gawk man page on BSDi

Man page or keyword search:  
man Server   6284 pages
apropos Keyword Search (all sections)
Output format
BSDi logo
[printable version]



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 pro-
       gramming language.  It conforms to the definition  of  the
       language	 in  the POSIX 1003.2 Command Language And Utili-
       ties 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 Labs  awk	 extensions,  and
       some GNU-specific extensions.

       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.

OPTION FORMAT
       Gawk options may be either the traditional POSIX one  let-
       ter options, or the 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.

       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.	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.

OPTIONS
       Gawk accepts the following options.

       -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 block of  an  AWK

Free Software Foundation   Apr 28 1999				1

GAWK(1)			 Utility Commands		  GAWK(1)

	      program.

       -f program-file
       --file program-file
	      Read  the AWK program source from the file program-
	      file, instead of from the first command line  argu-
	      ment.  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 Labs research
	      version of UNIX awk.  They  are  ignored	by  gawk,
	      since gawk has no pre-defined limits.

       -W traditional
       -W compat
       --traditional
       --compat
	      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
	      information.

       -W copyleft
       -W copyright
       --copyleft
       --copyright
	      Print the short version of the GNU copyright infor-
	      mation  message  on  the standard output, and exits
	      successfully.

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

       -W lint
       --lint Provide  warnings about constructs that are dubious
	      or non-portable to other AWK implementations.

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

Free Software Foundation   Apr 28 1999				2

GAWK(1)			 Utility Commands		  GAWK(1)

       -W posix
       --posix
	      This  turns on compatibility mode, with the follow-
	      ing additional restrictions:

	      o \x escape sequences are not recognized.

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

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

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

	      o The fflush() function is not available.

       -W re-interval
       --re-interval
	      Enable  the  use of interval expressions in regular
	      expression  matching  (see   Regular   Expressions,
	      below).	Interval  expressions were not tradition-
	      ally available in the AWK language. The POSIX stan-
	      dard  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 func-
	      tions  (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
       --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 options 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 is mainly for consistency
	      with the argument parsing convention used	 by  most

Free Software Foundation   Apr 28 1999				3

GAWK(1)			 Utility Commands		  GAWK(1)

	      other POSIX programs.

       In  compatibility  mode,	 any other options are flagged as
       illegal, 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.

AWK PROGRAM EXECUTION
       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 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 will read 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
       programs.

       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 ``/'' charac-
       ter, 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 compiles the program into an inter-
       nal  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  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.

Free Software Foundation   Apr 28 1999				4

GAWK(1)			 Utility Commands		  GAWK(1)

       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 pattern in the AWK program.	For each  pattern
       that  the  record  matches,  the associated action is exe-
       cuted.  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).

VARIABLES, RECORDS AND FIELDS
       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.

   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  charac-
       ter, that character separates records.  Otherwise, RS is a
       regular expression.  Text in the input that  matches  this
       regular	expression will separate 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.

   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 sepa-
       rated 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 that the
       value of IGNORECASE  (see  below)  will	also  affect  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	 numbers,  each	 field	is expected to have fixed
       width, and gawk will split up the record using the  speci-
       fied widths.  The value of FS is ignored.  Assigning a new
       value to FS overrides the use of FIELDWIDTHS, and restores

Free Software Foundation   Apr 28 1999				5

GAWK(1)			 Utility Commands		  GAWK(1)

       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.  The
       value  of a field may be assigned to as well.  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
       record.

       References to non-existent fields (i.e. fields after  $NF)
       produce the null-string. However, assigning to a non-exis-
       tent field (e.g., $(NF+2) = 5) will increase the value  of
       NF,  create any intervening fields with the null string as
       their value, and cause the value of $0 to  be  recomputed,
       with the fields being separated by the value of OFS.  Ref-
       erences 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.

   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.

       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., ENVIRON["HOME"]
		   might be /home/arnold).  Changing  this  array
		   does	 not  affect the environment seen by pro-
		   grams which gawk spawns via redirection or the
		   system()  function.	 (This	may  change  in a
		   future version of gawk.)

Free Software Foundation   Apr 28 1999				6

GAWK(1)			 Utility Commands		  GAWK(1)

       ERRNO	   If a system error occurs either doing a  redi-
		   rection  for	 getline,  during a read for get-
		   line, or during a  close(),	then  ERRNO  will
		   contain a string describing the error.

