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CGI(3)		      User Contributed Perl Documentation		CGI(3)

NAME
       CGI - Handle Common Gateway Interface requests and responses

SYNOPSIS
	   use CGI;

	   my $q = CGI->new;

	   # Process an	HTTP request
	    @values  = $q->param('form_field');

	    $fh	     = $q->upload('file_field');

	    $riddle  = $query->cookie('riddle_name');
	    %answers = $query->cookie('answers');

	   # Prepare various HTTP responses
	   print $q->header();
	   print $q->header('application/json');

	       $cookie1	= $q->cookie(-name=>'riddle_name', -value=>"The	Sphynx's Question");
	       $cookie2	= $q->cookie(-name=>'answers', -value=>\%answers);
	   print $q->header(
	       -type	=> 'image/gif',
	       -expires	=> '+3d',
	       -cookie	=> [$cookie1,$cookie2]
	       );

	  print	 $q->redirect('http://somewhere.else/in/movie/land');

DESCRIPTION
       CGI.pm is a stable, complete and	mature solution	for processing and
       preparing HTTP requests and responses.  Major features including
       processing form submissions, file uploads, reading and writing cookies,
       query string generation and manipulation, and processing	and preparing
       HTTP headers. Some HTML generation utilities are	included as well.

       CGI.pm performs very well in in a vanilla CGI.pm	environment and	also
       comes with built-in support for mod_perl	and mod_perl2 as well as
       FastCGI.

       It has the benefit of having developed and refined over 10 years	with
       input from dozens of contributors and being deployed on thousands of
       websites.  CGI.pm has been included in the Perl distribution since Perl
       5.4, and	has become a de-facto standard.

   PROGRAMMING STYLE
       There are two styles of programming with	CGI.pm,	an object-oriented
       style and a function-oriented style.  In	the object-oriented style you
       create one or more CGI objects and then use object methods to create
       the various elements of the page.  Each CGI object starts out with the
       list of named parameters	that were passed to your CGI script by the
       server.	You can	modify the objects, save them to a file	or database
       and recreate them.  Because each	object corresponds to the "state" of
       the CGI script, and because each	object's parameter list	is independent
       of the others, this allows you to save the state	of the script and
       restore it later.

       For example, using the object oriented style, here is how you create a
       simple "Hello World" HTML page:

	  #!/usr/local/bin/perl	-w
	  use CGI;			       # load CGI routines
	  $q = CGI->new;			# create new CGI object
	  print	$q->header,		       # create	the HTTP header
		$q->start_html('hello world'), # start the HTML
		$q->h1('hello world'),	       # level 1 header
		$q->end_html;		       # end the HTML

       In the function-oriented	style, there is	one default CGI	object that
       you rarely deal with directly.  Instead you just	call functions to
       retrieve	CGI parameters,	create HTML tags, manage cookies, and so on.
       This provides you with a	cleaner	programming interface, but limits you
       to using	one CGI	object at a time.  The following example prints	the
       same page, but uses the function-oriented interface.  The main
       differences are that we now need	to import a set	of functions into our
       name space (usually the "standard" functions), and we don't need	to
       create the CGI object.

	  #!/usr/local/bin/perl
	  use CGI qw/:standard/;	   # load standard CGI routines
	  print	header,			   # create the	HTTP header
		start_html('hello world'), # start the HTML
		h1('hello world'),	   # level 1 header
		end_html;		   # end the HTML

       The examples in this document mainly use	the object-oriented style.
       See HOW TO IMPORT FUNCTIONS for important information on	function-
       oriented	programming in CGI.pm

   CALLING CGI.PM ROUTINES
       Most CGI.pm routines accept several arguments, sometimes	as many	as 20
       optional	ones!  To simplify this	interface, all routines	use a named
       argument	calling	style that looks like this:

	  print	$q->header(-type=>'image/gif',-expires=>'+3d');

       Each argument name is preceded by a dash.  Neither case nor order
       matters in the argument list.  -type, -Type, and	-TYPE are all
       acceptable.  In fact, only the first argument needs to begin with a
       dash.  If a dash	is present in the first	argument, CGI.pm assumes
       dashes for the subsequent ones.

       Several routines	are commonly called with just one argument.  In	the
       case of these routines you can provide the single argument without an
       argument	name.  header()	happens	to be one of these routines.  In this
       case, the single	argument is the	document type.

	  print	$q->header('text/html');

       Other such routines are documented below.

       Sometimes named arguments expect	a scalar, sometimes a reference	to an
       array, and sometimes a reference	to a hash.  Often, you can pass	any
       type of argument	and the	routine	will do	whatever is most appropriate.
       For example, the	param()	routine	is used	to set a CGI parameter to a
       single or a multi-valued	value.	The two	cases are shown	below:

	  $q->param(-name=>'veggie',-value=>'tomato');
	  $q->param(-name=>'veggie',-value=>['tomato','tomahto','potato','potahto']);

       A large number of routines in CGI.pm actually aren't specifically
       defined in the module, but are generated	automatically as needed.
       These are the "HTML shortcuts," routines	that generate HTML tags	for
       use in dynamically-generated pages.  HTML tags have both	attributes
       (the attribute="value" pairs within the tag itself) and contents	(the
       part between the	opening	and closing pairs.)  To	distinguish between
       attributes and contents,	CGI.pm uses the	convention of passing HTML
       attributes as a hash reference as the first argument, and the contents,
       if any, as any subsequent arguments.  It	works out like this:

	  Code				 Generated HTML
	  ----				 --------------
	  h1()				 <h1>
	  h1('some','contents');	 <h1>some contents</h1>
	  h1({-align=>left});		 <h1 align="LEFT">
	  h1({-align=>left},'contents'); <h1 align="LEFT">contents</h1>

       HTML tags are described in more detail later.

       Many newcomers to CGI.pm	are puzzled by the difference between the
       calling conventions for the HTML	shortcuts, which require curly braces
       around the HTML tag attributes, and the calling conventions for other
       routines, which manage to generate attributes without the curly
       brackets.  Don't	be confused.  As a convenience the curly braces	are
       optional	in all but the HTML shortcuts.	If you like, you can use curly
       braces when calling any routine that takes named	arguments.  For
       example:

	  print	$q->header( {-type=>'image/gif',-expires=>'+3d'} );

       If you use the -w switch, you will be warned that some CGI.pm argument
       names conflict with built-in Perl functions.  The most frequent of
       these is	the -values argument, used to create multi-valued menus, radio
       button clusters and the like.  To get around this warning, you have
       several choices:

       1.  Use another name for	the argument, if one is	available.  For
	   example, -value is an alias for -values.

       2.  Change the capitalization, e.g. -Values

       3.  Put quotes around the argument name,	e.g. '-values'

       Many routines will do something useful with a named argument that it
       doesn't recognize.  For example,	you can	produce	non-standard HTTP
       header fields by	providing them as named	arguments:

	 print $q->header(-type	 =>  'text/html',
			  -cost	 =>  'Three smackers',
			  -annoyance_level => 'high',
			  -complaints_to   => 'bit bucket');

       This will produce the following nonstandard HTTP	header:

	  HTTP/1.0 200 OK
	  Cost:	Three smackers
	  Annoyance-level: high
	  Complaints-to: bit bucket
	  Content-type:	text/html

       Notice the way that underscores are translated automatically into
       hyphens.	 HTML-generating routines perform a different type of
       translation.

       This feature allows you to keep up with the rapidly changing HTTP and
       HTML "standards".

   CREATING A NEW QUERY	OBJECT (OBJECT-ORIENTED	STYLE):
	    $query = CGI->new;

       This will parse the input (from POST, GET and DELETE methods) and store
       it into a perl5 object called $query.

       Any filehandles from file uploads will have their position reset	to the
       beginning of the	file.

   CREATING A NEW QUERY	OBJECT FROM AN INPUT FILE
	    $query = CGI->new(INPUTFILE);

       If you provide a	file handle to the new() method, it will read
       parameters from the file	(or STDIN, or whatever).  The file can be in
       any of the forms	describing below under debugging (i.e. a series	of
       newline delimited TAG=VALUE pairs will work).  Conveniently, this type
       of file is created by the save()	method (see below).  Multiple records
       can be saved and	restored.

       Perl purists will be pleased to know that this syntax accepts
       references to file handles, or even references to filehandle globs,
       which is	the "official" way to pass a filehandle:

	   $query = CGI->new(\*STDIN);

       You can also initialize the CGI object with a FileHandle	or IO::File
       object.

       If you are using	the function-oriented interface	and want to initialize
       CGI state from a	file handle, the way to	do this	is with
       restore_parameters().  This will	(re)initialize the default CGI object
       from the	indicated file handle.

	   open	(IN,"test.in") || die;
	   restore_parameters(IN);
	   close IN;

       You can also initialize the query object	from a hash reference:

	   $query = CGI->new( {'dinosaur'=>'barney',
			      'song'=>'I love you',
			      'friends'=>[qw/Jessica George Nancy/]}
			   );

       or from a properly formatted, URL-escaped query string:

	   $query = CGI->new('dinosaur=barney&color=purple');

       or from a previously existing CGI object	(currently this	clones the
       parameter list, but none	of the other object-specific fields, such as
       autoescaping):

	   $old_query =	CGI->new;
	   $new_query =	CGI->new($old_query);

       To create an empty query, initialize it from an empty string or hash:

	  $empty_query = CGI->new("");

	      -or-

	  $empty_query = CGI->new({});

   FETCHING A LIST OF KEYWORDS FROM THE	QUERY:
	    @keywords =	$query->keywords

       If the script was invoked as the	result of an <ISINDEX> search, the
       parsed keywords can be obtained as an array using the keywords()
       method.

   FETCHING THE	NAMES OF ALL THE PARAMETERS PASSED TO YOUR SCRIPT:
	    @names = $query->param

       If the script was invoked with a	parameter list (e.g.
       "name1=value1&name2=value2&name3=value3"), the param() method will
       return the parameter names as a list.  If the script was	invoked	as an
       <ISINDEX> script	and contains a string without ampersands (e.g.
       "value1+value2+value3") , there will be a single	parameter named
       "keywords" containing the "+"-delimited keywords.

       NOTE: As	of version 1.5,	the array of parameter names returned will be
       in the same order as they were submitted	by the browser.	 Usually this
       order is	the same as the	order in which the parameters are defined in
       the form	(however, this isn't part of the spec, and so isn't
       guaranteed).

   FETCHING THE	VALUE OR VALUES	OF A SINGLE NAMED PARAMETER:
	   @values = $query->param('foo');

		     -or-

	   $value = $query->param('foo');

       Pass the	param()	method a single	argument to fetch the value of the
       named parameter.	If the parameter is multivalued	(e.g. from multiple
       selections in a scrolling list),	you can	ask to receive an array.
       Otherwise the method will return	a single value.

       If a value is not given in the query string, as in the queries
       "name1=&name2=",	it will	be returned as an empty	string.

       If the parameter	does not exist at all, then param() will return	undef
       in a scalar context, and	the empty list in a list context.

   SETTING THE VALUE(S)	OF A NAMED PARAMETER:
	   $query->param('foo','an','array','of','values');

       This sets the value for the named parameter 'foo' to an array of
       values.	This is	one way	to change the value of a field AFTER the
       script has been invoked once before.  (Another way is with the
       -override parameter accepted by all methods that	generate form
       elements.)

       param() also recognizes a named parameter style of calling described in
       more detail later:

	   $query->param(-name=>'foo',-values=>['an','array','of','values']);

				     -or-

	   $query->param(-name=>'foo',-value=>'the value');

   APPENDING ADDITIONAL	VALUES TO A NAMED PARAMETER:
	  $query->append(-name=>'foo',-values=>['yet','more','values']);

       This adds a value or list of values to the named	parameter.  The	values
       are appended to the end of the parameter	if it already exists.
       Otherwise the parameter is created.  Note that this method only
       recognizes the named argument calling syntax.

   IMPORTING ALL PARAMETERS INTO A NAMESPACE:
	  $query->import_names('R');

       This creates a series of	variables in the 'R' namespace.	 For example,
       $R::foo,	@R:foo.	 For keyword lists, a variable @R::keywords will
       appear.	If no namespace	is given, this method will assume 'Q'.
       WARNING:	 don't import anything into 'main'; this is a major security
       risk!!!!

       NOTE 1: Variable	names are transformed as necessary into	legal Perl
       variable	names.	All non-legal characters are transformed into
       underscores.  If	you need to keep the original names, you should	use
       the param() method instead to access CGI	variables by name.

       NOTE 2: In older	versions, this method was called import().  As of
       version 2.20, this name has been	removed	completely to avoid conflict
       with the	built-in Perl module import operator.

   DELETING A PARAMETER	COMPLETELY:
	   $query->delete('foo','bar','baz');

       This completely clears a	list of	parameters.  It	sometimes useful for
       resetting parameters that you don't want	passed down between script
       invocations.

       If you are using	the function call interface, use "Delete()" instead to
       avoid conflicts with Perl's built-in delete operator.

   DELETING ALL	PARAMETERS:
	  $query->delete_all();

       This clears the CGI object completely.  It might	be useful to ensure
       that all	the defaults are taken when you	create a fill-out form.

       Use Delete_all()	instead	if you are using the function call interface.

   HANDLING NON-URLENCODED ARGUMENTS
       If POSTed data is not of	type application/x-www-form-urlencoded or
       multipart/form-data, then the POSTed data will not be processed,	but
       instead be returned as-is in a parameter	named POSTDATA.	 To retrieve
       it, use code like this:

	  my $data = $query->param('POSTDATA');

       Likewise	if PUTed data can be retrieved with code like this:

	  my $data = $query->param('PUTDATA');

       (If you don't know what the preceding means, don't worry	about it.  It
       only affects people trying to use CGI for XML processing	and other
       specialized tasks.)

   DIRECT ACCESS TO THE	PARAMETER LIST:
	  $q->param_fetch('address')->[1] = '1313 Mockingbird Lane';
	  unshift @{$q->param_fetch(-name=>'address')},'George Munster';

       If you need access to the parameter list	in a way that isn't covered by
       the methods given in the	previous sections, you can obtain a direct
       reference to it by calling the param_fetch() method with	the name of
       the parameter.  This will return	an array reference to the named
       parameter, which	you then can manipulate	in any way you like.

       You can also use	a named	argument style using the -name argument.

   FETCHING THE	PARAMETER LIST AS A HASH:
	   $params = $q->Vars;
	   print $params->{'address'};
	   @foo	= split("\0",$params->{'foo'});
	   %params = $q->Vars;

	   use CGI ':cgi-lib';
	   $params = Vars;

       Many people want	to fetch the entire parameter list as a	hash in	which
       the keys	are the	names of the CGI parameters, and the values are	the
       parameters' values.  The	Vars() method does this.  Called in a scalar
       context,	it returns the parameter list as a tied	hash reference.
       Changing	a key changes the value	of the parameter in the	underlying CGI
       parameter list.	Called in a list context, it returns the parameter
       list as an ordinary hash.  This allows you to read the contents of the
       parameter list, but not to change it.

