  options  are  allowed.
                      Bytecode  can  be  generated  using  -Wcompile.  Libmawk may refuse to load
                      bytecode generated on a different system if byte order, type sizes or  dump
                      version differs.

       -v var=value   assigns value to program variable var.

       --             indicates the unambiguous end of options.

       The  above  options will be available with any Posix compatible implementation of AWK, and
       implementation specific options are prefaced with -W.  lmawk provides six:

       -W version     lmawk writes its version and copyright to stdout  and  compiled  limits  to
                      stderr and exits 0.

       -W debug       include location info in the compiled code; location information is visible
                      in the dump and when debugging libmawk.

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

       -W dumpsym     writes  a  list  of  global  symbols  to  stdout and exits 0 (on successful
                      compilation).

       -W compile     writes a binary dump of the bytecode to stdout. This bytecode can be loaded
                      using the -b switch.

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

       -W maxmem=num  limit dynamic memory allocation during compilation  and  execution  to  num
                      bytes  and  exit  with  out-of-the-memory  error  if  more  memory is to be
                      allocated.  Optional suffixes are k for kilobyte  and  m  for  megabyte.  0
                      means unlimited, which is also the default.

       -W exec file   Program  text  is  read  from  file  and this is the last option. Useful on
                      systems that support the  #!   "magic  number"  convention  for  executable
                      scripts.

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

       -W posix_space forces lmawk not to consider '\n' to be space.

       The short forms -W[vdiesp] are recognized and on some systems -We is  mandatory  to  avoid
       command line length limitations.

THE AWK LANGUAGE

   1. Program structure
       An AWK program is a sequence of pattern {action} pairs and user function definitions.

       A pattern can be:
              BEGIN
              END
              expression
              expression , expression

       One,  but  not  both,  of  pattern {action} can be omitted.   If {action} is omitted it is
       implicitly { print }.  If pattern is omitted, then it is implicitly  matched.   BEGIN  and
       END 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, &&, ||, do, else, the right
       parenthesis of an if, while or for 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.

              if ( expr ) statement

              if ( expr ) statement else statement

              while ( expr ) statement

              do statement while ( expr )

              for ( opt_expr ; opt_expr ; opt_expr ) statement

              for ( var in array ) statement

              continue

              break

   2. Data types, conversion and comparison
       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., lmawk ignores the escape.

       There  are  really three basic data types; the third is number and string 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 null, 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 atof(3).  A numeric expression is converted to string by
       replacing expr with sprintf(CONVFMT, expr), unless expr can be  represented  on  the  host
       machine  as an exact integer then it is converted to sprintf("%d", expr).  Sprintf() is an
       AWK built-in that duplicates the functionality of sprintf(3), and CONVFMT  is  a  built-in
       variable  used  for  internal  conversion from number to string and initialized to "%.6g".
       Explicit type conversions can be forced, expr "" is string and expr+0 is numeric.

       To evaluate, expr1 rel-op expr2, 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, if ( expr ) statement, a string expression evaluates true if
       and only if it is not the empty string ""; numeric values if and only if  not  numerically
       zero.

   3. Regular expressions
       In  the  AWK language, records, fields and strings are often tested for matching a regular
       expression.  Regular expressions are enclosed in slashes, and

            expr ~ /r/

       is an AWK expression that evaluates to 1 if expr "matches" r, which means a  substring  of
       expr  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/ { action }   and   $0 ~ /r/ { action }

       are  the same, and for each input record that matches r, action is executed.  In fact, /r/
       is an AWK expression that is equivalent to ($0 ~ /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  egrep(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 follows:

              r1r2         matches r1 followed immediately by r2 (concatenation).

              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 !~ 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.

       lmawk  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 | lmawk { gsub(//, "X") ; print }
            XaXbXcX

   4. Records and fields
       Records  are  read  in  one at a time, and stored in the field variable $0.  The record is
       split into fields which are stored in $1, $2, ..., $NF.  The built-in variable NF  is  set
       to the number of fields, and NR and FNR are incremented by 1.  Fields above $NF are set to
       "".

       Assignment to $0 causes the fields and NF to be recomputed.  Assignment  to  NF  or  to  a
       field  causes  $0  to  be  reconstructed  by  concatenating  the  $i's  separated  by OFS.
       Assignment to a field with index greater than  NF,  increases  NF  and  causes  $0  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 |
            lmawk '{ print($1>100, $1>"100", $2>100, $2>"100") }'
            0 1 1 1

       $0 and $2 are string and $1 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.

