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Updated: Wednesday, July 27, 2022

awk (1g)


awk - pattern scanning and processing language


gawk [ POSIX or GNU style options ] -f program-file [ -- ] file ...
gawk [ POSIX or GNU style options ] [ -- ] program-text file ...


GAWK(1)                        Utility Commands                        GAWK(1)

       gawk - pattern scanning and processing language

       gawk [ POSIX or GNU style options ] -f program-file [ -- ] file ...
       gawk [ POSIX or GNU style options ] [ -- ] program-text file ...

       Gawk  is  the  GNU Project's implementation of the AWK programming lan-
       guage.  It conforms to the definition of  the  language  in  the  POSIX
       1003.1  standard.   This version in turn is based on the description in
       The AWK Programming Language, by Aho, Kernighan, and Weinberger.   Gawk
       provides  the additional features found in the current version of Brian
       Kernighan's awk and numerous GNU-specific extensions.

       The command line consists of options to gawk itself,  the  AWK  program
       text  (if  not supplied via the -f or --include options), and values to
       be made available in the ARGC and ARGV pre-defined AWK variables.

       When gawk is invoked with the --profile  option,  it  starts  gathering
       profiling statistics from the execution of the program.  Gawk runs more
       slowly in this mode, and automatically produces an execution profile in
       the file awkprof.out when done.  See the --profile option, below.

       Gawk  also has an integrated debugger. An interactive debugging session
       can be started by supplying the --debug option to the command line.  In
       this mode of execution, gawk loads the AWK source code and then prompts
       for debugging commands.  Gawk can only debug AWK  program  source  pro-
       vided with the -f and --include options.  The debugger is documented in
       GAWK: Effective AWK Programming.

       Gawk options may be either traditional POSIX-style one letter  options,
       or  GNU-style  long  options.   POSIX  options start with a single "-",
       while long options start with "--".  Long options are provided for both
       GNU-specific features and for POSIX-mandated features.

       Gawk-specific  options  are  typically used in long-option form.  Argu-
       ments to long options are either joined with the option by an  =  sign,
       with no intervening spaces, or they may be provided in the next command
       line argument.  Long options may be abbreviated, as long as the  abbre-
       viation remains unique.

       Additionally,  every  long  option has a corresponding short option, so
       that the option's functionality may be used from within #!   executable

       Gawk accepts the following options.  Standard options are listed first,
       followed by options for gawk extensions, listed alphabetically by short

       -f program-file
       --file program-file
              Read  the AWK program source from the file program-file, instead
              of from the  first  command  line  argument.   Multiple  -f  (or
              --file)  options may be used.  Files read with -f are treated as
              if they begin with an implicit @namespace "awk" statement.

       -F fs
       --field-separator fs
              Use fs for the input field separator (the value of the FS prede-
              fined variable).

       -v var=val
       --assign var=val
              Assign  the  value  val to the variable var, before execution of
              the program begins.  Such variable values are available  to  the
              BEGIN rule of an AWK program.

              Treat  all input data as single-byte characters. In other words,
              don't pay any attention to the locale information when  attempt-
              ing  to  process  strings  as multibyte characters.  The --posix
              option overrides this one.

              Run in compatibility mode.  In compatibility mode, gawk  behaves
              identically  to  Brian Kernighan's awk; none of the GNU-specific
              extensions are recognized.  See GNU EXTENSIONS, below, for  more

              Print the short version of the GNU copyright information message
              on the standard output and exit successfully.

              Print a sorted list of global variables, their types  and  final
              values  to file.  If no file is provided, gawk uses a file named
              awkvars.out in the current directory.
              Having a list of all the global variables is a good way to  look
              for  typographical  errors in your programs.  You would also use
              this option if you have a large program with a lot of functions,
              and  you want to be sure that your functions don't inadvertently
              use global variables that you meant to be  local.   (This  is  a
              particularly  easy  mistake  to  make with simple variable names
              like i, j, and so on.)

              Enable debugging of AWK  programs.   By  default,  the  debugger
              reads commands interactively from the keyboard (standard input).
              The optional file argument specifies a file with a list of  com-
              mands for the debugger to execute non-interactively.

       -e program-text
       --source program-text
              Use program-text as AWK program source code.  This option allows
              the easy intermixing of library functions (used via the  -f  and
              --include options) with source code entered on the command line.
              It is intended primarily for medium to large AWK  programs  used
              in  shell  scripts.  Each argument supplied via -e is treated as
              if it begins with an implicit @namespace "awk" statement.

       -E file
       --exec file
              Similar to -f, however, this is option  is  the  last  one  pro-
              cessed.   This should be used with #!  scripts, particularly for
              CGI applications, to avoid passing in options or source code (!)
              on  the  command line from a URL.  This option disables command-
              line variable assignments.

              Scan and parse the AWK program, and generate a GNU .pot  (Porta-
              ble Object Template) format file on standard output with entries
              for all localizable strings in the program.  The program  itself
              is  not  executed.   See  the  GNU gettext distribution for more
              information on .pot files.

       --help Print a relatively short summary of the available options on the
              standard  output.   (Per the GNU Coding Standards, these options
              cause an immediate, successful exit.)

       -i include-file
       --include include-file
              Load an awk source library.  This searches for the library using
              the  AWKPATH environment variable.  If the initial search fails,
              another attempt will be made after appending  the  .awk  suffix.
              The  file  will be loaded only once (i.e., duplicates are elimi-
              nated), and the  code  does  not  constitute  the  main  program
              source.   Files read with --include are treated as if they begin
              with an implicit @namespace "awk" statement.

              Print the internal byte code names as  they  are  executed  when
              running  the  program.  The  trace is printed to standard error.
              Each ``op code'' is preceded by a + sign in the output.

       -l lib
       --load lib
              Load a  gawk  extension  from  the  shared  library  lib.   This
              searches  for the library using the AWKLIBPATH environment vari-
              able.  If the initial search fails, another attempt will be made
              after  appending the default shared library suffix for the plat-
              form.  The library initialization  routine  is  expected  to  be
              named dl_load().

       -L [value]
              Provide warnings about constructs that are dubious or non-porta-
              ble to other AWK implementations.  With an optional argument  of
              fatal,  lint warnings become fatal errors.  This may be drastic,
              but its use will certainly encourage the development of  cleaner
              AWK  programs.  With an optional argument of invalid, only warn-
              ings about things that are actually invalid are  issued.   (This
              is not fully implemented yet.)  With an optional argument of no-
              ext, warnings about gawk extensions are disabled.

              Force arbitrary precision arithmetic on numbers. This option has
              no  effect  if  gawk is not compiled to use the GNU MPFR and GMP
              libraries.  (In such a case, gawk issues a warning.)

              Recognize octal and hexadecimal values in input data.  Use  this
              option with great caution!

              Force  gawk  to  use  the  locale's decimal point character when
              parsing input data.  Although the POSIX standard  requires  this
              behavior,  and  gawk  does  so  when  --posix  is in effect, the
              default is to follow traditional behavior and use  a  period  as
              the  decimal  point, even in locales where the period is not the
              decimal point character.   This  option  overrides  the  default
              behavior,  without  the full draconian strictness of the --posix

              Output a pretty printed version of the program to file.   If  no
              file is provided, gawk uses a file named awkprof.out in the cur-
              rent directory.  This option implies --no-optimize.

              Enable gawk's default optimizations upon the internal  represen-
              tation  of  the  program.   Currently, this just includes simple
              constant folding.  This option is on by default.

              Start a profiling session, and send the profiling data to  prof-
              file.   The default is awkprof.out.  The profile contains execu-
              tion counts of each statement in the program in the left  margin
              and  function  call counts for each user-defined function.  This
              option implies --no-optimize.

              This turns on compatibility mode, with the following  additional

              o \x escape sequences are not recognized.

              o You cannot continue lines after ?  and :.

              o The synonym func for the keyword function is not recognized.

              o The operators ** and **= cannot be used in place of ^ and ^=.

              Enable  the  use  of  interval expressions in regular expression
              matching (see Regular Expressions, below).  Interval expressions
              were not traditionally available in the AWK language.  The POSIX
              standard added them, to make awk and egrep consistent with  each
              other.  They are enabled by default, but this option remains for
              use together with --traditional.

              Disable gawk's default optimizations upon the internal represen-
              tation of the program.

              Run gawk in sandbox mode, disabling the system() function, input
              redirection with getline,  output  redirection  with  print  and
              printf,  and  loading  dynamic  extensions.   Command  execution
              (through pipelines) is also disabled.  This effectively blocks a
              script  from  accessing  local  resources,  except for the files
              specified on the command line.

              Provide warnings about constructs that are not portable  to  the
              original version of UNIX awk.

              Print  version  information  for this particular copy of gawk on
              the standard output.  This is useful mainly for knowing  if  the
              current  copy  of gawk on your system is up to date with respect
              to whatever the Free Software Foundation is distributing.   This
              is  also  useful when reporting bugs.  (Per the GNU Coding Stan-
              dards, these options cause an immediate, successful exit.)

       --     Signal the end of options. This is useful to allow further argu-
              ments  to the AWK program itself to start with a "-".  This pro-
              vides consistency with the argument parsing convention  used  by
              most other POSIX programs.

       In  compatibility  mode,  any other options are flagged as invalid, but
       are otherwise ignored.  In normal operation, as long  as  program  text
       has  been supplied, unknown options are passed on to the AWK program in
       the ARGV array for processing.  This is particularly useful for running
       AWK programs via the #!  executable interpreter mechanism.

       For  POSIX  compatibility,  the  -W option may be used, followed by the
       name of a long option.

       An AWK program consists of a sequence of optional directives,  pattern-
       action statements, and optional function definitions.