       When using this,	the thing you must watch out for are multivalued CGI
       parameters.  Because a hash cannot distinguish between scalar and list
       context,	multivalued parameters will be returned	as a packed string,
       separated by the	"\0" (null) character.	You must split this packed
       string in order to get at the individual	values.	 This is the
       convention introduced long ago by Steve Brenner in his cgi-lib.pl
       module for Perl version 4.

       If you wish to use Vars() as a function,	import the :cgi-lib set	of
       function	calls (also see	the section on CGI-LIB compatibility).

   SAVING THE STATE OF THE SCRIPT TO A FILE:
	   $query->save(\*FILEHANDLE)

       This will write the current state of the	form to	the provided
       filehandle.  You	can read it back in by providing a filehandle to the
       new() method.  Note that	the filehandle can be a	file, a	pipe, or
       whatever!

       The format of the saved file is:

	       NAME1=VALUE1
	       NAME1=VALUE1'
	       NAME2=VALUE2
	       NAME3=VALUE3
	       =

       Both name and value are URL escaped.  Multi-valued CGI parameters are
       represented as repeated names.  A session record	is delimited by	a
       single =	symbol.	 You can write out multiple records and	read them back
       in with several calls to	new.  You can do this across several sessions
       by opening the file in append mode, allowing you	to create primitive
       guest books, or to keep a history of users' queries.  Here's a short
       example of creating multiple session records:

	  use CGI;

	  open (OUT,'>>','test.out') ||	die;
	  $records = 5;
	  for (0..$records) {
	      my $q = CGI->new;
	      $q->param(-name=>'counter',-value=>$_);
	      $q->save(\*OUT);
	  }
	  close	OUT;

	  # reopen for reading
	  open (IN,'<','test.out') || die;
	  while	(!eof(IN)) {
	      my $q = CGI->new(\*IN);
	      print $q->param('counter'),"\n";
	  }

       The file	format used for	save/restore is	identical to that used by the
       Whitehead Genome	Center's data exchange format "Boulderio", and can be
       manipulated and even databased using Boulderio utilities.  See

	 http://stein.cshl.org/boulder/

       for further details.

       If you wish to use this method from the function-oriented (non-OO)
       interface, the exported name for	this method is save_parameters().

   RETRIEVING CGI ERRORS
       Errors can occur	while processing user input, particularly when
       processing uploaded files.  When	these errors occur, CGI	will stop
       processing and return an	empty parameter	list.  You can test for	the
       existence and nature of errors using the	cgi_error() function.  The
       error messages are formatted as HTTP status codes. You can either
       incorporate the error text into an HTML page, or	use it as the value of
       the HTTP	status:

	   my $error = $q->cgi_error;
	   if ($error) {
	       print $q->header(-status=>$error),
		     $q->start_html('Problems'),
		     $q->h2('Request not processed'),
		     $q->strong($error);
	       exit 0;
	   }

       When using the function-oriented	interface (see the next	section),
       errors may only occur the first time you	call param(). Be ready for
       this!

   USING THE FUNCTION-ORIENTED INTERFACE
       To use the function-oriented interface, you must	specify	which CGI.pm
       routines	or sets	of routines to import into your	script's namespace.
       There is	a small	overhead associated with this importation, but it
       isn't much.

	  use CGI <list	of methods>;

       The listed methods will be imported into	the current package; you can
       call them directly without creating a CGI object	first.	This example
       shows how to import the param() and header() methods, and then use them
       directly:

	  use CGI 'param','header';
	  print	header('text/plain');
	  $zipcode = param('zipcode');

       More frequently,	you'll import common sets of functions by referring to
       the groups by name.  All	function sets are preceded with	a ":"
       character as in ":html3"	(for tags defined in the HTML 3	standard).

       Here is a list of the function sets you can import:

       :cgi
	   Import all CGI-handling methods, such as param(), path_info() and
	   the like.

       :form
	   Import all fill-out form generating methods,	such as	textfield().

       :html2
	   Import all methods that generate HTML 2.0 standard elements.

       :html3
	   Import all methods that generate HTML 3.0 elements (such as
	   <table>, <super> and	<sub>).

       :html4
	   Import all methods that generate HTML 4 elements (such as <abbrev>,
	   <acronym> and <thead>).

       :netscape
	   Import the <blink>, <fontsize> and <center> tags.

       :html
	   Import all HTML-generating shortcuts	(i.e. 'html2', 'html3',
	   'html4' and 'netscape')

       :standard
	   Import "standard" features, 'html2',	'html3', 'html4', 'form' and
	   'cgi'.

       :all
	   Import all the available methods.  For the full list, see the
	   CGI.pm code,	where the variable %EXPORT_TAGS	is defined.

       If you import a function	name that is not part of CGI.pm, the module
       will treat it as	a new HTML tag and generate the	appropriate
       subroutine.  You	can then use it	like any other HTML tag.  This is to
       provide for the rapidly-evolving	HTML "standard."  For example, say
       Microsoft comes out with	a new tag called <gradient> (which causes the
       user's desktop to be flooded with a rotating gradient fill until	his
       machine reboots).  You don't need to wait for a new version of CGI.pm
       to start	using it immediately:

	  use CGI qw/:standard :html3 gradient/;
	  print	gradient({-start=>'red',-end=>'blue'});

       Note that in the	interests of execution speed CGI.pm does not use the
       standard	Exporter syntax	for specifying load symbols.  This may change
       in the future.

       If you import any of the	state-maintaining CGI or form-generating
       methods,	a default CGI object will be created and initialized
       automatically the first time you	use any	of the methods that require
       one to be present.  This	includes param(), textfield(), submit()	and
       the like.  (If you need direct access to	the CGI	object,	you can	find
       it in the global	variable $CGI::Q).  By importing CGI.pm	methods, you
       can create visually elegant scripts:

	  use CGI qw/:standard/;
	  print
	      header,
	      start_html('Simple Script'),
	      h1('Simple Script'),
	      start_form,
	      "What's your name? ",textfield('name'),p,
	      "What's the combination?",
	      checkbox_group(-name=>'words',
			     -values=>['eenie','meenie','minie','moe'],
			     -defaults=>['eenie','moe']),p,
	      "What's your favorite color?",
	      popup_menu(-name=>'color',
			 -values=>['red','green','blue','chartreuse']),p,
	      submit,
	      end_form,
	      hr,"\n";

	   if (param) {
	      print
		  "Your	name is	",em(param('name')),p,
		  "The keywords	are: ",em(join(", ",param('words'))),p,
		  "Your	favorite color is ",em(param('color')),".\n";
	   }
	   print end_html;

   PRAGMAS
       In addition to the function sets, there are a number of pragmas that
       you can import.	Pragmas, which are always preceded by a	hyphen,	change
       the way that CGI.pm functions in	various	ways.  Pragmas,	function sets,
       and individual functions	can all	be imported in the same	use() line.
       For example, the	following use statement	imports	the standard set of
       functions and enables debugging mode (pragma -debug):

	  use CGI qw/:standard -debug/;

       The current list	of pragmas is as follows:

       -any
	   When	you use	CGI -any, then any method that the query object
	   doesn't recognize will be interpreted as a new HTML tag.  This
	   allows you to support the next ad hoc HTML extension.  This lets
	   you go wild with new	and unsupported	tags:

	      use CGI qw(-any);
	      $q=CGI->new;
	      print $q->gradient({speed=>'fast',start=>'red',end=>'blue'});

	   Since using <cite>any</cite>	causes any mistyped method name	to be
	   interpreted as an HTML tag, use it with care	or not at all.

       -compile
	   This	causes the indicated autoloaded	methods	to be compiled up
	   front, rather than deferred to later.  This is useful for scripts
	   that	run for	an extended period of time under FastCGI or mod_perl,
	   and for those destined to be	crunched by Malcolm Beattie's Perl
	   compiler.  Use it in	conjunction with the methods or	method
	   families you	plan to	use.

	      use CGI qw(-compile :standard :html3);

	   or even

	      use CGI qw(-compile :all);

	   Note	that using the -compile	pragma in this way will	always have
	   the effect of importing the compiled	functions into the current
	   namespace.  If you want to compile without importing	use the
	   compile() method instead:

	      use CGI();
	      CGI->compile();

	   This	is particularly	useful in a mod_perl environment, in which you
	   might want to precompile all	CGI routines in	a startup script, and
	   then	import the functions individually in each mod_perl script.

       -nosticky
	   By default the CGI module implements	a state-preserving behavior
	   called "sticky" fields.  The	way this works is that if you are
	   regenerating	a form,	the methods that generate the form field
	   values will interrogate param() to see if similarly-named
	   parameters are present in the query string. If they find a like-
	   named parameter, they will use it to	set their default values.

	   Sometimes this isn't	what you want.	The -nosticky pragma prevents
	   this	behavior.  You can also	selectively change the sticky behavior
	   in each element that	you generate.

       -tabindex
	   Automatically add tab index attributes to each form field. With
	   this	option turned off, you can still add tab indexes manually by
	   passing a -tabindex option to each field-generating method.

       -no_undef_params
	   This	keeps CGI.pm from including undef params in the	parameter
	   list.

       -no_xhtml
	   By default, CGI.pm versions 2.69 and	higher emit XHTML
	   (http://www.w3.org/TR/xhtml1/).  The	-no_xhtml pragma disables this
	   feature.  Thanks to Michalis	Kabrianis <kabrianis@hellug.gr>	for
	   this	feature.

	   If start_html()'s -dtd parameter specifies an HTML 2.0, 3.2,	4.0 or
	   4.01	DTD, XHTML will	automatically be disabled without needing to
	   use this pragma.

       -utf8
	   This	makes CGI.pm treat all parameters as UTF-8 strings. Use	this
	   with	care, as it will interfere with	the processing of binary
	   uploads. It is better to manually select which fields are expected
	   to return utf-8 strings and convert them using code like this:

	    use	Encode;
	    my $arg = decode utf8=>param('foo');

       -nph
	   This	makes CGI.pm produce a header appropriate for an NPH (no
	   parsed header) script.  You may need	to do other things as well to
	   tell	the server that	the script is NPH.  See	the discussion of NPH
	   scripts below.

       -newstyle_urls
	   Separate the	name=value pairs in CGI	parameter query	strings	with
	   semicolons rather than ampersands.  For example:

	      ?name=fred;age=24;favorite_color=3

	   Semicolon-delimited query strings are always	accepted, and will be
	   emitted by self_url() and query_string(). newstyle_urls became the
	   default in version 2.64.

       -oldstyle_urls
	   Separate the	name=value pairs in CGI	parameter query	strings	with
	   ampersands rather than semicolons.  This is no longer the default.

       -autoload
	   This	overrides the autoloader so that any function in your program
	   that	is not recognized is referred to CGI.pm	for possible
	   evaluation.	This allows you	to use all the CGI.pm functions
	   without adding them to your symbol table, which is of concern for
	   mod_perl users who are worried about	memory consumption.  Warning:
	   when	-autoload is in	effect,	you cannot use "poetry mode"
	   (functions without the parenthesis).	 Use hr() rather than hr, or
	   add something like use subs qw/hr p header/ to the top of your
	   script.

       -no_debug
	   This	turns off the command-line processing features.	 If you	want
	   to run a CGI.pm script from the command line	to produce HTML, and
	   you don't want it to	read CGI parameters from the command line or
	   STDIN, then use this	pragma:

	      use CGI qw(-no_debug :standard);

       -debug
	   This	turns on full debugging.  In addition to reading CGI arguments
	   from	the command-line processing, CGI.pm will pause and try to read
	   arguments from STDIN, producing the message "(offline mode: enter
	   name=value pairs on standard	input)"	features.

	   See the section on debugging	for more details.

       -private_tempfiles
	   CGI.pm can process uploaded file. Ordinarily	it spools the uploaded
	   file	to a temporary directory, then deletes the file	when done.
	   However, this opens the risk	of eavesdropping as described in the
	   file	upload section.	 Another CGI script author could peek at this
	   data	during the upload, even	if it is confidential information. On
	   Unix	systems, the -private_tempfiles	pragma will cause the
	   temporary file to be	unlinked as soon as it is opened and before
	   any data is written into it,	reducing, but not eliminating the risk
	   of eavesdropping (there is still a potential	race condition).  To
	   make	life harder for	the attacker, the program chooses tempfile
	   names by calculating	a 32 bit checksum of the incoming HTTP
	   headers.

	   To ensure that the temporary	file cannot be read by other CGI
	   scripts, use	suEXEC or a CGI	wrapper	program	to run your script.
	   The temporary file is created with mode 0600	(neither world nor
	   group readable).

	   The temporary directory is selected using the following algorithm:

	       1. if $CGITempFile::TMPDIRECTORY	is already set,	use that

	       2. if the environment variable TMPDIR exists, use the location
	       indicated.

	       3. Otherwise try	the locations /usr/tmp,	/var/tmp, C:\temp,
	       /tmp, /temp, ::Temporary	Items, and \WWW_ROOT.

	   Each	of these locations is checked that it is a directory and is
	   writable.  If not, the algorithm tries the next choice.

   SPECIAL FORMS FOR IMPORTING HTML-TAG	FUNCTIONS
       Many of the methods generate HTML tags.	As described below, tag
       functions automatically generate	both the opening and closing tags.
       For example:

	 print h1('Level 1 Header');

       produces

	 <h1>Level 1 Header</h1>

       There will be some times	when you want to produce the start and end
       tags yourself.  In this case, you can use the form start_tag_name and
       end_tag_name, as	in:

	 print start_h1,'Level 1 Header',end_h1;

       With a few exceptions (described	below),	start_tag_name and
       end_tag_name functions are not generated	automatically when you use
       CGI.  However, you can specify the tags you want	to generate start/end
       functions for by	putting	an asterisk in front of	their name, or,
       alternatively, requesting either	"start_tag_name" or "end_tag_name" in
       the import list.

       Example:

	 use CGI qw/:standard *table start_ul/;

       In this example,	the following functions	are generated in addition to
       the standard ones:

       1. start_table()	(generates a <table> tag)
       2. end_table() (generates a </table> tag)
       3. start_ul() (generates	a <ul> tag)
       4. end_ul() (generates a	</ul> tag)

GENERATING DYNAMIC DOCUMENTS
       Most of CGI.pm's	functions deal with creating documents on the fly.
       Generally you will produce the HTTP header first, followed by the
       document	itself.	 CGI.pm	provides functions for generating HTTP headers
       of various types	as well	as for generating HTML.	 For creating GIF
       images, see the GD.pm module.

       Each of these functions produces	a fragment of HTML or HTTP which you
       can print out directly so that it displays in the browser window,
       append to a string, or save to a	file for later use.

   CREATING A STANDARD HTTP HEADER:
       Normally	the first thing	you will do in any CGI script is print out an
       HTTP header.  This tells	the browser what type of document to expect,
       and gives other optional	information, such as the language, expiration
       date, and whether to cache the document.	 The header can	also be
       manipulated for special purposes, such as server	push and pay per view
       pages.

	       print header;

		    -or-

	       print header('image/gif');

		    -or-

	       print header('text/html','204 No	response');

		    -or-

	       print header(-type=>'image/gif',
				    -nph=>1,
				    -status=>'402 Payment required',
				    -expires=>'+3d',
				    -cookie=>$cookie,
				    -charset=>'utf-7',
				    -attachment=>'foo.gif',
				    -Cost=>'$2.00');

       header()	returns	the Content-type: header.  You can provide your	own
       MIME type if you	choose,	otherwise it defaults to text/html.  An
       optional	second parameter specifies the status code and a human-
       readable	message.  For example, you can specify 204, "No	response" to
       create a	script that tells the browser to do nothing at all. Note that
       RFC 2616	expects	the human-readable phase to be there as	well as	the
       numeric status code.