   5. Expressions and operators
       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 null.

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

              assignment          =  +=  -=  *=  /=  %=  ^=
              conditional         ?  :
              logical or          ||
              logical and         &&
              array membership    in
              matching       ~   !~
              relational          <  >   <=  >=  ==  !=
              concatenation       (no explicit operator)
              add ops             +  -
              mul ops             *  /  %
              unary               +  -
              logical not         !
              exponentiation      ^
              inc and dec         ++ -- (both post and pre)
              field               $

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

   6. Arrays
       Awk  provides  one-dimensional arrays.  Array elements are expressed as array[expr].  Expr
       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,
       expr in array evaluates to 1 if array[expr] exists, else to 0.

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

            for ( var in array ) statement

       sets  var  to  each index of array and executes statement.  The order that var transverses
       the indices of array is not defined.

       The statement, delete array[expr], causes array[expr] not to  exist.   lmawk  supports  an
       extension, delete array, which deletes all elements of array.

       Multidimensional  arrays  are  synthesized  with concatenation using the built-in variable
       SUBSEP.  array[expr1,expr2] is equivalent to array[expr1 SUBSEP  expr2].   Testing  for  a
       multidimensional element uses a parenthesized index, such as

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

   7. Builtin-variables
       The following variables are built-in and initialized before program execution.

              ARGC      number of command line arguments.

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

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

              ENVIRON   array indexed by environment variables.  An environment string, var=value
                        is stored as ENVIRON[var] = value.

              FILENAME  name of the current input file.

              FNR       current record number in FILENAME.

              FS        splits records into fields as a regular expression.

              NF        number of fields in the current record.

              NR        current record number in the total input stream.

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

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

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

              RLENGTH   length set by the last call to the built-in function, match().

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

              RSTART    index set by the last call to match().

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

              ERRNO     misc built-in functions (libmawk extensions) use this variable to rerport
                        error.  All  extension  calls  will  set  this variable before returning,
                        therefor ERRNO holds the result of the last call. An empty  string  value
                        means no error. Error messages are formatted in a way that the first word
                        is an unique integer, followed by a human readable error message from the
                        second word. int(ERRNO) can be used to acquire the error code, which then
                        can be used as a  secondary  output  from  the  extension  function.  For
                        example, an awk program can use valueof() to determine if a global symbol
                        exists and is a function or a variable or anything else.

              LIBPATH   is a semicolon separated list of search paths. When loading an awk script
                        by  file  name  (-f  command  line  argument  or include from another awk
                        script) these paths are inserted before the file name, in order,  one  by
                        one,  until the first path that allows opening the file. An empty path is
                        equivalent to the current working directory. LIBPATH can be modified from
                        the  command  line  using -v, as arguments are scanned before loading the
                        scripts.  Setting  LIBPATH  to  empty  string  results  in  the  original
                        behaviour of mawk. LIBPATH is ignored for script file names starting with
                        slash ('/') as those are assumed to be absolute paths.

   8. Built-in functions
       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 replacements is returned.  If t is
                     omitted, $0 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 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, RSTART is  set  to  the
                     return  value.  RLENGTH is set to the length of the match or -1 if no match.
                     If the empty string is matched, RLENGTH 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, FS is used.

              sprintf(format,expr-list)
                     Returns a string constructed from expr-list according to  format.   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.

       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(expr)  srand()
                     Seeds the random number generator, using the clock if expr is  omitted,  and
                     returns  the  value  of  the  previous  seed.  lmawk seeds the random number
                     generator from the clock at startup  so  there  is  no  real  need  to  call
                     srand().  Srand(expr) is useful for repeating pseudo random sequences.

       Misc functions (libmawk extensions)

              call(fname,arg1,arg2,...)
                     Call  awk  function  fname  with  the supplied arguments. If the call fails,
                     empty value, else the return value  of  the  callee  is  returned.  Built-in
                     variable ERRNO is always set.

              acall(fname,arrname)
                     Call awk function fname with arguments supplied in array named arrname (both
                     arguments are strings naming an  existing  object).   The  array  should  be
                     indexed  from  1. Number of arguments is determined by looking for the first
                     empty (non-existing) index in the array. If the  call  fails,  empty  value,
                     else  the return value of the callee is returned. Built-in variable ERRNO is
                     always set.

              valueof(vname [,idx])
                     Return the value of variable fname; if the variable is an array, return  the
                     element indexed by idx (which must be present in this case). If index is not
                     present or is empty (""), the variable is expected to  be  scalar.  Built-in
                     variable  ERRNO  is  always  set.  NOTE:  valueof() has access to the global
                     symbol table only.  It will  fail  to  resolve  anything  else  than  global
                     objects;  most  notably  it will fail on local variables, $ arguments and on
                     most of the built-in variables.

