path: root/doc/gawk.1

GAWK(1)                                  Utility Commands                                 GAWK(1)

NAME
       gawk - pattern scanning and processing language

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

DESCRIPTION
       Gawk  is the GNU Project's implementation of the AWK programming language.  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 Wein-
       berger.  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 op-
       tion, 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 pro-
       gram  source  provided  with  the -f and --include options.  The debugger is documented in
       GAWK: Effective AWK Programming.

OPTION FORMAT
       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.  Arguments 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 abbreviation remains unique.

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

OPTIONS
       Gawk accepts the following options.  Standard options are listed first,  followed  by  op-
       tions for gawk extensions, listed alphabetically by short option.

       -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 predefined 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.

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

       -c
       --traditional
              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 information.

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

       -d[file]
       --dump-variables[=file]
              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 pro-
              gram with a lot of functions, and you want to be sure that your functions don't in-
              advertently  use  global variables that you meant to be local.  (This is a particu-
              larly easy mistake to make with simple variable names like i, j, and so on.)

       -D[file]
       --debug[=file]
              Enable debugging of AWK programs.  By default, the debugger reads commands interac-
              tively  from the keyboard (standard input).  The optional file argument specifies a
              file with a list of commands 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 intermix-
              ing  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 pro-
              grams used in shell scripts.  Each argument supplied via -e is treated as if it be-
              gins with an implicit @namespace "awk" statement.

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

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

       -h
       --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 envi-
              ronment 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
              eliminated), 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.

       -I
       --trace
              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 variable.  If the initial search fails, another
              attempt will be made after appending the default  shared  library  suffix  for  the
              platform.  The library initialization routine is expected to be named dl_load().

       -L [value]
       --lint[=value]
              Provide warnings about constructs that are dubious or non-portable to other AWK im-
              plementations.  With an optional argument of fatal, lint warnings become fatal  er-
              rors.  This may be drastic, but its use will certainly encourage the development of
              cleaner AWK programs.  With an optional argument of invalid,  only  warnings  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.

       -M
       --bignum
              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 is-
              sues a warning.)

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

       -N
       --use-lc-numeric
              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 option.

       -o[file]
       --pretty-print[=file]
              Output a pretty printed version of the program to file.  If no  file  is  provided,
              gawk  uses  a file named awkprof.out in the current directory.  This option implies
              --no-optimize.

       -O
       --optimize
              Enable gawk's default optimizations upon the internal representation  of  the  pro-
              gram.  Currently, this just includes simple constant folding.  This option is on by
              default.

       -p[prof-file]
       --profile[=prof-file]
              Start a profiling session, and send the profiling data to prof-file.   The  default
              is  awkprof.out.   The  profile  contains execution 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.

       -P
       --posix
              This turns on compatibility mode, with the following additional restrictions:

              +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 ^=.

       -r
       --re-interval
              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.

       -s
       --no-optimize
              Disable  gawk's  default optimizations upon the internal representation of the pro-
              gram.

       -S
       --sandbox
              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 com-
              mand line.

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

       -V
       --version
              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 Standards, these  op-
              tions cause an immediate, successful exit.)

       --     Signal  the  end  of  options. This is useful to allow further arguments to the AWK
              program itself to start with a "-".  This provides 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 ig-
       nored.  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.

AWK PROGRAM EXECUTION
       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 specified, 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  to-
       gether.  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 programs.

       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 "/" character,
       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 speci-
       fied via the -v option are performed.  Next, gawk compiles 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 assign-
       ment.  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 values to the variables AWK uses to control how input is broken into fields  and
       records.   It  is  also  useful for controlling state if multiple 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 file.

       For each record in the input, gawk tests to see if it matches any pattern in the AWK  pro-
       gram.  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 produces a warning, but
       is otherwise skipped.  If either of the --posix or --traditional options  is  given,  then
       gawk reverts to treating directories on the command line as a fatal error.

VARIABLES, RECORDS AND FIELDS
       AWK  variables are dynamic; they come into existence when they are first used.  Their val-
       ues 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 dimensional 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 pro-
       gram runs; these are described as needed and summarized below.

   Records
       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 in-
       put  that matches this regular expression separates the record.  However, in compatibility
       mode, only the first character of its string value is used for separating 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 newline character always acts as a field separator,  in  addition  to
       whatever value FS may have.

   Fields
       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 sepa-
       rate field.  Otherwise, 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 ex-
       pression.

       If the FIELDWIDTHS variable is set to a space-separated list of numbers, each field is ex-
       pected  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 num-
       ber of characters 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 regular 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 refer-
       enced 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 record.