       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 separator.	The fixed
		   field  width	 facility  is still experimental;
		   the semantics may change as gawk evolves  over
		   time.

       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 block.

       FNR	   The input record number in the  current  input
		   file.

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

       IGNORECASE  Controls the case-sensitivity of  all  regular
		   expression  and  string operations. If IGNORE-
		   CASE has a non-zero value, then string compar-
		   isons  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() pre-defined functions will
		   all ignore case when doing regular  expression
		   operations.	 Thus, if IGNORECASE is not equal
		   to zero, /aB/ matches all of the strings "ab",
		   "aB",  "Ab",	 and "AB".  As with all AWK vari-
		   ables, 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 character
		   set is used when ignoring case.  NOTE: In ver-
		   sions  of  gawk  prior to 3.0, IGNORECASE only
		   affected regular expression operations. It now
		   affects string comparisons as well.

       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

Free Software Foundation   Apr 28 1999				7

GAWK(1)			 Utility Commands		  GAWK(1)

		   default.

       ORS	   The output record separator, by default a new-
		   line.

       RS	   The input record separator, by default a  new-
		   line.

       RT	   The	record	terminator.   Gawk sets RT to the
		   input text that matched the character or regu-
		   lar expression specified by RS.

       RSTART	   The	index  of  the first character matched by
		   match(); 0 if no match.

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

       SUBSEP	   The	character  used to separate multiple sub-
		   scripts in array elements, by default  "\034".

   Arrays
       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 multi-
       ply 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 associative, i.e. indexed by string val-
       ues.

       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.

Free Software Foundation   Apr 28 1999				8

GAWK(1)			 Utility Commands		  GAWK(1)

   Variable Typing And Conversion
       Variables  and  fields may be (floating point) numbers, or
       strings, or both. How the value of a  variable  is  inter-
       preted  depends	upon  its  context.  If used in a numeric
       expression, it will be treated as a number, if used  as	a
       string it will be treated as a string.

       To  force  a  variable to be treated as a number, add 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 conver-
       sion is accomplished using atof(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 vari-
       able 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 numeri-
       cally.  Otherwise, the numeric value  is	 converted  to	a
       string  and a string comparison is performed.  Two strings
       are compared, of course, as  strings.   According  to  the
       POSIX standard, even if two strings are numeric strings, a
       numeric comparison is performed.	 However, this is clearly
       incorrect, and gawk does not do this.

       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).

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 will be executed for  every  single
       record of input.	 A missing action is equivalent to

Free Software Foundation   Apr 28 1999				9

GAWK(1)			 Utility Commands		  GAWK(1)

	      { 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 statements themselves.

   Patterns
       AWK patterns may be one of the following:

	      BEGIN
	      END
	      /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  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 state-
       ment 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 actions.  These generally
       test whether certain fields match certain regular  expres-
       sions.

Free Software Foundation   Apr 28 1999			       10

GAWK(1)			 Utility Commands		  GAWK(1)

       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 combin-
       ing more primitive pattern expressions. As  in  most  lan-
       guages,	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  com-
       bine 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 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

Free Software Foundation   Apr 28 1999			       11

GAWK(1)			 Utility Commands		  GAWK(1)

		  the braces, the preceding regexp 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  begin-
		  ning 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 underscore).

       \W	  matches any character	 that  is  not	word-con-
		  stituent.

       \`	  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 below) are also legal 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 characters 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  regexp  inside  the
       brackets	 of  a character list.	Character classes consist
       of [:, a keyword denoting the class, and :].  Here are the
       character classes defined by the POSIX standard.

       [:alnum:]
	      Alphanumeric characters.

       [:alpha:]
	      Alphabetic characters.

Free Software Foundation   Apr 28 1999			       12

GAWK(1)			 Utility Commands		  GAWK(1)

       [: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 con-
	      trol characters.)

       [:punct:]
	      Punctuation characters  (characters  that	 are  not
	      letter,  digits, control characters, or space char-
	      acters).