       The last	example	shows the named	argument style for passing arguments
       to the CGI methods using	named parameters.  Recognized parameters are
       -type, -status, -expires, and -cookie.  Any other named parameters will
       be stripped of their initial hyphens and	turned into header fields,
       allowing	you to specify any HTTP	header you desire.  Internal
       underscores will	be turned into hyphens:

	   print header(-Content_length=>3002);

       Most browsers will not cache the	output from CGI	scripts.  Every	time
       the browser reloads the page, the script	is invoked anew.  You can
       change this behavior with the -expires parameter.  When you specify an
       absolute	or relative expiration interval	with this parameter, some
       browsers	and proxy servers will cache the script's output until the
       indicated expiration date.  The following forms are all valid for the
       -expires	field:

	       +30s				 30 seconds from now
	       +10m				 ten minutes from now
	       +1h				 one hour from now
	       -1d				 yesterday (i.e. "ASAP!")
	       now				 immediately
	       +3M				 in three months
	       +10y				 in ten	years time
	       Thursday, 25-Apr-1999 00:40:33 GMT  at the indicated time & date

       The -cookie parameter generates a header	that tells the browser to
       provide a "magic	cookie"	during all subsequent transactions with	your
       script.	Some cookies have a special format that	includes interesting
       attributes such as expiration time.  Use	the cookie() method to create
       and retrieve session cookies.

       The -nph	parameter, if set to a true value, will	issue the correct
       headers to work with a NPH (no-parse-header) script.  This is important
       to use with certain servers that	expect all their scripts to be NPH.

       The -charset parameter can be used to control the character set sent to
       the browser.  If	not provided, defaults to ISO-8859-1.  As a side
       effect, this sets the charset() method as well.

       The -attachment parameter can be	used to	turn the page into an
       attachment.  Instead of displaying the page, some browsers will prompt
       the user	to save	it to disk.  The value of the argument is the
       suggested name for the saved file.  In order for	this to	work, you may
       have to set the -type to	"application/octet-stream".

       The -p3p	parameter will add a P3P tag to	the outgoing header.  The
       parameter can be	an arrayref or a space-delimited string	of P3P tags.
       For example:

	  print	header(-p3p=>[qw(CAO DSP LAW CURa)]);
	  print	header(-p3p=>'CAO DSP LAW CURa');

       In either case, the outgoing header will	be formatted as:

	 P3P: policyref="/w3c/p3p.xml" cp="CAO DSP LAW CURa"

       CGI.pm will accept valid	multi-line headers when	each line is separated
       with a CRLF value ("\r\n" on most platforms) followed by	at least one
       space. For example:

	   print header( -ingredients => "ham\r\n\seggs\r\n\sbacon" );

       Invalid multi-line header input will trigger in an exception. When
       multi-line headers are received,	CGI.pm will always output them back as
       a single	line, according	to the folding rules of	RFC 2616: the newlines
       will be removed,	while the white	space remains.

   GENERATING A	REDIRECTION HEADER
	  print	$q->redirect('http://somewhere.else/in/movie/land');

       Sometimes you don't want	to produce a document yourself,	but simply
       redirect	the browser elsewhere, perhaps choosing	a URL based on the
       time of day or the identity of the user.

       The redirect() method redirects the browser to a	different URL.	If you
       use redirection like this, you should not print out a header as well.

       You should always use full URLs (including the http: or ftp: part) in
       redirection requests.  Relative URLs will not work correctly.

       You can also use	named arguments:

	   print $q->redirect(
	       -uri=>'http://somewhere.else/in/movie/land',
		   -nph=>1,
		-status=>'301 Moved Permanently');

       All names arguments recognized by header() are also recognized by
       redirect(). However, most HTTP headers, including those generated by
       -cookie and -target, are	ignored	by the browser.

       The -nph	parameter, if set to a true value, will	issue the correct
       headers to work with a NPH (no-parse-header) script.  This is important
       to use with certain servers, such as Microsoft IIS, which expect	all
       their scripts to	be NPH.

       The -status parameter will set the status of the	redirect.  HTTP
       defines three different possible	redirection status codes:

	    301	Moved Permanently
	    302	Found
	    303	See Other

       The default if not specified is 302, which means	"moved temporarily."
       You may change the status to another status code	if you wish.  Be
       advised that changing the status	to anything other than 301, 302	or 303
       will probably break redirection.

       Note that the human-readable phrase is also expected to be present to
       conform with RFC	2616, section 6.1.

   CREATING THE	HTML DOCUMENT HEADER
	  print	start_html(-title=>'Secrets of the Pyramids',
				   -author=>'fred@capricorn.org',
				   -base=>'true',
				   -target=>'_blank',
				   -meta=>{'keywords'=>'pharaoh	secret mummy',
					   'copyright'=>'copyright 1996	King Tut'},
				   -style=>{'src'=>'/styles/style1.css'},
				   -BGCOLOR=>'blue');

       The start_html()	routine	creates	the top	of the page, along with	a lot
       of optional information that controls the page's	appearance and
       behavior.

       This method returns a canned HTML header	and the	opening	<body> tag.
       All parameters are optional.  In	the named parameter form, recognized
       parameters are -title, -author, -base, -xbase, -dtd, -lang and -target
       (see below for the explanation).	 Any additional	parameters you
       provide,	such as	the unofficial BGCOLOR attribute, are added to the
       <body> tag.  Additional parameters must be proceeded by a hyphen.

       The argument -xbase allows you to provide an HREF for the <base>	tag
       different from the current location, as in

	   -xbase=>"http://home.mcom.com/"

       All relative links will be interpreted relative to this tag.

       The argument -target allows you to provide a default target frame for
       all the links and fill-out forms	on the page.  This is a	non-standard
       HTTP feature which only works with some browsers!

	   -target=>"answer_window"

       All relative links will be interpreted relative to this tag.  You add
       arbitrary meta information to the header	with the -meta argument.  This
       argument	expects	a reference to a hash containing name/value pairs of
       meta information.  These	will be	turned into a series of	header <meta>
       tags that look something	like this:

	   <meta name="keywords" content="pharaoh secret mummy">
	   <meta name="description" content="copyright 1996 King Tut">

       To create an HTTP-EQUIV type of <meta> tag, use -head, described	below.

       The -style argument is used to incorporate cascading stylesheets	into
       your code.  See the section on CASCADING	STYLESHEETS for	more
       information.

       The -lang argument is used to incorporate a language attribute into the
       <html> tag.  For	example:

	   print $q->start_html(-lang=>'fr-CA');

       The default if not specified is "en-US" for US English, unless the -dtd
       parameter specifies an HTML 2.0 or 3.2 DTD, in which case the lang
       attribute is left off.  You can force the lang attribute	to left	off in
       other cases by passing an empty string (-lang=>'').

       The -encoding argument can be used to specify the character set for
       XHTML.  It defaults to iso-8859-1 if not	specified.

       The -dtd	argument can be	used to	specify	a public DTD identifier
       string. For example:

	   -dtd	=> '-//W3C//DTD	HTML 4.01 Transitional//EN')

       Alternatively, it can take public and system DTD	identifiers as an
       array:

	   dtd => [ '-//W3C//DTD HTML 4.01 Transitional//EN', 'http://www.w3.org/TR/html4/loose.dtd' ]

       For the public DTD identifier to	be considered, it must be valid.
       Otherwise it will be replaced by	the default DTD. If the	public DTD
       contains	'XHTML', CGI.pm	will emit XML.

       The -declare_xml	argument, when used in conjunction with	XHTML, will
       put a <?xml> declaration	at the top of the HTML header. The sole
       purpose of this declaration is to declare the character set encoding.
       In the absence of -declare_xml, the output HTML will contain a <meta>
       tag that	specifies the encoding,	allowing the HTML to pass most
       validators.  The	default	for -declare_xml is false.

       You can place other arbitrary HTML elements to the <head> section with
       the -head tag.  For example, to place a <link> element in the head
       section,	use this:

	   print start_html(-head=>Link({-rel=>'shortcut icon',
					 -href=>'favicon.ico'}));

       To incorporate multiple HTML elements into the <head> section, just
       pass an array reference:

	   print start_html(-head=>[
				    Link({-rel=>'next',
					  -href=>'http://www.capricorn.com/s2.html'}),
				    Link({-rel=>'previous',
					  -href=>'http://www.capricorn.com/s1.html'})
				    ]
			    );

       And here's how to create	an HTTP-EQUIV <meta> tag:

	     print start_html(-head=>meta({-http_equiv => 'Content-Type',
					   -content    => 'text/html'}))

       JAVASCRIPTING: The -script, -noScript, -onLoad, -onMouseOver,
       -onMouseOut and -onUnload parameters are	used to	add JavaScript calls
       to your pages.  -script should point to a block of text containing
       JavaScript function definitions.	 This block will be placed within a
       <script>	block inside the HTML (not HTTP) header.  The block is placed
       in the header in	order to give your page	a fighting chance of having
       all its JavaScript functions in place even if the user presses the stop
       button before the page has loaded completely.  CGI.pm attempts to
       format the script in such a way that JavaScript-naive browsers will not
       choke on	the code: unfortunately	there are some browsers, such as
       Chimera for Unix, that get confused by it nevertheless.

       The -onLoad and -onUnload parameters point to fragments of JavaScript
       code to execute when the	page is	respectively opened and	closed by the
       browser.	 Usually these parameters are calls to functions defined in
       the -script field:

	     $query = CGI->new;
	     print header;
	     $JSCRIPT=<<END;
	     //	Ask a silly question
	     function riddle_me_this() {
		var r =	prompt("What walks on four legs	in the morning,	" +
			      "two legs	in the afternoon, " +
			      "and three legs in the evening?");
		response(r);
	     }
	     //	Get a silly answer
	     function response(answer) {
		if (answer == "man")
		   alert("Right	you are!");
		else
		   alert("Wrong!  Guess	again.");
	     }
	     END
	     print start_html(-title=>'The Riddle of the Sphinx',
				      -script=>$JSCRIPT);

       Use the -noScript parameter to pass some	HTML text that will be
       displayed on browsers that do not have JavaScript (or browsers where
       JavaScript is turned off).

       The <script> tag, has several attributes	including "type", "charset"
       and "src".  "src" allows	you to keep JavaScript code in an external
       file. To	use these attributes pass a HASH reference in the -script
       parameter containing one	or more	of -type, -src,	or -code:

	   print $q->start_html(-title=>'The Riddle of the Sphinx',
				-script=>{-type=>'JAVASCRIPT',
					  -src=>'/javascript/sphinx.js'}
				);

	   print $q->(-title=>'The Riddle of the Sphinx',
		      -script=>{-type=>'PERLSCRIPT',
				-code=>'print "hello world!\n;"'}
		      );

       A final feature allows you to incorporate multiple <script> sections
       into the	header.	 Just pass the list of script sections as an array
       reference.  this	allows you to specify different	source files for
       different dialects of JavaScript.  Example:

	    print $q->start_html(-title=>'The Riddle of	the Sphinx',
				 -script=>[
					   { -type => 'text/javascript',
					     -src      => '/javascript/utilities10.js'
					   },
					   { -type => 'text/javascript',
					     -src      => '/javascript/utilities11.js'
					   },
					   { -type => 'text/jscript',
					     -src      => '/javascript/utilities12.js'
					   },
					   { -type => 'text/ecmascript',
					     -src      => '/javascript/utilities219.js'
					   }
					]
				    );

       The option "-language" is a synonym for -type, and is supported for
       backwards compatibility.

       The old-style positional	parameters are as follows:

       Parameters:
       1.  The title

       2.  The author's	e-mail address (will create a <link rev="MADE">	tag if
	   present

       3.  A 'true' flag if you	want to	include	a <base> tag in	the header.
	   This	helps resolve relative addresses to absolute ones when the
	   document is moved, but makes	the document hierarchy non-portable.
	   Use with care!

       4, 5, 6...
	   Any other parameters	you want to include in the <body> tag.	This
	   is a	good place to put HTML extensions, such	as colors and
	   wallpaper patterns.

   ENDING THE HTML DOCUMENT:
	       print $q->end_html;

       This ends an HTML document by printing the </body></html> tags.

   CREATING A SELF-REFERENCING URL THAT	PRESERVES STATE	INFORMATION:
	   $myself = $q->self_url;
	   print q(<a href="$myself">I'm talking to myself.</a>);

       self_url() will return a	URL, that, when	selected, will reinvoke	this
       script with all its state information intact.  This is most useful when
       you want	to jump	around within the document using internal anchors but
       you don't want to disrupt the current contents of the form(s).
       Something like this will	do the trick.

	    $myself = $q->self_url;
	    print "<a href=\"$myself#table1\">See table	1</a>";
	    print "<a href=\"$myself#table2\">See table	2</a>";
	    print "<a href=\"$myself#yourself\">See for	yourself</a>";

       If you want more	control	over what's returned, using the	url() method
       instead.

       You can also retrieve the unprocessed query string with query_string():

	   $the_string = $q->query_string();

       The behavior of calling query_string is currently undefined when	the
       HTTP method is something	other than GET.

   OBTAINING THE SCRIPT'S URL
	   $full_url	  = url();
	   $full_url	  = url(-full=>1);  #alternative syntax
	   $relative_url  = url(-relative=>1);
	   $absolute_url  = url(-absolute=>1);
	   $url_with_path = url(-path_info=>1);
	   $url_with_path_and_query = url(-path_info=>1,-query=>1);
	   $netloc	  = url(-base => 1);

       url() returns the script's URL in a variety of formats.	Called without
       any arguments, it returns the full form of the URL, including host name
       and port	number

	   http://your.host.com/path/to/script.cgi

       You can modify this format with the following named arguments:

       -absolute
	   If true, produce an absolute	URL, e.g.

	       /path/to/script.cgi

       -relative
	   Produce a relative URL.  This is useful if you want to reinvoke
	   your	script with different parameters. For example:

	       script.cgi

       -full
	   Produce the full URL, exactly as if called without any arguments.
	   This	overrides the -relative	and -absolute arguments.

       -path (-path_info)
	   Append the additional path information to the URL.  This can	be
	   combined with -full,	-absolute or -relative.	 -path_info is
	   provided as a synonym.

       -query (-query_string)
	   Append the query string to the URL.	This can be combined with
	   -full, -absolute or -relative.  -query_string is provided as	a
	   synonym.

       -base
	   Generate just the protocol and net location,	as in
	   http://www.foo.com:8000

       -rewrite
	   If Apache's mod_rewrite is turned on, then the script name and path
	   info	probably won't match the request that the user sent. Set
	   -rewrite=>1 (default) to return URLs	that match what	the user sent
	   (the	original request URI). Set -rewrite=>0 to return URLs that
	   match the URL after mod_rewrite's rules have	run.

