Quick ?s
Cheat Sheets
Man Pages
The Lynx
GAWK(1) 		       Utility Commands 		       GAWK(1)

       gawk - pattern scanning and processing language

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

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

       Gawk  is  the  GNU Projects implementation of the AWK programming lan
       guage.  It conforms to the definition of  the  language	in  the  POSIX
       1003.2  Command	Language And Utilities Standard.  This version in turn
       is based on the description in The AWK Programming  Language,  by  Aho,
       Kernighan,  and	Weinberger,  with the additional features found in the
       System V Release 4 version of UNIX awk.	Gawk also provides more recent
       Bell  Laboratories  awk extensions, and a number of GNU-specific exten

       Pgawk is the profiling version of gawk.	It is identical in  every  way
       to  gawk,  except  that	programs run more slowly, and it automatically
       produces an execution profile in the file awkprof.out when  done.   See
       the --profile option, below.

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

       Gawk options may be either traditional POSIX 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-spe
       cific features and for POSIX-mandated features.

       Following the POSIX standard, gawk-specific options  are  supplied  via
       arguments  to  the -W option.  Multiple -W options may be supplied Each
       -W option has a corresponding long option, as  detailed	below.	 Argu
       ments  to  long options are either joined with the option by an = sign,
       with no intervening spaces, or they may be provided in the next command
       line  argument.	Long options may be abbreviated, as long as the abbre
       viation remains unique.

       Gawk accepts the following options, listed alphabetically.

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

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

       -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.

       -mf NNN
       -mr NNN
	      Set various memory limits to the value NNN.  The f flag sets the
	      maximum number of fields, and the r flag sets the maximum record
	      size.  These two flags and the -m option are from the Bell Labo
	      ratories research version of UNIX  awk.	They  are  ignored  by
	      gawk, since gawk has no pre-defined limits.

       -W compat
       -W traditional
	      Run  in compatibility mode.  In compatibility mode, gawk behaves
	      identically to UNIX awk; none of the GNU-specific extensions are
	      recognized.   The  use  of  --traditional  is preferred over the
	      other forms of this option.  See GNU EXTENSIONS, below, for more

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

       -W 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 program with a lot of functions,
	      and  you want to be sure that your functions dont inadvertently
	      use global variables that you meant to be  local.   (This  is  a
	      particularly  easy  mistake  to  make with simple variable names
	      like i, j, and so on.)

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

       -W gen-po
	      Scan and parse the AWK program, and generate a  GNU  .po	format
	      file on standard output with entries for all localizable strings
	      in the program.  The program itself is not  executed.   See  the
	      GNU gettext distribution for more information on .po files.

       -W help
       -W usage
	      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.)

       -W lint[=value]
	      Provide  warnings  about	constructs  that  are  dubious or non-
	      portable	to  other  AWK	implementations.   With  an   optional
	      argument	of fatal, lint warnings become fatal errors.  This may
	      be drastic, but its use will certainly encourage the development
	      of  cleaner AWK programs.  With an optional argument of invalid,
	      only warnings about things that are actually invalid are issued.
	      (This is not fully implemented yet.)

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

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

       -W posix
	      This  turns on compatibility mode, with the following additional

	       \x escape sequences are not recognized.

	       Only space and tab act as field separators when FS is set to a
		single space, newline does not.

	       You cannot continue lines after ?  and :.

	       The synonym func for the keyword function is not recognized.

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

	       The fflush() function is not available.

       -W profile[=prof_file]
	      Send profiling data to prof_file.  The default  is  awkprof.out.
	      When  run with gawk, the profile is just a pretty printed ver
	      sion of the program.  When run with pgawk, the profile  contains
	      execution  counts  of  each statement in the program in the left
	      margin and function call counts for each user-defined  function.

       -W 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.   However, their use is likely to break old AWK programs,
	      so gawk only provides them  if  they  are  requested  with  this
	      option, or when --posix is specified.

       -W source program-text
       --source program-text
	      Use program-text as AWK program source code.  This option allows
	      the easy intermixing of library functions (used via the  -f  and
	      --file  options)	with  source code entered on the command line.
	      It is intended primarily for medium to large AWK	programs  used
	      in shell scripts.

       -W 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 Stan
	      dards, these options cause an immediate, successful exit.)