       [: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 alphanu-
       meric  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.	With  the
       POSIX  character classes, you can write /[[:alnum:]]/, and
       this will match all 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  sev-
       eral  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 symbols is a multi-character collating

Free Software Foundation   Apr 28 1999			       13

GAWK(1)			 Utility Commands		  GAWK(1)

	      element enclosed in [.  and .].  For example, if ch
	      is  a collating element, then [[.ch.]]  is a regexp
	      that matches this collating element, while [ch]  is
	      a regexp 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 regexp that
	      matches any of
	       .BR e ,
	       .BR e' , or
	       .BR 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 charac-
       ter  classes;  they  do not recognize collating symbols or
       equivalence classes.

       The \y, \B, \<, \>, \w, \W, \`, and \' operators are  spe-
       cific  to gawk; they are extensions based on facilities in
       the GNU regexp libraries.

       The various command line options control how  gawk  inter-
       prets characters in regexps.

       No options
	      In  the  default case, gawk provide all the facili-
	      ties of POSIX regexps and the GNU regexp	operators
	      described above.	However, interval expressions are
	      not supported.

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

       --traditional
	      Traditional Unix awk regexps are matched.	 The  GNU
	      operators are not special, interval expressions are
	      not available, 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 reg-
	      exp metacharacters.

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

Free Software Foundation   Apr 28 1999			       14

GAWK(1)			 Utility Commands		  GAWK(1)

   Actions
       Action statements are enclosed in braces, { and }.  Action
       statements consist of the usual	assignment,  conditional,
       and looping statements found in most languages. The opera-
       tors,  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 post-
		   fix.

       ^	   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 expression is expr2, other-
		   wise it is expr3.  Only one of expr2 and expr3
		   is evaluated.

Free Software Foundation   Apr 28 1999			       15

GAWK(1)			 Utility Commands		  GAWK(1)

       = += -=
       *= /= %= ^= 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 }

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

       close(file)	     Close file (or pipe, see below).

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

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

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

       getline var <file     Set var from next record of file.

       next		     Stop processing  the  current  input
			     record.  The  next	 input	record is
			     read and processing starts over with
			     the  first	 pattern  in the AWK pro-
			     gram. If the end of the  input  data
			     is	 reached,  the	END  block(s), if
			     any, are executed.

       nextfile		     Stop processing  the  current  input
			     file.   The  next	input record read
			     comes  from  the  next  input  file.
			     FILENAME and ARGIND are updated, FNR
			     is reset to 1, and processing starts
			     over  with	 the first pattern in the
			     AWK program. If the end of the input
			     data  is  reached, the END block(s),
			     if any, are executed.  NOTE: Earlier

Free Software Foundation   Apr 28 1999			       16

GAWK(1)			 Utility Commands		  GAWK(1)

			     versions  of gawk used next file, as
			     two words. While this usage is still
			     recognized,  it  generates a warning
			     message  and  will	  eventually   be
			     removed.

       print		     Prints the current record.	 The out-
			     put record is  terminated	with  the
			     value of the ORS variable.

       print expr-list	     Prints expressions.  Each expression
			     is separated by the value of the OFS
			     variable.	The output record is ter-
			     minated with the value  of	 the  ORS
			     variable.

       print expr-list >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 sys-
			     tems.)

       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.

       Other input/output  redirections	 are  also  allowed.  For
       print and printf, >>file appends output to the file, while
       | command writes on a pipe.  In a similar fashion, command
       |  getline  pipes  into getline.	 The getline command will
       return 0 on end of file, and -1 on an error.

   The printf Statement
       The AWK versions of the	printf	statement  and	sprintf()
       function (see below) accept the following conversion spec-
       ification 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,

Free Software Foundation   Apr 28 1999			       17

GAWK(1)			 Utility Commands		  GAWK(1)

	      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
	      nonsignificant zeros  suppressed.	  The  %G  format
	      uses %E instead of %e.

       %o     An unsigned octal number (again, an integer).

       %s     A character string.

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

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

       There are optional, additional  parameters  that	 may  lie
       between the % and the control letter:

       -      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 let-
	      ters.  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 will always  contain
	      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

Free Software Foundation   Apr 28 1999			       18

GAWK(1)			 Utility Commands		  GAWK(1)

	      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 signif-
	      icant digits.  For the %d, %o, %i, %u, %x,  and  %X
	      formats,	it specifies the minimum number of digits
	      to print.	 For a string, it specifies  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 will cause  their  values
       to be taken from the argument list to printf or sprintf().

   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).  Other  special
       filenames  provide access to information about the running
       gawk process.  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 current process, in decimal, termi-
		   nated with a newline.