   MIXING POST AND URL PARAMETERS
	  $color = url_param('color');

       It is possible for a script to receive CGI parameters in	the URL	as
       well as in the fill-out form by creating	a form that POSTs to a URL
       containing a query string (a "?"	mark followed by arguments).  The
       param() method will always return the contents of the POSTed fill-out
       form, ignoring the URL's	query string.  To retrieve URL parameters,
       call the	url_param() method.  Use it in the same	way as param().	 The
       main difference is that it allows you to	read the parameters, but not
       set them.

       Under no	circumstances will the contents	of the URL query string
       interfere with similarly-named CGI parameters in	POSTed forms.  If you
       try to mix a URL	query string with a form submitted with	the GET
       method, the results will	not be what you	expect.

CREATING STANDARD HTML ELEMENTS:
       CGI.pm defines general HTML shortcut methods for	many HTML tags.	 HTML
       shortcuts are named after a single HTML element and return a fragment
       of HTML text. Example:

	  print	$q->blockquote(
			    "Many years	ago on the island of",
			    $q->a({href=>"http://crete.org/"},"Crete"),
			    "there lived a Minotaur named",
			    $q->strong("Fred."),
			   ),
	      $q->hr;

       This results in the following HTML code (extra newlines have been added
       for readability):

	  <blockquote>
	  Many years ago on the	island of
	  <a href="http://crete.org/">Crete</a>	there lived
	  a minotaur named <strong>Fred.</strong>
	  </blockquote>
	  <hr>

       If you find the syntax for calling the HTML shortcuts awkward, you can
       import them into	your namespace and dispense with the object syntax
       completely (see the next	section	for more details):

	  use CGI ':standard';
	  print	blockquote(
	     "Many years ago on	the island of",
	     a({href=>"http://crete.org/"},"Crete"),
	     "there lived a minotaur named",
	     strong("Fred."),
	     ),
	     hr;

   PROVIDING ARGUMENTS TO HTML SHORTCUTS
       The HTML	methods	will accept zero, one or multiple arguments.  If you
       provide no arguments, you get a single tag:

	  print	hr;    #  <hr>

       If you provide one or more string arguments, they are concatenated
       together	with spaces and	placed between opening and closing tags:

	  print	h1("Chapter","1"); # <h1>Chapter 1</h1>"

       If the first argument is	a hash reference, then the keys	and values of
       the hash	become the HTML	tag's attributes:

	  print	a({-href=>'fred.html',-target=>'_new'},
	     "Open a new frame");

		   <a href="fred.html",target="_new">Open a new	frame</a>

       You may dispense	with the dashes	in front of the	attribute names	if you
       prefer:

	  print	img {src=>'fred.gif',align=>'LEFT'};

		  <img align="LEFT" src="fred.gif">

       Sometimes an HTML tag attribute has no argument.	 For example, ordered
       lists can be marked as COMPACT.	The syntax for this is an argument
       that that points	to an undef string:

	  print	ol({compact=>undef},li('one'),li('two'),li('three'));

       Prior to	CGI.pm version 2.41, providing an empty	('') string as an
       attribute argument was the same as providing undef.  However, this has
       changed in order	to accommodate those who want to create	tags of	the
       form <img alt="">.  The difference is shown in these two	pieces of
       code:

	  CODE			 RESULT
	  img({alt=>undef})	 <img alt>
	  img({alt=>''})	 <img alt="">

   THE DISTRIBUTIVE PROPERTY OF	HTML SHORTCUTS
       One of the cool features	of the HTML shortcuts is that they are
       distributive.  If you give them an argument consisting of a reference
       to a list, the tag will be distributed across each element of the list.
       For example, here's one way to make an ordered list:

	  print	ul(
		    li({-type=>'disc'},['Sneezy','Doc','Sleepy','Happy'])
		  );

       This example will result	in HTML	output that looks like this:

	  <ul>
	    <li	type="disc">Sneezy</li>
	    <li	type="disc">Doc</li>
	    <li	type="disc">Sleepy</li>
	    <li	type="disc">Happy</li>
	  </ul>

       This is extremely useful	for creating tables.  For example:

	  print	table({-border=>undef},
		  caption('When	Should You Eat Your Vegetables?'),
		  Tr({-align=>'CENTER',-valign=>'TOP'},
		  [
		     th(['Vegetable', 'Breakfast','Lunch','Dinner']),
		     td(['Tomatoes' , 'no', 'yes', 'yes']),
		     td(['Broccoli' , 'no', 'no',  'yes']),
		     td(['Onions'   , 'yes','yes', 'yes'])
		  ]
		  )
	       );

   HTML	SHORTCUTS AND LIST INTERPOLATION
       Consider	this bit of code:

	  print	blockquote(em('Hi'),'mom!'));

       It will ordinarily return the string that you probably expect, namely:

	  <blockquote><em>Hi</em> mom!</blockquote>

       Note the	space between the element "Hi" and the element "mom!".	CGI.pm
       puts the	extra space there using	array interpolation, which is
       controlled by the magic $" variable.  Sometimes this extra space	is not
       what you	want, for example, when	you are	trying to align	a series of
       images.	In this	case, you can simply change the	value of $" to an
       empty string.

	  {
	     local($") = '';
	     print blockquote(em('Hi'),'mom!'));
	   }

       I suggest you put the code in a block as	shown here.  Otherwise the
       change to $" will affect	all subsequent code until you explicitly reset
       it.

   NON-STANDARD	HTML SHORTCUTS
       A few HTML tags don't follow the	standard pattern for various reasons.

       comment() generates an HTML comment (<!-- comment -->).	Call it	like

	   print comment('here is my comment');

       Because of conflicts with built-in Perl functions, the following
       functions begin with initial caps:

	   Select
	   Tr
	   Link
	   Delete
	   Accept
	   Sub

       In addition, start_html(), end_html(), start_form(), end_form(),
       start_multipart_form() and all the fill-out form	tags are special.  See
       their respective	sections.

   AUTOESCAPING	HTML
       By default, all HTML that is emitted by the form-generating functions
       is passed through a function called escapeHTML():

       $escaped_string = escapeHTML("unescaped string");
	   Escape HTML formatting characters in	a string.

       Provided	that you have specified	a character set	of ISO-8859-1 (the
       default), the standard HTML escaping rules will be used.	 The "<"
       character becomes "&lt;", ">" becomes "&gt;", "&" becomes "&amp;", and
       the quote character becomes "&quot;".  In addition, the hexadecimal
       0x8b and	0x9b characters, which some browsers incorrectly interpret as
       the left	and right angle-bracket	characters, are	replaced by their
       numeric character entities ("&#8249" and	"&#8250;").  If	you manually
       change the charset, either by calling the charset() method explicitly
       or by passing a -charset	argument to header(), then all characters will
       be replaced by their numeric entities, since CGI.pm has no lookup table
       for all the possible encodings.

       "escapeHTML()" expects the supplied string to be	a character string.
       This means you should Encode::decode data received from "outside" and
       Encode::encode your strings before sending them back outside. If	your
       source code UTF-8 encoded and you want to upgrade string	literals in
       your source to character	strings, you can use "use utf8". See
       perlunitut, perlunifaq and perlunicode for more information on how Perl
       handles the difference between bytes and	characters.

       The automatic escaping does not apply to	other shortcuts, such as h1().
       You should call escapeHTML() yourself on	untrusted data in order	to
       protect your pages against nasty	tricks that people may enter into
       guestbooks, etc..  To change the	character set, use charset().  To turn
       autoescaping off	completely, use	autoEscape(0):

       $charset	= charset([$charset]);
	   Get or set the current character set.

       $flag = autoEscape([$flag]);
	   Get or set the value	of the autoescape flag.

   PRETTY-PRINTING HTML
       By default, all the HTML	produced by these functions comes out as one
       long line without carriage returns or indentation. This is yuck,	but it
       does reduce the size of the documents by	10-20%.	 To get	pretty-printed
       output, please use CGI::Pretty, a subclass contributed by Brian
       Paulsen.

CREATING FILL-OUT FORMS:
       General note  The various form-creating methods all return strings to
       the caller, containing the tag or tags that will	create the requested
       form element.  You are responsible for actually printing	out these
       strings.	 It's set up this way so that you can place formatting tags
       around the form elements.

       Another note The	default	values that you	specify	for the	forms are only
       used the	first time the script is invoked (when there is	no query
       string).	 On subsequent invocations of the script (when there is	a
       query string), the former values	are used even if they are blank.

       If you want to change the value of a field from its previous value, you
       have two	choices:

       (1) call	the param() method to set it.

       (2) use the -override (alias -force) parameter (a new feature in
       version 2.15).  This forces the default value to	be used, regardless of
       the previous value:

	  print	textfield(-name=>'field_name',
				  -default=>'starting value',
				  -override=>1,
				  -size=>50,
				  -maxlength=>80);

       Yet another note	By default, the	text and labels	of form	elements are
       escaped according to HTML rules.	 This means that you can safely	use
       "<CLICK ME>" as the label for a button.	However, it also interferes
       with your ability to incorporate	special	HTML character sequences, such
       as &Aacute;, into your fields.  If you wish to turn off automatic
       escaping, call the autoEscape() method with a false value immediately
       after creating the CGI object:

	  $query = CGI->new;
	  $query->autoEscape(0);

       Note that autoEscape() is exclusively used to effect the	behavior of
       how some	CGI.pm HTML generation functions handle	escaping. Calling
       escapeHTML() explicitly will always escape the HTML.

       A Lurking Trap! Some of the form-element	generating methods return
       multiple	tags.  In a scalar context, the	tags will be concatenated
       together	with spaces, or	whatever is the	current	value of the $"
       global.	In a list context, the methods will return a list of elements,
       allowing	you to modify them if you wish.	 Usually you will not notice
       this behavior, but beware of this:

	   printf("%s\n",end_form())

       end_form() produces several tags, and only the first of them will be
       printed because the format only expects one value.

       <p>

   CREATING AN ISINDEX TAG
	  print	isindex(-action=>$action);

		-or-

	  print	isindex($action);

       Prints out an <isindex> tag.  Not very exciting.	 The parameter -action
       specifies the URL of the	script to process the query.  The default is
       to process the query with the current script.

   STARTING AND	ENDING A FORM
	   print start_form(-method=>$method,
			   -action=>$action,
			   -enctype=>$encoding);
	     <... various form stuff ...>
	   print end_form;

	       -or-

	   print start_form($method,$action,$encoding);
	     <... various form stuff ...>
	   print end_form;

       start_form() will return	a <form> tag with the optional method, action
       and form	encoding that you specify.  The	defaults are:

	   method: POST
	   action: this	script
	   enctype: application/x-www-form-urlencoded for non-XHTML
		    multipart/form-data	for XHTML, see multipart/form-data below.

       end_form() returns the closing </form> tag.

       Start_form()'s enctype argument tells the browser how to	package	the
       various fields of the form before sending the form to the server.  Two
       values are possible:

       Note: These methods were	previously named startform() and endform().
       These methods are now DEPRECATED.  Please use start_form() and
       end_form() instead.

       application/x-www-form-urlencoded
	   This	is the older type of encoding.	It is compatible with many CGI
	   scripts and is suitable for short fields containing text data.  For
	   your	convenience, CGI.pm stores the name of this encoding type in
	   &CGI::URL_ENCODED.

       multipart/form-data
	   This	is the newer type of encoding.	It is suitable for forms that
	   contain very	large fields or	that are intended for transferring
	   binary data.	 Most importantly, it enables the "file	upload"
	   feature.  For your convenience, CGI.pm stores the name of this
	   encoding type in &CGI::MULTIPART

	   Forms that use this type of encoding	are not	easily interpreted by
	   CGI scripts unless they use CGI.pm or another library designed to
	   handle them.

	   If XHTML is activated (the default),	then forms will	be
	   automatically created using this type of encoding.

       The start_form()	method uses the	older form of encoding by default
       unless XHTML is requested.  If you want to use the newer	form of
       encoding	by default, you	can call start_multipart_form()	instead	of
       start_form().  The method end_multipart_form() is an alias to
       end_form().

       JAVASCRIPTING: The -name	and -onSubmit parameters are provided for use
       with JavaScript.	 The -name parameter gives the form a name so that it
       can be identified and manipulated by JavaScript functions.  -onSubmit
       should point to a JavaScript function that will be executed just	before
       the form	is submitted to	your server.  You can use this opportunity to
       check the contents of the form for consistency and completeness.	 If
       you find	something wrong, you can put up	an alert box or	maybe fix
       things up yourself.  You	can abort the submission by returning false
       from this function.

       Usually the bulk	of JavaScript functions	are defined in a <script>
       block in	the HTML header	and -onSubmit points to	one of these function
       call.  See start_html() for details.

   FORM	ELEMENTS
       After starting a	form, you will typically create	one or more
       textfields, popup menus,	radio groups and other form elements.  Each of
       these elements takes a standard set of named arguments.	Some elements
       also have optional arguments.  The standard arguments are as follows:

       -name
	   The name of the field. After	submission this	name can be used to
	   retrieve the	field's	value using the	param()	method.

       -value, -values
	   The initial value of	the field which	will be	returned to the	script
	   after form submission.  Some	form elements, such as text fields,
	   take	a single scalar	-value argument. Others, such as popup menus,
	   take	a reference to an array	of values. The two arguments are
	   synonyms.

       -tabindex
	   A numeric value that	sets the order in which	the form element
	   receives focus when the user	presses	the tab	key. Elements with
	   lower values	receive	focus first.

       -id A string identifier that can	be used	to identify this element to
	   JavaScript and DHTML.

       -override
	   A boolean, which, if	true, forces the element to take on the	value
	   specified by	-value,	overriding the sticky behavior described
	   earlier for the -nosticky pragma.

       -onChange, -onFocus, -onBlur, -onMouseOver, -onMouseOut,	-onSelect
	   These are used to assign JavaScript event handlers. See the
	   JavaScripting section for more details.

       Other common arguments are described in the next	section. In addition
       to these, all attributes	described in the HTML specifications are
       supported.

   CREATING A TEXT FIELD
	   print textfield(-name=>'field_name',
			   -value=>'starting value',
			   -size=>50,
			   -maxlength=>80);
	       -or-

	   print textfield('field_name','starting value',50,80);

       textfield() will	return a text input field.

       Parameters
       1.  The first parameter is the required name for	the field (-name).

       2.  The optional	second parameter is the	default	starting value for the
	   field contents (-value, formerly known as -default).

       3.  The optional	third parameter	is the size of the field in
		 characters (-size).

       4.  The optional	fourth parameter is the	maximum	number of characters
	   the
		 field will accept (-maxlength).

       As with all these methods, the field will be initialized	with its
       previous	contents from earlier invocations of the script.  When the
       form is processed, the value of the text	field can be retrieved with:

	      $value = param('foo');

       If you want to reset it from its	initial	value after the	script has
       been called once, you can do so like this:

	      param('foo',"I'm taking over this	value!");

   CREATING A BIG TEXT FIELD
	  print	textarea(-name=>'foo',
				 -default=>'starting value',
				 -rows=>10,
				 -columns=>50);

	       -or

	  print	textarea('foo','starting value',10,50);

       textarea() is just like textfield, but it allows	you to specify rows
       and columns for a multiline text	entry box.  You	can provide a starting
       value for the field, which can be long and contain multiple lines.