              @include "filename"
              @load "filename"
              @namespace "name"
              pattern   { action statements }
              function name(parameter list) { statements }

       Gawk  first reads the program source from the program-file(s) if speci-
       fied, from arguments to --source, or from the first non-option argument
       on  the command line.  The -f and --source options may be used multiple
       times on the command line.  Gawk reads the program text as if  all  the
       program-files  and  command  line  source  texts  had been concatenated
       together.  This is useful for  building  libraries  of  AWK  functions,
       without  having to include them in each new AWK program that uses them.
       It also provides the ability to mix library functions with command line

       In addition, lines beginning with @include may be used to include other
       source files into your program, making library use even  easier.   This
       is equivalent to using the --include option.

       Lines beginning with @load may be used to load extension functions into
       your program.  This is equivalent to using the --load option.

       The environment variable AWKPATH specifies a search path  to  use  when
       finding  source files named with the -f and --include options.  If this
       variable does not exist, the default path is  ".:/usr/local/share/awk".
       (The  actual  directory may vary, depending upon how gawk was built and
       installed.)  If a file name given to the -f option contains a "/" char-
       acter, no path search is performed.

       The environment variable AWKLIBPATH specifies a search path to use when
       finding source files named with the --load option.   If  this  variable
       does not exist, the default path is "/usr/local/lib/gawk".  (The actual
       directory may vary, depending upon how gawk was built and installed.)

       Gawk executes AWK programs in the following order.  First, all variable
       assignments specified via the -v option are performed.  Next, gawk com-
       piles the program into an internal form.  Then, gawk executes the  code
       in  the  BEGIN  rule(s)  (if  any), and then proceeds to read each file
       named in the ARGV array (up to ARGV[ARGC-1]).  If there  are  no  files
       named on the command line, gawk reads the standard input.

       If a filename on the command line has the form var=val it is treated as
       a variable assignment.  The variable var will  be  assigned  the  value
       val.   (This  happens  after any BEGIN rule(s) have been run.)  Command
       line variable assignment is most useful for dynamically assigning  val-
       ues  to  the  variables  AWK  uses  to control how input is broken into
       fields and records.  It is also useful for controlling state if  multi-
       ple passes are needed over a single data file.

       If  the value of a particular element of ARGV is empty (""), gawk skips
       over it.

       For each input file, if a BEGINFILE  rule  exists,  gawk  executes  the
       associated  code before processing the contents of the file. Similarly,
       gawk executes the code associated with  ENDFILE  after  processing  the

       For  each record in the input, gawk tests to see if it matches any pat-
       tern in the AWK program.  For each pattern  that  the  record  matches,
       gawk  executes  the  associated action.  The patterns are tested in the
       order they occur in the program.

       Finally, after all the input is exhausted, gawk executes  the  code  in
       the END rule(s) (if any).

   Command Line Directories
       According  to  POSIX,  files named on the awk command line must be text
       files.  The behavior is ``undefined'' if they are not.   Most  versions
       of awk treat a directory on the command line as a fatal error.

       Starting with version 4.0 of gawk, a directory on the command line pro-
       duces a warning, but is otherwise skipped.  If either of the --posix or
       --traditional  options is given, then gawk reverts to treating directo-
       ries on the command line as a fatal error.

       AWK variables are dynamic; they come into existence when they are first
       used.   Their  values  are either floating-point numbers or strings, or
       both, depending upon how they  are  used.   Additionally,  gawk  allows
       variables  to  have  regular-expression  type.  AWK also has one dimen-
       sional arrays; arrays with multiple dimensions may be simulated.   Gawk
       provides true arrays of arrays; see Arrays, below.  Several pre-defined
       variables are set as a program runs; these are described as needed  and
       summarized below.

       Normally, records are separated by newline characters.  You can control
       how records are separated by assigning values to the built-in  variable
       RS.   If  RS is any single character, that character separates records.
       Otherwise, RS is a regular expression.  Text in the input that  matches
       this  regular expression separates the record.  However, in compatibil-
       ity mode, only the first character of its string value is used for sep-
       arating  records.   If  RS  is set to the null string, then records are
       separated by empty lines.  When RS is set to the null string, the  new-
       line  character  always acts as a field separator, in addition to what-
       ever value FS may have.

       As each input record is read, gawk splits the record into fields, using
       the value of the FS variable as the field separator.  If FS is a single
       character, fields are separated by that character.  If FS is  the  null
       string,  then each individual character becomes a separate field.  Oth-
       erwise, FS is expected to be a full regular expression.  In the special
       case  that FS is a single space, fields are separated by runs of spaces
       and/or tabs and/or newlines.  NOTE: The value of IGNORECASE (see below)
       also  affects how fields are split when FS is a regular expression, and
       how records are separated when RS is a regular expression.

       If the FIELDWIDTHS variable is set to a space-separated  list  of  num-
       bers,  each  field  is expected to have fixed width, and gawk splits up
       the record using the specified widths.  Each field width may optionally
       be preceded by a colon-separated value specifying the number of charac-
       ters to skip before the field starts.  The  value  of  FS  is  ignored.
       Assigning a new value to FS or FPAT overrides the use of FIELDWIDTHS.

       Similarly, if the FPAT variable is set to a string representing a regu-
       lar expression, each field is made up of text that matches that regular
       expression.  In  this case, the regular expression describes the fields
       themselves, instead of the text that separates the fields.  Assigning a
       new value to FS or FIELDWIDTHS overrides the use of FPAT.

       Each  field  in the input record may be referenced by its position: $1,
       $2, and so on.  $0 is the whole record, including leading and  trailing
       whitespace.  Fields need not be referenced by constants:

              n = 5
              print $n

       prints the fifth field in the input record.

       The  variable  NF  is  set  to  the total number of fields in the input

       References to non-existent fields (i.e., fields after $NF) produce  the
       null string.  However, assigning to a non-existent field (e.g., $(NF+2)
       = 5) increases the value of NF, creates any intervening fields with the
       null  string  as  their values, and causes the value of $0 to be recom-
       puted, with the fields being separated by the value of OFS.  References
       to  negative  numbered  fields  cause  a  fatal error.  Decrementing NF
       causes the values of fields past the new value  to  be  lost,  and  the
       value  of  $0  to be recomputed, with the fields being separated by the
       value of OFS.

       Assigning a value to an existing field causes the whole  record  to  be
       rebuilt  when  $0  is  referenced.   Similarly, assigning a value to $0
       causes the record to be resplit, creating new values for the fields.

   Built-in Variables
       Gawk's built-in variables are:

       ARGC        The number of command  line  arguments  (does  not  include
                   options to gawk, or the program source).

       ARGIND      The index in ARGV of the current file being processed.

       ARGV        Array of command line arguments.  The array is indexed from
                   0 to ARGC - 1.  Dynamically changing the contents  of  ARGV
                   can control the files used for data.

       BINMODE     On  non-POSIX  systems,  specifies use of "binary" mode for
                   all file I/O.  Numeric values of 1, 2, or 3,  specify  that
                   input  files,  output  files,  or  all files, respectively,
                   should use binary I/O.  String values of "r", or "w"  spec-
                   ify that input files, or output files, respectively, should
                   use binary I/O.  String values of "rw" or "wr" specify that
                   all files should use binary I/O.  Any other string value is
                   treated as "rw", but generates a warning message.

       CONVFMT     The conversion format for numbers, "%.6g", by default.

       ENVIRON     An array containing the values of the current  environment.
                   The  array  is  indexed  by the environment variables, each
                   element being the  value  of  that  variable  (e.g.,  ENVI-
                   RON["HOME"] might be "/home/arnold").

                   In  POSIX  mode,  changing  this  array does not affect the
                   environment seen by programs which gawk  spawns  via  redi-
                   rection  or the system() function.  Otherwise, gawk updates
                   its real environment so that programs  it  spawns  see  the

       ERRNO       If  a  system  error  occurs either doing a redirection for
                   getline, during a read for getline, or  during  a  close(),
                   then  ERRNO  is  set to a string describing the error.  The
                   value is subject to translation in non-English locales.  If
                   the  string  in  ERRNO corresponds to a system error in the
                   errno(3) variable, then the numeric value can be  found  in
                   PROCINFO["errno"].        For       non-system      errors,
                   PROCINFO["errno"] will be zero.

       FIELDWIDTHS A whitespace-separated list of  field  widths.   When  set,
                   gawk  parses  the input into fields of fixed width, instead
                   of using the value of the FS variable as the field  separa-
                   tor.   Each  field  width  may  optionally be preceded by a
                   colon-separated value specifying the number  of  characters
                   to skip before the field starts.  See Fields, above.

       FILENAME    The name of the current input file.  If no files are speci-
                   fied on the command line, the value  of  FILENAME  is  "-".
                   However,  FILENAME  is  undefined  inside  the  BEGIN  rule
                   (unless set by getline).

       FNR         The input record number in the current input file.

       FPAT        A regular expression describing the contents of the  fields
                   in  a record.  When set, gawk parses the input into fields,
                   where the fields match the regular expression,  instead  of
                   using  the value of FS as the field separator.  See Fields,

       FS          The input field separator, a space by default.  See Fields,

       FUNCTAB     An  array  whose  indices  and corresponding values are the
                   names of all the user-defined or extension functions in the
                   program.   NOTE:  You may not use the delete statement with
                   the FUNCTAB array.

       IGNORECASE  Controls the case-sensitivity of all regular expression and
                   string  operations.   If  IGNORECASE  has a non-zero value,
                   then string comparisons  and  pattern  matching  in  rules,
                   field  splitting  with  FS and FPAT, record separating with
                   RS, regular expression matching with ~ and !~, and the gen-
                   sub(),  gsub(),  index(), match(), patsplit(), split(), and
                   sub() built-in functions all ignore case when doing regular
                   expression  operations.   NOTE:  Array  subscripting is not
                   affected.  However, the asort() and asorti() functions  are
                   Thus,  if IGNORECASE is not equal to zero, /aB/ matches all
                   of the strings "ab", "aB", "Ab", and "AB".  As with all AWK
                   variables,  the initial value of IGNORECASE is zero, so all
                   regular expression and string operations are normally case-

       LINT        Provides  dynamic  control of the --lint option from within
                   an AWK program.  When true, gawk prints lint warnings. When
                   false,  it  does  not.   The  values allowed for the --lint
                   option may also be assigned to LINT, with the same effects.
                   Any other true value just prints warnings.