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

       /dev/user   Reading this file returns a single record ter-
		   minated  with a newline.  The fields are sepa-
		   rated 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.

Free Software Foundation   Apr 28 1999			       19

GAWK(1)			 Utility Commands		  GAWK(1)

       /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"

       These  file  names may also be used on the command line to
       name data files.

   Numeric Functions
       AWK has the following pre-defined 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 between 0 and 1.

       sin(expr)     returns  the sine of expr, which is in radi-
		     ans.

       sqrt(expr)    the square root function.

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

   String Functions
       Gawk has the following pre-defined string functions:

       gensub(r, s, h [, t])   search the  target  string  t  for

Free Software Foundation   Apr 28 1999			       20

GAWK(1)			 Utility Commands		  GAWK(1)

			       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 no t is  sup-
			       plied, $0 is used instead.  Within
			       the  replacement	  text	 s,   the
			       sequence	 \n,  where  n is a digit
			       from 1 to 9, may be used to  indi-
			       cate  just  the	text that matched
			       the n'th parenthesized  subexpres-
			       sion.  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	&.  See AWK Language Pro-
			       gramming for a  fuller  discussion
			       of  the	rules  for  &'s and back-
			       slashes in the replacement text of
			       sub(), gsub(), and gensub().

       index(s, t)	       returns	the index of the string t
			       in the string s, or 0 if t is  not
			       present.

       length([s])	       returns	the  length of the string
			       s, or the length of $0 if s is not
			       supplied.

       match(s, r)	       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.

       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.

Free Software Foundation   Apr 28 1999			       21

GAWK(1)			 Utility Commands		  GAWK(1)

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

       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 corre-
			       sponding 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  corre-
			       sponding	 upper-case counterparts.
			       Non-alphabetic characters are left
			       unchanged.

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

       systime() returns the current time of day as the number of
		 seconds  since	 the Epoch (Midnight UTC, January
		 1, 1970 on POSIX systems).

       strftime([format [, timestamp]])
		 formats timestamp according to the specification
		 in  format.  The timestamp should be of the same
		 form as returned by systime().	 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) will be used.  See the
		 specification for  the	 strftime()  function  in
		 ANSI C for the format conversions that are guar-
		 anteed 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.

   String Constants
       String  constants  in  AWK  are	sequences  of  characters

Free Software Foundation   Apr 28 1999			       22

GAWK(1)			 Utility Commands		  GAWK(1)

       enclosed	 between  double quotes ("). Within strings, cer-
       tain escape sequences are recognized, as in C. These are:

       \\   A literal backslash.

       \a   The ``alert'' character; usually the ASCII BEL  char-
	    acter.

       \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 hexadeci-
	    mal digits following the \x.  As in ANSI C, all  fol-
	    lowing  hexadecimal digits are considered part of the
	    escape sequence.  (This feature should tell us  some-
	    thing  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 reg-
       ular expressions (e.g., /[ \t\f\n\r\v]/ matches whitespace
       characters).

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

FUNCTIONS
       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 parame-
       ters 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

Free Software Foundation   Apr 28 1999			       23

GAWK(1)			 Utility Commands		  GAWK(1)

       value.

       Since functions were not originally part of the	AWK  lan-
       guage, 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 & b are local
	      {
		   .....
	      }

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

       The  left  parenthesis  in  a function call is required to
       immediately follow the function name, without  any  inter-
       vening  white space.  This is to avoid a syntactic ambigu-
       ity 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.  Func-
       tion parameters used as local variables are initialized to
       the  null string and the number zero upon function invoca-
       tion.

       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 will warn 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.

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):

Free Software Foundation   Apr 28 1999			       24

GAWK(1)			 Utility Commands		  GAWK(1)

	    { print NR, $0 }

SEE ALSO
       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.

       AWK Language Programming, Edition 1.0,  published  by  the
       Free Software Foundation, 1995.

POSIX COMPATIBILITY
       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 incorporates the following user visible
       features which are not described in the AWK book, but  are
       part of the Bell Labs version of awk, and are in the POSIX
       standard.

       The -v option for assigning variables before program  exe-
       cution  starts  is  new.	  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,  this
       option was added to accommodate applications that depended
       upon the old behavior.  (This feature was agreed	 upon  by
       both the AT&T and GNU developers.)