       --     Signal the end of options. This is useful to allow further argu
	      ments  to  the  AWK program itself to start with a -.  This is
	      mainly for consistency with the argument parsing convention used
	      by most other POSIX programs.
       In  compatibility  mode,  any other options are flagged as invalid, but
       are otherwise ignored.  In normal operation, as long  as  program  text
       has  been supplied, unknown options are passed on to the AWK program in
       the ARGV array for processing.  This is particularly useful for running
       AWK programs via the #! executable interpreter mechanism.
       An  AWK program consists of a sequence of pattern-action statements and
       optional function definitions.
	      pattern	{ action statements }
	      function name(parameter list) { statements }
       Gawk first reads the program source from the program-file(s) if	speci
       fied, from arguments to --source, or from the first non-option argument
       on the command line.  The -f and --source options may be used  multiple
       times  on  the command line.  Gawk reads the program text as if all the
       program-files and command  line	source	texts  had  been  concatenated
       together.   This  is  useful  for  building libraries of AWK functions,
       without having to include them in each new AWK program that uses  them.
       It also provides the ability to mix library functions with command line
       The environment variable AWKPATH specifies a search path  to  use  when
       finding	source	files named with the -f option.  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.
       Gawk executes AWK programs in the following order.  First, all variable
       assignments specified via the -v option are performed.  Next, gawk com
       piles  the program into an internal form.  Then, gawk executes the code
       in the BEGIN block(s) (if any), and then proceeds  to  read  each  file
       named  in  the  ARGV array.  If there are no files named on the command
       line, gawk reads the standard input.
       If a filename on the command line has the form var=val it is treated as
       a  variable  assignment.   The  variable var will be assigned the value
       val.  (This happens after any BEGIN block(s) have been  run.)   Command
       line  variable assignment is most useful for dynamically assigning val
       ues to the variables AWK uses to  control  how  input  is  broken  into
       fields  and records.  It is also useful for controlling state if multi
       ple passes are needed over a single data file.
       If the value of a particular element of ARGV is empty (""), gawk  skips
       over it.
       For  each record in the input, gawk tests to see if it matches any pat
       tern in the AWK program.  For each pattern that the record matches, the
       associated  action  is  executed.  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 block(s) (if any).
       AWK variables are dynamic; they come into existence when they are first
       used.  Their values are either floating-point numbers  or  strings,  or
       both,  depending  upon how they are used.  AWK also has one dimensional
       arrays; arrays with multiple dimensions may be simulated.  Several pre-
       defined variables are set as a program runs; these will be described as
       needed and summarized below.
       Normally, records are separated by newline characters.  You can control
       how  records are separated by assigning values to the built-in variable
       RS.  If RS is any single character, that character  separates  records.
       Otherwise,  RS is a regular expression.	Text in the input that matches
       this  regular   expression   separates	the   record.	 However,   in
       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  blank  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.
       As each input record is read, gawk splits the record into fields, using
       the value of the FS variable as the field separator.  If FS is a single
       character,  fields  are separated by that character.  If FS is the null
       string, then each individual character becomes a separate field.   Oth
       erwise, FS is expected to be a full regular expression.	In the special
       case that FS is a single space, fields are separated by runs of	spaces
       and/or  tabs  and/or  newlines.	 (But  see  the discussion of --posix,
       below).	NOTE: The value of IGNORECASE (see  below)  also  affects  how
       fields  are  split when FS is a regular expression, and how records are
       separated when RS is a regular expression.
       If the FIELDWIDTHS variable is set to a space separated	list  of  num
       bers,  each  field  is expected to have fixed width, and gawk splits up
       the record using the specified widths.  The value  of  FS  is  ignored.
       Assigning  a  new  value  to  FS  overrides the use of FIELDWIDTHS, and
       restores the default behavior.
       Each field in the input record may be referenced by its	position,  $1,
       $2,  and so on.	$0 is the whole record.  Fields need not be referenced
       by constants:
	      n = 5
	      print $n
       prints the fifth field in the input record.
       The variable NF is set to the total  number  of	fields	in  the  input
       References  to  non-existent fields (i.e. fields after $NF) produce the
       null-string.  However, assigning to a non-existent field (e.g., $(NF+2)
       = 5) increases the value of NF, creates any intervening fields with the
       null string as their value, and causes the value of  $0	to  be	recom
       puted, with the fields being separated by the value of OFS.  References
       to negative numbered fields  cause  a  fatal  error.   Decrementing  NF
       causes  the  values  of	fields	past the new value to be lost, and the
       value of $0 to be recomputed, with the fields being  separated  by  the
       value of OFS.
       Assigning  a  value  to an existing field causes the whole record to be
       rebuilt when $0 is referenced.  Similarly,  assigning  a  value	to  $0
       causes the record to be resplit, creating new values for the fields.
   Built-in Variables
       Gawks built-in variables are:
       ARGC	   The	number	of  command  line  arguments (does not include
		   options to gawk, or the program source).
       ARGIND	   The index in ARGV of the current file being processed.