       NF          The number of fields in the current input record.

       NR          The total number of input records seen so far.

       OFMT        The output format for numbers, "%.6g", by default.

       OFS         The output field separator, a space by default.

       ORS         The output record separator, by default a newline.

       PREC        The working precision of arbitrary precision floating-point
                   numbers, 53 by default.

       PROCINFO    The elements of this array provide  access  to  information
                   about  the running AWK program.  On some systems, there may
                   be elements in the array,  "group1"  through  "groupn"  for
                   some  n,  which  is the number of supplementary groups that
                   the process has.  Use the in operator  to  test  for  these
                   elements.   The  following  elements  are  guaranteed to be

                   PROCINFO["argv"]     The command line arguments as received
                                        by  gawk at the C-language level.  The
                                        subscripts start from zero.

                   PROCINFO["egid"]     The value  of  the  getegid(2)  system

                   PROCINFO["errno"]    The  value  of  errno(3) when ERRNO is
                                        set to the associated error message.

                   PROCINFO["euid"]     The value  of  the  geteuid(2)  system

                   PROCINFO["FS"]       "FS"  if field splitting with FS is in
                                        effect, "FPAT" if field splitting with
                                        FPAT  is  in  effect, "FIELDWIDTHS" if
                                        field splitting with FIELDWIDTHS is in
                                        effect,  or  "API" if API input parser
                                        field splitting is in effect.

                   PROCINFO["gid"]      The  value  of  the  getgid(2)  system

                                        A  subarray,  indexed  by the names of
                                        all identifiers used in  the  text  of
                                        the  AWK program.  The values indicate
                                        what gawk knows about the  identifiers
                                        after it has finished parsing the pro-
                                        gram; they are not updated  while  the
                                        program  runs.   For  each identifier,
                                        the value of the element is one of the

                                        "array"     The   identifier   is   an

                                        "builtin"   The identifier is a built-
                                                    in function.

                                        "extension" The   identifier   is   an
                                                    extension function  loaded
                                                    via @load or --load.

                                        "scalar"    The    identifier   is   a

                                        "untyped"   The identifier is  untyped
                                                    (could be used as a scalar
                                                    or  array,  gawk   doesn't
                                                    know yet).

                                        "user"      The  identifier is a user-
                                                    defined function.

                   PROCINFO["pgrpid"]   The value  of  the  getpgrp(2)  system

                   PROCINFO["pid"]      The  value  of  the  getpid(2)  system

                   PROCINFO["platform"] A string indicating the  platform  for
                                        which  gawk  was  compiled.  It is one

                                        "djgpp", "mingw"
                                               Microsoft Windows, using either
                                               DJGPP, or MinGW, respectively.

                                        "os2"  OS/2.

                                               GNU/Linux,  Cygwin,  Mac  OS X,
                                               and legacy Unix systems.

                                        "vms"  OpenVMS or Vax/VMS.

                   PROCINFO["ppid"]     The value  of  the  getppid(2)  system

                   PROCINFO["strftime"] The  default  time  format  string for
                                        strftime().    Changing   its    value
                                        affects  how  strftime()  formats time
                                        values when called with no arguments.

                   PROCINFO["uid"]      The  value  of  the  getuid(2)  system

                   PROCINFO["version"]  The version of gawk.

                   The  following  elements  are  present  if  loading dynamic
                   extensions is available:

                          The major version of the extension API.

                          The minor version of the extension API.

                   The following elements are available  if  MPFR  support  is
                   compiled into gawk:

                          The  version  of  the GNU GMP library used for arbi-
                          trary precision number support in gawk.

                          The version of the GNU MPFR library used  for  arbi-
                          trary precision number support in gawk.

                          The  maximum  precision  supported  by  the GNU MPFR
                          library for arbitrary precision floating-point  num-

                          The  minimum  precision  allowed  by  the  GNU  MPFR
                          library for arbitrary precision floating-point  num-

                   The  following  elements  may  set  by  a program to change
                   gawk's behavior:

                          If this exists, then I/O errors for all redirections
                          become nonfatal.

                   PROCINFO["name", "NONFATAL"]
                          Make I/O errors for name be nonfatal.

                   PROCINFO["command", "pty"]
                          Use a pseudo-tty for two-way communication with com-
                          mand instead of setting up two one-way pipes.

                   PROCINFO["input", "READ_TIMEOUT"]
                          The timeout in milliseconds for  reading  data  from
                          input,  where  input  is  a  redirection string or a
                          filename. A value of zero or less than zero means no

                   PROCINFO["input", "RETRY"]
                          If  an  I/O  error  that  may be retried occurs when
                          reading  data  from  input,  and  this  array  entry
                          exists, then getline returns -2 instead of following
                          the default behavior of returning -1 and configuring
                          input  to return no further data.  An I/O error that
                          may be retried is one where errno(3) has  the  value
                          EAGAIN,  EWOULDBLOCK, EINTR, or ETIMEDOUT.  This may
                          be  useful  in  conjunction  with  PROCINFO["input",
                          "READ_TIMEOUT"]   or  in  situations  where  a  file
                          descriptor has been configured to behave in  a  non-
                          blocking fashion.

                          If  this  element exists in PROCINFO, then its value
                          controls the order in which array elements are  tra-
                          versed   in   for   loops.    Supported  values  are
                          "@ind_str_asc",   "@ind_num_asc",   "@val_type_asc",
                          "@val_str_asc",   "@val_num_asc",   "@ind_str_desc",
                          "@ind_num_desc", "@val_type_desc",  "@val_str_desc",
                          "@val_num_desc",  and  "@unsorted".   The  value can
                          also be the name (as a  string)  of  any  comparison
                          function defined as follows:

                               function cmp_func(i1, v1, i2, v2)

                          where  i1  and i2 are the indices, and v1 and v2 are
                          the corresponding values of the two  elements  being
                          compared.   It  should  return  a  number less than,
                          equal to, or greater than 0, depending  on  how  the
                          elements of the array are to be ordered.

       ROUNDMODE   The rounding mode to use for arbitrary precision arithmetic
                   on numbers, by default "N" (IEEE-754 roundTiesToEven mode).
                   The accepted values are:

                   "A" or "a"
                          for  rounding away from zero.  These are only avail-
                          able if your version of the GNU  MPFR  library  sup-
                          ports rounding away from zero.

                   "D" or "d" for roundTowardNegative.

                   "N" or "n" for roundTiesToEven.

                   "U" or "u" for roundTowardPositive.

                   "Z" or "z" for roundTowardZero.

       RS          The input record separator, by default a newline.

       RT          The record terminator.  Gawk sets RT to the input text that
                   matched the character or regular  expression  specified  by

       RSTART      The  index  of the first character matched by match(); 0 if
                   no match.  (This implies that character  indices  start  at

       RLENGTH     The  length  of  the  string  matched  by match(); -1 if no

       SUBSEP      The string used to separate multiple  subscripts  in  array
                   elements, by default "\034".

       SYMTAB      An  array  whose  indices  are  the  names of all currently
                   defined global variables and arrays in  the  program.   The
                   array  may be used for indirect access to read or write the
                   value of a variable:

                        foo = 5
                        SYMTAB["foo"] = 4
                        print foo    # prints 4

                   The typeof() function may be used to test if an element  in
                   SYMTAB  is  an array.  You may not use the delete statement
                   with the SYMTAB array, nor assign to elements with an index
                   that is not a variable name.

       TEXTDOMAIN  The text domain of the AWK program; used to find the local-
                   ized translations for the program's strings.

       Arrays are subscripted with an expression between  square  brackets  ([
       and ]).  If the expression is an expression list (expr, expr ...)  then
       the array subscript is a string consisting of the concatenation of  the
       (string) value of each expression, separated by the value of the SUBSEP
       variable.  This facility  is  used  to  simulate  multiply  dimensioned
       arrays.  For example:

              i = "A"; j = "B"; k = "C"
              x[i, j, k] = "hello, world\n"

       assigns the string "hello, world\n" to the element of the array x which
       is indexed by the string "A\034B\034C".  All arrays in AWK are associa-
       tive, i.e., indexed by string values.

       The  special  operator  in may be used to test if an array has an index
       consisting of a particular value:

              if (val in array)
                   print array[val]

       If the array has multiple subscripts, use (i, j) in array.

       The in construct may also be used in a for loop to iterate over all the
       elements  of  an  array.   However,  the (i, j) in array construct only
       works in tests, not in for loops.

       An element may be deleted from an array  using  the  delete  statement.
       The  delete statement may also be used to delete the entire contents of
       an array, just by specifying the array name without a subscript.

       gawk supports true multidimensional arrays. It does  not  require  that
       such arrays be ``rectangular'' as in C or C++.  For example:

              a[1] = 5
              a[2][1] = 6
              a[2][2] = 7

       NOTE:  You may need to tell gawk that an array element is really a sub-
       array in order to use it where gawk expects an array (such  as  in  the
       second argument to split()).  You can do this by creating an element in
       the subarray and then deleting it with the delete statement.

       Gawk provides a simple namespace facility to help work around the  fact
       that all variables in AWK are global.

       A  qualified name consists of a two simple identifiers joined by a dou-
       ble colon (::).  The left-hand identifier represents the namespace  and
       the  right-hand identifier is the variable within it.  All simple (non-
       qualified) names are considered to be in the ``current'' namespace; the
       default  namespace  is  awk.   However,  simple  identifiers consisting
       solely of uppercase letters are forced into the awk namespace, even  if
       the current namespace is different.