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

       When processing arguments, gawk uses  the  special  option
       ``--''  to  signal the end of arguments.	 In compatibility
       mode, it will warn about, but otherwise ignore,	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
       AT&T's); the tolower() and  toupper()  built-in	functions
       (from  AT&T);  and the ANSI C conversion specifications in
       printf (done first in AT&T's version).

Free Software Foundation   Apr 28 1999			       25

GAWK(1)			 Utility Commands		  GAWK(1)

GNU EXTENSIONS
       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	 --tradi-
       tional option.

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

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

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

	      o The systime(),	strftime(),  and  gensub()  func-
		tions.

	      o The special file names available for I/O redirec-
		tion are not recognized.

	      o The ARGIND, ERRNO, and RT variables are not  spe-
		cial.

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

	      o The FIELDWIDTHS variable  and  fixed-width  field
		splitting.

	      o The use of RS as a regular expression.

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

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

	      o The use of delete array to delete the entire con-
		tents of an array.

       The  AWK	 book  does  not  define  the return value of the
       close() function.  Gawk's close() returns the  value  from
       fclose(3),  or  pclose(3),  when	 closing  a file or pipe,
       respectively.

       When gawk is invoked with the --traditional option, if the
       fs argument to the -F option is ``t'', then FS will be 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

Free Software Foundation   Apr 28 1999			       26

GAWK(1)			 Utility Commands		  GAWK(1)

       special case, it is not the default behavior.  This behav-
       ior also does not occur if --posix has been specified.  To
       really  get  a tab character as the field separator, it is
       best to use quotes: gawk -F'\t' ....

HISTORICAL FEATURES
       There are two features of historical  AWK  implementations
       that  gawk  supports.   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 will issue a warning about its  use  if
       --lint is specified on the command line.

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

ENVIRONMENT VARIABLES
       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 will
       issue a warning message to this effect.

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

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

       If your system actually has support for	/dev/fd	 and  the
       associated /dev/stdin, /dev/stdout, and /dev/stderr files,
       you may get different output from gawk than you would  get
       on  a  system  without  those files.  When gawk interprets
       these files internally,	it  synchronizes  output  to  the
       standard	 output	 with  output  to /dev/stdout, while on a
       system with those files, the output is actually to differ-
       ent open files.	Caveat Emptor.

       Syntactically  invalid  single  character programs tend to
       overflow the parse stack, generating  a	rather	unhelpful

Free Software Foundation   Apr 28 1999			       27

GAWK(1)			 Utility Commands		  GAWK(1)

       message.	  Such	programs  are  surprisingly  difficult to
       diagnose in the completely general case, and the effort to
       do so really is not worth it.

VERSION INFORMATION
       This man page documents gawk, version 3.0.4.

AUTHORS
       The  original  version of UNIX awk was designed and imple-
       mented  by  Alfred  Aho,	 Peter	Weinberger,   and   Brian
       Kernighan  of AT&T Bell Labs. Brian Kernighan continues to
       maintain and enhance it.

       Paul Rubin and Jay Fenlason, of the Free Software  Founda-
       tion,  wrote gawk, to be compatible with the original ver-
       sion of awk distributed in  Seventh  Edition  UNIX.   John
       Woods  contributed  a number of bug fixes.  David Trueman,
       with contributions from Arnold Robbins, made gawk compati-
       ble  with  the new version of UNIX awk.	Arnold Robbins is
       the current 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  Darrel
       Hankerson.  Fred Fish supplied support for the Amiga.

BUG REPORTS
       If  you find a bug in gawk, please send electronic mail to
       bug-gnu-utils@gnu.org,	with	a    carbon    copy    to
       arnold@gnu.org.	 Please include your operating system and
       its revision, the version of gawk,  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  refer-
       ence  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 unre-
       liable  way  to report bugs. Instead, please use the elec-
       tronic mail addresses given above.

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

Free Software Foundation   Apr 28 1999			       28

GAWK(1)			 Utility Commands		  GAWK(1)

COPYING PERMISSIONS
       Copyright  (C))	1996,97,98,99  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 ver-
       sions  of this manual page under the conditions for verba-
       tim 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 permis-
       sion notice may be stated in a translation approved by the
       Foundation.

Free Software Foundation   Apr 28 1999			       29

[top]

List of man pages available for BSDi

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net