       ARGV	   Array of command line arguments.  The array is indexed from
		   0  to  ARGC - 1.  Dynamically changing the contents of ARGV
		   can control the files used for data.
       BINMODE	   On non-POSIX systems, specifies use of  binary  mode  for
		   all	file  I/O.  Numeric values of 1, 2, or 3, specify that
		   input files, output	files,	or  all  files,  respectively,
		   should  use binary I/O.  String values of "r", or "w" spec
		   ify that input files, or output files, respectively, should
		   use binary I/O.  String values of "rw" or "wr" specify that
		   all files should use binary I/O.  Any other string value is
		   treated as "rw", but generates a warning message.
       CONVFMT	   The conversion format for numbers, "%.6g", by default.
       ENVIRON	   An  array containing the values of the current environment.
		   The array is indexed by  the  environment  variables,  each
		   element  being  the	value  of  that  variable (e.g., ENVI
		   RON["HOME"] might be /home/arnold).	 Changing  this  array
		   does not affect the environment seen by programs which gawk
		   spawns via redirection or the system() function.
       ERRNO	   If a system error occurs either  doing  a  redirection  for
		   getline,  during  a	read for getline, or during a close(),
		   then ERRNO will contain a string describing the error.  The
		   value is subject to translation in non-English locales.
       FIELDWIDTHS A  white-space  separated  list  of fieldwidths.  When set,
		   gawk parses the input into fields of fixed  width,  instead
		   of  using the value of the FS variable as the field separa
       FILENAME    The name of the current input file.	If no files are speci
		   fied  on  the  command  line, the value of FILENAME is -.
		   However, FILENAME  is  undefined  inside  the  BEGIN  block
		   (unless set by getline).
       FNR	   The input record number in the current input file.
       FS	   The input field separator, a space by default.  See Fields,
       IGNORECASE  Controls the case-sensitivity of all regular expression and
		   string  operations.	 If  IGNORECASE  has a non-zero value,
		   then string comparisons  and  pattern  matching  in	rules,
		   field splitting with FS, record separating with RS, regular
		   expression matching	with  ~  and  !~,  and	the  gensub(),
		   gsub(), index(), match(), split(), and sub() built-in func
		   tions all ignore case when doing regular expression	opera
		   tions.  NOTE: Array subscripting is not affected.  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 normally case-
		   sensitive.  Under Unix, the full ISO 8859-1 Latin-1 charac
		   ter	set is used when ignoring case.  As of gawk 3.1.4, the
		   case equivalencies are fully locale-aware, based on	the  C
		    facilities such as isalpha(), and tolupper().
       LINT	   Provides  dynamic  control of the --lint option from within
		   an AWK program.  When true, gawk prints lint warnings. When
		   false,  it  does  not.   When  assigned  the  string  value
		   "fatal", lint warnings become fatal	errors,  exactly  like
		   --lint=fatal.  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.
       PROCINFO    The	elements  of  this array provide access to information
		   about the running AWK program.  On some systems, there  may
		   be  elements  in  the  array, "group1" through "groupn" for
		   some n, which is the number of  supplementary  groups  that
		   the	process  has.	Use  the in operator to test for these
		   elements.  The following  elements  are  guaranteed	to  be
		   PROCINFO["egid"]   the value of the getegid(2) system call.
		   PROCINFO["euid"]   the value of the geteuid(2) system call.
		   PROCINFO["FS"]     "FS"  if	field  splitting with FS is in
				      effect, or "FIELDWIDTHS" if field split
				      ting with FIELDWIDTHS is in effect.
		   PROCINFO["gid"]    the  value of the getgid(2) system call.
		   PROCINFO["pgrpid"] the process group ID of the current pro
		   PROCINFO["pid"]    the process ID of the current process.
		   PROCINFO["ppid"]   the  parent  process  ID	of the current
		   PROCINFO["uid"]    the value of the getuid(2) system  call.
				      The  version of gawk.  This is available
				      from version 3.1.4 and later.
       RS	   The input record separator, by default a newline.
       RT	   The record terminator.  Gawk sets RT to the input text that
		   matched  the  character  or regular expression specified by
       RSTART	   The index of the first character matched by match();  0  if
		   no  match.	(This  implies that character indices start at
       RLENGTH	   The length of the string  matched  by  match();  -1	if  no
       SUBSEP	   The character used to separate multiple subscripts in array
		   elements, by default "\034".
       TEXTDOMAIN  The text domain of the AWK program; used to find the local
		   ized translations for the programs strings.
       Arrays  are  subscripted  with an expression between square brackets ([
       and ]).	If the expression is an expression list (expr, expr ...)  then
       the  array subscript is a string consisting of the concatenation of the
       (string) value of each expression, separated by the value of the SUBSEP
       variable.   This  facility  is  used  to  simulate multiply dimensioned
       arrays.	For example:
	      i = "A"; j = "B"; k = "C"
	      x[i, j, k] = "hello, world\n"
       assigns the string "hello, world\n" to the element of the array x which
       is indexed by the string "A\034B\034C".	All arrays in AWK are associa
       tive, i.e. indexed by string values.
       The special operator in may be used in an if or while statement to  see
       if an array has an index consisting of a particular value.
	      if (val in array)
		   print array[val]
       If the array has multiple subscripts, use (i, j) in array.
       The in construct may also be used in a for loop to iterate over all the
       elements of an array.
       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.
   Variable Typing And Conversion
       Variables and fields may be (floating point) numbers,  or  strings,  or
       both.  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 0 to it; to force it
       to be treated as a string, concatenate it with the null string.
       When a string must be converted to a number, the conversion  is	accom
       plished	using  strtod(3).   A number is converted to a string by using