       You change the current namespace with an @namespace "name" directive.

       The  standard  predefined  builtin  function  names  may not be used as
       namespace names.  The names of additional functions  provided  by  gawk
       may be used as namespace names or as simple identifiers in other names-
       paces.  For more details, see GAWK: Effective AWK Programming.

   Variable Typing And Conversion
       Variables and fields may be (floating point) numbers,  or  strings,  or
       both.   They  may also be regular expressions. How the value of a vari-
       able is interpreted depends upon its context.  If  used  in  a  numeric
       expression, it will be treated as a number; if used as a string it will
       be treated as a string.

       To force a variable to be treated as a number, add zero to it; to force
       it to be treated as a string, concatenate it with the null string.

       Uninitialized  variables  have  the  numeric  value zero and the string
       value "" (the null, or empty, string).

       When a string must be converted to a number, the conversion  is  accom-
       plished  using  strtod(3).   A number is converted to a string by using
       the value of CONVFMT as  a  format  string  for  sprintf(3),  with  the
       numeric  value  of  the variable as the argument.  However, even though
       all numbers in AWK are floating-point, integral values are always  con-
       verted as integers.  Thus, given

              CONVFMT = "%2.2f"
              a = 12
              b = a ""

       the variable b has a string value of "12" and not "12.00".

       NOTE:  When  operating in POSIX mode (such as with the --posix option),
       beware that locale settings may interfere with the way decimal  numbers
       are  treated:  the  decimal separator of the numbers you are feeding to
       gawk must conform to what your locale would expect, be it a  comma  (,)
       or a period (.).

       Gawk  performs  comparisons  as  follows: If two variables are numeric,
       they are compared numerically.  If one value is numeric and  the  other
       has  a  string  value  that is a "numeric string," then comparisons are
       also done numerically.  Otherwise, the numeric value is converted to  a
       string and a string comparison is performed.  Two strings are compared,
       of course, as strings.

       Note that string constants, such as "57", are not numeric strings, they
       are  string  constants.   The  idea of "numeric string" only applies to
       fields, getline input, FILENAME, ARGV elements,  ENVIRON  elements  and
       the  elements  of  an  array  created by split() or patsplit() that are
       numeric strings.  The basic idea is that  user  input,  and  only  user
       input, that looks numeric, should be treated that way.

   Octal and Hexadecimal Constants
       You may use C-style octal and hexadecimal constants in your AWK program
       source code.  For example, the octal value 011 is equal to  decimal  9,
       and the hexadecimal value 0x11 is equal to decimal 17.

   String Constants
       String  constants  in  AWK are sequences of characters enclosed between
       double quotes (like "value").  Within strings, certain escape sequences
       are recognized, as in C.  These are:

       \\   A literal backslash.

       \a   The "alert" character; usually the ASCII BEL character.

       \b   Backspace.

       \f   Form-feed.

       \n   Newline.

       \r   Carriage return.

       \t   Horizontal tab.

       \v   Vertical tab.

       \xhex digits
            The character represented by the string of hexadecimal digits fol-
            lowing the \x.  Up to two following hexadecimal digits are consid-
            ered  part  of the escape sequence.  E.g., "\x1B" is the ASCII ESC
            (escape) character.

       \ddd The character represented by the 1-, 2-, or  3-digit  sequence  of
            octal digits.  E.g., "\033" is the ASCII ESC (escape) character.

       \c   The literal character c.

       In compatibility mode, the characters represented by octal and hexadec-
       imal escape sequences  are  treated  literally  when  used  in  regular
       expression constants.  Thus, /a\52b/ is equivalent to /a\*b/.

   Regexp Constants
       A  regular  expression  constant  is  a sequence of characters enclosed
       between forward slashes (like /value/).  Regular expression matching is
       described more fully below; see Regular Expressions.

       The escape sequences described earlier may also be used inside constant
       regular expressions (e.g., /[ \t\f\n\r\v]/ matches  whitespace  charac-

       Gawk  provides  strongly  typed regular expression constants. These are
       written with a leading @ symbol (like so:  @/value/).   Such  constants
       may  be  assigned  to scalars (variables, array elements) and passed to
       user-defined functions. Variables that have been so assigned have regu-
       lar expression type.

       AWK is a line-oriented language.  The pattern comes first, and then the
       action.  Action statements are enclosed in { and }.  Either the pattern
       may be missing, or the action may be missing, but, of course, not both.
       If the pattern is missing, the action executes for every single  record
       of input.  A missing action is equivalent to

              { print }

       which prints the entire record.

       Comments  begin with the # character, and continue until the end of the
       line.  Empty lines may be used to  separate  statements.   Normally,  a
       statement  ends with a newline, however, this is not the case for lines
       ending in a comma, {, ?, :, &&, or ||.  Lines ending in do or else also
       have  their  statements  automatically continued on the following line.
       In other cases, a line can be continued by ending it  with  a  "\",  in
       which  case  the  newline  is ignored.  However, a "\" after a # is not

       Multiple statements may be put on one line by separating  them  with  a
       ";".   This  applies to both the statements within the action part of a
       pattern-action pair (the usual case), and to the pattern-action  state-
       ments themselves.

       AWK patterns may be one of the following:

              /regular expression/
              relational expression
              pattern && pattern
              pattern || pattern
              pattern ? pattern : pattern
              ! pattern
              pattern1, pattern2

       BEGIN  and  END  are two special kinds of patterns which are not tested
       against the input.  The action parts of all BEGIN patterns  are  merged
       as if all the statements had been written in a single BEGIN rule.  They
       are executed before any of the input is read.  Similarly, all  the  END
       rules are merged, and executed when all the input is exhausted (or when
       an exit statement is executed).  BEGIN and END patterns cannot be  com-
       bined  with  other patterns in pattern expressions.  BEGIN and END pat-
       terns cannot have missing action parts.

       BEGINFILE and ENDFILE are additional special patterns whose actions are
       executed  before  reading  the  first record of each command-line input
       file and after reading the last record of each file.  Inside the BEGIN-
       FILE  rule,  the  value  of  ERRNO  is the empty string if the file was
       opened successfully.  Otherwise, there is some problem  with  the  file
       and  the code should use nextfile to skip it. If that is not done, gawk
       produces its usual fatal error for files that cannot be opened.

       For /regular expression/ patterns, the associated statement is executed
       for  each  input  record  that matches the regular expression.  Regular
       expressions are the same as  those  in  egrep(1),  and  are  summarized

       A  relational  expression may use any of the operators defined below in
       the section on actions.  These generally test  whether  certain  fields
       match certain regular expressions.

       The  &&,  ||, and !  operators are logical AND, logical OR, and logical
       NOT, respectively, as in C.  They do short-circuit evaluation, also  as
       in  C,  and  are used for combining more primitive pattern expressions.
       As in most languages, parentheses may be used to change  the  order  of

       The  ?:  operator is like the same operator in C.  If the first pattern
       is true then the pattern used for testing is the second pattern, other-
       wise  it  is  the  third.  Only one of the second and third patterns is

       The pattern1, pattern2 form of an expression is called a range pattern.
       It  matches  all input records starting with a record that matches pat-
       tern1, and continuing until a record that matches pattern2,  inclusive.
       It does not combine with any other sort of pattern expression.

   Regular Expressions
       Regular  expressions  are  the  extended kind found in egrep.  They are
       composed of characters as follows:

       c          Matches the non-metacharacter c.

       \c         Matches the literal character c.

       .          Matches any character including newline.

       ^          Matches the beginning of a string.

       $          Matches the end of a string.

       [abc...]   A character list: matches any of the characters abc....  You
                  may  include a range of characters by separating them with a
                  dash.  To include a literal dash in the list, put  it  first
                  or last.

       [^abc...]  A  negated  character  list:  matches  any  character except

       r1|r2      Alternation: matches either r1 or r2.

       r1r2       Concatenation: matches r1, and then r2.

       r+         Matches one or more r's.

       r*         Matches zero or more r's.

       r?         Matches zero or one r's.

       (r)        Grouping: matches r.

       r{n,m}     One or two numbers inside braces denote an interval  expres-
                  sion.   If  there is one number in the braces, the preceding
                  regular expression r is repeated n times.  If there are  two
                  numbers  separated  by  a comma, r is repeated n to m times.
                  If there is one number  followed  by  a  comma,  then  r  is
                  repeated at least n times.

       \y         Matches  the empty string at either the beginning or the end
                  of a word.

       \B         Matches the empty string within a word.

       \<         Matches the empty string at the beginning of a word.

       \>         Matches the empty string at the end of a word.

       \s         Matches any whitespace character.

       \S         Matches any nonwhitespace character.

       \w         Matches any word-constituent character  (letter,  digit,  or

       \W         Matches any character that is not word-constituent.

       \`         Matches  the  empty  string  at  the  beginning  of a buffer

       \'         Matches the empty string at the end of a buffer.

       The escape sequences that are valid in  string  constants  (see  String
       Constants) are also valid in regular expressions.

       Character  classes  are  a feature introduced in the POSIX standard.  A
       character class is a special notation for describing lists  of  charac-
       ters  that  have  a specific attribute, but where the actual characters
       themselves can vary from country to country and/or from  character  set
       to  character  set.   For  example, the notion of what is an alphabetic
       character differs in the USA and in France.

       A character class is only valid in  a  regular  expression  inside  the
       brackets  of a character list.  Character classes consist of [:, a key-
       word denoting the class, and :].  The character classes defined by  the
       POSIX standard are:

       [:alnum:]  Alphanumeric characters.

       [:alpha:]  Alphabetic characters.

       [:blank:]  Space or tab characters.

       [:cntrl:]  Control characters.