       References  to non-existent fields (i.e., fields after $NF) produce the null string.  How-
       ever, 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 recomputed, 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.  Nu-
                   meric 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"
                   specify 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  mes-
                   sage.

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

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

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

       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 separator.  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 specified 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 ex-
                   pression,  instead  of  using  the  value  of  FS as the field separator.  See
                   Fields, above.

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

       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 match-
                   ing in rules, field splitting with FS and FPAT,  record  separating  with  RS,
                   regular  expression matching with ~ and !~, and the gensub(), gsub(), index(),
                   match(), patsplit(), split(), and sub() built-in  functions  all  ignore  case
                   when doing regular expression operations.  NOTE: Array subscripting is not af-
                   fected.  However, the asort() and asorti() functions are affected.
                   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  nor-
                   mally case-sensitive.

       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 al-
                   lowed  for  the  --lint option may also be assigned to LINT, with the same ef-
                   fects.  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 de-
                   fault.

       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 follow-
                   ing elements are guaranteed to be available:

                   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 call.

                   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 call.

                   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 call.

                   PROCINFO["identifiers"]
                                        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 program; they are not updated while the pro-
                                        gram runs.  For each identifier, the value of the element
                                        is one of the following:

                                        "array"     The identifier is an array.

                                        "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 scalar.

                                        "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 call.

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

                   PROCINFO["platform"] A  string indicating the platform for which gawk was com-
                                        piled.  It is one of:

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

                                        "os2"  OS/2.

                                        "posix"
                                               GNU/Linux,  Cygwin, Mac OS X, and legacy Unix sys-
                                               tems.

                                        "vms"  OpenVMS or Vax/VMS.

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

                   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 call.

                   PROCINFO["version"]  The version of gawk.

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

                   PROCINFO["api_major"]
                          The major version of the extension API.

                   PROCINFO["api_minor"]
                          The minor version of the extension API.

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

                   PROCINFO["gmp_version"]
                          The version of the GNU GMP library used for arbitrary precision  number
                          support in gawk.

                   PROCINFO["mpfr_version"]
                          The version of the GNU MPFR library used for arbitrary precision number
                          support in gawk.

                   PROCINFO["prec_max"]
                          The maximum precision supported by the GNU MPFR library  for  arbitrary
                          precision floating-point numbers.

                   PROCINFO["prec_min"]
                          The  minimum  precision  allowed  by the GNU MPFR library for arbitrary
                          precision floating-point numbers.

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

                   PROCINFO["NONFATAL"]
                          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 command instead of set-
                          ting 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 timeout.

                   PROCINFO["input", "RETRY"]
                          If  an  I/O error that may be retried occurs when reading data from in-
                          put, 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.

                   PROCINFO["sorted_in"]
                          If this element exists in PROCINFO, then its value controls  the  order
                          in  which  array elements are traversed 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 fol-
                          lows:

                               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 de-
                   fault "N" (IEEE-754 roundTiesToEven mode).  The accepted values are:

                   "A" or "a"
                          for rounding away from zero.  These are only available if your  version
                          of the GNU MPFR library supports 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 char-
                   acter or regular expression specified by RS.

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

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

       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 ele-
                   ments with an index that is not a variable name.

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

   Arrays
       Arrays  are  subscripted with an expression between square brackets ([ and ]).  If the ex-
       pression is an expression list (expr, expr ...)  then the array subscript is a string con-
       sisting  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  ar-
       rays.  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 associative, i.e., indexed by string values.

       The special operator in may be used to test if an array has an index consisting of a  par-
       ticular 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 ar-
       ray.  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 ``rec-
       tangular'' 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 subarray 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 state-
       ment.

   Namespaces
       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 double colon (::).  The
       left-hand identifier represents the namespace and the right-hand identifier is  the  vari-
       able  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 dif-
       ferent.

       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 namespaces.  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 variable is interpreted depends upon its con-
       text.  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 accomplished using str-
       tod(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 converted 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  nu-
       merically.   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 con-
       verted  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  con-
       stants.   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  pat-
       split() 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 following the \x.  Up
            to two following hexadecimal digits are  considered  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  hexadecimal  escape  se-
       quences 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  expres-
       sions (e.g., /[ \t\f\n\r\v]/ matches whitespace characters).

       Gawk  provides strongly typed regular expression constants. These are written with a lead-
       ing @ 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 regular expression type.

PATTERNS AND ACTIONS
       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 special.

       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 statements themselves.

   Patterns
       AWK patterns may be one of the following:

              BEGIN
              END
              BEGINFILE
              ENDFILE
              /regular expression/
              relational expression
              pattern && 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 writ-
       ten in a single BEGIN rule.  They are executed before any of the  input  is  read.   Simi-
       larly, 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 combined with other pat-
       terns in pattern expressions.  BEGIN and END patterns 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 BEGINFILE 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 below.