   CREATING A PASSWORD FIELD
	  print	password_field(-name=>'secret',
				       -value=>'starting value',
				       -size=>50,
				       -maxlength=>80);
	       -or-

	  print	password_field('secret','starting value',50,80);

       password_field()	is identical to	textfield(), except that its contents
       will be starred out on the web page.

   CREATING A FILE UPLOAD FIELD
	   print filefield(-name=>'uploaded_file',
				   -default=>'starting value',
				   -size=>50,
				   -maxlength=>80);
	       -or-

	   print filefield('uploaded_file','starting value',50,80);

       filefield() will	return a file upload field.  In	order to take full
       advantage of this you must use the new multipart	encoding scheme	for
       the form.  You can do this either by calling start_form() with an
       encoding	type of	&CGI::MULTIPART, or by calling the new method
       start_multipart_form() instead of vanilla start_form().

       Parameters
       1.  The first parameter is the required name for	the field (-name).

       2.  The optional	second parameter is the	starting value for the field
	   contents to be used as the default file name	(-default).

	   For security	reasons, browsers don't	pay any	attention to this
	   field, and so the starting value will always	be blank.  Worse, the
	   field loses its "sticky" behavior and forgets its previous
	   contents.  The starting value field is called for in	the HTML
	   specification, however, and possibly	some browser will eventually
	   provide support for it.

       3.  The optional	third parameter	is the size of the field in characters
	   (-size).

       4.  The optional	fourth parameter is the	maximum	number of characters
	   the field will accept (-maxlength).

       JAVASCRIPTING: The -onChange, -onFocus, -onBlur,	-onMouseOver,
       -onMouseOut and -onSelect parameters are	recognized.  See textfield()
       for details.

   PROCESSING A	FILE UPLOAD FIELD
       Basics

       When the	form is	processed, you can retrieve an IO::Handle compatible
       handle for a file upload	field like this:

	 $lightweight_fh  = $q->upload('field_name');

	 # undef may be	returned if it's not a valid file handle
	 if (defined $lightweight_fh) {
	   # Upgrade the handle	to one compatible with IO::Handle:
	   my $io_handle = $lightweight_fh->handle;

	   open	(OUTFILE,'>>','/usr/local/web/users/feedback');
	   while ($bytesread = $io_handle->read($buffer,1024)) {
	     print OUTFILE $buffer;
	   }
	 }

       In a list context, upload() will	return an array	of filehandles.	 This
       makes it	possible to process forms that use the same name for multiple
       upload fields.

       If you want the entered file name for the file, you can just call
       param():

	 $filename = $q->param('field_name');

       Different browsers will return slightly different things	for the	name.
       Some browsers return the	filename only.	Others return the full path to
       the file, using the path	conventions of the user's machine.
       Regardless, the name returned is	always the name	of the file on the
       user's machine, and is unrelated	to the name of the temporary file that
       CGI.pm creates during upload spooling (see below).

       When a file is uploaded the browser usually sends along some
       information along with it in the	format of headers.  The	information
       usually includes	the MIME content type. To retrieve this	information,
       call uploadInfo().  It returns a	reference to a hash containing all the
       document	headers.

	      $filename	= $q->param('uploaded_file');
	      $type = $q->uploadInfo($filename)->{'Content-Type'};
	      unless ($type eq 'text/html') {
	       die "HTML FILES ONLY!";
	      }

       If you are using	a machine that recognizes "text" and "binary" data
       modes, be sure to understand when and how to use	them (see the Camel
       book).  Otherwise you may find that binary files	are corrupted during
       file uploads.

       Accessing the temp files	directly

       When processing an uploaded file, CGI.pm	creates	a temporary file on
       your hard disk and passes you a file handle to that file. After you are
       finished	with the file handle, CGI.pm unlinks (deletes) the temporary
       file. If	you need to you	can access the temporary file directly.	You
       can access the temp file	for a file upload by passing the file name to
       the tmpFileName() method:

	      $filename	= $query->param('uploaded_file');
	      $tmpfilename = $query->tmpFileName($filename);

       The temporary file will be deleted automatically	when your program
       exits unless you	manually rename	it. On some operating systems (such as
       Windows NT), you	will need to close the temporary file's	filehandle
       before your program exits.  Otherwise the attempt to delete the
       temporary file will fail.

       Handling	interrupted file uploads

       There are occasionally problems involving parsing the uploaded file.
       This usually happens when the user presses "Stop" before	the upload is
       finished.  In this case,	CGI.pm will return undef for the name of the
       uploaded	file and set cgi_error() to the	string "400 Bad	request
       (malformed multipart POST)".  This error	message	is designed so that
       you can incorporate it into a status code to be sent to the browser.
       Example:

	  $file	= $q->upload('uploaded_file');
	  if (!$file &&	$q->cgi_error) {
	     print $q->header(-status=>$q->cgi_error);
	     exit 0;
	  }

       You are free to create a	custom HTML page to complain about the error,
       if you wish.

       Progress	bars for file uploads and avoiding temp	files

       CGI.pm gives you	low-level access to file upload	management through a
       file upload hook. You can use this feature to completely	turn off the
       temp file storage of file uploads, or potentially write your own	file
       upload progress meter.

       This is much like the UPLOAD_HOOK facility available in
       Apache::Request,	with the exception that	the first argument to the
       callback	is an Apache::Upload object, here it's the remote filename.

	$q = CGI->new(\&hook [,$data [,$use_tempfile]]);

	sub hook {
	       my ($filename, $buffer, $bytes_read, $data) = @_;
	       print  "Read $bytes_read	bytes of $filename\n";
	}

       The $data field is optional; it lets you	pass configuration information
       (e.g. a database	handle)	to your	hook callback.

       The $use_tempfile field is a flag that lets you turn on and off
       CGI.pm's	use of a temporary disk-based file during file upload. If you
       set this	to a FALSE value (default true)	then
       $q->param('uploaded_file') will no longer work, and the only way	to get
       at the uploaded data is via the hook you	provide.

       If using	the function-oriented interface, call the CGI::upload_hook()
       method before calling param() or	any other CGI functions:

	 CGI::upload_hook(\&hook [,$data [,$use_tempfile]]);

       This method is not exported by default.	You will have to import	it
       explicitly if you wish to use it	without	the CGI:: prefix.

       Troubleshooting file uploads on Windows

       If you are using	CGI.pm on a Windows platform and find that binary
       files get slightly larger when uploaded but that	text files remain the
       same, then you have forgotten to	activate binary	mode on	the output
       filehandle.  Be sure to call binmode() on any handle that you create to
       write the uploaded file to disk.

       Older ways to process file uploads

       ( This section is here for completeness.	if you are building a new
       application with	CGI.pm,	you can	skip it. )

       The original way	to process file	uploads	with CGI.pm was	to use
       param().	The value it returns has a dual	nature as both a file name and
       a lightweight filehandle. This dual nature is problematic if you
       following the recommended practice of having "use strict" in your code.
       Perl will complain when you try to use a	string as a filehandle.	 More
       seriously, it is	possible for the remote	user to	type garbage into the
       upload field, in	which case what	you get	from param() is	not a
       filehandle at all, but a	string.

       To solve	this problem the upload() method was added, which always
       returns a lightweight filehandle. This generally	works well, but	will
       have trouble interoperating with	some other modules because the file
       handle is not derived from IO::Handle. So that brings us	to current
       recommendation given above, which is to call the	handle() method	on the
       file handle returned by upload().  That upgrades	the handle to an
       IO::Handle. It's	a big win for compatibility for	a small	penalty	of
       loading IO::Handle the first time you call it.

   CREATING A POPUP MENU
	  print	popup_menu('menu_name',
				   ['eenie','meenie','minie'],
				   'meenie');

	     -or-

	  %labels = ('eenie'=>'your first choice',
		     'meenie'=>'your second choice',
		     'minie'=>'your third choice');
	  %attributes =	('eenie'=>{'class'=>'class of first choice'});
	  print	popup_menu('menu_name',
				   ['eenie','meenie','minie'],
		 'meenie',\%labels,\%attributes);

	       -or (named parameter style)-

	  print	popup_menu(-name=>'menu_name',
				   -values=>['eenie','meenie','minie'],
				   -default=>['meenie','minie'],
		 -labels=>\%labels,
		 -attributes=>\%attributes);

       popup_menu() creates a menu.

       1.  The required	first argument is the menu's name (-name).

       2.  The required	second argument	(-values) is an	array reference
	   containing the list of menu items in	the menu.  You can pass	the
	   method an anonymous array, as shown in the example, or a reference
	   to a	named array, such as "\@foo".

       3.  The optional	third parameter	(-default) is the name of the default
	   menu	choice.	 If not	specified, the first item will be the default.
	   The values of the previous choice will be maintained	across
	   queries. Pass an array reference to select multiple defaults.

       4.  The optional	fourth parameter (-labels) is provided for people who
	   want	to use different values	for the	user-visible label inside the
	   popup menu and the value returned to	your script.  It's a pointer
	   to an hash relating menu values to user-visible labels.  If you
	   leave this parameter	blank, the menu	values will be displayed by
	   default.  (You can also leave a label undefined if you want to).

       5.  The optional	fifth parameter	(-attributes) is provided to assign
	   any of the common HTML attributes to	an individual menu item. It's
	   a pointer to	a hash relating	menu values to another hash with the
	   attribute's name as the key and the attribute's value as the	value.

       When the	form is	processed, the selected	value of the popup menu	can be
       retrieved using:

	     $popup_menu_value = param('menu_name');

   CREATING AN OPTION GROUP
       Named parameter style

	 print popup_menu(-name=>'menu_name',
			 -values=>[qw/eenie meenie minie/,
				   optgroup(-name=>'optgroup_name',
						    -values => ['moe','catch'],
						    -attributes=>{'catch'=>{'class'=>'red'}})],
			 -labels=>{'eenie'=>'one',
				   'meenie'=>'two',
				   'minie'=>'three'},
			 -default=>'meenie');

	 Old style
	 print popup_menu('menu_name',
			 ['eenie','meenie','minie',
			  optgroup('optgroup_name', ['moe', 'catch'],
					  {'catch'=>{'class'=>'red'}})],'meenie',
			 {'eenie'=>'one','meenie'=>'two','minie'=>'three'});

       optgroup() creates an option group within a popup menu.

       1.  The required	first argument (-name) is the label attribute of the
	   optgroup and	is not inserted	in the parameter list of the query.

       2.  The required	second argument	(-values)  is an array reference
	   containing the list of menu items in	the menu.  You can pass	the
	   method an anonymous array, as shown in the example, or a reference
	   to a	named array, such as \@foo.  If	you pass a HASH	reference, the
	   keys	will be	used for the menu values, and the values will be used
	   for the menu	labels (see -labels below).

       3.  The optional	third parameter	(-labels) allows you to	pass a
	   reference to	a hash containing user-visible labels for one or more
	   of the menu items.  You can use this	when you want the user to see
	   one menu string, but	have the browser return	your program a
	   different one.  If you don't	specify	this, the value	string will be
	   used	instead	("eenie", "meenie" and "minie" in this example).  This
	   is equivalent to using a hash reference for the -values parameter.

       4.  An optional fourth parameter	(-labeled) can be set to a true	value
	   and indicates that the values should	be used	as the label attribute
	   for each option element within the optgroup.

       5.  An optional fifth parameter (-novals) can be	set to a true value
	   and indicates to suppress the val attribute in each option element
	   within the optgroup.

	   See the discussion on optgroup at W3C
	   (http://www.w3.org/TR/REC-html40/interact/forms.html#edef-OPTGROUP)
	   for details.

       6.  An optional sixth parameter (-attributes) is	provided to assign any
	   of the common HTML attributes to an individual menu item. It's a
	   pointer to a	hash relating menu values to another hash with the
	   attribute's name as the key and the attribute's value as the	value.

   CREATING A SCROLLING	LIST
	  print	scrolling_list('list_name',
				       ['eenie','meenie','minie','moe'],
	       ['eenie','moe'],5,'true',{'moe'=>{'class'=>'red'}});
	     -or-

	  print	scrolling_list('list_name',
				       ['eenie','meenie','minie','moe'],
				       ['eenie','moe'],5,'true',
	       \%labels,%attributes);

	       -or-

	  print	scrolling_list(-name=>'list_name',
				       -values=>['eenie','meenie','minie','moe'],
				       -default=>['eenie','moe'],
				       -size=>5,
				       -multiple=>'true',
	       -labels=>\%labels,
	       -attributes=>\%attributes);

       scrolling_list()	creates	a scrolling list.

       Parameters:
       1.  The first and second	arguments are the list name (-name) and	values
	   (-values).  As in the popup menu, the second	argument should	be an
	   array reference.

       2.  The optional	third argument (-default) can be either	a reference to
	   a list containing the values	to be selected by default, or can be a
	   single value	to select.  If this argument is	missing	or undefined,
	   then	nothing	is selected when the list first	appears.  In the named
	   parameter version, you can use the synonym "-defaults" for this
	   parameter.

       3.  The optional	fourth argument	is the size of the list	(-size).

       4.  The optional	fifth argument can be set to true to allow multiple
	   simultaneous	selections (-multiple).	 Otherwise only	one selection
	   will	be allowed at a	time.

       5.  The optional	sixth argument is a pointer to a hash containing long
	   user-visible	labels for the list items (-labels).  If not provided,
	   the values will be displayed.

       6.  The optional	sixth parameter	(-attributes) is provided to assign
	   any of the common HTML attributes to	an individual menu item. It's
	   a pointer to	a hash relating	menu values to another hash with the
	   attribute's name as the key and the attribute's value as the	value.

	   When	this form is processed,	all selected list items	will be
	   returned as a list under the	parameter name 'list_name'.  The
	   values of the selected items	can be retrieved with:

		 @selected = param('list_name');

   CREATING A GROUP OF RELATED CHECKBOXES
	  print	checkbox_group(-name=>'group_name',
				       -values=>['eenie','meenie','minie','moe'],
				       -default=>['eenie','moe'],
				       -linebreak=>'true',
				       -disabled => ['moe'],
	       -labels=>\%labels,
	       -attributes=>\%attributes);

	  print	checkbox_group('group_name',
				       ['eenie','meenie','minie','moe'],
	       ['eenie','moe'],'true',\%labels,
	       {'moe'=>{'class'=>'red'}});

	  HTML3-COMPATIBLE BROWSERS ONLY:

	  print	checkbox_group(-name=>'group_name',
				       -values=>['eenie','meenie','minie','moe'],
				       -rows=2,-columns=>2);

       checkbox_group()	creates	a list of checkboxes that are related by the
       same name.

       Parameters:
       1.  The first and second	arguments are the checkbox name	and values,
	   respectively	(-name and -values).  As in the	popup menu, the	second
	   argument should be an array reference.  These values	are used for
	   the user-readable labels printed next to the	checkboxes as well as
	   for the values passed to your script	in the query string.