       the value of CONVFMT as	a  format  string  for	sprintf(3),  with  the
       numeric	value  of  the variable as the argument.  However, even though
       all numbers in AWK are floating-point, integral values are always  con
       verted as integers.  Thus, given
	      CONVFMT = "%2.2f"
	      a = 12
	      b = a ""
       the variable b has a string value of "12" and not "12.00".
       Gawk  performs  comparisons  as	follows: If two variables are numeric,
       they are compared numerically.  If one value is numeric and  the  other
       has  a  string  value  that is a numeric string, then comparisons are
       also done numerically.  Otherwise, the numeric value is converted to  a
       string and a string comparison is performed.  Two strings are compared,
       of course, as strings.  Note that the POSIX standard applies  the  con
       cept  of  numeric  string everywhere, even to string constants.	How
       ever, this is clearly incorrect, and gawk does not  do  this.   (Fortu
       nately, this is fixed in the next version of the standard.)
       Note that string constants, such as "57", are not numeric strings, they
       are string constants.  The idea of numeric  string  only  applies  to
       fields,	getline  input,  FILENAME, ARGV elements, ENVIRON elements and
       the elements of an array created by split() that are  numeric  strings.
       The  basic  idea  is  that  user input, and only user input, that looks
       numeric, should be treated that way.
       Uninitialized variables have the numeric value 0 and the  string  value
       "" (the null, or empty, string).
   Octal and Hexadecimal Constants
       Starting  with version 3.1 of gawk , you may use C-style octal and hex
       adecimal 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 (").  Within strings, certain escape sequences are recog
       nized, as in C.	These are:
       \\   A literal backslash.
       \a   The alert character; usually the ASCII BEL character.
       \b   backspace.
       \f   form-feed.
       \n   newline.
       \r   carriage return.
       \t   horizontal tab.
       \v   vertical tab.
       \xhex digits
	    The character represented by the string of hexadecimal digits fol
	    lowing the \x.  As in ANSI C, all following hexadecimal digits are
	    considered part of the escape sequence.  (This feature should tell
	    us something about language design by committee.)  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.
       The  escape  sequences may also be used inside constant regular expres
       sions (e.g., /[ \t\f\n\r\v]/ matches whitespace characters).
       In compatibility mode, the characters represented by octal and hexadec
       imal  escape  sequences	are  treated  literally  when  used in regular
       expression constants.  Thus, /a\52b/ is equivalent to /a\*b/.
       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 is executed 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.  Blank 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 ,, {, ?, :, &&, 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 will be ignored.
       Multiple statements may be put on one line by separating  them  with  a
       ;.   This  applies to both the statements within the action part of a
       pattern-action pair (the usual case), and to the pattern-action	state
       ments themselves.
       AWK patterns may be one of the following:
	      /regular expression/
	      relational expression
	      pattern && pattern
	      pattern || pattern
	      pattern ? pattern : pattern
	      ! pattern
	      pattern1, pattern2
       BEGIN  and  END	are two special kinds of patterns which are not tested
       against the input.  The action parts of all BEGIN patterns  are	merged
       as  if  all  the  statements  had been written in a single BEGIN block.
       They are executed before any of the input is read.  Similarly, all  the
       END blocks 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  patterns	in pattern expressions.  BEGIN and END
       patterns cannot have missing action parts.
       For /regular expression/ patterns, the associated statement is executed
       for  each  input  record  that matches the regular expression.  Regular
       expressions are the same as  those  in  egrep(1),  and  are  summarized
       A  relational  expression may use any of the operators defined below in
       the section on actions.	These generally test  whether  certain	fields
       match certain regular expressions.
       The  &&,  ||, and !  operators are logical AND, logical OR, and logical
       NOT, respectively, as in C.  They do short-circuit evaluation, also  as
       in  C,  and  are used for combining more primitive pattern expressions.
       As in most languages, parentheses may be used to change	the  order  of
       The  ?:	operator is like the same operator in C.  If the first pattern
       is true then the pattern used for testing is the second pattern, other
       wise  it  is  the  third.  Only one of the second and third patterns is
       The pattern1, pattern2 form of an expression is called a range pattern.
       It  matches  all input records starting with a record that matches pat
       tern1, and continuing until a record that matches pattern2,  inclusive.
       It does not combine with any other sort of pattern expression.
   Regular Expressions
       Regular	expressions  are  the  extended kind found in egrep.  They are
       composed of characters as follows:
       c	  matches the non-metacharacter c.
       \c	  matches the literal character c.
       .	  matches any character including newline.
       ^	  matches the beginning of a string.
       $	  matches the end of a string.
       [abc...]   character list, matches any of the characters abc....
       [^abc...]  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 rs.
       r*	  matches zero or more rs.
       r?	  matches zero or one rs.
       (r)	  grouping: matches r.
       r{n,m}	  One  or two numbers inside braces denote an interval expres
		  sion.  If there is one number in the braces,	the  preceding
		  regular  expression r is repeated n times.  If there are two
		  numbers separated by a comma, r is repeated n  to  m	times.
		  If  there  is  one  number  followed	by  a comma, then r is
		  repeated at least n times.
		  Interval expressions are only available if either --posix or
		  --re-interval is specified on the command line.