       A relational expression may use any of the operators defined below in the section  on  ac-
       tions.  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 evaluation.

       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, otherwise it is the third.  Only one of
       the second and third patterns is evaluated.

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

   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 abc....

       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}
       r{n,}
       r{n,m}     One or two numbers inside braces denote an interval expression.   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 underscore).

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

       \`         Matches the empty string at the beginning of a buffer (string).

       \'         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 characters that have a  specific  attribute,  but
       where  the actual characters themselves can vary from country to country and/or from char-
       acter 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 keyword denoting the class, and :].  The charac-
       ter 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 characters.)

       [:punct:]  Punctuation characters (characters that are not letter, digits, control charac-
                  ters, 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 characters, 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 repre-
       sented with more than one character, as well as several characters that are equivalent for
       collating,  or  sorting, purposes.  (E.g., in French, a plain "e" and a grave-accented "e`"
       are equivalent.)

       Collating Symbols
              A collating symbol is a multi-character collating element enclosed in [.   and  .].
              For  example,  if ch is a collating element, 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", "e'", and "e`".  In this case, [[=e=]] is a regular ex-
              pression that matches any of e, e', or e`.

       These features are very valuable in non-English speaking locales.  The  library  functions
       that  gawk  uses  for regular expression matching currently 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 expres-
       sions.

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

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

       --traditional
              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 reg-
              ular expression metacharacters.

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

   Actions
       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.

   Operators
       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 expression 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
              break
              continue
              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, RT.

       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.  Coprocesses are a gawk extension.   (The  command
                             can  also  be  a socket.  See the subsection Special File Names, be-
                             low.)

       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 terminated 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, below.

       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
       EOF.

   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  hexadecimal  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 in-
               stead of e.

       %f, %F  A floating point number of the form [-]ddd.dddddd.  If the system 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  nonsignificant  zeros  sup-
               pressed.  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 letter:

       count$ Use the count'th argument at this point in the formatting.  This is called a  posi-
              tional specifier and is intended primarily for use in translated versions of format
              strings, not in the original 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 modifier.

       #      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 ze-
              roes  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 charac-
              ter with floating point formats.  This requires correct locale support in the C li-
              brary and in the definition of the current locale.

       width  The  field  should be padded to this width.  The field is normally padded with spa-
              ces.  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
              significant  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 precision, supply the count$ after the * in  the  format  string.   For  example,
       "%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  operator  for  creating
       TCP/IP network connections:

       /inet/tcp/lport/rhost/rport
       /inet4/tcp/lport/rhost/rport
       /inet6/tcp/lport/rhost/rport
              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 operator.

       /inet/udp/lport/rhost/rport
       /inet4/udp/lport/rhost/rport
       /inet6/udp/lport/rhost/rport
              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 num-
                     ber 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  sequential  inte-
                               gers starting with 1. If the optional destination array d is spec-
                               ified, first duplicate s into d, and then sort d, leaving the  in-
                               dices  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  de-
                               scribed  in  PROCINFO["sorted_in"].  s and d are allowed to be the
                               same array; this only makes sense when supplying the  third  argu-
                               ment 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 values are those of the original  in-
                               dices.   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 beginning 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  supplied,  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 subexpression.  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 expression r in the string
                               t,  substitute  the  string  s, and return the number of substitu-
                               tions.  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:  Ef-
                               fective  AWK  Programming for a fuller discussion of the rules for
                               ampersands and backslashes  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 array.

       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 subexpression in r.   The  zero'th
                               element of a contains the portion of s matched by the entire regu-
                               lar expression r.  Subscripts a[n, "start"],  and  a[n,  "length"]
                               provide  the starting index in the string and length respectively,
                               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.  El-
                               ement values are the portions of s that matched r.  The  value  of
                               seps[i]  is  the possibly null separator 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  be-
                               tween  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 par-
                               ticular, if r is a single-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.   Otherwise,
                               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 functions 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 preceding 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 negative (the de-
                 fault), 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 de-
                 fault format is available 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 integers, doing the operation, and then  con-
       verting 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 bits.

       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 bits.

       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 arguments.

       isarray(x) Return true if x is an array, false otherwise.  This function 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'' locations (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  cate-
              gory.   The  default  value for domain is the current value of TEXTDOMAIN.  The de-
              fault 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 sup-
              ply 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 sup-
              ply a text domain.  Use TEXTDOMAIN if you want to use the current domain.

   Boolean Valued Functions
       You can create special Boolean-typed values; see the manual for how they work and why they
       exist.

       mkbool(expression)
              Based  on  the  boolean  value  of expression return either a true value or a false
              value.  True values have numeric value one.  False values have numeric value zero.