       2.  The optional	third argument (-default) can be either	a reference to
	   a list containing the values	to be checked by default, or can be a
	   single value	to checked.  If	this argument is missing or undefined,
	   then	nothing	is selected when the list first	appears.

       3.  The optional	fourth argument	(-linebreak) can be set	to true	to
	   place line breaks between the checkboxes so that they appear	as a
	   vertical list.  Otherwise, they will	be strung together on a
	   horizontal line.

       The optional -labels argument is	a pointer to a hash relating the
       checkbox	values to the user-visible labels that will be printed next to
       them.  If not provided, the values will be used as the default.

       The optional parameters -rows, and -columns cause checkbox_group() to
       return an HTML3 compatible table	containing the checkbox	group
       formatted with the specified number of rows and columns.	 You can
       provide just the	-columns parameter if you wish;	checkbox_group will
       calculate the correct number of rows for	you.

       The option -disabled takes an array of checkbox values and disables
       them by greying them out	(this may not be supported by all browsers).

       The optional -attributes	argument is provided to	assign any of the
       common HTML attributes to an individual menu item. It's a pointer to a
       hash relating menu values to another hash with the attribute's name as
       the key and the attribute's value as the	value.

       The optional -tabindex argument can be used to control the order	in
       which radio buttons receive focus when the user presses the tab button.
       If passed a scalar numeric value, the first element in the group	will
       receive this tab	index and subsequent elements will be incremented by
       one.  If	given a	reference to an	array of radio button values, then the
       indexes will be jiggered	so that	the order specified in the array will
       correspond to the tab order.  You can also pass a reference to a	hash
       in which	the hash keys are the radio button values and the values are
       the tab indexes of each button.	Examples:

	 -tabindex => 100    #	this group starts at index 100 and counts up
	 -tabindex => ['moe','minie','eenie','meenie']	# tab in this order
	 -tabindex => {meenie=>100,moe=>101,minie=>102,eenie=>200} # tab in this order

       The optional -labelattributes argument will contain attributes attached
       to the <label> element that surrounds each button.

       When the	form is	processed, all checked boxes will be returned as a
       list under the parameter	name 'group_name'.  The	values of the "on"
       checkboxes can be retrieved with:

	     @turned_on	= param('group_name');

       The value returned by checkbox_group() is actually an array of button
       elements.  You can capture them and use them within tables, lists, or
       in other	creative ways:

	   @h =	checkbox_group(-name=>'group_name',-values=>\@values);
	   &use_in_creative_way(@h);

   CREATING A STANDALONE CHECKBOX
	   print checkbox(-name=>'checkbox_name',
				  -checked=>1,
				  -value=>'ON',
				  -label=>'CLICK ME');

	       -or-

	   print checkbox('checkbox_name','checked','ON','CLICK	ME');

       checkbox() is used to create an isolated	checkbox that isn't logically
       related to any others.

       Parameters:
       1.  The first parameter is the required name for	the checkbox (-name).
	   It will also	be used	for the	user-readable label printed next to
	   the checkbox.

       2.  The optional	second parameter (-checked) specifies that the
	   checkbox is turned on by default.  Synonyms are -selected and -on.

       3.  The optional	third parameter	(-value) specifies the value of	the
	   checkbox when it is checked.	 If not	provided, the word "on"	is
	   assumed.

       4.  The optional	fourth parameter (-label) is the user-readable label
	   to be attached to the checkbox.  If not provided, the checkbox name
	   is used.

       The value of the	checkbox can be	retrieved using:

	   $turned_on =	param('checkbox_name');

   CREATING A RADIO BUTTON GROUP
	  print	radio_group(-name=>'group_name',
				    -values=>['eenie','meenie','minie'],
				    -default=>'meenie',
				    -linebreak=>'true',
		  -labels=>\%labels,
		  -attributes=>\%attributes);

	       -or-

	  print	radio_group('group_name',['eenie','meenie','minie'],
		   'meenie','true',\%labels,\%attributes);

	  HTML3-COMPATIBLE BROWSERS ONLY:

	  print	radio_group(-name=>'group_name',
				    -values=>['eenie','meenie','minie','moe'],
				    -rows=2,-columns=>2);

       radio_group() creates a set of logically-related	radio buttons (turning
       one member of the group on turns	the others off)

       Parameters:
       1.  The first argument is the name of the group and is required
	   (-name).

       2.  The second argument (-values) is the	list of	values for the radio
	   buttons.  The values	and the	labels that appear on the page are
	   identical.  Pass an array reference in the second argument, either
	   using an anonymous array, as	shown, or by referencing a named array
	   as in "\@foo".

       3.  The optional	third parameter	(-default) is the name of the default
	   button to turn on. If not specified,	the first item will be the
	   default.  You can provide a nonexistent button name,	such as	"-" to
	   start up with no buttons selected.

       4.  The optional	fourth parameter (-linebreak) can be set to 'true' to
	   put line breaks between the buttons,	creating a vertical list.

       5.  The optional	fifth parameter	(-labels) is a pointer to an
	   associative array relating the radio	button values to user-visible
	   labels to be	used in	the display.  If not provided, the values
	   themselves are displayed.

       All modern browsers can take advantage of the optional parameters
       -rows, and -columns.  These parameters cause radio_group() to return an
       HTML3 compatible	table containing the radio group formatted with	the
       specified number	of rows	and columns.  You can provide just the
       -columns	parameter if you wish; radio_group will	calculate the correct
       number of rows for you.

       To include row and column headings in the returned table, you can use
       the -rowheaders and -colheaders parameters.  Both of these accept a
       pointer to an array of headings to use.	The headings are just
       decorative.  They don't reorganize the interpretation of	the radio
       buttons -- they're still	a single named unit.

       The optional -tabindex argument can be used to control the order	in
       which radio buttons receive focus when the user presses the tab button.
       If passed a scalar numeric value, the first element in the group	will
       receive this tab	index and subsequent elements will be incremented by
       one.  If	given a	reference to an	array of radio button values, then the
       indexes will be jiggered	so that	the order specified in the array will
       correspond to the tab order.  You can also pass a reference to a	hash
       in which	the hash keys are the radio button values and the values are
       the tab indexes of each button.	Examples:

	 -tabindex => 100    #	this group starts at index 100 and counts up
	 -tabindex => ['moe','minie','eenie','meenie']	# tab in this order
	 -tabindex => {meenie=>100,moe=>101,minie=>102,eenie=>200} # tab in this order

       The optional -attributes	argument is provided to	assign any of the
       common HTML attributes to an individual menu item. It's a pointer to a
       hash relating menu values to another hash with the attribute's name as
       the key and the attribute's value as the	value.

       The optional -labelattributes argument will contain attributes attached
       to the <label> element that surrounds each button.

       When the	form is	processed, the selected	radio button can be retrieved
       using:

	     $which_radio_button = param('group_name');

       The value returned by radio_group() is actually an array	of button
       elements.  You can capture them and use them within tables, lists, or
       in other	creative ways:

	   @h =	radio_group(-name=>'group_name',-values=>\@values);
	   &use_in_creative_way(@h);

   CREATING A SUBMIT BUTTON
	  print	submit(-name=>'button_name',
			       -value=>'value');

	       -or-

	  print	submit('button_name','value');

       submit()	will create the	query submission button.  Every	form should
       have one	of these.

       Parameters:
       1.  The first argument (-name) is optional.  You	can give the button a
	   name	if you have several submission buttons in your form and	you
	   want	to distinguish between them.

       2.  The second argument (-value)	is also	optional.  This	gives the
	   button a value that will be passed to your script in	the query
	   string. The name will also be used as the user-visible label.

       3.  You can use -label as an alias for -value.  I always	get confused
	   about which of -name	and -value changes the user-visible label on
	   the button.

       You can figure out which	button was pressed by using different values
       for each	one:

	    $which_one = param('button_name');

   CREATING A RESET BUTTON
	  print	reset

       reset() creates the "reset" button.  Note that it restores the form to
       its value from the last time the	script was called, NOT necessarily to
       the defaults.

       Note that this conflicts	with the Perl reset() built-in.	 Use
       CORE::reset() to	get the	original reset function.

   CREATING A DEFAULT BUTTON
	  print	defaults('button_label')

       defaults() creates a button that, when invoked, will cause the form to
       be completely reset to its defaults, wiping out all the changes the
       user ever made.

   CREATING A HIDDEN FIELD
	       print hidden(-name=>'hidden_name',
				    -default=>['value1','value2'...]);

		       -or-

	       print hidden('hidden_name','value1','value2'...);

       hidden()	produces a text	field that can't be seen by the	user.  It is
       useful for passing state	variable information from one invocation of
       the script to the next.

       Parameters:
       1.  The first argument is required and specifies	the name of this field
	   (-name).

       2.  The second argument is also required	and specifies its value
	   (-default).	In the named parameter style of	calling, you can
	   provide a single value here or a reference to a whole list

       Fetch the value of a hidden field this way:

	    $hidden_value = param('hidden_name');

       Note, that just like all	the other form elements, the value of a	hidden
       field is	"sticky".  If you want to replace a hidden field with some
       other values after the script has been called once you'll have to do it
       manually:

	    param('hidden_name','new','values','here');

   CREATING A CLICKABLE	IMAGE BUTTON
	    print image_button(-name=>'button_name',
				       -src=>'/source/URL',
				       -align=>'MIDDLE');

	       -or-

	    print image_button('button_name','/source/URL','MIDDLE');

       image_button() produces a clickable image.  When	it's clicked on	the
       position	of the click is	returned to your script	as "button_name.x" and
       "button_name.y",	where "button_name" is the name	you've assigned	to it.

       Parameters:
       1.  The first argument (-name) is required and specifies	the name of
	   this	field.

       2.  The second argument (-src) is also required and specifies the URL

       3. The third option (-align, optional) is an alignment type, and	may be
       TOP, BOTTOM or MIDDLE

       Fetch the value of the button this way:
	    $x = param('button_name.x');
	    $y = param('button_name.y');

   CREATING A JAVASCRIPT ACTION	BUTTON
	    print button(-name=>'button_name',
				 -value=>'user visible label',
				 -onClick=>"do_something()");

	       -or-

	    print button('button_name',"user visible value","do_something()");

       button()	produces an "<input>" tag with "type="button"".	 When it's
       pressed the fragment of JavaScript code pointed to by the -onClick
       parameter will be executed.

HTTP COOKIES
       Browsers	support	a so-called "cookie" designed to help maintain state
       within a	browser	session.  CGI.pm has several methods that support
       cookies.

       A cookie	is a name=value	pair much like the named parameters in a CGI
       query string.  CGI scripts create one or	more cookies and send them to
       the browser in the HTTP header.	The browser maintains a	list of
       cookies that belong to a	particular Web server, and returns them	to the
       CGI script during subsequent interactions.

       In addition to the required name=value pair, each cookie	has several
       optional	attributes:

       1. an expiration	time
	   This	is a time/date string (in a special GMT	format)	that indicates
	   when	a cookie expires.  The cookie will be saved and	returned to
	   your	script until this expiration date is reached if	the user exits
	   the browser and restarts it.	 If an expiration date isn't
	   specified, the cookie will remain active until the user quits the
	   browser.

       2. a domain
	   This	is a partial or	complete domain	name for which the cookie is
	   valid.  The browser will return the cookie to any host that matches
	   the partial domain name.  For example, if you specify a domain name
	   of ".capricorn.com",	then the browser will return the cookie	to Web
	   servers running on any of the machines "www.capricorn.com",
	   "www2.capricorn.com", "feckless.capricorn.com", etc.	 Domain	names
	   must	contain	at least two periods to	prevent	attempts to match on
	   top level domains like ".edu".  If no domain	is specified, then the
	   browser will	only return the	cookie to servers on the host the
	   cookie originated from.

       3. a path
	   If you provide a cookie path	attribute, the browser will check it
	   against your	script's URL before returning the cookie.  For
	   example, if you specify the path "/cgi-bin",	then the cookie	will
	   be returned to each of the scripts "/cgi-bin/tally.pl",
	   "/cgi-bin/order.pl",	and "/cgi-bin/customer_service/complain.pl",
	   but not to the script "/cgi-private/site_admin.pl".	By default,
	   path	is set to "/", which causes the	cookie to be sent to any CGI
	   script on your site.

       4. a "secure" flag
	   If the "secure" attribute is	set, the cookie	will only be sent to
	   your	script if the CGI request is occurring on a secure channel,
	   such	as SSL.

       The interface to	HTTP cookies is	the cookie() method:

	   $cookie = cookie(-name=>'sessionID',
				    -value=>'xyzzy',
				    -expires=>'+1h',
				    -path=>'/cgi-bin/database',
				    -domain=>'.capricorn.org',
				    -secure=>1);
	   print header(-cookie=>$cookie);

       cookie()	creates	a new cookie.  Its parameters include:

       -name
	   The name of the cookie (required).  This can	be any string at all.
	   Although browsers limit their cookie	names to non-whitespace
	   alphanumeric	characters, CGI.pm removes this	restriction by
	   escaping and	unescaping cookies behind the scenes.

       -value
	   The value of	the cookie.  This can be any scalar value, array
	   reference, or even hash reference.  For example, you	can store an
	   entire hash into a cookie this way:

		   $cookie=cookie(-name=>'family information',
					  -value=>\%childrens_ages);

       -path
	   The optional	partial	path for which this cookie will	be valid, as
	   described above.

       -domain
	   The optional	partial	domain for which this cookie will be valid, as
	   described above.

       -expires
	   The optional	expiration date	for this cookie.  The format is	as
	   described in	the section on the header() method:

		   "+1h"  one hour from	now

       -secure
	   If set to true, this	cookie will only be used within	a secure SSL
	   session.

       The cookie created by cookie() must be incorporated into	the HTTP
       header within the string	returned by the	header() method:

	       use CGI ':standard';
	       print header(-cookie=>$my_cookie);

       To create multiple cookies, give	header() an array reference:

	       $cookie1	= cookie(-name=>'riddle_name',
					 -value=>"The Sphynx's Question");
	       $cookie2	= cookie(-name=>'answers',
					 -value=>\%answers);
	       print header(-cookie=>[$cookie1,$cookie2]);

       To retrieve a cookie, request it	by name	by calling cookie() method
       without the -value parameter. This example uses the object-oriented
       form:

	       use CGI;
	       $query =	CGI->new;
	       $riddle = $query->cookie('riddle_name');
	       %answers	= $query->cookie('answers');

       Cookies created with a single scalar value, such	as the "riddle_name"
       cookie, will be returned	in that	form.  Cookies with array and hash
       values can also be retrieved.

       The cookie and CGI namespaces are separate.  If you have	a parameter
       named 'answers' and a cookie named 'answers', the values	retrieved by
       param() and cookie() are	independent of each other.  However, it's
       simple to turn a	CGI parameter into a cookie, and vice-versa:

	  # turn a CGI parameter into a	cookie
	  $c=cookie(-name=>'answers',-value=>[param('answers')]);
	  # vice-versa
	  param(-name=>'answers',-value=>[cookie('answers')]);

       If you call cookie() without any	parameters, it will return a list of
       the names of all	cookies	passed to your script:

	 @cookies = cookie();

       See the cookie.cgi example script for some ideas	on how to use cookies
       effectively.