       \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.

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

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

       \	 matches  the  empty  string  at  the  beginning  of a buffer

       \	 matches the empty string at the end of a buffer.

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

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

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

       [:alnum:]  Alphanumeric characters.

       [:alpha:]  Alphabetic characters.

       [:blank:]  Space or tab characters.

       [:cntrl:]  Control characters.

       [:digit:]  Numeric characters.

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

       [:lower:]  Lower-case alphabetic characters.

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

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

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

       [:upper:]  Upper-case alphabetic characters.

       [:xdigit:] Characters that are hexadecimal digits.

       For  example,  before the POSIX standard, to match alphanumeric charac
       ters, you would have had to write /[A-Za-z0-9]/.  If your character set
       had  other  alphabetic characters in it, this would not match them, and
       if your character set collated differently from ASCII, this  might  not
       even match the ASCII alphanumeric characters.  With the POSIX character
       classes, you can write /[[:alnum:]]/, and this matches  the  alphabetic
       and numeric characters in your character set.

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

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

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

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

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

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

       No options
	      In the default case, gawk provide all the  facilities  of  POSIX
	      regular  expressions  and  the  GNU regular expression operators
	      described above.	However, interval  expressions	are  not  sup

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

	      Traditional  Unix  awk regular expressions are matched.  The GNU
	      operators are not special, interval expressions are  not	avail
	      able,  and  neither are the POSIX character classes ([[:alnum:]]
	      and so on).   Characters	described  by  octal  and  hexadecimal
	      escape  sequences  are treated literally, even if they represent
	      regular expression metacharacters.

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

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

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

       (...)	   Grouping

       $	   Field reference.

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

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

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

       * / %	   Multiplication, division, and modulus.

       + -	   Addition and subtraction.

       space	   String concatenation.

       < >
       <= >=
       != ==	   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 was intended.

       in	   Array membership.

       &&	   Logical AND.

       ||	   Logical OR.

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

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

   Control Statements
       The control statements are as follows:

	      if (condition) statement [ else statement ]
	      while (condition) statement
	      do statement while (condition)
	      for (expr1; expr2; expr3) statement
	      for (var in array) statement
	      delete array[index]
	      delete array
	      exit [ expression ]
	      { statements }

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

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

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

       getline file Prints  expressions  on file.  Each expression is
			     separated by the value of the OFS variable.   The
			     output record is terminated with the value of the
			     ORS variable.

       printf fmt, expr-list Format and print.

       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

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

       Additional output redirections are allowed for print and printf.

       print ... >> file
	      appends output to the file.

       print ... | command
	      writes on a pipe.

       print ... |& command
	      sends data to a co-process.

       The getline command returns 0 on end of file and -1 on an error.   Upon
       an error, ERRNO contains a string describing the problem.

       NOTE: If using a pipe or co-process to getline, or from print or printf
       within a loop, you must use close() to create new instances of the com
       mand.  AWK does not automatically close pipes or co-processes 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:

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

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

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

       %f      A floating point number of the form [-]ddd.dddddd.

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

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

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

       %s      A character string.

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

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

       NOTE: When using the integer format-control letters for values that are
       outside the range of a C long integer, gawk switches to the  %g	format
       specifier.  If  --lint is provided on the command line gawk warns about
       this.  Other versions of awk may print invalid values or  do  something
       else entirely.