       [:digit:]  Numeric characters.

       [:graph:]  Characters that are both printable and visible.  (A space is
                  printable, but not visible, while an a is both.)

       [:lower:]  Lowercase alphabetic characters.

       [:print:]  Printable characters (characters that are not control  char-

       [:punct:]  Punctuation characters (characters that are not letter, dig-
                  its, control characters, or space characters).

       [:space:]  Space characters (such as space, tab, and formfeed, to  name
                  a few).

       [:upper:]  Uppercase alphabetic characters.

       [:xdigit:] Characters that are hexadecimal digits.

       For  example,  before the POSIX standard, to match alphanumeric charac-
       ters, you would have had to write /[A-Za-z0-9]/.  If your character set
       had  other  alphabetic characters in it, this would not match them, and
       if your character set collated differently from ASCII, this  might  not
       even match the ASCII alphanumeric characters.  With the POSIX character
       classes, you can write /[[:alnum:]]/, and this matches  the  alphabetic
       and numeric characters in your character set, no matter what it is.

       Two  additional special sequences can appear in character lists.  These
       apply to non-ASCII  character  sets,  which  can  have  single  symbols
       (called  collating  elements)  that  are represented with more than one
       character, as well as several characters that are equivalent  for  col-
       lating,  or  sorting,  purposes.   (E.g.,  in French, a plain "e" and a
       grave-accented "`" are equivalent.)

       Collating Symbols
              A  collating  symbol  is  a  multi-character  collating  element
              enclosed  in [.  and .].  For example, if ch is a collating ele-
              ment, then [[.ch.]]  is a regular expression that  matches  this
              collating  element,  while  [ch]  is  a  regular expression that
              matches either c or h.

       Equivalence Classes
              An equivalence class is a locale-specific name  for  a  list  of
              characters  that are equivalent.  The name is enclosed in [= and
              =].  For example, the name e might be used to represent  all  of
              "e",  "'",  and "`".  In this case, [[=e=]] is a regular expres-
              sion that matches any of e, ', or `.

       These features are very valuable in non-English speaking locales.   The
       library  functions  that gawk uses for regular expression matching cur-
       rently only recognize POSIX character classes; they  do  not  recognize
       collating symbols or equivalence classes.

       The  \y,  \B, \<, \>, \s, \S, \w, \W, \`, and \' operators are specific
       to gawk; they are extensions based on facilities  in  the  GNU  regular
       expression libraries.

       The various command line options control how gawk interprets characters
       in regular expressions.

       No options
              In the default case, gawk provides all the facilities  of  POSIX
              regular  expressions  and  the  GNU regular expression operators
              described above.

              Only POSIX regular expressions are supported, the GNU  operators
              are not special.  (E.g., \w matches a literal w).

              Traditional  UNIX  awk regular expressions are matched.  The GNU
              operators are not special,  and  interval  expressions  are  not
              available.  Characters described by octal and hexadecimal escape
              sequences are treated literally, even if they represent  regular
              expression metacharacters.

              Allow  interval  expressions  in  regular  expressions,  even if
              --traditional has been provided.

       Action statements are enclosed in braces, { and }.   Action  statements
       consist  of  the  usual assignment, conditional, and looping statements
       found in  most  languages.   The  operators,  control  statements,  and
       input/output statements available are patterned after those in C.

       The operators in AWK, in order of decreasing precedence, are:

       (...)       Grouping

       $           Field reference.

       ++ --       Increment and decrement, both prefix and postfix.

       ^           Exponentiation  (**  may  also  be  used,  and  **= for the
                   assignment operator).

       + - !       Unary plus, unary minus, and logical negation.

       * / %       Multiplication, division, and modulus.

       + -         Addition and subtraction.

       space       String concatenation.

       |   |&      Piped I/O for getline, print, and printf.

       < > <= >= == !=
                   The regular relational operators.

       ~ !~        Regular expression match, negated match.  NOTE: Do not  use
                   a constant regular expression (/foo/) on the left-hand side
                   of a ~ or !~.  Only use one on the  right-hand  side.   The
                   expression  /foo/  ~  exp  has  the  same meaning as (($0 ~
                   /foo/) ~ exp).  This is usually not what you want.

       in          Array membership.

       &&          Logical AND.

       ||          Logical OR.

       ?:          The C conditional expression.  This has the  form  expr1  ?
                   expr2  : expr3.  If expr1 is true, the value of the expres-
                   sion is expr2, otherwise it is expr3.  Only  one  of  expr2
                   and expr3 is evaluated.

       = += -= *= /= %= ^=
                   Assignment.   Both  absolute  assignment  (var = value) and
                   operator-assignment (the other forms) are supported.

   Control Statements
       The control statements are as follows:

              if (condition) statement [ else statement ]
              while (condition) statement
              do statement while (condition)
              for (expr1; expr2; expr3) statement
              for (var in array) statement
              delete array[index]
              delete array
              exit [ expression ]
              { statements }
              switch (expression) {
              case value|regex : statement
              [ default: statement ]

   I/O Statements
       The input/output statements are as follows:

       close(file [, how])   Close file, pipe or coprocess.  The optional  how
                             should  only  be  used  when closing one end of a
                             two-way pipe to a coprocess.  It must be a string
                             value, either "to" or "from".

       getline               Set  $0  from  the next input record; set NF, NR,
                             FNR, RT.

       getline <file         Set $0 from the next record of file; set NF, RT.

       getline var           Set var from the next input record; set NR,  FNR,

       getline var <file     Set var from the next record of file; set RT.

       command | getline [var]
                             Run  command, piping the output either into $0 or
                             var, as above, and RT.

       command |& getline [var]
                             Run command as  a  coprocess  piping  the  output
                             either  into $0 or var, as above, and RT.  Copro-
                             cesses are a gawk extension.   (The  command  can
                             also  be  a  socket.   See the subsection Special
                             File Names, below.)

       next                  Stop processing the current input  record.   Read
                             the  next  input record and start processing over
                             with the first pattern in the AWK program.   Upon
                             reaching  the  end of the input data, execute any
                             END rule(s).

       nextfile              Stop processing the current input file.  The next
                             input record read comes from the next input file.
                             Update FILENAME and ARGIND, reset FNR to  1,  and
                             start  processing  over with the first pattern in
                             the AWK program.  Upon reaching the  end  of  the
                             input data, execute any ENDFILE and END rule(s).

       print                 Print  the  current record.  The output record is
                             terminated with the value of ORS.

       print expr-list       Print expressions.  Each expression is  separated
                             by the value of OFS.  The output record is termi-
                             nated with the value of ORS.

       print expr-list >file Print expressions on file.   Each  expression  is
                             separated by the value of OFS.  The output record
                             is terminated with the value of ORS.

       printf fmt, expr-list Format and  print.   See  The  printf  Statement,

       printf fmt, expr-list >file
                             Format and print on file.

       system(cmd-line)      Execute the command cmd-line, and return the exit
                             status.  (This may not be available on  non-POSIX
                             systems.)   See  GAWK:  Effective AWK Programming
                             for the full details on the exit status.

       fflush([file])        Flush any buffers associated with the open output
                             file  or  pipe file.  If file is missing or if it
                             is the null string, then flush  all  open  output
                             files and pipes.

       Additional output redirections are allowed for print and printf.

       print ... >> file
              Append output to the file.

       print ... | command
              Write on a pipe.

       print ... |& command
              Send  data  to  a coprocess or socket.  (See also the subsection
              Special File Names, below.)

       The getline command returns 1 on success, zero on end of file,  and  -1
       on  an  error.   If the errno(3) value indicates that the I/O operation
       may be retried, and PROCINFO["input",  "RETRY"]  is  set,  then  -2  is
       returned  instead of -1, and further calls to getline may be attempted.
       Upon an error, ERRNO is set to a string describing the problem.

       NOTE: Failure in opening a two-way socket results in a non-fatal  error
       being  returned to the calling function. If using a pipe, coprocess, or
       socket to getline, or from print or printf within a loop, you must  use
       close() to create new instances of the command or socket.  AWK does not
       automatically close pipes, sockets, or  coprocesses  when  they  return

   The printf Statement
       The  AWK  versions  of the printf statement and sprintf() function (see
       below) accept the following conversion specification formats:

       %a, %A  A floating point number of the form [-]0xh.hhhhp+-dd (C99 hexa-
               decimal  floating point format).  For %A, uppercase letters are
               used instead of lowercase ones.

       %c      A single character.  If the argument used for %c is numeric, it
               is treated as a character and printed.  Otherwise, the argument
               is assumed to be a string, and the only first character of that
               string is printed.

       %d, %i  A decimal number (the integer part).

       %e, %E  A floating point number of the form [-]d.dddddde[+-]dd.  The %E
               format uses E instead of e.

       %f, %F  A floating point number of the form [-]ddd.dddddd.  If the sys-
               tem  library supports it, %F is available as well. This is like
               %f, but uses capital letters for special  "not  a  number"  and
               "infinity" values. If %F is not available, gawk uses %f.

       %g, %G  Use %e or %f conversion, whichever is shorter, with nonsignifi-
               cant zeros suppressed.  The %G format uses %E instead of %e.

       %o      An unsigned octal number (also an integer).

       %u      An unsigned decimal number (again, an integer).

       %s      A character string.

       %x, %X  An unsigned hexadecimal number (an  integer).   The  %X  format
               uses ABCDEF instead of abcdef.

       %%      A single % character; no argument is converted.

       Optional,  additional  parameters may lie between the % and the control

       count$ Use the count'th argument at this point in the formatting.  This
              is  called  a positional specifier and is intended primarily for
              use in translated versions of format strings, not in the  origi-
              nal text of an AWK program.  It is a gawk extension.

       -      The expression should be left-justified within its field.

       space  For  numeric  conversions,  prefix positive values with a space,
              and negative values with a minus sign.