USER-DEFINED FUNCTIONS
       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  ac-
       tions.  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 provision 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  follow  the  function
       name, without any intervening whitespace.  This avoids a syntactic ambiguity with the con-
       catenation operator.  This restriction does not apply to  the  built-in  functions  listed
       above.

       Functions  may  call  each  other and may be recursive.  Function parameters 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 "falling 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 variable.  Then use the  variable  as  if  it
       were the name of a function, prefixed 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 ex-
       tension functions.

       If --lint has been provided, gawk warns about calls to undefined functions 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 deprecated.

DYNAMICALLY LOADING NEW FUNCTIONS
       You  can dynamically add new functions written in C or C++ to the running gawk interpreter
       with the @load statement.  The full details are beyond the scope of this manual page;  see
       GAWK: Effective AWK Programming.

SIGNALS
       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 pro-
       file and function call stack and then exit.

INTERNATIONALIZATION
       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  program.   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 underscores.

       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 pro-
           gram.

       5.  Provide appropriate translations, and build and install the corresponding .gmo files.

       The internationalization features are described in full detail in GAWK: Effective AWK Pro-
       gramming.

POSIX COMPATIBILITY
       A primary goal for gawk is compatibility with the POSIX standard, as well as with the lat-
       est 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 version 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 ear-
       lier implementations, when such an assignment appeared before any file names, the  assign-
       ment  would  happen  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 devel-
       opers and the GNU developers.)

       When  processing  arguments,  gawk uses the special option "--" to signal the end of argu-
       ments.  In compatibility mode, it warns about but otherwise 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 re-
       turn 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  Laborato-
       ries  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  Labo-
       ratories version).

HISTORICAL FEATURES
       There  is one feature of historical AWK implementations that gawk supports: It is possible
       to call the length() built-in function not only with no argument, but even without  paren-
       theses!  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.

GNU EXTENSIONS
       Gawk has a too-large number of extensions to POSIX awk.  They are described in  this  sec-
       tion.   All the extensions described here can be disabled by invoking gawk with the --tra-
       ditional 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 mechanism).

       +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.

       +o The ARGIND, BINMODE, ERRNO, LINT, PREC, ROUNDMODE, RT and TEXTDOMAIN 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 recognized.

       +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 texts.

       +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(), gen-
         sub(), 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() re-
       turns the value from fclose(3), or pclose(3), when closing an output file or pipe, respec-
       tively.  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 oc-
       cur  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' ....

ENVIRONMENT VARIABLES
       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 ap-
       pending .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  millisec-
       onds 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 re-
       tries, and GAWK_MSEC_SLEEP the interval between retries.  The interval is in milliseconds.
       On systems that do not support usleep(3), the value is rounded up to an integral number of
       seconds.

       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.

EXIT STATUS
       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.

VERSION INFORMATION
       This man page documents gawk, version 5.1.

AUTHORS
       The original version of UNIX awk was designed and implemented by Alfred Aho,  Peter  Wein-
       berger,  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 contrib-
       uted a number of bug fixes.  David Trueman, with contributions from Arnold  Robbins,  made
       gawk  compatible  with  the  new version of UNIX awk.  Arnold Robbins is the current main-
       tainer.

       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.

BUG REPORTS
       If you find a bug in gawk, please send electronic mail to  bug-gawk@gnu.org.   Please  in-
       clude  your  operating system and its revision, 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 setting the environment variable LC_ALL to LC_ALL=C causes things to behave as you  ex-
       pect.  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 oc-
       casionally 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.  In-
       stead, 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 maintainer.

BUGS
       The  -F option is not necessary given the command line variable assignment feature; it re-
       mains only for backwards compatibility.

SEE ALSO
       egrep(1), sed(1), getpid(2), getppid(2),  getpgrp(2),  getuid(2),  geteuid(2),  getgid(2),
       getegid(2), getgroups(2), printf(3), strftime(3), usleep(3)

       The  AWK Programming Language, Alfred V. Aho, Brian W. Kernighan, Peter J. Weinberger, Ad-
       dison-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 https://www.gnu.org/software/gawk/manual.

       The GNU gettext documentation, available online at https://www.gnu.org/software/gettext.

EXAMPLES
       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") }'

ACKNOWLEDGEMENTS
       Brian Kernighan provided valuable assistance during testing and debugging.  We thank him.

COPYING PERMISSIONS
       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 Foundation, 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 manual page into another
       language,  under  the  above conditions for modified versions, except that this permission
       notice may be stated in a translation approved by the Foundation.

Free Software Foundation                   Jul 05 2021                                    GAWK(1)