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

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

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

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

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

       #      Use  an  alternate  form for certain control letters.  For %o,
	      supply a leading zero.  For %x, and %X, supply a leading	0x  or
	      0X  for a nonzero result.  For %e, %E, 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, that indicates output should
	      be padded with zeroes instead of spaces.	This applies  even  to
	      non-numeric  output  formats.  This flag only has an effect when
	      the field width is wider than the value to be printed.

       width  The field should be padded to this width.  The field is normally
	      padded  with  spaces.  If the 0 flag has been used, it is padded
	      with zeroes.

       .prec  A number that specifies the precision to use when printing.  For
	      the  %e, %E, 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, %o, %i, %u, %x, and %X formats,  it	speci
	      fies  the  minimum number of digits to print.  For %s, it speci
	      fies the maximum number  of  characters  from  the  string  that
	      should be printed.

       The dynamic width and prec capabilities of the ANSI C printf() routines
       are supported.  A * in place of either the width or prec specifications
       causes  their  values  to  be taken from the argument list to printf or
       sprintf().  To use a positional specifier with a dynamic width or  pre
       cision,	supply	the  count$  after  the  *  in the format string.  For
       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	gawks parent process (usually the shell).  These file
       names may also be used on the command line to  name  data  files.   The
       filenames are:

       /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 |& co-process
       operator for creating TCP/IP network connections.

       /inet/tcp/lport/rhost/rport  File for 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.

       /inet/udp/lport/rhost/rport  Similar, but use UDP/IP instead of TCP/IP.

       /inet/raw/lport/rhost/rport  Reserved for future use.

       Other special filenames provide access to information about the running
       gawk  process.	These  filenames  are  now obsolete.  Use the PROCINFO
       array to obtain the information they provide.  The filenames are:

       /dev/pid    Reading this file returns the process  ID  of  the  current
		   process, in decimal, terminated with a newline.

       /dev/ppid   Reading this file returns the parent process ID of the cur
		   rent process, in decimal, terminated with a newline.

       /dev/pgrpid Reading this file returns the process group ID of the  cur
		   rent process, in decimal, terminated with a newline.

       /dev/user   Reading this file returns a single record terminated with a
		   newline.  The fields are separated with spaces.  $1 is  the
		   value  of the getuid(2) system call, $2 is the value of the
		   geteuid(2) system call, $3 is the value  of	the  getgid(2)
		   system  call,  and $4 is the value of the getegid(2) system
		   call.  If there are any additional  fields,	they  are  the
		   group  IDs  returned  by getgroups(2).  Multiple groups may
		   not be supported on all systems.

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

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

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

       exp(expr)     The exponential function.

       int(expr)     Truncates to integer.

       log(expr)     The natural logarithm function.

       rand()	     Returns a random number N, between 0 and 1, such that 0
		     N < 1.

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

       sqrt(expr)    The square root function.

       srand([expr]) Uses  expr as a new seed for the random number generator.
		     If no expr is provided, the time of  day  is  used.   The
		     return  value  is the previous seed for the random number

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

       asort(s [, d])	       Returns the number of elements  in  the	source
			       array  s.   The	contents of s are sorted using
			       gawks normal rules for comparing  values,  and
			       the  indexes  of  the  sorted  values  of s are
			       replaced with sequential integers starting with
			       1. If the optional destination array d is spec
			       ified, then s is first duplicated into  d,  and
			       then  d	is  sorted, leaving the indexes of the
			       source array s unchanged.

       asorti(s [, d])	       Returns the number of elements  in  the	source
			       array  s.   The behavior is the same as that of
			       asort(), except that the array indices are used
			       for  sorting, not the array values.  When done,
			       the array is indexed numerically, and the  val
			       ues  are  those	of  the original indices.  The
			       original values are lost; thus provide a second
			       array if you wish to preserve the original.

       gensub(r, s, h [, t])   Search  the  target string t for matches of the
			       regular expression r.  If h is a string	begin
			       ning with g or G, then replace all matches of r
			       with s.	Otherwise, h is  a  number  indicating
			       which  match of r to replace.  If t is not sup
			       plied, $0 is used instead.  Within the replace
			       ment  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 nth 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 expres
			       sion  r	in the string t, substitute the string
			       s, and return the number of substitutions.   If
			       t  is  not  supplied,  use  $0.	 An  &	in the
			       replacement text is replaced with the text that
			       was  actually matched.  Use \& to get a literal
			       &.  (This must be typed	as  "\\&";  see  GAWK:
			       Effective  AWK Programming for a fuller discus
			       sion of the rules for &s  and  backslashes  in
			       the replacement text of sub(), gsub(), and gen

       index(s, t)	       Returns the index of the string t in the string
			       s,  or  0  if  t is not present.  (This implies
			       that character indices start at one.)