       +      The plus sign, used before the width modifier (see below),  says
              to  always  supply  a  sign for numeric conversions, even if the
              data to be formatted is positive.  The  +  overrides  the  space

       #      Use  an  "alternate  form" for certain control letters.  For %o,
              supply a leading zero.  For %x, and %X, supply a leading  0x  or
              0X  for  a  nonzero  result.   For %e, %E, %f and %F, the result
              always contains a decimal point.  For %g, and %G, trailing zeros
              are not removed from the result.

       0      A leading 0 (zero) acts as a flag, indicating that output should
              be padded with zeroes instead of spaces.  This applies  only  to
              the  numeric  output formats.  This flag only has an effect when
              the field width is wider than the value to be printed.

       '      A single quote character instructs gawk to insert  the  locale's
              thousands-separator  character into decimal numbers, and to also
              use the locale's decimal point  character  with  floating  point
              formats.   This requires correct locale support in the C library
              and in the definition of the current locale.

       width  The field should be padded to this width.  The field is normally
              padded with spaces.  With the 0 flag, it is padded with zeroes.

       .prec  A number that specifies the precision to use when printing.  For
              the %e, %E, %f and %F, formats, this  specifies  the  number  of
              digits  you want printed to the right of the decimal point.  For
              the %g, and %G formats, it specifies the maximum number of  sig-
              nificant digits.  For the %d, %i, %o, %u, %x, and %X formats, it
              specifies the minimum number of digits to  print.   For  the  %s
              format,  it  specifies the maximum number of characters from the
              string that should be printed.

       The dynamic width and prec capabilities of the ISO C printf()  routines
       are supported.  A * in place of either the width or prec specifications
       causes their values to be taken from the argument  list  to  printf  or
       sprintf().   To use a positional specifier with a dynamic width or pre-
       cision, supply the count$ after the * in the format string.  For  exam-
       ple, "%3$*2$.*1$s".

   Special File Names
       When  doing I/O redirection from either print or printf into a file, or
       via getline from a file,  gawk  recognizes  certain  special  filenames
       internally.   These  filenames  allow  access  to open file descriptors
       inherited from gawk's parent process (usually the shell).   These  file
       names  may  also  be  used on the command line to name data files.  The
       filenames are:

       -           The standard input.

       /dev/stdin  The standard input.

       /dev/stdout The standard output.

       /dev/stderr The standard error output.

       /dev/fd/n   The file associated with the open file descriptor n.

       These are particularly useful for error messages.  For example:

              print "You blew it!" > "/dev/stderr"

       whereas you would otherwise have to use

              print "You blew it!" | "cat 1>&2"

       The following special filenames may be used with the |& coprocess oper-
       ator for creating TCP/IP network connections:

              Files for a TCP/IP connection on local port lport to remote host
              rhost on remote port rport.  Use a port of 0 to have the  system
              pick a port.  Use /inet4 to force an IPv4 connection, and /inet6
              to force an  IPv6  connection.   Plain  /inet  uses  the  system
              default (most likely IPv4).  Usable only with the |& two-way I/O

              Similar, but use UDP/IP instead of TCP/IP.

   Numeric Functions
       AWK has the following built-in arithmetic functions:

       atan2(y, x)   Return the arctangent of y/x in radians.

       cos(expr)     Return the cosine of expr, which is in radians.

       exp(expr)     The exponential function.

       int(expr)     Truncate to integer.

       log(expr)     The natural logarithm function.

       rand()        Return a random number N, between zero and one, such that
                     0 <= N < 1.

       sin(expr)     Return the sine of expr, which is in radians.

       sqrt(expr)    Return the square root of expr.

       srand([expr]) Use expr as the new seed for the random number generator.
                     If no expr is provided, use the time of day.  Return  the
                     previous seed for the random number generator.

   String Functions
       Gawk has the following built-in string functions:

       asort(s [, d [, how] ]) Return  the  number  of  elements in the source
                               array s.  Sort the contents of s  using  gawk's
                               normal  rules for comparing values, and replace
                               the indices of the sorted values s with sequen-
                               tial  integers starting with 1. If the optional
                               destination array d is specified, first  dupli-
                               cate  s  into  d,  and then sort d, leaving the
                               indices of the source array  s  unchanged.  The
                               optional  string how controls the direction and
                               the comparison mode.  Valid values for how  are
                               any     of     the     strings     valid    for
                               PROCINFO["sorted_in"].  It can also be the name
                               of   a   user-defined  comparison  function  as
                               described in PROCINFO["sorted_in"].   s  and  d
                               are  allowed  to  be  the same array; this only
                               makes sense when supplying the  third  argument
                               as well.

       asorti(s [, d [, how] ])
                               Return  the  number  of  elements in the source
                               array s.  The behavior is the same as  that  of
                               asort(), except that the array indices are used
                               for sorting, not the array values.  When  done,
                               the  array is indexed numerically, and the val-
                               ues are those of  the  original  indices.   The
                               original values are lost; thus provide a second
                               array if you wish  to  preserve  the  original.
                               The  purpose  of the optional string how is the
                               same as described previously for asort().  Here
                               too,  s and d are allowed to be the same array;
                               this only makes sense when supplying the  third
                               argument as well.

       gensub(r, s, h [, t])   Search  the  target string t for matches of the
                               regular expression r.  If h is a string  begin-
                               ning with g or G, then replace all matches of r
                               with s.  Otherwise, h is  a  number  indicating
                               which  match of r to replace.  If t is not sup-
                               plied, use $0 instead.  Within the  replacement
                               text  s,  the  sequence  \n, where n is a digit
                               from 1 to 9, may be used to indicate  just  the
                               text that matched the n'th parenthesized subex-
                               pression.   The  sequence  \0  represents   the
                               entire  matched  text, as does the character &.
                               Unlike sub() and gsub(), the modified string is
                               returned as the result of the function, and the
                               original target string is not changed.

       gsub(r, s [, t])        For each substring matching the regular expres-
                               sion  r  in the string t, substitute the string
                               s, and return the number of substitutions.   If
                               t  is  not  supplied,  use  $0.   An  &  in the
                               replacement text is replaced with the text that
                               was  actually matched.  Use \& to get a literal
                               &.  (This must be typed  as  "\\&";  see  GAWK:
                               Effective  AWK Programming for a fuller discus-
                               sion of the  rules  for  ampersands  and  back-
                               slashes  in  the  replacement  text  of  sub(),
                               gsub(), and gensub().)

       index(s, t)             Return the index of the string t in the  string
                               s,  or zero if t is not present.  (This implies
                               that character indices start at one.)  It is  a
                               fatal error to use a regexp constant for t.

       length([s])             Return  the  length  of  the  string  s, or the
                               length of $0 if s is not supplied.  As  a  non-
                               standard  extension,  with  an  array argument,
                               length() returns the number of elements in  the

       match(s, r [, a])       Return  the  position  in  s  where the regular
                               expression r  occurs,  or  zero  if  r  is  not
                               present,  and  set  the  values  of  RSTART and
                               RLENGTH.  Note that the argument order  is  the
                               same as for the ~ operator: str ~ re.  If array
                               a is provided, a is cleared and then elements 1
                               through  n  are  filled  with the portions of s
                               that match the corresponding parenthesized sub-
                               expression in r.  The zero'th element of a con-
                               tains the portion of s matched  by  the  entire
                               regular    expression   r.    Subscripts   a[n,
                               "start"], and a[n, "length"] provide the start-
                               ing  index  in  the  string  and length respec-
                               tively, of each matching substring.

       patsplit(s, a [, r [, seps] ])
                               Split the string s into the  array  a  and  the
                               separators array seps on the regular expression
                               r, and return the number  of  fields.   Element
                               values  are  the  portions of s that matched r.
                               The value of seps[i] is the possibly null sepa-
                               rator  that  appeared after a[i].  The value of
                               seps[0] is the possibly null leading separator.
                               If  r  is  omitted,  FPAT is used instead.  The
                               arrays a and seps are cleared first.  Splitting
                               behaves  identically  to  field  splitting with
                               FPAT, described above.

       split(s, a [, r [, seps] ])
                               Split the string s into the  array  a  and  the
                               separators array seps on the regular expression
                               r, and return the number of fields.   If  r  is
                               omitted,  FS is used instead.  The arrays a and
                               seps are cleared first.  seps[i] is  the  field
                               separator matched by r between a[i] and a[i+1].
                               If r is a single space, then leading whitespace
                               in  s goes into the extra array element seps[0]
                               and trailing whitespace  goes  into  the  extra
                               array  element  seps[n],  where n is the return
                               value  of  split(s,  a,  r,  seps).   Splitting
                               behaves   identically   to   field   splitting,
                               described above.  In particular, if r is a sin-
                               gle-character  string,  that string acts as the
                               separator, even if it happens to be  a  regular
                               expression metacharacter.

       sprintf(fmt, expr-list) Print  expr-list  according  to fmt, and return
                               the resulting string.

       strtonum(str)           Examine str, and return its numeric value.   If
                               str  begins  with  a  leading 0, treat it as an
                               octal number.  If str begins with a leading  0x
                               or  0X, treat it as a hexadecimal number.  Oth-
                               erwise, assume it is a decimal number.

       sub(r, s [, t])         Just like gsub(), but replace  only  the  first
                               matching substring.  Return either zero or one.

       substr(s, i [, n])      Return  the  at most n-character substring of s
                               starting at i.  If n is omitted, use  the  rest
                               of s.

       tolower(str)            Return  a  copy of the string str, with all the
                               uppercase characters in str translated to their
                               corresponding   lowercase  counterparts.   Non-
                               alphabetic characters are left unchanged.

       toupper(str)            Return a copy of the string str, with  all  the
                               lowercase characters in str translated to their
                               corresponding  uppercase  counterparts.    Non-
                               alphabetic characters are left unchanged.