WORKING	WITH FRAMES
       It's possible for CGI.pm	scripts	to write into several browser panels
       and windows using the HTML 4 frame mechanism.  There are	three
       techniques for defining new frames programmatically:

       1. Create a <Frameset> document
	   After writing out the HTTP header, instead of creating a standard
	   HTML	document using the start_html()	call, create a <frameset>
	   document that defines the frames on the page.  Specify your
	   script(s) (with appropriate parameters) as the SRC for each of the
	   frames.

	   There is no specific	support	for creating <frameset>	sections in
	   CGI.pm, but the HTML	is very	simple to write.

       2. Specify the destination for the document in the HTTP header
	   You may provide a -target parameter to the header() method:

	       print header(-target=>'ResultsWindow');

	   This	will tell the browser to load the output of your script	into
	   the frame named "ResultsWindow".  If	a frame	of that	name doesn't
	   already exist, the browser will pop up a new	window and load	your
	   script's document into that.	 There are a number of magic names
	   that	you can	use for	targets.  See the HTML "<frame>" documentation
	   for details.

       3. Specify the destination for the document in the <form> tag
	   You can specify the frame to	load in	the FORM tag itself.  With
	   CGI.pm it looks like	this:

	       print start_form(-target=>'ResultsWindow');

	   When	your script is reinvoked by the	form, its output will be
	   loaded into the frame named "ResultsWindow".	 If one	doesn't
	   already exist a new window will be created.

       The script "frameset.cgi" in the	examples directory shows one way to
       create pages in which the fill-out form and the response	live in	side-
       by-side frames.

SUPPORT	FOR JAVASCRIPT
       The usual way to	use JavaScript is to define a set of functions in a
       <SCRIPT>	block inside the HTML header and then to register event
       handlers	in the various elements	of the page. Events include such
       things as the mouse passing over	a form element,	a button being
       clicked,	the contents of	a text field changing, or a form being
       submitted. When an event	occurs that involves an	element	that has
       registered an event handler, its	associated JavaScript code gets
       called.

       The elements that can register event handlers include the <BODY>	of an
       HTML document, hypertext	links, all the various elements	of a fill-out
       form, and the form itself. There	are a large number of events, and each
       applies only to the elements for	which it is relevant. Here is a
       partial list:

       onLoad
	   The browser is loading the current document.	Valid in:

		+ The HTML <BODY> section only.

       onUnload
	   The browser is closing the current page or frame. Valid for:

		+ The HTML <BODY> section only.

       onSubmit
	   The user has	pressed	the submit button of a form. This event
	   happens just	before the form	is submitted, and your function	can
	   return a value of false in order to abort the submission.  Valid
	   for:

		+ Forms	only.

       onClick
	   The mouse has clicked on an item in a fill-out form.	Valid for:

		+ Buttons (including submit, reset, and	image buttons)
		+ Checkboxes
		+ Radio	buttons

       onChange
	   The user has	changed	the contents of	a field. Valid for:

		+ Text fields
		+ Text areas
		+ Password fields
		+ File fields
		+ Popup	Menus
		+ Scrolling lists

       onFocus
	   The user has	selected a field to work with. Valid for:

		+ Text fields
		+ Text areas
		+ Password fields
		+ File fields
		+ Popup	Menus
		+ Scrolling lists

       onBlur
	   The user has	deselected a field (gone to work somewhere else).
	   Valid for:

		+ Text fields
		+ Text areas
		+ Password fields
		+ File fields
		+ Popup	Menus
		+ Scrolling lists

       onSelect
	   The user has	changed	the part of a text field that is selected.
	   Valid for:

		+ Text fields
		+ Text areas
		+ Password fields
		+ File fields

       onMouseOver
	   The mouse has moved over an element.

		+ Text fields
		+ Text areas
		+ Password fields
		+ File fields
		+ Popup	Menus
		+ Scrolling lists

       onMouseOut
	   The mouse has moved off an element.

		+ Text fields
		+ Text areas
		+ Password fields
		+ File fields
		+ Popup	Menus
		+ Scrolling lists

       In order	to register a JavaScript event handler with an HTML element,
       just use	the event name as a parameter when you call the	corresponding
       CGI method. For example,	to have	your validateAge() JavaScript code
       executed	every time the textfield named "age" changes, generate the
       field like this:

	print textfield(-name=>'age',-onChange=>"validateAge(this)");

       This example assumes that you've	already	declared the validateAge()
       function	by incorporating it into a <SCRIPT> block. The CGI.pm
       start_html() method provides a convenient way to	create this section.

       Similarly, you can create a form	that checks itself over	for
       consistency and alerts the user if some essential value is missing by
       creating	it this	way:
	 print start_form(-onSubmit=>"validateMe(this)");

       See the javascript.cgi script for a demonstration of how	this all
       works.

LIMITED	SUPPORT	FOR CASCADING STYLE SHEETS
       CGI.pm has limited support for HTML3's cascading	style sheets (css).
       To incorporate a	stylesheet into	your document, pass the	start_html()
       method a	-style parameter.  The value of	this parameter may be a
       scalar, in which	case it	is treated as the source URL for the
       stylesheet, or it may be	a hash reference.  In the latter case you
       should provide the hash with one	or more	of -src	or -code.  -src	points
       to a URL	where an externally-defined stylesheet can be found.  -code
       points to a scalar value	to be incorporated into	a <style> section.
       Style definitions in -code override similarly-named ones	in -src, hence
       the name	"cascading."

       You may also specify the	type of	the stylesheet by adding the optional
       -type parameter to the hash pointed to by -style.  If not specified,
       the style defaults to 'text/css'.

       To refer	to a style within the body of your document, add the -class
       parameter to any	HTML element:

	   print h1({-class=>'Fancy'},'Welcome to the Party');

       Or define styles	on the fly with	the -style parameter:

	   print h1({-style=>'Color: red;'},'Welcome to	Hell');

       You may also use	the new	span() element to apply	a style	to a section
       of text:

	   print span({-style=>'Color: red;'},
		      h1('Welcome to Hell'),
		      "Where did that handbasket get to?"
		      );

       Note that you must import the ":html3" definitions to have the span()
       method available.  Here's a quick and dirty example of using CSS's.
       See the CSS specification at http://www.w3.org/Style/CSS/ for more
       information.

	   use CGI qw/:standard	:html3/;

	   #here's a stylesheet	incorporated directly into the page
	   $newStyle=<<END;
	   <!--
	   P.Tip {
	       margin-right: 50pt;
	       margin-left: 50pt;
	       color: red;
	   }
	   P.Alert {
	       font-size: 30pt;
	       font-family: sans-serif;
	     color: red;
	   }
	   -->
	   END
	   print header();
	   print start_html( -title=>'CGI with Style',
			     -style=>{-src=>'http://www.capricorn.com/style/st1.css',
				      -code=>$newStyle}
			    );
	   print h1('CGI with Style'),
		 p({-class=>'Tip'},
		   "Better read	the cascading style sheet spec before playing with this!"),
		 span({-style=>'color: magenta'},
		      "Look Mom, no hands!",
		      p(),
		      "Whooo wee!"
		      );
	   print end_html;

       Pass an array reference to -code	or -src	in order to incorporate
       multiple	stylesheets into your document.

       Should you wish to incorporate a	verbatim stylesheet that includes
       arbitrary formatting in the header, you may pass	a -verbatim tag	to the
       -style hash, as follows:

       print start_html	(-style	 =>  {-verbatim	=> '@import
       url("/server-common/css/'.$cssFile.'");',
			 -src	 =>  '/server-common/css/core.css'});

       This will generate an HTML header that contains this:

	<link rel="stylesheet" type="text/css"	href="/server-common/css/core.css">
	  <style type="text/css">
	  @import url("/server-common/css/main.css");
	  </style>

       Any additional arguments	passed in the -style value will	be
       incorporated into the <link> tag.  For example:

	start_html(-style=>{-src=>['/styles/print.css','/styles/layout.css'],
				 -media	=> 'all'});

       This will give:

	<link rel="stylesheet" type="text/css" href="/styles/print.css"	media="all"/>
	<link rel="stylesheet" type="text/css" href="/styles/layout.css" media="all"/>

       <p>

       To make more complicated	<link> tags, use the Link() function and pass
       it to start_html() in the -head argument, as in:

	 @h = (Link({-rel=>'stylesheet',-type=>'text/css',-src=>'/ss/ss.css',-media=>'all'}),
	       Link({-rel=>'stylesheet',-type=>'text/css',-src=>'/ss/fred.css',-media=>'paper'}));
	 print start_html({-head=>\@h})

       To create primary and  "alternate" stylesheet, use the -alternate
       option:

	start_html(-style=>{-src=>[
				  {-src=>'/styles/print.css'},
				  {-src=>'/styles/alt.css',-alternate=>1}
				  ]
			   });

DEBUGGING
       If you are running the script from the command line or in the perl
       debugger, you can pass the script a list	of keywords or parameter=value
       pairs on	the command line or from standard input	(you don't have	to
       worry about tricking your script	into reading from environment
       variables).  You	can pass keywords like this:

	   your_script.pl keyword1 keyword2 keyword3

       or this:

	  your_script.pl keyword1+keyword2+keyword3

       or this:

	   your_script.pl name1=value1 name2=value2

       or this:

	   your_script.pl name1=value1&name2=value2

       To turn off this	feature, use the -no_debug pragma.

       To test the POST	method,	you may	enable full debugging with the -debug
       pragma.	This will allow	you to feed newline-delimited name=value pairs
       to the script on	standard input.

       When debugging, you can use quotes and backslashes to escape characters
       in the familiar shell manner, letting you place spaces and other	funny
       characters in your parameter=value pairs:

	  your_script.pl "name1='I am a	long value'" "name2=two\ words"

       Finally,	you can	set the	path info for the script by prefixing the
       first name/value	parameter with the path	followed by a question mark
       (?):

	   your_script.pl /your/path/here?name1=value1&name2=value2

   DUMPING OUT ALL THE NAME/VALUE PAIRS
       The Dump() method produces a string consisting of all the query's
       name/value pairs	formatted nicely as a nested list.  This is useful for
       debugging purposes:

	   print Dump

       Produces	something that looks like:

	   <ul>
	   <li>name1
	       <ul>
	       <li>value1
	       <li>value2
	       </ul>
	   <li>name2
	       <ul>
	       <li>value1
	       </ul>
	   </ul>

       As a shortcut, you can interpolate the entire CGI object	into a string
       and it will be replaced with the	a nice HTML dump shown above:

	   $query=CGI->new;
	   print "<h2>Current Values</h2> $query\n";

FETCHING ENVIRONMENT VARIABLES
       Some of the more	useful environment variables can be fetched through
       this interface.	The methods are	as follows:

       Accept()
	   Return a list of MIME types that the	remote browser accepts.	If you
	   give	this method a single argument corresponding to a MIME type, as
	   in Accept('text/html'), it will return a floating point value
	   corresponding to the	browser's preference for this type from	0.0
	   (don't want)	to 1.0.	 Glob types (e.g. text/*) in the browser's
	   accept list are handled correctly.

	   Note	that the capitalization	changed	between	version	2.43 and 2.44
	   in order to avoid conflict with Perl's accept() function.

       raw_cookie()
	   Returns the HTTP_COOKIE variable.  Cookies have a special format,
	   and this method call	just returns the raw form (?cookie dough).
	   See cookie()	for ways of setting and	retrieving cooked cookies.

	   Called with no parameters, raw_cookie() returns the packed cookie
	   structure.  You can separate	it into	individual cookies by
	   splitting on	the character sequence "; ".  Called with the name of
	   a cookie, retrieves the unescaped form of the cookie.  You can use
	   the regular cookie()	method to get the names, or use	the
	   raw_fetch() method from the CGI::Cookie module.

       user_agent()
	   Returns the HTTP_USER_AGENT variable.  If you give this method a
	   single argument, it will attempt to pattern match on	it, allowing
	   you to do something like user_agent(Mozilla);

       path_info()
	   Returns additional path information from the	script URL.  E.G.
	   fetching /cgi-bin/your_script/additional/stuff will result in
	   path_info() returning "/additional/stuff".

	   NOTE: The Microsoft Internet	Information Server is broken with
	   respect to additional path information.  If you use the Perl	DLL
	   library, the	IIS server will	attempt	to execute the additional path
	   information as a Perl script.  If you use the ordinary file
	   associations	mapping, the path information will be present in the
	   environment,	but incorrect.	The best thing to do is	to avoid using
	   additional path information in CGI scripts destined for use with
	   IIS.

       path_translated()
	   As per path_info() but returns the additional path information
	   translated into a physical path, e.g.
	   "/usr/local/etc/httpd/htdocs/additional/stuff".

	   The Microsoft IIS is	broken with respect to the translated path as
	   well.

       remote_host()
	   Returns either the remote host name or IP address.  if the former
	   is unavailable.

       remote_addr()
	   Returns the remote host IP address, or 127.0.0.1 if the address is
	   unavailable.

       script_name() Return the	script name as a partial URL, for self-
       referring scripts.
       referer()
	   Return the URL of the page the browser was viewing prior to
	   fetching your script.  Not available	for all	browsers.

       auth_type ()
	   Return the authorization/verification method	in use for this
	   script, if any.

       server_name ()
	   Returns the name of the server, usually the machine's host name.

       virtual_host ()
	   When	using virtual hosts, returns the name of the host that the
	   browser attempted to	contact

       server_port ()
	   Return the port that	the server is listening	on.

       virtual_port ()
	   Like	server_port() except that it takes virtual hosts into account.
	   Use this when running with virtual hosts.

       server_software ()
	   Returns the server software and version number.

       remote_user ()
	   Return the authorization/verification name used for user
	   verification, if this script	is protected.

       user_name ()
	   Attempt to obtain the remote	user's name, using a variety of
	   different techniques.  This only works with older browsers such as
	   Mosaic.  Newer browsers do not report the user name for privacy
	   reasons!

       request_method()
	   Returns the method used to access your script, usually one of
	   'POST', 'GET' or 'HEAD'.

       content_type()
	   Returns the content_type of data submitted in a POST, generally
	   multipart/form-data or application/x-www-form-urlencoded

       http()
	   Called with no arguments returns the	list of	HTTP environment
	   variables, including	such things as HTTP_USER_AGENT,
	   HTTP_ACCEPT_LANGUAGE, and HTTP_ACCEPT_CHARSET, corresponding	to the
	   like-named HTTP header fields in the	request.  Called with the name
	   of an HTTP header field, returns its	value.	Capitalization and the
	   use of hyphens versus underscores are not significant.

	   For example,	all three of these examples are	equivalent:

	      $requested_language = http('Accept-language');
	      $requested_language = http('Accept_language');
	      $requested_language = http('HTTP_ACCEPT_LANGUAGE');

       https()
	   The same as http(), but operates on the HTTPS environment variables
	   present when	the SSL	protocol is in effect.	Can be used to
	   determine whether SSL is turned on.