   9. Input and output
       There are two output statements, print and printf.

              print  writes $0  ORS to standard output.

              print expr1, expr2, ..., exprn
                     writes expr1 OFS expr2 OFS  ...  exprn  ORS  to  standard  output.   Numeric
                     expressions are converted to string with OFMT.

              printf format, expr-list
                     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  OFMT  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 > file, >> file or | command to  the  end  of  the  print  statement.
       Redirection opens file or command only once, subsequent redirections append to the already
       open stream.  By convention, lmawk associates the filename "/dev/stderr" with stderr which
       allows  print  and  printf  to  be  redirected  to  stderr.  lmawk also associates "-" and
       "/dev/stdout" with stdin and stdout which allows these streams to be passed to  functions.
       Opening  /dev/fd/N  will do an fdopen() on file descriptor N, where N is an integer - this
       is a libmawk extension. If any of the /dev heuristics  needs  to  be  bypassed  (i.e.  the
       script wants to open the real /dev/stdout or the real /dev/fd/5), the leading slash should
       be doubled (e.g. //dev/fd/5).

       The input function getline has the following variations.

              getline
                     reads into $0, updates the fields, NF, NR and FNR.

              getline < file
                     reads into $0 from file, updates the fields and NF.

              getline var
                     reads the next record into var, updates NR and FNR.

              getline var < file
                     reads the next record of file into var.

               command | getline
                     pipes a record from command into $0 and updates the fields and NF.

               command | getline var
                     pipes a record from command into var.

       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 close(expr) closes the file or pipe associated with expr.  Close returns 0 if
       expr is an open file, the exit status if expr 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  fflush(expr)  flushes the output file or pipe associated with expr.  Fflush
       returns 0 if expr is an open output stream else -1.  Fflush without  an  argument  flushes
       stdout.  Fflush with an empty argument ("") flushes all open output.

       The  function system(expr) uses /bin/sh to execute expr and returns the exit status of the
       command expr.  Changes made to the ENVIRON array are not passed to commands executed  with
       system or pipes.

   10. User defined functions
       The syntax for a user defined function is

            function name( args ) { statements }

       The function body can contain a return statement

            return opt_expr

       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 null.  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.

   11. Splitting strings, records and files
       Awk programs use the same algorithm to split strings into arrays with split(), and records
       into  fields on FS.  lmawk uses essentially the same algorithm to split files into records
       on RS.

       Split(expr,A,sep) works as follows:

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

              (2)    If sep = " " (a single space), then <SPACE> is trimmed from  the  front  and
                     back of expr, and sep becomes <SPACE>.  lmawk defines <SPACE> as the regular
                     expression /[ \t\n]+/.  Otherwise sep 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 expr is not string, it is converted to string.  If expr is then the empty
                     string  "",  split()  returns  0  and  A  is set empty.  Otherwise, all non-
                     overlapping, non-null and longest matches of sep in expr, separate expr 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 $1, $2,...,
       $NF.  If $0 is empty, NF is set to 0 and all $i to "".

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

              E.g., if FS = ":+" and $0 = "a::b:" , then NF = 3 and $1 = "a", $2 = "b" and  $3  =
              "",  but  if "a::b:" is the contents of an input file and RS = ":+", then there are
              two records "a" and "b".

       RS = " " is not special.

       If FS = "", then lmawk breaks the  record  into  individual  characters,  and,  similarly,
       split(s,A,"") places the individual characters of s into A.

   12. Multi-line records
       Since  lmawk  interprets RS as a regular expression, multi-line records are easy.  Setting
       RS = "\n\n+", makes one or more blank lines separate records.  If FS = " " (the  default),
       then single newlines, by the rules for <SPACE> above, become space and single newlines are
       field separators.

              For example, if a file is "a b\nc\n\n", RS = "\n\n+" and FS = " ",  then  there  is
              one  record "a b\nc" with three fields "a", "b" and "c".  Changing FS = "\n", gives
              two fields "a b" and "c"; changing FS =  "",  gives  one  field  identical  to  the
              record.

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

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

   13. Program execution
       This  section  describes  the  order of program execution.  First ARGC is set to the total
       number of command line arguments passed to the execution phase of the program.  ARGV[0] is
       set  the  name  of  the  AWK interpreter and ARGV[1] ...  ARGV[ARGC-1] holds the remaining
       command line arguments exclusive of options and program source.  For example with

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

       ARGC = 5 with ARGV[0] = "lmawk", ARGV[1] = "v=1", ARGV[2] = "A", ARGV[3] =  "t=hello"  and
       ARGV[4] = "B".