       length([s])	       Returns the length of  the  string  s,  or  the
			       length  of  $0  if s is not supplied.  Starting
			       with version 3.1.5, as  a  non-standard	exten
			       sion,  with an array argument, length() returns
			       the number of elements in the array.

       match(s, r [, a])       Returns the position in	s  where  the  regular
			       expression  r occurs, or 0 if r is not present,
			       and sets the  values  of  RSTART  and  RLENGTH.
			       Note that the argument order is the same as for
			       the ~ operator: str ~ re.  If array a  is  pro
			       vided, 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 0th element of a contains the  por
			       tion of s matched by the entire regular expres
			       sion r.	Subscripts  a[n,  "start"],  and  a[n,
			       "length"]  provide  the	starting  index in the
			       string and length respectively, of each	match
			       ing substring.

       split(s, a [, r])       Splits  the  string  s  into the array a on the
			       regular expression r, and returns the number of
			       fields.	 If  r is omitted, FS is used instead.
			       The  array  a  is  cleared  first.    Splitting
			       behaves	 identically   to   field   splitting,
			       described above.

       sprintf(fmt, expr-list) Prints expr-list according to fmt, and  returns
			       the resulting string.

       strtonum(str)	       Examines  str,  and  returns its numeric value.
			       If str begins  with  a  leading	0,  strtonum()
			       assumes	that  str  is an octal number.	If str
			       begins with a  leading  0x  or  0X,  strtonum()
			       assumes that str is a hexadecimal number.

       sub(r, s [, t])	       Just  like  gsub(), but only the first matching
			       substring is replaced.

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

       tolower(str)	       Returns a copy of the string str, with all  the
			       upper-case  characters  in  str	translated  to
			       their  corresponding  lower-case  counterparts.
			       Non-alphabetic characters are left unchanged.

       toupper(str)	       Returns	a copy of the string str, with all the
			       lower-case  characters  in  str	translated  to
			       their  corresponding  upper-case  counterparts.
			       Non-alphabetic characters are left unchanged.

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

		 Turns datespec into a time stamp of the same form as returned
		 by  systime().   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 respectively the full year includ
		 ing 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, and 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 cal
		 endar is assumed, with year 0 preceding year 1  and  year  -1
		 preceding  year  0.   The  time is assumed to be in the local
		 timezone.  If the 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  default),
		 mktime()  attempts  to determine whether daylight saving time
		 is in effect for the specified time.  If  datespec  does  not
		 contain  enough  elements  or if the resulting time is out of
		 range, mktime() returns -1.

       strftime([format [, timestamp]])
		 Formats timestamp according to the specification  in  format.
		 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.  See the specification for the
		 strftime() function in ANSI C for the format conversions that
		 are guaranteed to be available.  A public-domain  version  of
		 strftime(3)  and  a  man  page for it come with gawk; if that
		 version was used to build gawk, then all of  the  conversions
		 described in that man page are available to gawk.

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

   Bit Manipulations Functions
       Starting with version 3.1 of gawk, the following bit manipulation func
       tions are available.  They work by converting double-precision floating
       point values to unsigned long integers, doing the operation,  and  then
       converting the result back to floating point.  The functions are:

       and(v1, v2)	   Return the bitwise AND of the values provided by v1
			   and v2.

       compl(val)	   Return the bitwise complement of val.

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

       or(v1, v2)	   Return  the bitwise OR of the values provided by v1
			   and v2.

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

       xor(v1, v2)	   Return the bitwise XOR of the values provided by v1
			   and v2.

   Internationalization Functions
       Starting with version 3.1 of gawk, 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])
	      Specifies the directory where gawk looks for the .mo  files,  in
	      case they will not or cannot be placed in the standard loca
	      tions (e.g., during testing).  It returns  the  directory  where
	      domain is bound.
	      The  default domain is the value of TEXTDOMAIN.  If directory is
	      the null string (""), then bindtextdomain() returns the  current
	      binding for the given domain.

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

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

       Functions in AWK are defined as follows:

	      function name(parameter list) { statements }

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

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

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

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

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

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

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

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

       The word func may be used in place of function.

       Beginning with version 3.1 of gawk, you can dynamically add new	built-
       in  functions  to  the  running gawk interpreter.  The full details are
       beyond the scope of this manual page; see GAWK: Effective AWK  Program
       ming for the details.

       extension(object, function)
	       Dynamically  link  the  shared object file named by object, and
	       invoke function in  that  object,  to  perform  initialization.
	       These  should  both  be provided as strings.  Returns the value
	       returned by function.

       This function is provided and documented in GAWK:  Effective  AWK  Pro
       gramming,  but everything about this feature is likely to change in the
       next release.  We STRONGLY recommend that you do not use  this  feature
       for anything that you arent willing to redo.

       pgawk  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 contin
       ues to run.  SIGHUP causes it to dump the  profile  and	function  call
       stack and then exit.