       Gawk  is  multibyte aware.  This means that index(), length(), substr()
       and match() all work in terms of characters, not bytes.

   Time Functions
       Since one of the primary uses of AWK programs is processing  log  files
       that  contain time stamp information, gawk provides the following func-
       tions for obtaining time stamps and formatting them.

       mktime(datespec [, utc-flag])
                 Turn datespec into a time stamp of the same form as  returned
                 by  systime(),  and  return  the  result.   The datespec is a
                 string of the form YYYY MM DD HH MM SS[ DST].   The  contents
                 of  the  string are six or seven numbers representing respec-
                 tively the full year including century, the month from  1  to
                 12,  the  day  of the month from 1 to 31, the hour of the day
                 from 0 to 23, the minute from 0 to 59, the second from  0  to
                 60,  and  an  optional  daylight  saving flag.  The values of
                 these numbers need not be within the  ranges  specified;  for
                 example,  an  hour  of  -1 means 1 hour before midnight.  The
                 origin-zero Gregorian calendar is assumed, with year  0  pre-
                 ceding  year  1 and year -1 preceding year 0.  If utc-flag is
                 present and is non-zero or non-null, the time is  assumed  to
                 be in the UTC time zone; otherwise, the time is assumed to be
                 in the local time zone.  If the DST daylight saving  flag  is
                 positive,  the time is assumed to be daylight saving time; if
                 zero, the time is assumed to be standard time; and  if  nega-
                 tive  (the  default),  mktime() attempts to determine whether
                 daylight saving time is in effect for the specified time.  If
                 datespec does not contain enough elements or if the resulting
                 time is out of range, mktime() returns -1.

       strftime([format [, timestamp[, utc-flag]]])
                 Format timestamp according to the  specification  in  format.
                 If  utc-flag  is  present  and  is  non-zero or non-null, the
                 result is in UTC, otherwise the result is in local time.  The
                 timestamp  should  be  of  the  same form as returned by sys-
                 time().  If timestamp is missing, the current time of day  is
                 used.   If  format is missing, a default format equivalent to
                 the output of date(1) is used.  The default format is  avail-
                 able  in PROCINFO["strftime"].  See the specification for the
                 strftime() function in ISO C for the format conversions  that
                 are guaranteed to be available.

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

   Bit Manipulations Functions
       Gawk supplies the following bit manipulation functions.  They  work  by
       converting  double-precision  floating  point values to uintmax_t inte-
       gers, doing the operation, and  then  converting  the  result  back  to
       floating point.

       NOTE:  Passing  negative  operands  to  any of these functions causes a
       fatal error.

       The functions are:

       and(v1, v2 [, ...]) Return the bitwise AND of the  values  provided  in
                           the argument list.  There must be at least two.

       compl(val)          Return the bitwise complement of val.

       lshift(val, count)  Return  the  value  of  val,  shifted left by count

       or(v1, v2 [, ...])  Return the bitwise OR of the values provided in the
                           argument list.  There must be at least two.

       rshift(val, count)  Return  the  value  of  val, shifted right by count

       xor(v1, v2 [, ...]) Return the bitwise XOR of the  values  provided  in
                           the argument list.  There must be at least two.

   Type Functions
       The  following  functions  provide type related information about their

       isarray(x) Return true if x is an array, false otherwise.   This  func-
                  tion is mainly for use with the elements of multidimensional
                  arrays and with function parameters.

       typeof(x)  Return a string indicating the type of x.  The  string  will
                  be  one  of "array", "number", "regexp", "string", "strnum",
                  "unassigned", or "undefined".

   Internationalization Functions
       The following functions may be used from within your  AWK  program  for
       translating strings at run-time.  For full details, see GAWK: Effective
       AWK Programming.

       bindtextdomain(directory [, domain])
              Specify the directory where gawk looks for the  .gmo  files,  in
              case they will not or cannot be placed in the ``standard'' loca-
              tions (e.g., during testing).  It returns  the  directory  where
              domain is ``bound.''
              The  default domain is the value of TEXTDOMAIN.  If directory is
              the null string (""), then bindtextdomain() returns the  current
              binding for the given domain.

       dcgettext(string [, domain [, category]])
              Return  the  translation  of  string  in  text domain domain for
              locale category category.  The default value for domain  is  the
              current  value of TEXTDOMAIN.  The default value for category is
              If you supply a value for category, it must be a string equal to
              one  of the known locale categories described in GAWK: Effective
              AWK Programming.  You must  also  supply  a  text  domain.   Use
              TEXTDOMAIN if you want to use the current domain.

       dcngettext(string1, string2, number [, domain [, category]])
              Return  the  plural  form  used for number of the translation of
              string1 and string2 in text domain domain  for  locale  category
              category.   The default value for domain is the current value of
              TEXTDOMAIN.  The default value for category is "LC_MESSAGES".
              If you supply a value for category, it must be a string equal to
              one  of the known locale categories described in GAWK: Effective
              AWK Programming.  You must  also  supply  a  text  domain.   Use
              TEXTDOMAIN if you want to use the current domain.

       Functions in AWK are defined as follows:

              function name(parameter list) { statements }

       Functions  execute  when  they  are  called  from within expressions in
       either patterns or actions.  Actual parameters supplied in the function
       call  are  used  to  instantiate  the formal parameters declared in the
       function.  Arrays are passed by reference, other variables  are  passed
       by value.

       Since  functions were not originally part of the AWK language, the pro-
       vision for local variables is rather clumsy: They are declared as extra
       parameters  in the parameter list.  The convention is to separate local
       variables from real parameters by extra spaces in the  parameter  list.
       For example:

              function  f(p, q,     a, b)   # a and b are local

              /abc/     { ... ; f(1, 2) ; ... }

       The left parenthesis in a function call is required to immediately fol-
       low the function name, without any intervening whitespace.  This avoids
       a  syntactic  ambiguity with the concatenation operator.  This restric-
       tion does not apply to the built-in functions listed above.

       Functions may call each other and may be recursive.   Function  parame-
       ters used as local variables are initialized to the null string and the
       number zero upon function invocation.

       Use return expr to return a value from a function.  The return value is
       undefined if no value is provided, or if the function returns by "fall-
       ing off" the end.

       As a gawk extension, functions may be called indirectly.  To  do  this,
       assign  the  name of the function to be called, as a string, to a vari-
       able.  Then use the variable as if it were the name of a function, pre-
       fixed with an @ sign, like so:
              function myfunc()
                   print "myfunc called"

              {    ...
                   the_func = "myfunc"
                   @the_func()    # call through the_func to myfunc
       As  of  version 4.1.2, this works with user-defined functions, built-in
       functions, and extension functions.

       If --lint has been provided, gawk warns about calls to undefined  func-
       tions  at  parse  time,  instead  of at run time.  Calling an undefined
       function at run time is a fatal error.

       The word func may be used in place of function, although this is depre-

       You  can  dynamically add new functions written in C or C++ to the run-
       ning gawk interpreter with the @load statement.  The full  details  are
       beyond  the scope of this manual page; see GAWK: Effective AWK Program-

       The gawk profiler accepts two signals.  SIGUSR1 causes  it  to  dump  a
       profile  and  function  call stack to the profile file, which is either
       awkprof.out, or whatever file was named with the --profile option.   It
       then  continues  to  run.   SIGHUP  causes gawk to dump the profile and
       function call stack and then exit.

       String constants are sequences of characters enclosed in double quotes.
       In non-English speaking environments, it is possible to mark strings in
       the AWK program as requiring translation to the local natural language.
       Such  strings  are  marked in the AWK program with a leading underscore
       ("_").  For example,

              gawk 'BEGIN { print "hello, world" }'

       always prints hello, world.  But,

              gawk 'BEGIN { print _"hello, world" }'

       might print bonjour, monde in France.

       There are several steps involved in producing and running a localizable
       AWK program.

       1.  Add  a BEGIN action to assign a value to the TEXTDOMAIN variable to
           set the text domain to a name associated with your program:

                BEGIN { TEXTDOMAIN = "myprog" }

           This allows gawk to find the .gmo file associated  with  your  pro-
           gram.  Without this step, gawk uses the messages text domain, which
           likely does not contain translations for your program.

       2.  Mark all strings that should  be  translated  with  leading  under-

       3.  If necessary, use the dcgettext() and/or bindtextdomain() functions
           in your program, as appropriate.

       4.  Run gawk --gen-pot -f myprog.awk > myprog.pot to  generate  a  .pot
           file for your program.

       5.  Provide  appropriate translations, and build and install the corre-
           sponding .gmo files.

       The internationalization features are described in full detail in GAWK:
       Effective AWK Programming.

       A  primary  goal  for gawk is compatibility with the POSIX standard, as
       well as with the latest version of Brian Kernighan's awk.  To this end,
       gawk  incorporates  the  following  user visible features which are not
       described in the AWK book, but are part of the Brian  Kernighan's  ver-
       sion of awk, and are in the POSIX standard.

       The  book  indicates that command line variable assignment happens when
       awk would otherwise open the argument as a file,  which  is  after  the
       BEGIN rule is executed.  However, in earlier implementations, when such
       an assignment appeared before any file names, the assignment would hap-
       pen before the BEGIN rule was run.  Applications came to depend on this
       "feature."  When awk was changed to match  its  documentation,  the  -v
       option  for  assigning  variables before program execution was added to
       accommodate applications that depended upon the  old  behavior.   (This
       feature  was  agreed  upon by both the Bell Laboratories developers and
       the GNU developers.)

       When processing arguments, gawk uses the special option "--" to  signal
       the end of arguments.  In compatibility mode, it warns about but other-
       wise ignores undefined options.  In normal  operation,  such  arguments
       are passed on to the AWK program for it to process.