       Next,  each  BEGIN  block is executed in order.  If the program consists entirely of BEGIN
       blocks, then execution terminates, else an input stream is opened and execution continues.
       If  ARGC  equals  1,  the  input  stream is set to stdin, else  the command line arguments
       ARGV[1] ...  ARGV[ARGC-1] 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 var=string.  When an ARGV[i] is examined
       as a possible file argument, if it is  empty  it  is  skipped;  if  it  is  an  assignment
       argument, the assignment to var takes place and i skips to the next argument; else ARGV[i]
       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 BEGIN
       action opens input.  "-" as a file argument denotes stdin.

       Once an input stream is open, each input record is tested against each pattern, and if  it
       matches,  the  associated  action  is  executed.   An  expression pattern matches if it is
       boolean true (see the end of section 2).  A BEGIN pattern matches  before  any  input  has
       been  read,  and  an  END pattern matches after all input has been read.  A range pattern,
       expr1,expr2 , matches every record  between  the  match  of  expr1  and  the  match  expr2
       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  END  pattern  is
       considered matched and all END actions are executed.

       In  the  example, the assignment v=1 takes place after the BEGIN actions 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 END actions are executed.

       Program flow at the pattern {action} level can be changed with the

            next
            exit  opt_expr

       statements.  A next statement causes the next input record to be read and pattern  testing
       to  restart with the first pattern {action} pair in the program.  An exit statement causes
       immediate execution of the END actions or program termination if there are none or if  the
       exit  occurs  in  an  END  action.  The opt_expr sets the exit value of the program unless
       overridden by a later exit or subsequent error.

   14. include
       libmawk introduces source inclusion feature. Syntax is:

            include "filename"

       Include statements must be on top level (outside of blocks). If file name
       starts with a plus sign ('+'), the script file is not loaded if it has
       been already loaded (by another include or -f command line argument).

EXAMPLES

       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
            }

COMPATIBILITY ISSUES

       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:

              New  functions:  toupper()  and  tolower();  libmawk  extensions:  call(), acall(),
              valueof().

              New variables: ENVIRON[] and CONVFMT; libmawk  extension:  ERRNO,  LIBPATH.   As  a
              libmawk extension, ENVIRON affects the environment of children processes.

              As  a  libmawk extension, new built-in variable LIBPATH is used as a list of search
              paths while loading scripts from the command line or from include.

              If a script name starts with plus ('+'), the file is not  loaded  if  it  has  been
              loaded  earlier (to avoid double loading libs trough -f and/or include).  This is a
              libmawk extension.

              It is possible to include a  script  from  another  script  using  keyword  include
              "scriptname.awk" (libmawk extension).

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

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

       Posix AWK is oriented to operate on files a line at a time.  RS 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, RS = "", makes one or more blank lines  separate
       records,  allowing  multi-line  records.   When  RS = "", "\n" is always a field separator
       regardless of the value in FS.

       lmawk, on the other hand, allows RS to be a regular  expression.   When  "\n"  appears  in
       records, it is treated as space, and FS 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,
       lmawk 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 lmawk, 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, lmawk 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{out,err}" or \x hex escape  sequences  in  strings.
       Unlike  ANSI  C,  lmawk  limits the number of digits that follows \x to two as the current
       implementation only supports 8 bit characters.  The built-in fflush first  appeared  in  a
       recent  (1993)  AT&T  awk  released  to  netlib,  and  is  not part of the posix standard.
       Aggregate deletion with delete array is not part of the posix standard.

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

       Finally, here is how lmawk 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.

              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".

              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 RLENGTH to 0.

              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.

              If getline encounters end of file, getline var, leaves var  unchanged.   Similarly,
              on  entry to the END actions, $0, the fields and NF have their value unaltered from
              the last record.

SEE ALSO

       egrep(1), mawk(1)

       Aho, Kernighan and Weinberger, The AWK Programming  Language,  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.

       The  GAWK Manual, 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.

BUGS

       lmawk cannot handle ascii NUL \0 in the source or data files.  You can  output  NUL  using
       printf with %c, and any other 8 bit character is acceptable input.

       lmawk 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 lmawk 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.

AUTHOR

       mawk: Mike Brennan (brennan@whidbey.com).

       libmawk extensions: Tibor Palinkas (libmawk@igor2.repo.hu).