USING NPH SCRIPTS
       NPH, or "no-parsed-header", scripts bypass the server completely	by
       sending the complete HTTP header	directly to the	browser.  This has
       slight performance benefits, but	is of most use for taking advantage of
       HTTP extensions that are	not directly supported by your server, such as
       server push and PICS headers.

       Servers use a variety of	conventions for	designating CGI	scripts	as
       NPH.  Many Unix servers look at the beginning of	the script's name for
       the prefix "nph-".  The Macintosh WebSTAR server	and Microsoft's
       Internet	Information Server, in contrast, try to	decide whether a
       program is an NPH script	by examining the first line of script output.

       CGI.pm supports NPH scripts with	a special NPH mode.  When in this
       mode, CGI.pm will output	the necessary extra header information when
       the header() and	redirect() methods are called.

       The Microsoft Internet Information Server requires NPH mode.  As	of
       version 2.30, CGI.pm will automatically detect when the script is
       running under IIS and put itself	into this mode.	 You do	not need to do
       this manually, although it won't	hurt anything if you do.  However,
       note that if you	have applied Service Pack 6, much of the functionality
       of NPH scripts, including the ability to	redirect while setting a
       cookie, do not work at all on IIS without a special patch from
       Microsoft.  See
       http://web.archive.org/web/20010812012030/http://support.microsoft.com/support/kb/articles/Q280/3/41.ASP
       Non-Parsed Headers Stripped From	CGI Applications That Have nph-	Prefix
       in Name.

       In the use statement
	   Simply add the "-nph" pragma	to the list of symbols to be imported
	   into	your script:

		 use CGI qw(:standard -nph)

       By calling the nph() method:
	   Call	nph() with a non-zero parameter	at any point after using
	   CGI.pm in your program.

		 CGI->nph(1)

       By using	-nph parameters
	   in the header() and redirect()  statements:

		 print header(-nph=>1);

Server Push
       CGI.pm provides four simple functions for producing multipart documents
       of the type needed to implement server push.  These functions were
       graciously provided by Ed Jordan	<ed@fidalgo.net>.  To import these
       into your namespace, you	must import the	":push"	set.  You are also
       advised to put the script into NPH mode and to set $| to	1 to avoid
       buffering problems.

       Here is a simple	script that demonstrates server	push:

	 #!/usr/local/bin/perl
	 use CGI qw/:push -nph/;
	 $| = 1;
	 print multipart_init(-boundary=>'----here we go!');
	 for (0	.. 4) {
	     print multipart_start(-type=>'text/plain'),
		   "The	current	time is	",scalar(localtime),"\n";
	     if	($_ < 4) {
		     print multipart_end;
	     } else {
		     print multipart_final;
	     }
	     sleep 1;
	 }

       This script initializes server push by calling multipart_init().	 It
       then enters a loop in which it begins a new multipart section by
       calling multipart_start(), prints the current local time, and ends a
       multipart section with multipart_end().	It then	sleeps a second, and
       begins again. On	the final iteration, it	ends the multipart section
       with multipart_final() rather than with multipart_end().

       multipart_init()
	     multipart_init(-boundary=>$boundary);

	   Initialize the multipart system.  The -boundary argument specifies
	   what	MIME boundary string to	use to separate	parts of the document.
	   If not provided, CGI.pm chooses a reasonable	boundary for you.

       multipart_start()
	     multipart_start(-type=>$type)

	   Start a new part of the multipart document using the	specified MIME
	   type.  If not specified, text/html is assumed.

       multipart_end()
	     multipart_end()

	   End a part.	You must remember to call multipart_end() once for
	   each	multipart_start(), except at the end of	the last part of the
	   multipart document when multipart_final() should be called instead
	   of multipart_end().

       multipart_final()
	     multipart_final()

	   End all parts.  You should call multipart_final() rather than
	   multipart_end() at the end of the last part of the multipart
	   document.

       Users interested	in server push applications should also	have a look at
       the CGI::Push module.

Avoiding Denial	of Service Attacks
       A potential problem with	CGI.pm is that,	by default, it attempts	to
       process form POSTings no	matter how large they are.  A wily hacker
       could attack your site by sending a CGI script a	huge POST of many
       megabytes.  CGI.pm will attempt to read the entire POST into a
       variable, growing hugely	in size	until it runs out of memory.  While
       the script attempts to allocate the memory the system may slow down
       dramatically.  This is a	form of	denial of service attack.

       Another possible	attack is for the remote user to force CGI.pm to
       accept a	huge file upload.  CGI.pm will accept the upload and store it
       in a temporary directory	even if	your script doesn't expect to receive
       an uploaded file.  CGI.pm will delete the file automatically when it
       terminates, but in the meantime the remote user may have	filled up the
       server's	disk space, causing problems for other programs.

       The best	way to avoid denial of service attacks is to limit the amount
       of memory, CPU time and disk space that CGI scripts can use.  Some Web
       servers come with built-in facilities to	accomplish this. In other
       cases, you can use the shell limit or ulimit commands to	put ceilings
       on CGI resource usage.

       CGI.pm also has some simple built-in protections	against	denial of
       service attacks,	but you	must activate them before you can use them.
       These take the form of two global variables in the CGI name space:

       $CGI::POST_MAX
	   If set to a non-negative integer, this variable puts	a ceiling on
	   the size of POSTings, in bytes.  If CGI.pm detects a	POST that is
	   greater than	the ceiling, it	will immediately exit with an error
	   message.  This value	will affect both ordinary POSTs	and multipart
	   POSTs, meaning that it limits the maximum size of file uploads as
	   well.  You should set this to a reasonably high value, such as 1
	   megabyte.

       $CGI::DISABLE_UPLOADS
	   If set to a non-zero	value, this will disable file uploads
	   completely.	Other fill-out form values will	work as	usual.

       You can use these variables in either of	two ways.

       1. On a script-by-script	basis
	   Set the variable at the top of the script, right after the "use"
	   statement:

	       use CGI qw/:standard/;
	       use CGI::Carp 'fatalsToBrowser';
	       $CGI::POST_MAX=1024 * 100;  # max 100K posts
	       $CGI::DISABLE_UPLOADS = 1;  # no	uploads

       2. Globally for all scripts
	   Open	up CGI.pm, find	the definitions	for $POST_MAX and
	   $DISABLE_UPLOADS, and set them to the desired values.  You'll find
	   them	towards	the top	of the file in a subroutine named
	   initialize_globals().

       An attempt to send a POST larger	than $POST_MAX bytes will cause
       param() to return an empty CGI parameter	list.  You can test for	this
       event by	checking cgi_error(), either after you create the CGI object
       or, if you are using the	function-oriented interface, call <param()>
       for the first time.  If the POST	was intercepted, then cgi_error() will
       return the message "413 POST too	large".

       This error message is actually defined by the HTTP protocol, and	is
       designed	to be returned to the browser as the CGI script's status
	code.  For example:

	  $uploaded_file = param('upload');
	  if (!$uploaded_file && cgi_error()) {
	     print header(-status=>cgi_error());
	     exit 0;
	  }

       However it isn't	clear that any browser currently knows what to do with
       this status code.  It might be better just to create an HTML page that
       warns the user of the problem.

COMPATIBILITY WITH CGI-LIB.PL
       To make it easier to port existing programs that	use cgi-lib.pl the
       compatibility routine "ReadParse" is provided.  Porting is simple:

       OLD VERSION

	   require "cgi-lib.pl";
	   &ReadParse;
	   print "The value of the antique is $in{antique}.\n";

       NEW VERSION

	   use CGI;
	   CGI::ReadParse();
	   print "The value of the antique is $in{antique}.\n";

       CGI.pm's	ReadParse() routine creates a tied variable named %in, which
       can be accessed to obtain the query variables.  Like ReadParse, you can
       also provide your own variable.	Infrequently used features of
       ReadParse, such as the creation of @in and $in variables, are not
       supported.

       Once you	use ReadParse, you can retrieve	the query object itself	this
       way:

	   $q =	$in{CGI};
	   print $q->textfield(-name=>'wow',
		   -value=>'does this really work?');

       This allows you to start	using the more interesting features of CGI.pm
       without rewriting your old scripts from scratch.

       An even simpler way to mix cgi-lib calls	with CGI.pm calls is to	import
       both the	":cgi-lib" and ":standard" method:

	use CGI	qw(:cgi-lib :standard);
	&ReadParse;
	print "The price of your purchase is $in{price}.\n";
	print textfield(-name=>'price',	-default=>'$1.99');

   Cgi-lib functions that are available	in CGI.pm
       In compatibility	mode, the following cgi-lib.pl functions are available
       for your	use:

	ReadParse()
	PrintHeader()
	HtmlTop()
	HtmlBot()
	SplitParam()
	MethGet()
	MethPost()

   Cgi-lib functions that are not available in CGI.pm
	 * Extended form of ReadParse()
	   The extended	form of	ReadParse() that provides for file upload
	   spooling, is	not available.

	 * MyBaseURL()
	   This	function is not	available.  Use	CGI.pm's url() method instead.

	 * MyFullURL()
	   This	function is not	available.  Use	CGI.pm's self_url() method
	   instead.

	 * CgiError(), CgiDie()
	   These functions are not supported.  Look at CGI::Carp for the way I
	   prefer to handle error messages.

	 * PrintVariables()
	   This	function is not	available.  To achieve the same	effect,
	      just print out the CGI object:

	      use CGI qw(:standard);
	      $q = CGI->new;
	      print h1("The Variables Are"),$q;

	 * PrintEnv()
	   This	function is not	available. You'll have to roll your own	if you really need it.

AUTHOR INFORMATION
       The CGI.pm distribution is copyright 1995-2007, Lincoln D. Stein. It is
       distributed under GPL and the Artistic License 2.0. It is currently
       maintained by Mark Stosberg with	help from many contributors.

       Address bug reports and comments	to:
       https://rt.cpan.org/Public/Dist/Display.html?Queue=CGI.pm When sending
       bug reports, please provide the version of CGI.pm, the version of Perl,
       the name	and version of your Web	server,	and the	name and version of
       the operating system you	are using.  If the problem is even remotely
       browser dependent, please provide information about the affected
       browsers	as well.

CREDITS
       Thanks very much	to:

       Matt Heffron (heffron@falstaff.css.beckman.com)
       James Taylor (james.taylor@srs.gov)
       Scott Anguish <sanguish@digifix.com>
       Mike Jewell (mlj3u@virginia.edu)
       Timothy Shimmin (tes@kbs.citri.edu.au)
       Joergen Haegg (jh@axis.se)
       Laurent Delfosse	(delfosse@delfosse.com)
       Richard Resnick (applepi1@aol.com)
       Craig Bishop (csb@barwonwater.vic.gov.au)
       Tony Curtis (tc@vcpc.univie.ac.at)
       Tim Bunce (Tim.Bunce@ig.co.uk)
       Tom Christiansen	(tchrist@convex.com)
       Andreas Koenig (k@franz.ww.TU-Berlin.DE)
       Tim MacKenzie (Tim.MacKenzie@fulcrum.com.au)
       Kevin B.	Hendricks (kbhend@dogwood.tyler.wm.edu)
       Stephen Dahmen (joyfire@inxpress.net)
       Ed Jordan (ed@fidalgo.net)
       David Alan Pisoni (david@cnation.com)
       Doug MacEachern (dougm@opengroup.org)
       Robin Houston (robin@oneworld.org)
       ...and many many	more...
	   for suggestions and bug fixes.

A COMPLETE EXAMPLE OF A	SIMPLE FORM-BASED SCRIPT
	       #!/usr/local/bin/perl

	       use CGI ':standard';

	       print header;
	       print start_html("Example CGI.pm	Form");
	       print "<h1> Example CGI.pm Form</h1>\n";
	       print_prompt();
	       do_work();
	       print_tail();
	       print end_html;

	       sub print_prompt	{
		  print	start_form;
		  print	"<em>What's your name?</em><br>";
		  print	textfield('name');
		  print	checkbox('Not my real name');

		  print	"<p><em>Where can you find English Sparrows?</em><br>";
		  print	checkbox_group(
					-name=>'Sparrow	locations',
					-values=>[England,France,Spain,Asia,Hoboken],
					-linebreak=>'yes',
					-defaults=>[England,Asia]);

		  print	"<p><em>How far	can they fly?</em><br>",
		       radio_group(
			       -name=>'how far',
			       -values=>['10 ft','1 mile','10 miles','real far'],
			       -default=>'1 mile');

		  print	"<p><em>What's your favorite color?</em>  ";
		  print	popup_menu(-name=>'Color',
					   -values=>['black','brown','red','yellow'],
					   -default=>'red');

		  print	hidden('Reference','Monty Python and the Holy Grail');

		  print	"<p><em>What have you got there?</em><br>";
		  print	scrolling_list(
				-name=>'possessions',
				-values=>['A Coconut','A Grail','An Icon',
					  'A Sword','A Ticket'],
				-size=>5,
				-multiple=>'true');

		  print	"<p><em>Any parting comments?</em><br>";
		  print	textarea(-name=>'Comments',
					 -rows=>10,
					 -columns=>50);

		  print	"<p>",reset;
		  print	submit('Action','Shout');
		  print	submit('Action','Scream');
		  print	end_form;
		  print	"<hr>\n";
	       }

	       sub do_work {

		  print	"<h2>Here are the current settings in this form</h2>";

		  for my $key (param) {
		     print "<strong>$key</strong> -> ";
		     my	@values	= param($key);
		     print join(", ",@values),"<br>\n";
		 }
	       }

	       sub print_tail {
		  print	<<END;
	       <hr>
	       <address>Lincoln	D. Stein</address><br>
	       <a href="/">Home	Page</a>
	       END
	       }

BUGS
       Please report them.

SEE ALSO
       CGI::Carp - provides a Carp implementation tailored to the CGI
       environment.

       CGI::Fast - supports running CGI	applications under FastCGI

       CGI::Pretty - pretty prints HTML	generated by CGI.pm (with a
       performance penalty)

POD ERRORS
       Hey! The	above document had some	coding errors, which are explained
       below:

       Around line 5513:
	   Expected text after =item, not a number

       Around line 5517:
	   Expected text after =item, not a number

       Around line 5521:
	   Expected text after =item, not a number

       Around line 6083:
	   Expected text after =item, not a number

       Around line 6087:
	   Expected text after =item, not a number

       Around line 6092:
	   Expected text after =item, not a number

       Around line 6097:
	   Expected text after =item, not a number

       Around line 6166:
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perl v5.24.1			  2012-11-14				CGI(3)

NAME | SYNOPSIS | DESCRIPTION | GENERATING DYNAMIC DOCUMENTS | CREATING STANDARD HTML ELEMENTS: | CREATING FILL-OUT FORMS: | HTTP COOKIES | WORKING WITH FRAMES | SUPPORT FOR JAVASCRIPT | LIMITED SUPPORT FOR CASCADING STYLE SHEETS | DEBUGGING | FETCHING ENVIRONMENT VARIABLES | USING NPH SCRIPTS | Server Push | Avoiding Denial of Service Attacks | COMPATIBILITY WITH CGI-LIB.PL | AUTHOR INFORMATION | CREDITS | A COMPLETE EXAMPLE OF A SIMPLE FORM-BASED SCRIPT | BUGS | SEE ALSO | POD ERRORS

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