       The  AWK  book  does not define the return value of srand().  The POSIX
       standard has it return the seed it was using, to allow keeping track of
       random  number  sequences.   Therefore srand() in gawk also returns its
       current seed.

       Other features are: The use of multiple -f options (from MKS awk);  the
       ENVIRON array; the \a, and \v escape sequences (done originally in gawk
       and fed back into the Bell Laboratories  version);  the  tolower()  and
       toupper()  built-in functions (from the Bell Laboratories version); and
       the ISO C conversion specifications in printf (done first in  the  Bell
       Laboratories version).

       There  is  one feature of historical AWK implementations that gawk sup-
       ports: It is possible to call the length() built-in function  not  only
       with no argument, but even without parentheses!  Thus,

              a = length     # Holy Algol 60, Batman!

       is the same as either of

              a = length()
              a = length($0)

       Using  this  feature  is poor practice, and gawk issues a warning about
       its use if --lint is specified on the command line.

       Gawk has a too-large number of  extensions  to  POSIX  awk.   They  are
       described  in  this  section.  All the extensions described here can be
       disabled by invoking gawk with the --traditional or --posix options.

       The following features of gawk are not available in POSIX awk.

       o No path search is performed  for  files  named  via  the  -f  option.
         Therefore the AWKPATH environment variable is not special.

       o There is no facility for doing file inclusion (gawk's @include mecha-

       o There is no facility for dynamically adding new functions written  in
         C (gawk's @load mechanism).

       o The \x escape sequence.

       o The ability to continue lines after ?  and :.

       o Octal and hexadecimal constants in AWK programs.

         variables are not special.

       o The IGNORECASE variable and its side-effects are not available.

       o The FIELDWIDTHS variable and fixed-width field splitting.

       o The FPAT variable and field splitting based on field values.

       o The FUNCTAB, SYMTAB, and PROCINFO arrays are not available.

       o The use of RS as a regular expression.

       o The special file names available for I/O redirection are  not  recog-

       o The |& operator for creating coprocesses.

       o The BEGINFILE and ENDFILE special patterns are not available.

       o The  ability to split out individual characters using the null string
         as the value of FS, and as the third argument to split().

       o An optional fourth argument  to  split()  to  receive  the  separator

       o The optional second argument to the close() function.

       o The optional third argument to the match() function.

       o The ability to use positional specifiers with printf and sprintf().

       o The ability to pass an array to length().

       o The and(), asort(), asorti(), bindtextdomain(), compl(), dcgettext(),
         dcngettext(),  gensub(),  lshift(),   mktime(),   or(),   patsplit(),
         rshift(), strftime(), strtonum(), systime() and xor() functions.

       o Localizable strings.

       o Non-fatal I/O.

       o Retryable I/O.

       The  AWK book does not define the return value of the close() function.
       Gawk's close() returns the value from  fclose(3),  or  pclose(3),  when
       closing an output file or pipe, respectively.  It returns the process's
       exit status when closing an input pipe.  The return value is -1 if  the
       named file, pipe or coprocess was not opened with a redirection.

       When  gawk is invoked with the --traditional option, if the fs argument
       to the -F option is "t", then FS is set to  the  tab  character.   Note
       that  typing  gawk  -F\t ...  simply causes the shell to quote the "t,"
       and does not pass "\t" to the -F option.  Since this is a  rather  ugly
       special  case, it is not the default behavior.  This behavior also does
       not occur if --posix has been specified.  To really get a tab character
       as  the  field  separator, it is best to use single quotes: gawk -F'\t'

       The AWKPATH environment variable can be  used  to  provide  a  list  of
       directories that gawk searches when looking for files named via the -f,
       --file, -i and --include options, and the @include directive.   If  the
       initial  search  fails, the path is searched again after appending .awk
       to the filename.

       The AWKLIBPATH environment variable can be used to provide  a  list  of
       directories  that gawk searches when looking for files named via the -l
       and --load options.

       The GAWK_READ_TIMEOUT environment variable can be  used  to  specify  a
       timeout in milliseconds for reading input from a terminal, pipe or two-
       way communication including sockets.

       For connection to a remote host via socket, GAWK_SOCK_RETRIES  controls
       the  number  of  retries,  and  GAWK_MSEC_SLEEP  the  interval  between
       retries.  The interval is in milliseconds. On systems that do not  sup-
       port  usleep(3),  the value is rounded up to an integral number of sec-

       If POSIXLY_CORRECT exists in the environment, then gawk behaves exactly
       as  if  --posix  had been specified on the command line.  If --lint has
       been specified, gawk issues a warning message to this effect.

       If the exit statement is used with a value, then gawk  exits  with  the
       numeric value given to it.

       Otherwise,  if there were no problems during execution, gawk exits with
       the value of the C constant EXIT_SUCCESS.  This is usually zero.

       If an error occurs, gawk  exits  with  the  value  of  the  C  constant
       EXIT_FAILURE.  This is usually one.

       If  gawk exits because of a fatal error, the exit status is 2.  On non-
       POSIX systems, this value may be mapped to EXIT_FAILURE.

       This man page documents gawk, version 5.1.

       The original version of UNIX awk was designed and implemented by Alfred
       Aho, Peter Weinberger, and Brian Kernighan of Bell Laboratories.  Brian
       Kernighan continues to maintain and enhance it.

       Paul Rubin and Jay Fenlason, of the  Free  Software  Foundation,  wrote
       gawk,  to be compatible with the original version of awk distributed in
       Seventh Edition UNIX.  John Woods contributed a number  of  bug  fixes.
       David  Trueman,  with contributions from Arnold Robbins, made gawk com-
       patible with the new version of UNIX awk.  Arnold Robbins is  the  cur-
       rent maintainer.

       See GAWK: Effective AWK Programming for a full list of the contributors
       to gawk and its documentation.

       See the README file in the gawk distribution for up-to-date information
       about maintainers and which ports are currently supported.

       If   you   find   a  bug  in  gawk,  please  send  electronic  mail  to
       bug-gawk@gnu.org.  Please include your operating system and  its  revi-
       sion,  the  version of gawk (from gawk --version), which C compiler you
       used to compile it, and a test program and data that are  as  small  as
       possible for reproducing the problem.

       Before  sending  a  bug report, please do the following things.  First,
       verify that you have the latest version of gawk.   Many  bugs  (usually
       subtle  ones)  are  fixed at each release, and if yours is out of date,
       the problem may already have been solved.  Second, please see  if  set-
       ting  the  environment  variable  LC_ALL  to  LC_ALL=C causes things to
       behave as you expect. If so, it's a locale issue, and may  or  may  not
       really  be a bug.  Finally, please read this man page and the reference
       manual carefully to be sure that what you think is  a  bug  really  is,
       instead of just a quirk in the language.

       Whatever  you do, do NOT post a bug report in comp.lang.awk.  While the
       gawk developers occasionally read this newsgroup, posting  bug  reports
       there is an unreliable way to report bugs.  Similarly, do NOT use a web
       forum (such as Stack Overflow) for reporting bugs.  Instead, please use
       the electronic mail addresses given above.  Really.

       If you're using a GNU/Linux or BSD-based system, you may wish to submit
       a bug report to the vendor of  your  distribution.   That's  fine,  but
       please send a copy to the official email address as well, since there's
       no guarantee that the bug report will be forwarded to  the  gawk  main-

       The  -F option is not necessary given the command line variable assign-
       ment feature; it remains only for backwards compatibility.

       See attributes(7) for descriptions of the following attributes:

       |Availability   | text/gawk        |
       |Stability      | Volatile         |

       egrep(1),  sed(1),  getpid(2),   getppid(2),   getpgrp(2),   getuid(2),
       geteuid(2),   getgid(2),  getegid(2),  getgroups(2),  printf(3),  strf-
       time(3), usleep(3)

       The AWK Programming Language, Alfred V. Aho, Brian W. Kernighan,  Peter
       J. Weinberger, Addison-Wesley, 1988.  ISBN 0-201-07981-X.

       GAWK:  Effective  AWK  Programming,  Edition 5.1, shipped with the gawk
       source.  The current version of this document is  available  online  at

       The     GNU     gettext     documentation,    available    online    at

       Print and sort the login names of all users:

                      BEGIN              { FS = ":" }
                                         { print $1 | "sort" }

       Count lines in a file:

                                         { nlines++ }
                      END                { print nlines }

       Precede each line by its number in the file:

                      { print FNR, $0 }

       Concatenate and line number (a variation on a theme):

                      { print NR, $0 }

       Run an external command for particular lines of data:

                      tail -f access_log |
                      awk '/myhome.html/ { system("nmap " $1 ">> logdir/myhome.html") }'

       Brian Kernighan provided valuable assistance during testing and  debug-
       ging.  We thank him.

       Copyright  (C)  1989,  1991,  1992, 1993, 1994, 1995, 1996, 1997, 1998,
       1999, 2001, 2002, 2003, 2004, 2005, 2007, 2009, 2010, 2011, 2012, 2013,
       2014,  2015,  2016, 2017, 2018, 2019, 2020, 2021, Free Software Founda-
       tion, Inc.

       Permission is granted to make and distribute verbatim  copies  of  this
       manual  page  provided  the copyright notice and this permission notice
       are preserved on all copies.

       Permission is granted to copy and distribute modified versions of  this
       manual  page  under  the conditions for verbatim copying, provided that
       the entire resulting derived work is distributed under the terms  of  a
       permission notice identical to this one.

       Permission  is granted to copy and distribute translations of this man-
       ual page into another language, under the above conditions for modified
       versions,  except that this permission notice may be stated in a trans-
       lation approved by the Foundation.

       Source code for open source software components in Oracle  Solaris  can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-

       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source                was                downloaded                from

       Further information about this software can be found on the open source
       community website at https://www.gnu.org/software/gawk.

Free Software Foundation          Jul 05 2021                          GAWK(1)