       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") }

       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 native natural lan
       guage. Such strings are marked in the AWK program with a leading under
       score (_).  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 .mo 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 under

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

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

       5.  Provide appropriate translations, and build and  install  a	corre
	   sponding .mo file.

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

       A primary goal for gawk is compatibility with the  POSIX  standard,  as
       well  as with the latest version of UNIX awk.  To this end, gawk incor
       porates the following user visible features which are not described  in
       the AWK book, but are part of the Bell Laboratories 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 block is executed.  However,  in  earlier	implementations,  when
       such an assignment appeared before any file names, the assignment would
       happen before the BEGIN block 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  and  the  GNU

       The  -W	option	for implementation specific features is from the POSIX

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

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

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

       There are two features of historical AWK implementations that gawk sup
       ports.  First, it is possible to call the  length()  built-in  function
       not only with no argument, but even without parentheses!  Thus,

	      a = length     # Holy Algol 60, Batman!

       is the same as either of

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

       This  feature is marked as deprecated in the POSIX standard, and gawk
       issues a warning about its use if --lint is specified  on  the  command

       The other feature is the use of either the continue or the break state
       ments outside the body of a while, for, or do  loop.   Traditional  AWK
       implementations	have  treated  such  usage  as	equivalent to the next
       statement.  Gawk supports this usage if --traditional has  been	speci

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

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

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

	The \x escape sequence.  (Disabled with --posix.)

	The fflush() function.	(Disabled with --posix.)

	The ability to	continue  lines  after	?   and  :.   (Disabled  with

	Octal and hexadecimal constants in AWK programs.

	The ARGIND, BINMODE, ERRNO, LINT, RT and TEXTDOMAIN variables are not

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

	The FIELDWIDTHS variable and fixed-width field splitting.

	The PROCINFO array is not available.

	The use of RS as a regular expression.

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

	The |& operator for creating co-processes.

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

	The optional second argument to the close() function.

	The optional third argument to the match() function.

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

	The use of delete array to delete the entire contents of an array.

	The use of nextfile to abandon processing of the current input	file.

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

	Localizable strings.

	Adding	new built-in functions dynamically with the extension() func

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

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

       If  gawk is configured with the --enable-switch option to the configure
       command, then it accepts an additional control-flow statement:
	      switch (expression) {
	      case value|regex : statement
	      [ default: statement ]

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

       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.

       egrep(1), getpid(2),  getppid(2),  getpgrp(2),  getuid(2),  geteuid(2),
       getgid(2), getegid(2), getgroups(2)

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

       GAWK: Effective AWK Programming, Edition 3.0,  published  by  the  Free
       Software Foundation, 2001.

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

       Syntactically invalid single character programs tend  to  overflow  the
       parse  stack, generating a rather unhelpful message.  Such programs are
       surprisingly difficult to diagnose in the completely general case,  and
       the effort to do so really is not worth it.

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

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

       The initial DOS port was done  by  Conrad  Kwok	and  Scott  Garfinkle.
       Scott Deifik is the current DOS maintainer.  Pat Rankin did the port to
       VMS, and Michal Jaegermann did the port to the Atari ST.  The  port  to
       OS/2  was done by Kai Uwe Rommel, with contributions and help from Dar
       rel Hankerson.  Fred Fish  supplied  support  for  the  Amiga,  Stephen
       Davies  provided  the  Tandem  port, and Martin Brown provided the BeOS

       This man page documents gawk, version 3.1.5.

       If you find a  bug  in  gawk,  please  send  electronic	mail  to  bug-
       gawk@gnu.org.   Please  include your operating system and its revision,
       the version of gawk (from gawk --version), what 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 two 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 read this man page and the
       reference manual carefully to be sure that what	you  think  is	a  bug
       really is, instead of just a quirk in the language.

       Whatever  you do, do NOT post a bug report in comp.lang.awk.  While the
       gawk developers occasionally read this newsgroup, posting  bug  reports
       there  is  an  unreliable  way to report bugs.  Instead, please use the
       electronic mail addresses given above.

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

       Brian Kernighan of Bell Laboratories provided valuable assistance  dur
       ing testing and debugging.  We thank him.

       Copyright  1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
       2001, 2002, 2003, 2004, 2005 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 man
       ual page into another language, under the above conditions for modified
       versions,  except that this permission notice may be stated in a trans
       lation approved by the Foundation.

Free Software Foundation	 June 26 2005			       GAWK(1)

Yals.net is © 1999-2009 Crescendo Communications
Sharing tech info on the web for more than a decade!
This page was generated Thu Apr 30 17:05:20 2009